This patch set enables the Intel flexible return and event delivery
(FRED) architecture with KVM VMX to allow guests to utilize FRED.
The FRED architecture defines simple new transitions that change
privilege level (ring transitions). The FRED architecture was
designed with the following goals:
1) Improve overall performance and response time by replacing event
delivery through the interrupt descriptor table (IDT event
delivery) and event return by the IRET instruction with lower
latency transitions.
2) Improve software robustness by ensuring that event delivery
establishes the full supervisor context and that event return
establishes the full user context.
The new transitions defined by the FRED architecture are FRED event
delivery and, for returning from events, two FRED return instructions.
FRED event delivery can effect a transition from ring 3 to ring 0, but
it is used also to deliver events incident to ring 0. One FRED
instruction (ERETU) effects a return from ring 0 to ring 3, while the
other (ERETS) returns while remaining in ring 0. Collectively, FRED
event delivery and the FRED return instructions are FRED transitions.
Intel VMX architecture is extended to run FRED guests, and the major
changes are:
1) New VMCS fields for FRED context management, which includes two new
event data VMCS fields, eight new guest FRED context VMCS fields and
eight new host FRED context VMCS fields.
2) VMX nested-exception support for proper virtualization of stack
levels introduced with FRED architecture.
Search for the latest FRED spec in most search engines with this search
pattern:
site:intel.com FRED (flexible return and event delivery) specification
As the native FRED patches are committed in the tip tree "x86/fred"
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=x86/fred,
and we have received a good amount of review comments for v1, it's time
to send out v2 based on this branch for further help from the community.
Patch 1-2 are cleanups to VMX basic and misc MSRs, which were sent
out earlier as a preparation for FRED changes:
https://lore.kernel.org/kvm/[email protected]/T/#u
Patch 3-15 add FRED support to VMX.
Patch 16-21 add FRED support to nested VMX.
Patch 22 exposes FRED and its baseline features to KVM guests.
Patch 23-25 add FRED selftests.
There is also a counterpart qemu patch set for FRED at:
https://lore.kernel.org/qemu-devel/[email protected]/T/,
which works with this patch set to allow KVM to run FRED guests.
Changes since v1:
* Always load the secondary VM exit controls (Sean Christopherson).
* Remove FRED VM entry/exit controls consistency checks in
setup_vmcs_config() (Sean Christopherson).
* Clear FRED VM entry/exit controls if FRED is not enumerated (Chao Gao).
* Use guest_can_use() to trace FRED enumeration in a vcpu (Chao Gao).
* Enable FRED MSRs intercept if FRED is no longer enumerated in CPUID
(Chao Gao).
* Move guest FRED states init into __vmx_vcpu_reset() (Chao Gao).
* Don't use guest_cpuid_has() in vmx_prepare_switch_to_{host,guest}(),
which are called from IRQ-disabled context (Chao Gao).
* Reset msr_guest_fred_rsp0 in __vmx_vcpu_reset() (Chao Gao).
* Fail host requested FRED MSRs access if KVM cannot virtualize FRED
(Chao Gao).
* Handle the case FRED MSRs are valid but KVM cannot virtualize FRED
(Chao Gao).
* Add sanity checks when writing to FRED MSRs.
* Explain why it is ok to only check CR4.FRED in kvm_is_fred_enabled()
(Chao Gao).
* Document event data should be equal to CR2/DR6/IA32_XFD_ERR instead
of using WARN_ON() (Chao Gao).
* Zero event data if a #NM was not caused by extended feature disable
(Chao Gao).
* Set the nested flag when there is an original interrupt (Chao Gao).
* Dump guest FRED states only if guest has FRED enabled (Nikolay Borisov).
* Add a prerequisite to SHADOW_FIELD_R[OW] macros
* Remove hyperv TLFS related changes (Jeremi Piotrowski).
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() to decouple
KVM's capability to virtualize a feature and host's enabling of a
feature (Chao Gao).
Xin Li (25):
KVM: VMX: Cleanup VMX basic information defines and usages
KVM: VMX: Cleanup VMX misc information defines and usages
KVM: VMX: Add support for the secondary VM exit controls
KVM: x86: Mark CR4.FRED as not reserved
KVM: VMX: Initialize FRED VM entry/exit controls in vmcs_config
KVM: VMX: Defer enabling FRED MSRs save/load until after set CPUID
KVM: VMX: Set intercept for FRED MSRs
KVM: VMX: Initialize VMCS FRED fields
KVM: VMX: Switch FRED RSP0 between host and guest
KVM: VMX: Add support for FRED context save/restore
KVM: x86: Add kvm_is_fred_enabled()
KVM: VMX: Handle FRED event data
KVM: VMX: Handle VMX nested exception for FRED
KVM: VMX: Disable FRED if FRED consistency checks fail
KVM: VMX: Dump FRED context in dump_vmcs()
KVM: VMX: Invoke vmx_set_cpu_caps() before nested setup
KVM: nVMX: Add support for the secondary VM exit controls
KVM: nVMX: Add a prerequisite to SHADOW_FIELD_R[OW] macros
KVM: nVMX: Add FRED VMCS fields
KVM: nVMX: Add support for VMX FRED controls
KVM: nVMX: Add VMCS FRED states checking
KVM: x86: Allow FRED/LKGS/WRMSRNS to be exposed to guests
KVM: selftests: Run debug_regs test with FRED enabled
KVM: selftests: Add a new VM guest mode to run user level code
KVM: selftests: Add fred exception tests
Documentation/virt/kvm/x86/nested-vmx.rst | 19 +
arch/x86/include/asm/kvm_host.h | 8 +-
arch/x86/include/asm/msr-index.h | 15 +-
arch/x86/include/asm/vmx.h | 59 ++-
arch/x86/kvm/cpuid.c | 4 +-
arch/x86/kvm/governed_features.h | 1 +
arch/x86/kvm/kvm_cache_regs.h | 17 +
arch/x86/kvm/svm/svm.c | 4 +-
arch/x86/kvm/vmx/capabilities.h | 30 +-
arch/x86/kvm/vmx/nested.c | 329 ++++++++++++---
arch/x86/kvm/vmx/nested.h | 2 +-
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmcs12.c | 19 +
arch/x86/kvm/vmx/vmcs12.h | 38 ++
arch/x86/kvm/vmx/vmcs_shadow_fields.h | 80 ++--
arch/x86/kvm/vmx/vmx.c | 385 +++++++++++++++---
arch/x86/kvm/vmx/vmx.h | 15 +-
arch/x86/kvm/x86.c | 103 ++++-
arch/x86/kvm/x86.h | 5 +-
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/kvm_util_base.h | 1 +
.../selftests/kvm/include/x86_64/processor.h | 36 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 5 +-
.../selftests/kvm/lib/x86_64/processor.c | 15 +-
tools/testing/selftests/kvm/lib/x86_64/vmx.c | 4 +-
.../testing/selftests/kvm/x86_64/debug_regs.c | 50 ++-
.../testing/selftests/kvm/x86_64/fred_test.c | 297 ++++++++++++++
27 files changed, 1320 insertions(+), 223 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/fred_test.c
base-commit: e13841907b8fda0ae0ce1ec03684665f578416a8
--
2.43.0
Define VMX basic information fields with BIT_ULL()/GENMASK_ULL(), and
replace hardcoded VMX basic numbers with these field macros.
Save the full/raw value of MSR_IA32_VMX_BASIC in the global vmcs_config
as type u64 to get rid of the hi/lo crud, and then use VMX_BASIC helpers
to extract info as needed.
VMX_EPTP_MT_{WB,UC} values 0x6 and 0x0 are generic x86 memory type
values, no need to prefix them with VMX_EPTP_.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
Acked-by: Kai Huang <[email protected]>
---
Changes since v4:
* Do not split VMX_BASIC bit definitions across multiple files (Kai
Huang).
* Put some words to the changelog to justify changes around memory
type macros (Kai Huang).
* Remove a leftover ';' (Kai Huang).
Changes since v3:
* Remove vmx_basic_vmcs_basic_cap() (Kai Huang).
* Add 2 macros VMX_BASIC_VMCS12_SIZE and VMX_BASIC_MEM_TYPE_WB to
avoid keeping 2 their bit shift macros (Kai Huang).
Changes since v2:
* Simply save the full/raw value of MSR_IA32_VMX_BASIC in the global
vmcs_config, and then use the helpers to extract info from it as
needed (Sean Christopherson).
* Move all VMX_MISC related changes to the second patch (Kai Huang).
* Commonize memory type definitions used in the VMX files, as memory
types are architectural.
Changes since v1:
* Don't add field shift macros unless it's really needed, extra layer
of indirect makes it harder to read (Sean Christopherson).
* Add a static_assert() to ensure that VMX_BASIC_FEATURES_MASK doesn't
overlap with VMX_BASIC_RESERVED_BITS (Sean Christopherson).
* read MSR_IA32_VMX_BASIC into an u64 rather than 2 u32 (Sean
Christopherson).
* Add 2 new functions for extracting fields from VMX basic (Sean
Christopherson).
* Drop the tools header update (Sean Christopherson).
* Move VMX basic field macros to arch/x86/include/asm/vmx.h.
---
arch/x86/include/asm/msr-index.h | 9 ---------
arch/x86/include/asm/vmx.h | 18 ++++++++++++++++--
arch/x86/kvm/vmx/capabilities.h | 6 ++----
arch/x86/kvm/vmx/nested.c | 31 ++++++++++++++++++++-----------
arch/x86/kvm/vmx/vmx.c | 24 ++++++++++--------------
5 files changed, 48 insertions(+), 40 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 1f9dc9bd13eb..e8af4cf01e89 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1113,15 +1113,6 @@
#define MSR_IA32_VMX_VMFUNC 0x00000491
#define MSR_IA32_VMX_PROCBASED_CTLS3 0x00000492
-/* VMX_BASIC bits and bitmasks */
-#define VMX_BASIC_VMCS_SIZE_SHIFT 32
-#define VMX_BASIC_TRUE_CTLS (1ULL << 55)
-#define VMX_BASIC_64 0x0001000000000000LLU
-#define VMX_BASIC_MEM_TYPE_SHIFT 50
-#define VMX_BASIC_MEM_TYPE_MASK 0x003c000000000000LLU
-#define VMX_BASIC_MEM_TYPE_WB 6LLU
-#define VMX_BASIC_INOUT 0x0040000000000000LLU
-
/* Resctrl MSRs: */
/* - Intel: */
#define MSR_IA32_L3_QOS_CFG 0xc81
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 4dba17363008..353538b79ce5 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -121,6 +121,17 @@
#define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff
+/* x86 memory types, explicitly used in VMX only */
+#define MEM_TYPE_WB 0x6ULL
+#define MEM_TYPE_UC 0x0ULL
+
+/* VMX_BASIC bits */
+#define VMX_BASIC_32BIT_PHYS_ADDR_ONLY BIT_ULL(48)
+#define VMX_BASIC_DUAL_MONITOR_TREATMENT BIT_ULL(49)
+#define VMX_BASIC_INOUT BIT_ULL(54)
+#define VMX_BASIC_TRUE_CTLS BIT_ULL(55)
+
+
#define VMX_MISC_PREEMPTION_TIMER_RATE_MASK 0x0000001f
#define VMX_MISC_SAVE_EFER_LMA 0x00000020
#define VMX_MISC_ACTIVITY_HLT 0x00000040
@@ -144,6 +155,11 @@ static inline u32 vmx_basic_vmcs_size(u64 vmx_basic)
return (vmx_basic & GENMASK_ULL(44, 32)) >> 32;
}
+static inline u32 vmx_basic_vmcs_mem_type(u64 vmx_basic)
+{
+ return (vmx_basic & GENMASK_ULL(53, 50)) >> 50;
+}
+
static inline int vmx_misc_preemption_timer_rate(u64 vmx_misc)
{
return vmx_misc & VMX_MISC_PREEMPTION_TIMER_RATE_MASK;
@@ -506,8 +522,6 @@ enum vmcs_field {
#define VMX_EPTP_PWL_5 0x20ull
#define VMX_EPTP_AD_ENABLE_BIT (1ull << 6)
#define VMX_EPTP_MT_MASK 0x7ull
-#define VMX_EPTP_MT_WB 0x6ull
-#define VMX_EPTP_MT_UC 0x0ull
#define VMX_EPT_READABLE_MASK 0x1ull
#define VMX_EPT_WRITABLE_MASK 0x2ull
#define VMX_EPT_EXECUTABLE_MASK 0x4ull
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 41a4533f9989..86ce8bb96bed 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -54,9 +54,7 @@ struct nested_vmx_msrs {
};
struct vmcs_config {
- int size;
- u32 basic_cap;
- u32 revision_id;
+ u64 basic;
u32 pin_based_exec_ctrl;
u32 cpu_based_exec_ctrl;
u32 cpu_based_2nd_exec_ctrl;
@@ -76,7 +74,7 @@ extern struct vmx_capability vmx_capability __ro_after_init;
static inline bool cpu_has_vmx_basic_inout(void)
{
- return (((u64)vmcs_config.basic_cap << 32) & VMX_BASIC_INOUT);
+ return vmcs_config.basic & VMX_BASIC_INOUT;
}
static inline bool cpu_has_virtual_nmis(void)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 6329a306856b..14d0167825dd 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1226,23 +1226,29 @@ static bool is_bitwise_subset(u64 superset, u64 subset, u64 mask)
return (superset | subset) == superset;
}
+#define VMX_BASIC_FEATURES_MASK \
+ (VMX_BASIC_DUAL_MONITOR_TREATMENT | \
+ VMX_BASIC_INOUT | \
+ VMX_BASIC_TRUE_CTLS)
+
+#define VMX_BASIC_RESERVED_BITS \
+ (GENMASK_ULL(63, 56) | GENMASK_ULL(47, 45) | BIT_ULL(31))
+
static int vmx_restore_vmx_basic(struct vcpu_vmx *vmx, u64 data)
{
- const u64 feature_and_reserved =
- /* feature (except bit 48; see below) */
- BIT_ULL(49) | BIT_ULL(54) | BIT_ULL(55) |
- /* reserved */
- BIT_ULL(31) | GENMASK_ULL(47, 45) | GENMASK_ULL(63, 56);
u64 vmx_basic = vmcs_config.nested.basic;
- if (!is_bitwise_subset(vmx_basic, data, feature_and_reserved))
+ static_assert(!(VMX_BASIC_FEATURES_MASK & VMX_BASIC_RESERVED_BITS));
+
+ if (!is_bitwise_subset(vmx_basic, data,
+ VMX_BASIC_FEATURES_MASK | VMX_BASIC_RESERVED_BITS))
return -EINVAL;
/*
* KVM does not emulate a version of VMX that constrains physical
* addresses of VMX structures (e.g. VMCS) to 32-bits.
*/
- if (data & BIT_ULL(48))
+ if (data & VMX_BASIC_32BIT_PHYS_ADDR_ONLY)
return -EINVAL;
if (vmx_basic_vmcs_revision_id(vmx_basic) !=
@@ -2726,11 +2732,11 @@ static bool nested_vmx_check_eptp(struct kvm_vcpu *vcpu, u64 new_eptp)
/* Check for memory type validity */
switch (new_eptp & VMX_EPTP_MT_MASK) {
- case VMX_EPTP_MT_UC:
+ case MEM_TYPE_UC:
if (CC(!(vmx->nested.msrs.ept_caps & VMX_EPTP_UC_BIT)))
return false;
break;
- case VMX_EPTP_MT_WB:
+ case MEM_TYPE_WB:
if (CC(!(vmx->nested.msrs.ept_caps & VMX_EPTP_WB_BIT)))
return false;
break;
@@ -6994,6 +7000,9 @@ static void nested_vmx_setup_misc_data(struct vmcs_config *vmcs_conf,
msrs->misc_high = 0;
}
+#define VMX_BSAIC_VMCS12_SIZE ((u64)VMCS12_SIZE << 32)
+#define VMX_BASIC_MEM_TYPE_WB (MEM_TYPE_WB << 50)
+
static void nested_vmx_setup_basic(struct nested_vmx_msrs *msrs)
{
/*
@@ -7005,8 +7014,8 @@ static void nested_vmx_setup_basic(struct nested_vmx_msrs *msrs)
msrs->basic =
VMCS12_REVISION |
VMX_BASIC_TRUE_CTLS |
- ((u64)VMCS12_SIZE << VMX_BASIC_VMCS_SIZE_SHIFT) |
- (VMX_BASIC_MEM_TYPE_WB << VMX_BASIC_MEM_TYPE_SHIFT);
+ VMX_BSAIC_VMCS12_SIZE |
+ VMX_BASIC_MEM_TYPE_WB;
if (cpu_has_vmx_basic_inout())
msrs->basic |= VMX_BASIC_INOUT;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cce92f701dee..a16b3de01e3f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2564,13 +2564,13 @@ static u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
struct vmx_capability *vmx_cap)
{
- u32 vmx_msr_low, vmx_msr_high;
u32 _pin_based_exec_control = 0;
u32 _cpu_based_exec_control = 0;
u32 _cpu_based_2nd_exec_control = 0;
u64 _cpu_based_3rd_exec_control = 0;
u32 _vmexit_control = 0;
u32 _vmentry_control = 0;
+ u64 basic_msr;
u64 misc_msr;
int i;
@@ -2689,29 +2689,25 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
_vmexit_control &= ~x_ctrl;
}
- rdmsr(MSR_IA32_VMX_BASIC, vmx_msr_low, vmx_msr_high);
+ rdmsrl(MSR_IA32_VMX_BASIC, basic_msr);
/* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
- if ((vmx_msr_high & 0x1fff) > PAGE_SIZE)
+ if ((vmx_basic_vmcs_size(basic_msr) > PAGE_SIZE))
return -EIO;
#ifdef CONFIG_X86_64
/* IA-32 SDM Vol 3B: 64-bit CPUs always have VMX_BASIC_MSR[48]==0. */
- if (vmx_msr_high & (1u<<16))
+ if (basic_msr & VMX_BASIC_32BIT_PHYS_ADDR_ONLY)
return -EIO;
#endif
/* Require Write-Back (WB) memory type for VMCS accesses. */
- if (((vmx_msr_high >> 18) & 15) != 6)
+ if (vmx_basic_vmcs_mem_type(basic_msr) != MEM_TYPE_WB)
return -EIO;
rdmsrl(MSR_IA32_VMX_MISC, misc_msr);
- vmcs_conf->size = vmx_msr_high & 0x1fff;
- vmcs_conf->basic_cap = vmx_msr_high & ~0x1fff;
-
- vmcs_conf->revision_id = vmx_msr_low;
-
+ vmcs_conf->basic = basic_msr;
vmcs_conf->pin_based_exec_ctrl = _pin_based_exec_control;
vmcs_conf->cpu_based_exec_ctrl = _cpu_based_exec_control;
vmcs_conf->cpu_based_2nd_exec_ctrl = _cpu_based_2nd_exec_control;
@@ -2861,13 +2857,13 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags)
if (!pages)
return NULL;
vmcs = page_address(pages);
- memset(vmcs, 0, vmcs_config.size);
+ memset(vmcs, 0, vmx_basic_vmcs_size(vmcs_config.basic));
/* KVM supports Enlightened VMCS v1 only */
if (kvm_is_using_evmcs())
vmcs->hdr.revision_id = KVM_EVMCS_VERSION;
else
- vmcs->hdr.revision_id = vmcs_config.revision_id;
+ vmcs->hdr.revision_id = vmx_basic_vmcs_revision_id(vmcs_config.basic);
if (shadow)
vmcs->hdr.shadow_vmcs = 1;
@@ -2960,7 +2956,7 @@ static __init int alloc_kvm_area(void)
* physical CPU.
*/
if (kvm_is_using_evmcs())
- vmcs->hdr.revision_id = vmcs_config.revision_id;
+ vmcs->hdr.revision_id = vmx_basic_vmcs_revision_id(vmcs_config.basic);
per_cpu(vmxarea, cpu) = vmcs;
}
@@ -3362,7 +3358,7 @@ static int vmx_get_max_ept_level(void)
u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level)
{
- u64 eptp = VMX_EPTP_MT_WB;
+ u64 eptp = MEM_TYPE_WB;
eptp |= (root_level == 5) ? VMX_EPTP_PWL_5 : VMX_EPTP_PWL_4;
--
2.43.0
The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when a guest
enumerates FRED, otherwise it is still a reserved bit.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/x86.h | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b5b2d0fde579..0d88873eba63 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -134,7 +134,7 @@
| X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
| X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
| X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP \
- | X86_CR4_LAM_SUP))
+ | X86_CR4_LAM_SUP | X86_CR4_FRED))
#define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 2f7e19166658..9a52016ebf5a 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -532,6 +532,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type);
__reserved_bits |= X86_CR4_PCIDE; \
if (!__cpu_has(__c, X86_FEATURE_LAM)) \
__reserved_bits |= X86_CR4_LAM_SUP; \
+ if (!__cpu_has(__c, X86_FEATURE_FRED)) \
+ __reserved_bits |= X86_CR4_FRED; \
__reserved_bits; \
})
--
2.43.0
Enable the secondary VM exit controls to prepare for FRED enabling.
The activation of the secondary VM exit controls is off now, and it
will be switched on when a VMX feature needing it is enabled.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Always load the secondary VM exit controls (Sean Christopherson).
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/include/asm/vmx.h | 3 +++
arch/x86/kvm/vmx/capabilities.h | 9 ++++++++-
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmx.c | 17 ++++++++++++++++-
arch/x86/kvm/vmx/vmx.h | 7 ++++++-
6 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 4fa2b3dd743e..ab9ec10a3fff 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1112,6 +1112,7 @@
#define MSR_IA32_VMX_TRUE_ENTRY_CTLS 0x00000490
#define MSR_IA32_VMX_VMFUNC 0x00000491
#define MSR_IA32_VMX_PROCBASED_CTLS3 0x00000492
+#define MSR_IA32_VMX_EXIT_CTLS2 0x00000493
/* Resctrl MSRs: */
/* - Intel: */
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 76518e21c54d..272af2004111 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -105,6 +105,7 @@
#define VM_EXIT_CLEAR_BNDCFGS 0x00800000
#define VM_EXIT_PT_CONCEAL_PIP 0x01000000
#define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000
+#define VM_EXIT_ACTIVATE_SECONDARY_CONTROLS 0x80000000
#define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff
@@ -250,6 +251,8 @@ enum vmcs_field {
TERTIARY_VM_EXEC_CONTROL_HIGH = 0x00002035,
PID_POINTER_TABLE = 0x00002042,
PID_POINTER_TABLE_HIGH = 0x00002043,
+ SECONDARY_VM_EXIT_CONTROLS = 0x00002044,
+ SECONDARY_VM_EXIT_CONTROLS_HIGH = 0x00002045,
GUEST_PHYSICAL_ADDRESS = 0x00002400,
GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
VMCS_LINK_POINTER = 0x00002800,
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index cb6588238f46..e8f3ad0f79ee 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -59,8 +59,9 @@ struct vmcs_config {
u32 cpu_based_exec_ctrl;
u32 cpu_based_2nd_exec_ctrl;
u64 cpu_based_3rd_exec_ctrl;
- u32 vmexit_ctrl;
u32 vmentry_ctrl;
+ u32 vmexit_ctrl;
+ u64 secondary_vmexit_ctrl;
u64 misc;
struct nested_vmx_msrs nested;
};
@@ -136,6 +137,12 @@ static inline bool cpu_has_tertiary_exec_ctrls(void)
CPU_BASED_ACTIVATE_TERTIARY_CONTROLS;
}
+static inline bool cpu_has_secondary_vmexit_ctrls(void)
+{
+ return vmcs_config.vmexit_ctrl &
+ VM_EXIT_ACTIVATE_SECONDARY_CONTROLS;
+}
+
static inline bool cpu_has_vmx_virtualize_apic_accesses(void)
{
return vmcs_config.cpu_based_2nd_exec_ctrl &
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
index 7c1996b433e2..7d45a6504200 100644
--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -47,6 +47,7 @@ struct vmcs_host_state {
struct vmcs_controls_shadow {
u32 vm_entry;
u32 vm_exit;
+ u64 secondary_vm_exit;
u32 pin;
u32 exec;
u32 secondary_exec;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 581967d20659..4023474ea002 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2569,6 +2569,7 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
u32 _cpu_based_2nd_exec_control = 0;
u64 _cpu_based_3rd_exec_control = 0;
u32 _vmexit_control = 0;
+ u64 _secondary_vmexit_control = 0;
u32 _vmentry_control = 0;
u64 basic_msr;
int i;
@@ -2688,6 +2689,11 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
_vmexit_control &= ~x_ctrl;
}
+ if (_vmexit_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+ _secondary_vmexit_control =
+ adjust_vmx_controls64(KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS,
+ MSR_IA32_VMX_EXIT_CTLS2);
+
rdmsrl(MSR_IA32_VMX_BASIC, basic_msr);
/* IA-32 SDM Vol 3B: VMCS size is never greater than 4kB. */
@@ -2709,8 +2715,9 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
vmcs_conf->cpu_based_exec_ctrl = _cpu_based_exec_control;
vmcs_conf->cpu_based_2nd_exec_ctrl = _cpu_based_2nd_exec_control;
vmcs_conf->cpu_based_3rd_exec_ctrl = _cpu_based_3rd_exec_control;
- vmcs_conf->vmexit_ctrl = _vmexit_control;
vmcs_conf->vmentry_ctrl = _vmentry_control;
+ vmcs_conf->vmexit_ctrl = _vmexit_control;
+ vmcs_conf->secondary_vmexit_ctrl = _secondary_vmexit_control;
rdmsrl(MSR_IA32_VMX_MISC, vmcs_conf->misc);
@@ -4421,6 +4428,11 @@ static u32 vmx_vmexit_ctrl(void)
~(VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL | VM_EXIT_LOAD_IA32_EFER);
}
+static u64 vmx_secondary_vmexit_ctrl(void)
+{
+ return vmcs_config.secondary_vmexit_ctrl;
+}
+
static void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -4766,6 +4778,9 @@ static void init_vmcs(struct vcpu_vmx *vmx)
vm_exit_controls_set(vmx, vmx_vmexit_ctrl());
+ if (cpu_has_secondary_vmexit_ctrls())
+ secondary_vm_exit_controls_set(vmx, vmx_secondary_vmexit_ctrl());
+
/* 22.2.1, 20.8.1 */
vm_entry_controls_set(vmx, vmx_vmentry_ctrl());
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index e3b0985bb74a..f470eeb2a5c8 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -506,7 +506,11 @@ static inline u8 vmx_get_rvi(void)
VM_EXIT_LOAD_IA32_EFER | \
VM_EXIT_CLEAR_BNDCFGS | \
VM_EXIT_PT_CONCEAL_PIP | \
- VM_EXIT_CLEAR_IA32_RTIT_CTL)
+ VM_EXIT_CLEAR_IA32_RTIT_CTL | \
+ VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+
+#define KVM_REQUIRED_VMX_SECONDARY_VM_EXIT_CONTROLS (0)
+#define KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS (0)
#define KVM_REQUIRED_VMX_PIN_BASED_VM_EXEC_CONTROL \
(PIN_BASED_EXT_INTR_MASK | \
@@ -610,6 +614,7 @@ static __always_inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u##b
}
BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS, 32)
BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS, 32)
+BUILD_CONTROLS_SHADOW(secondary_vm_exit, SECONDARY_VM_EXIT_CONTROLS, 64)
BUILD_CONTROLS_SHADOW(pin, PIN_BASED_VM_EXEC_CONTROL, 32)
BUILD_CONTROLS_SHADOW(exec, CPU_BASED_VM_EXEC_CONTROL, 32)
BUILD_CONTROLS_SHADOW(secondary_exec, SECONDARY_VM_EXEC_CONTROL, 32)
--
2.43.0
Add FRED MSRs to the valid passthrough MSR list and set FRED MSRs intercept
based on FRED enumeration.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Enable FRED MSRs intercept if FRED is no longer enumerated in CPUID
(Chao Gao).
---
arch/x86/kvm/vmx/vmx.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 34b6676f60d8..d58ed2d3d379 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -693,6 +693,9 @@ static bool is_valid_passthrough_msr(u32 msr)
case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 8:
/* LBR MSRs. These are handled in vmx_update_intercept_for_lbr_msrs() */
return true;
+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
+ /* FRED MSRs should be passthrough to FRED guests only */
+ return true;
}
r = possible_passthrough_msr_slot(msr) != -ENOENT;
@@ -7774,10 +7777,12 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ bool fred_enumerated;
kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
+ fred_enumerated = guest_can_use(vcpu, X86_FEATURE_FRED);
- if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
+ if (fred_enumerated) {
vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
secondary_vm_exit_controls_setbit(vmx,
SECONDARY_VM_EXIT_SAVE_IA32_FRED |
@@ -7788,6 +7793,16 @@ static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
SECONDARY_VM_EXIT_SAVE_IA32_FRED |
SECONDARY_VM_EXIT_LOAD_IA32_FRED);
}
+
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP0, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP1, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP2, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP3, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_STKLVLS, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP1, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP2, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP3, MSR_TYPE_RW, !fred_enumerated);
+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_CONFIG, MSR_TYPE_RW, !fred_enumerated);
}
static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
--
2.43.0
Clear FRED VM entry/exit controls when initializing a vCPU, and set
these controls only if FRED is enumerated after set CPUID.
FRED VM entry/exit controls need to be set to establish context
sufficient to support FRED event delivery immediately after VM entry
and exit. However it is not required to save/load FRED MSRs for
a non-FRED guest, which aren't supposed to access FRED MSRs.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Changes since v1:
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
* Clear FRED VM entry/exit controls if FRED is not enumerated (Chao Gao).
* Use guest_can_use() to trace FRED enumeration in a vcpu (Chao Gao).
---
arch/x86/kvm/governed_features.h | 1 +
arch/x86/kvm/vmx/vmx.c | 32 +++++++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/governed_features.h b/arch/x86/kvm/governed_features.h
index ad463b1ed4e4..507ca73e52e9 100644
--- a/arch/x86/kvm/governed_features.h
+++ b/arch/x86/kvm/governed_features.h
@@ -17,6 +17,7 @@ KVM_GOVERNED_X86_FEATURE(PFTHRESHOLD)
KVM_GOVERNED_X86_FEATURE(VGIF)
KVM_GOVERNED_X86_FEATURE(VNMI)
KVM_GOVERNED_X86_FEATURE(LAM)
+KVM_GOVERNED_X86_FEATURE(FRED)
#undef KVM_GOVERNED_X86_FEATURE
#undef KVM_GOVERNED_FEATURE
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4023474ea002..34b6676f60d8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4402,6 +4402,9 @@ static u32 vmx_vmentry_ctrl(void)
if (cpu_has_perf_global_ctrl_bug())
vmentry_ctrl &= ~VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
+ /* Whether to load guest FRED MSRs is deferred until after set CPUID */
+ vmentry_ctrl &= ~VM_ENTRY_LOAD_IA32_FRED;
+
return vmentry_ctrl;
}
@@ -4430,7 +4433,13 @@ static u32 vmx_vmexit_ctrl(void)
static u64 vmx_secondary_vmexit_ctrl(void)
{
- return vmcs_config.secondary_vmexit_ctrl;
+ u64 secondary_vmexit_ctrl = vmcs_config.secondary_vmexit_ctrl;
+
+ /* Whether to save/load FRED MSRs is deferred until after set CPUID */
+ secondary_vmexit_ctrl &= ~(SECONDARY_VM_EXIT_SAVE_IA32_FRED |
+ SECONDARY_VM_EXIT_LOAD_IA32_FRED);
+
+ return secondary_vmexit_ctrl;
}
static void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
@@ -7762,10 +7771,31 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
vmx->pt_desc.ctl_bitmask &= ~(0xfULL << (32 + i * 4));
}
+static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
+
+ if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
+ vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
+ secondary_vm_exit_controls_setbit(vmx,
+ SECONDARY_VM_EXIT_SAVE_IA32_FRED |
+ SECONDARY_VM_EXIT_LOAD_IA32_FRED);
+ } else {
+ vm_entry_controls_clearbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
+ secondary_vm_exit_controls_clearbit(vmx,
+ SECONDARY_VM_EXIT_SAVE_IA32_FRED |
+ SECONDARY_VM_EXIT_LOAD_IA32_FRED);
+ }
+}
+
static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ vmx_vcpu_config_fred_after_set_cpuid(vcpu);
+
/*
* XSAVES is effectively enabled if and only if XSAVE is also exposed
* to the guest. XSAVES depends on CR4.OSXSAVE, and CR4.OSXSAVE can be
--
2.43.0
Setup the global vmcs_config for FRED:
1) Add VM_ENTRY_LOAD_IA32_FRED to KVM_OPTIONAL_VMX_VM_ENTRY_CONTROLS to
have a FRED CPU load guest FRED MSRs from VMCS upon VM entry.
2) Add SECONDARY_VM_EXIT_SAVE_IA32_FRED to
KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU save
guest FRED MSRs to VMCS during VM exit.
3) add SECONDARY_VM_EXIT_LOAD_IA32_FRED to
KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU load
host FRED MSRs from VMCS during VM exit.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Remove FRED VM entry/exit controls consistency checks in
setup_vmcs_config() (Sean Christopherson).
---
arch/x86/include/asm/vmx.h | 3 +++
arch/x86/kvm/vmx/vmx.h | 7 +++++--
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 272af2004111..cb14f7e315f5 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -106,6 +106,8 @@
#define VM_EXIT_PT_CONCEAL_PIP 0x01000000
#define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000
#define VM_EXIT_ACTIVATE_SECONDARY_CONTROLS 0x80000000
+#define SECONDARY_VM_EXIT_SAVE_IA32_FRED 0x00000001
+#define SECONDARY_VM_EXIT_LOAD_IA32_FRED 0x00000002
#define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff
@@ -119,6 +121,7 @@
#define VM_ENTRY_LOAD_BNDCFGS 0x00010000
#define VM_ENTRY_PT_CONCEAL_PIP 0x00020000
#define VM_ENTRY_LOAD_IA32_RTIT_CTL 0x00040000
+#define VM_ENTRY_LOAD_IA32_FRED 0x00800000
#define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index f470eeb2a5c8..3ad52437f426 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -484,7 +484,8 @@ static inline u8 vmx_get_rvi(void)
VM_ENTRY_LOAD_IA32_EFER | \
VM_ENTRY_LOAD_BNDCFGS | \
VM_ENTRY_PT_CONCEAL_PIP | \
- VM_ENTRY_LOAD_IA32_RTIT_CTL)
+ VM_ENTRY_LOAD_IA32_RTIT_CTL | \
+ VM_ENTRY_LOAD_IA32_FRED)
#define __KVM_REQUIRED_VMX_VM_EXIT_CONTROLS \
(VM_EXIT_SAVE_DEBUG_CONTROLS | \
@@ -510,7 +511,9 @@ static inline u8 vmx_get_rvi(void)
VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
#define KVM_REQUIRED_VMX_SECONDARY_VM_EXIT_CONTROLS (0)
-#define KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS (0)
+#define KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS \
+ (SECONDARY_VM_EXIT_SAVE_IA32_FRED | \
+ SECONDARY_VM_EXIT_LOAD_IA32_FRED)
#define KVM_REQUIRED_VMX_PIN_BASED_VM_EXEC_CONTROL \
(PIN_BASED_EXT_INTR_MASK | \
--
2.43.0
Switch MSR_IA32_FRED_RSP0 between host and guest in
vmx_prepare_switch_to_{host,guest}().
MSR_IA32_FRED_RSP0 is used during ring 3 event delivery only, thus
KVM, running on ring 0, can run safely with guest FRED RSP0, i.e.,
no need to switch between host/guest FRED RSP0 during VM entry and
exit.
KVM should switch to host FRED RSP0 before returning to user level,
and switch to guest FRED RSP0 before entering guest mode.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Changes since v1:
* Don't use guest_cpuid_has() in vmx_prepare_switch_to_{host,guest}(),
which are called from IRQ-disabled context (Chao Gao).
* Reset msr_guest_fred_rsp0 in __vmx_vcpu_reset() (Chao Gao).
---
arch/x86/kvm/vmx/vmx.c | 17 +++++++++++++++++
arch/x86/kvm/vmx/vmx.h | 2 ++
2 files changed, 19 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b7b772183ee4..264378c3b784 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1337,6 +1337,16 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
}
wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
+
+ if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
+ /*
+ * MSR_IA32_FRED_RSP0 is top of task stack, which never changes.
+ * Thus it should be initialized only once.
+ */
+ if (unlikely(vmx->msr_host_fred_rsp0 == 0))
+ vmx->msr_host_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_guest_fred_rsp0);
+ }
#else
savesegment(fs, fs_sel);
savesegment(gs, gs_sel);
@@ -1381,6 +1391,11 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
invalidate_tss_limit();
#ifdef CONFIG_X86_64
wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
+
+ if (guest_can_use(&vmx->vcpu, X86_FEATURE_FRED)) {
+ vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_host_fred_rsp0);
+ }
#endif
load_fixmap_gdt(raw_smp_processor_id());
vmx->guest_state_loaded = false;
@@ -4889,6 +4904,8 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
#ifdef CONFIG_X86_64
if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmx->msr_guest_fred_rsp0 = 0;
+
vmcs_write64(GUEST_IA32_FRED_CONFIG, 0);
vmcs_write64(GUEST_IA32_FRED_RSP1, 0);
vmcs_write64(GUEST_IA32_FRED_RSP2, 0);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 3ad52437f426..176ad39be406 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -278,6 +278,8 @@ struct vcpu_vmx {
#ifdef CONFIG_X86_64
u64 msr_host_kernel_gs_base;
u64 msr_guest_kernel_gs_base;
+ u64 msr_host_fred_rsp0;
+ u64 msr_guest_fred_rsp0;
#endif
u64 spec_ctrl;
--
2.43.0
Initialize host VMCS FRED fields with host FRED MSRs' value and
guest VMCS FRED fields to 0.
FRED CPU states are managed in 9 new FRED MSRs, as well as a few
existing CPU registers and MSRs, e.g., CR4.FRED. To support FRED
context management, new VMCS fields corresponding to most of FRED
CPU state MSRs are added to both the host-state and guest-state
areas of VMCS.
Specifically no VMCS fields are added for FRED RSP0 and SSP0 MSRs,
because the 2 FRED MSRs are used during ring 3 event delivery only,
thus KVM, running on ring 0, can run safely even with guest FRED
RSP0 and SSP0. It can be deferred to load host FRED RSP0 and SSP0
until before returning to user level.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Changes since v1:
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() to decouple
KVM's capability to virtualize a feature and host's enabling of a
feature (Chao Gao).
* Move guest FRED states init into __vmx_vcpu_reset() (Chao Gao).
---
arch/x86/include/asm/vmx.h | 16 ++++++++++++++++
arch/x86/kvm/vmx/vmx.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index cb14f7e315f5..4889754415b5 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -280,12 +280,28 @@ enum vmcs_field {
GUEST_BNDCFGS_HIGH = 0x00002813,
GUEST_IA32_RTIT_CTL = 0x00002814,
GUEST_IA32_RTIT_CTL_HIGH = 0x00002815,
+ GUEST_IA32_FRED_CONFIG = 0x0000281a,
+ GUEST_IA32_FRED_RSP1 = 0x0000281c,
+ GUEST_IA32_FRED_RSP2 = 0x0000281e,
+ GUEST_IA32_FRED_RSP3 = 0x00002820,
+ GUEST_IA32_FRED_STKLVLS = 0x00002822,
+ GUEST_IA32_FRED_SSP1 = 0x00002824,
+ GUEST_IA32_FRED_SSP2 = 0x00002826,
+ GUEST_IA32_FRED_SSP3 = 0x00002828,
HOST_IA32_PAT = 0x00002c00,
HOST_IA32_PAT_HIGH = 0x00002c01,
HOST_IA32_EFER = 0x00002c02,
HOST_IA32_EFER_HIGH = 0x00002c03,
HOST_IA32_PERF_GLOBAL_CTRL = 0x00002c04,
HOST_IA32_PERF_GLOBAL_CTRL_HIGH = 0x00002c05,
+ HOST_IA32_FRED_CONFIG = 0x00002c08,
+ HOST_IA32_FRED_RSP1 = 0x00002c0a,
+ HOST_IA32_FRED_RSP2 = 0x00002c0c,
+ HOST_IA32_FRED_RSP3 = 0x00002c0e,
+ HOST_IA32_FRED_STKLVLS = 0x00002c10,
+ HOST_IA32_FRED_SSP1 = 0x00002c12,
+ HOST_IA32_FRED_SSP2 = 0x00002c14,
+ HOST_IA32_FRED_SSP3 = 0x00002c16,
PIN_BASED_VM_EXEC_CONTROL = 0x00004000,
CPU_BASED_VM_EXEC_CONTROL = 0x00004002,
EXCEPTION_BITMAP = 0x00004004,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d58ed2d3d379..b7b772183ee4 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1470,6 +1470,18 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
(unsigned long)(cpu_entry_stack(cpu) + 1));
}
+#ifdef CONFIG_X86_64
+ /* Per-CPU FRED MSRs */
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs_write64(HOST_IA32_FRED_RSP1, read_msr(MSR_IA32_FRED_RSP1));
+ vmcs_write64(HOST_IA32_FRED_RSP2, read_msr(MSR_IA32_FRED_RSP2));
+ vmcs_write64(HOST_IA32_FRED_RSP3, read_msr(MSR_IA32_FRED_RSP3));
+ vmcs_write64(HOST_IA32_FRED_SSP1, read_msr(MSR_IA32_FRED_SSP1));
+ vmcs_write64(HOST_IA32_FRED_SSP2, read_msr(MSR_IA32_FRED_SSP2));
+ vmcs_write64(HOST_IA32_FRED_SSP3, read_msr(MSR_IA32_FRED_SSP3));
+ }
+#endif
+
vmx->loaded_vmcs->cpu = cpu;
}
}
@@ -4321,6 +4333,15 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
*/
vmcs_write16(HOST_DS_SELECTOR, 0);
vmcs_write16(HOST_ES_SELECTOR, 0);
+
+ /*
+ * FRED MSRs are per-cpu, however FRED CONFIG and STKLVLS MSRs
+ * are the same on all CPUs, thus they are initialized here.
+ */
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs_write64(HOST_IA32_FRED_CONFIG, read_msr(MSR_IA32_FRED_CONFIG));
+ vmcs_write64(HOST_IA32_FRED_STKLVLS, read_msr(MSR_IA32_FRED_STKLVLS));
+ }
#else
vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
@@ -4865,6 +4886,19 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
*/
vmx->pi_desc.nv = POSTED_INTR_VECTOR;
vmx->pi_desc.sn = 1;
+
+#ifdef CONFIG_X86_64
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs_write64(GUEST_IA32_FRED_CONFIG, 0);
+ vmcs_write64(GUEST_IA32_FRED_RSP1, 0);
+ vmcs_write64(GUEST_IA32_FRED_RSP2, 0);
+ vmcs_write64(GUEST_IA32_FRED_RSP3, 0);
+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, 0);
+ vmcs_write64(GUEST_IA32_FRED_SSP1, 0);
+ vmcs_write64(GUEST_IA32_FRED_SSP2, 0);
+ vmcs_write64(GUEST_IA32_FRED_SSP3, 0);
+ }
+#endif
}
static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
--
2.43.0
Handle host initiated FRED MSR access requests to allow FRED context
to be set/get from user level.
During VM save/restore and live migration, FRED context needs to be
saved/restored, which requires FRED MSRs to be accessed from a user
level application, e.g., Qemu.
Note, handling of MSR_IA32_FRED_SSP0, i.e., MSR_IA32_PL0_SSP, is not
added yet, which is done in the KVM CET patch set.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Changes since v1:
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
* Fail host requested FRED MSRs access if KVM cannot virtualize FRED
(Chao Gao).
* Handle the case FRED MSRs are valid but KVM cannot virtualize FRED
(Chao Gao).
* Add sanity checks when writing to FRED MSRs.
---
arch/x86/kvm/vmx/vmx.c | 72 ++++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/x86.c | 47 +++++++++++++++++++++++++++
2 files changed, 119 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 264378c3b784..ee61d2c25cb0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1420,6 +1420,24 @@ static void vmx_write_guest_kernel_gs_base(struct vcpu_vmx *vmx, u64 data)
preempt_enable();
vmx->msr_guest_kernel_gs_base = data;
}
+
+static u64 vmx_read_guest_fred_rsp0(struct vcpu_vmx *vmx)
+{
+ preempt_disable();
+ if (vmx->guest_state_loaded)
+ vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
+ preempt_enable();
+ return vmx->msr_guest_fred_rsp0;
+}
+
+static void vmx_write_guest_fred_rsp0(struct vcpu_vmx *vmx, u64 data)
+{
+ preempt_disable();
+ if (vmx->guest_state_loaded)
+ wrmsrl(MSR_IA32_FRED_RSP0, data);
+ preempt_enable();
+ vmx->msr_guest_fred_rsp0 = data;
+}
#endif
void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
@@ -2019,6 +2037,33 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_KERNEL_GS_BASE:
msr_info->data = vmx_read_guest_kernel_gs_base(vmx);
break;
+ case MSR_IA32_FRED_RSP0:
+ msr_info->data = vmx_read_guest_fred_rsp0(vmx);
+ break;
+ case MSR_IA32_FRED_RSP1:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP1);
+ break;
+ case MSR_IA32_FRED_RSP2:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP2);
+ break;
+ case MSR_IA32_FRED_RSP3:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP3);
+ break;
+ case MSR_IA32_FRED_STKLVLS:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_STKLVLS);
+ break;
+ case MSR_IA32_FRED_SSP1:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP1);
+ break;
+ case MSR_IA32_FRED_SSP2:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP2);
+ break;
+ case MSR_IA32_FRED_SSP3:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP3);
+ break;
+ case MSR_IA32_FRED_CONFIG:
+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_CONFIG);
+ break;
#endif
case MSR_EFER:
return kvm_get_msr_common(vcpu, msr_info);
@@ -2226,6 +2271,33 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vmx_update_exception_bitmap(vcpu);
}
break;
+ case MSR_IA32_FRED_RSP0:
+ vmx_write_guest_fred_rsp0(vmx, data);
+ break;
+ case MSR_IA32_FRED_RSP1:
+ vmcs_write64(GUEST_IA32_FRED_RSP1, data);
+ break;
+ case MSR_IA32_FRED_RSP2:
+ vmcs_write64(GUEST_IA32_FRED_RSP2, data);
+ break;
+ case MSR_IA32_FRED_RSP3:
+ vmcs_write64(GUEST_IA32_FRED_RSP3, data);
+ break;
+ case MSR_IA32_FRED_STKLVLS:
+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, data);
+ break;
+ case MSR_IA32_FRED_SSP1:
+ vmcs_write64(GUEST_IA32_FRED_SSP1, data);
+ break;
+ case MSR_IA32_FRED_SSP2:
+ vmcs_write64(GUEST_IA32_FRED_SSP2, data);
+ break;
+ case MSR_IA32_FRED_SSP3:
+ vmcs_write64(GUEST_IA32_FRED_SSP3, data);
+ break;
+ case MSR_IA32_FRED_CONFIG:
+ vmcs_write64(GUEST_IA32_FRED_CONFIG, data);
+ break;
#endif
case MSR_IA32_SYSENTER_CS:
if (is_guest_mode(vcpu))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 363b1c080205..4e8d60f248e3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1451,6 +1451,9 @@ static const u32 msrs_to_save_base[] = {
MSR_STAR,
#ifdef CONFIG_X86_64
MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
+ MSR_IA32_FRED_RSP0, MSR_IA32_FRED_RSP1, MSR_IA32_FRED_RSP2,
+ MSR_IA32_FRED_RSP3, MSR_IA32_FRED_STKLVLS, MSR_IA32_FRED_SSP1,
+ MSR_IA32_FRED_SSP2, MSR_IA32_FRED_SSP3, MSR_IA32_FRED_CONFIG,
#endif
MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
@@ -1892,6 +1895,30 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data,
return 1;
data = (u32)data;
+ break;
+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
+ if (index != MSR_IA32_FRED_STKLVLS && is_noncanonical_address(data, vcpu))
+ return 1;
+ if ((index >= MSR_IA32_FRED_RSP0 && index <= MSR_IA32_FRED_RSP3) &&
+ (data & GENMASK_ULL(5, 0)))
+ return 1;
+ if ((index >= MSR_IA32_FRED_SSP1 && index <= MSR_IA32_FRED_SSP3) &&
+ (data & GENMASK_ULL(2, 0)))
+ return 1;
+
+ if (host_initiated) {
+ if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
+ return 1;
+ } else {
+ /*
+ * Inject #GP upon FRED MSRs accesses from a non-FRED guest,
+ * which also ensures no malicious guest can write to FRED
+ * MSRs to corrupt host FRED MSRs.
+ */
+ if (!guest_can_use(vcpu, X86_FEATURE_FRED))
+ return 1;
+ }
+
break;
}
@@ -1936,6 +1963,22 @@ int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
!guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
return 1;
break;
+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
+ if (host_initiated) {
+ if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
+ return 1;
+ } else {
+ /*
+ * Inject #GP upon FRED MSRs accesses from a non-FRED guest,
+ * which also ensures no malicious guest can write to FRED
+ * MSRs to corrupt host FRED MSRs.
+ */
+ if (!guest_can_use(vcpu, X86_FEATURE_FRED))
+ return 1;
+ }
+
+ break;
+
}
msr.index = index;
@@ -7364,6 +7407,10 @@ static void kvm_probe_msr_to_save(u32 msr_index)
if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR))
return;
break;
+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
+ if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
+ return;
+ break;
default:
break;
}
--
2.43.0
Add kvm_is_fred_enabled() to get if FRED is enabled on a vCPU.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Explain why it is ok to only check CR4.FRED (Chao Gao).
---
arch/x86/kvm/kvm_cache_regs.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index 75eae9c4998a..1d431c703fdf 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -187,6 +187,23 @@ static __always_inline bool kvm_is_cr4_bit_set(struct kvm_vcpu *vcpu,
return !!kvm_read_cr4_bits(vcpu, cr4_bit);
}
+/*
+ * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
+ * a vCPU is running with FRED enabled, because:
+ * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
+ * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
+ *
+ * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
+ */
+static __always_inline bool kvm_is_fred_enabled(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_X86_64
+ return kvm_is_cr4_bit_set(vcpu, X86_CR4_FRED);
+#else
+ return false;
+#endif
+}
+
static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu)
{
if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
--
2.43.0
Refuse to virtualize FRED if FRED consistency checks fail.
Suggested-by: Chao Gao <[email protected]>
Signed-off-by: Xin Li <[email protected]>
---
arch/x86/kvm/vmx/capabilities.h | 10 ++++++++++
arch/x86/kvm/vmx/vmx.c | 2 ++
2 files changed, 12 insertions(+)
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index e8f3ad0f79ee..73bf6618c425 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -400,6 +400,16 @@ static inline bool vmx_pebs_supported(void)
return boot_cpu_has(X86_FEATURE_PEBS) && kvm_pmu_cap.pebs_ept;
}
+static inline bool cpu_has_vmx_fred(void)
+{
+ return boot_cpu_has(X86_FEATURE_FRED) &&
+ (vmcs_config.basic & VMX_BASIC_NESTED_EXCEPTION) &&
+ (vmcs_config.vmexit_ctrl & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) &&
+ (vmcs_config.secondary_vmexit_ctrl & SECONDARY_VM_EXIT_SAVE_IA32_FRED) &&
+ (vmcs_config.secondary_vmexit_ctrl & SECONDARY_VM_EXIT_LOAD_IA32_FRED) &&
+ (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_FRED);
+}
+
static inline bool cpu_has_notify_vmexit(void)
{
return vmcs_config.cpu_based_2nd_exec_ctrl &
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1f265d526daf..a484b9ac2400 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8113,6 +8113,8 @@ static __init void vmx_set_cpu_caps(void)
kvm_cpu_cap_check_and_set(X86_FEATURE_DS);
kvm_cpu_cap_check_and_set(X86_FEATURE_DTES64);
}
+ if (!cpu_has_vmx_fred())
+ kvm_cpu_cap_clear(X86_FEATURE_FRED);
if (!enable_pmu)
kvm_cpu_cap_clear(X86_FEATURE_PDCM);
--
2.43.0
Add FRED related VMCS fields to dump_vmcs() to have it dump FRED context.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
* Dump guest FRED states only if guest has FRED enabled (Nikolay Borisov).
---
arch/x86/kvm/vmx/vmx.c | 46 +++++++++++++++++++++++++++++++++++-------
1 file changed, 39 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a484b9ac2400..e3409607122d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6392,7 +6392,7 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
struct vcpu_vmx *vmx = to_vmx(vcpu);
u32 vmentry_ctl, vmexit_ctl;
u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
- u64 tertiary_exec_control;
+ u64 tertiary_exec_control, secondary_vmexit_ctl;
unsigned long cr4;
int efer_slot;
@@ -6403,6 +6403,8 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
+ secondary_vmexit_ctl = cpu_has_secondary_vmexit_ctrls() ?
+ vmcs_read64(SECONDARY_VM_EXIT_CONTROLS) : 0;
cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
cr4 = vmcs_readl(GUEST_CR4);
@@ -6449,6 +6451,19 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
vmx_dump_sel("LDTR:", GUEST_LDTR_SELECTOR);
vmx_dump_dtsel("IDTR:", GUEST_IDTR_LIMIT);
vmx_dump_sel("TR: ", GUEST_TR_SELECTOR);
+#ifdef CONFIG_X86_64
+ if (kvm_is_fred_enabled(vcpu)) {
+ pr_err("FRED guest: config=0x%016llx, stack levels=0x%016llx\n"
+ "RSP0=0x%016lx, RSP1=0x%016llx\n"
+ "RSP2=0x%016llx, RSP3=0x%016llx\n",
+ vmcs_read64(GUEST_IA32_FRED_CONFIG),
+ vmcs_read64(GUEST_IA32_FRED_STKLVLS),
+ read_msr(MSR_IA32_FRED_RSP0),
+ vmcs_read64(GUEST_IA32_FRED_RSP1),
+ vmcs_read64(GUEST_IA32_FRED_RSP2),
+ vmcs_read64(GUEST_IA32_FRED_RSP3));
+ }
+#endif
efer_slot = vmx_find_loadstore_msr_slot(&vmx->msr_autoload.guest, MSR_EFER);
if (vmentry_ctl & VM_ENTRY_LOAD_IA32_EFER)
pr_err("EFER= 0x%016llx\n", vmcs_read64(GUEST_IA32_EFER));
@@ -6496,6 +6511,19 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
vmcs_readl(HOST_TR_BASE));
pr_err("GDTBase=%016lx IDTBase=%016lx\n",
vmcs_readl(HOST_GDTR_BASE), vmcs_readl(HOST_IDTR_BASE));
+#ifdef CONFIG_X86_64
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ pr_err("FRED host: config=0x%016llx, stack levels=0x%016llx\n"
+ "RSP0=0x%016llx, RSP1=0x%016llx\n"
+ "RSP2=0x%016llx, RSP3=0x%016llx\n",
+ vmcs_read64(HOST_IA32_FRED_CONFIG),
+ vmcs_read64(HOST_IA32_FRED_STKLVLS),
+ vmx->msr_host_fred_rsp0,
+ vmcs_read64(HOST_IA32_FRED_RSP1),
+ vmcs_read64(HOST_IA32_FRED_RSP2),
+ vmcs_read64(HOST_IA32_FRED_RSP3));
+ }
+#endif
pr_err("CR0=%016lx CR3=%016lx CR4=%016lx\n",
vmcs_readl(HOST_CR0), vmcs_readl(HOST_CR3),
vmcs_readl(HOST_CR4));
@@ -6517,25 +6545,29 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
pr_err("*** Control State ***\n");
pr_err("CPUBased=0x%08x SecondaryExec=0x%08x TertiaryExec=0x%016llx\n",
cpu_based_exec_ctrl, secondary_exec_control, tertiary_exec_control);
- pr_err("PinBased=0x%08x EntryControls=%08x ExitControls=%08x\n",
- pin_based_exec_ctrl, vmentry_ctl, vmexit_ctl);
+ pr_err("PinBased=0x%08x EntryControls=0x%08x\n",
+ pin_based_exec_ctrl, vmentry_ctl);
+ pr_err("ExitControls=0x%08x SecondaryExitControls=0x%016llx\n",
+ vmexit_ctl, secondary_vmexit_ctl);
pr_err("ExceptionBitmap=%08x PFECmask=%08x PFECmatch=%08x\n",
vmcs_read32(EXCEPTION_BITMAP),
vmcs_read32(PAGE_FAULT_ERROR_CODE_MASK),
vmcs_read32(PAGE_FAULT_ERROR_CODE_MATCH));
- pr_err("VMEntry: intr_info=%08x errcode=%08x ilen=%08x\n",
+ pr_err("VMEntry: intr_info=%08x errcode=%08x ilen=%08x event data=%016llx\n",
vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),
vmcs_read32(VM_ENTRY_EXCEPTION_ERROR_CODE),
- vmcs_read32(VM_ENTRY_INSTRUCTION_LEN));
+ vmcs_read32(VM_ENTRY_INSTRUCTION_LEN),
+ kvm_cpu_cap_has(X86_FEATURE_FRED) ? vmcs_read64(INJECTED_EVENT_DATA) : 0);
pr_err("VMExit: intr_info=%08x errcode=%08x ilen=%08x\n",
vmcs_read32(VM_EXIT_INTR_INFO),
vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
vmcs_read32(VM_EXIT_INSTRUCTION_LEN));
pr_err(" reason=%08x qualification=%016lx\n",
vmcs_read32(VM_EXIT_REASON), vmcs_readl(EXIT_QUALIFICATION));
- pr_err("IDTVectoring: info=%08x errcode=%08x\n",
+ pr_err("IDTVectoring: info=%08x errcode=%08x event data=%016llx\n",
vmcs_read32(IDT_VECTORING_INFO_FIELD),
- vmcs_read32(IDT_VECTORING_ERROR_CODE));
+ vmcs_read32(IDT_VECTORING_ERROR_CODE),
+ kvm_cpu_cap_has(X86_FEATURE_FRED) ? vmcs_read64(ORIGINAL_EVENT_DATA) : 0);
pr_err("TSC Offset = 0x%016llx\n", vmcs_read64(TSC_OFFSET));
if (secondary_exec_control & SECONDARY_EXEC_TSC_SCALING)
pr_err("TSC Multiplier = 0x%016llx\n",
--
2.43.0
Set injected-event data when injecting a #PF, #DB, or #NM caused
by extended feature disable using FRED event delivery, and save
original-event data for being used as injected-event data.
Unlike IDT using some extra CPU register as part of an event
context, e.g., %cr2 for #PF, FRED saves a complete event context
in its stack frame, e.g., FRED saves the faulting linear address
of a #PF into the event data field defined in its stack frame.
Thus a new VMX control field called injected-event data is added
to provide the event data that will be pushed into a FRED stack
frame for VM entries that inject an event using FRED event delivery.
In addition, a new VM exit information field called original-event
data is added to store the event data that would have saved into a
FRED stack frame for VM exits that occur during FRED event delivery.
After such a VM exit is handled to allow the original-event to be
delivered, the data in the original-event data VMCS field needs to
be set into the injected-event data VMCS field for the injection of
the original event.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Document event data should be equal to CR2/DR6/IA32_XFD_ERR instead
of using WARN_ON() (Chao Gao).
* Zero event data if a #NM was not caused by extended feature disable
(Chao Gao).
---
arch/x86/include/asm/vmx.h | 4 ++
arch/x86/kvm/vmx/vmx.c | 109 ++++++++++++++++++++++++++++---------
arch/x86/kvm/vmx/vmx.h | 1 +
arch/x86/kvm/x86.c | 10 +++-
4 files changed, 95 insertions(+), 29 deletions(-)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 4889754415b5..6b796c5c9c2b 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -256,8 +256,12 @@ enum vmcs_field {
PID_POINTER_TABLE_HIGH = 0x00002043,
SECONDARY_VM_EXIT_CONTROLS = 0x00002044,
SECONDARY_VM_EXIT_CONTROLS_HIGH = 0x00002045,
+ INJECTED_EVENT_DATA = 0x00002052,
+ INJECTED_EVENT_DATA_HIGH = 0x00002053,
GUEST_PHYSICAL_ADDRESS = 0x00002400,
GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
+ ORIGINAL_EVENT_DATA = 0x00002404,
+ ORIGINAL_EVENT_DATA_HIGH = 0x00002405,
VMCS_LINK_POINTER = 0x00002800,
VMCS_LINK_POINTER_HIGH = 0x00002801,
GUEST_IA32_DEBUGCTL = 0x00002802,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ee61d2c25cb0..f622fb90a098 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1871,9 +1871,29 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
vmx->vcpu.arch.event_exit_inst_len);
intr_info |= INTR_TYPE_SOFT_EXCEPTION;
- } else
+ } else {
intr_info |= INTR_TYPE_HARD_EXCEPTION;
+ if (kvm_is_fred_enabled(vcpu)) {
+ u64 event_data = 0;
+
+ if (is_debug(intr_info))
+ /*
+ * Compared to DR6, FRED #DB event data saved on
+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
+ * inverted, i.e.,
+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
+ */
+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
+ else if (is_page_fault(intr_info))
+ event_data = vcpu->arch.cr2;
+ else if (is_nm_fault(intr_info))
+ event_data = to_vmx(vcpu)->fred_xfd_event_data;
+
+ vmcs_write64(INJECTED_EVENT_DATA, event_data);
+ }
+ }
+
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
vmx_clear_hlt(vcpu);
@@ -7082,8 +7102,11 @@ static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu)
*
* Queuing exception is done in vmx_handle_exit. See comment there.
*/
- if (vcpu->arch.guest_fpu.fpstate->xfd)
+ if (vcpu->arch.guest_fpu.fpstate->xfd) {
rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
+ to_vmx(vcpu)->fred_xfd_event_data = vcpu->arch.cr0 & X86_CR0_TS
+ ? 0 : vcpu->arch.guest_fpu.xfd_err;
+ }
}
static void handle_exception_irqoff(struct vcpu_vmx *vmx)
@@ -7199,29 +7222,28 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
vmx->loaded_vmcs->entry_time));
}
-static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
- u32 idt_vectoring_info,
- int instr_len_field,
- int error_code_field)
+static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
{
- u8 vector;
- int type;
- bool idtv_info_valid;
-
- idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
+ u32 event_id = vectoring ? to_vmx(vcpu)->idt_vectoring_info
+ : vmcs_read32(VM_ENTRY_INTR_INFO_FIELD);
+ int instr_len_field = vectoring ? VM_EXIT_INSTRUCTION_LEN
+ : VM_ENTRY_INSTRUCTION_LEN;
+ int error_code_field = vectoring ? IDT_VECTORING_ERROR_CODE
+ : VM_ENTRY_EXCEPTION_ERROR_CODE;
+ int event_data_field = vectoring ? ORIGINAL_EVENT_DATA
+ : INJECTED_EVENT_DATA;
+ u8 vector = event_id & INTR_INFO_VECTOR_MASK;
+ int type = event_id & INTR_INFO_INTR_TYPE_MASK;
vcpu->arch.nmi_injected = false;
kvm_clear_exception_queue(vcpu);
kvm_clear_interrupt_queue(vcpu);
- if (!idtv_info_valid)
+ if (!(event_id & INTR_INFO_VALID_MASK))
return;
kvm_make_request(KVM_REQ_EVENT, vcpu);
- vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
- type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;
-
switch (type) {
case INTR_TYPE_NMI_INTR:
vcpu->arch.nmi_injected = true;
@@ -7236,10 +7258,31 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
fallthrough;
case INTR_TYPE_HARD_EXCEPTION:
- if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) {
- u32 err = vmcs_read32(error_code_field);
- kvm_requeue_exception_e(vcpu, vector, err);
- } else
+ if (kvm_is_fred_enabled(vcpu)) {
+ /* Save event data for being used as injected-event data */
+ u64 event_data = vmcs_read64(event_data_field);
+
+ switch (vector) {
+ case DB_VECTOR:
+ /* %dr6 should be equal to (event_data ^ DR6_RESERVED) */
+ vcpu->arch.dr6 = event_data ^ DR6_RESERVED;
+ break;
+ case NM_VECTOR:
+ to_vmx(vcpu)->fred_xfd_event_data = event_data;
+ break;
+ case PF_VECTOR:
+ /* %cr2 should be equal to event_data */
+ vcpu->arch.cr2 = event_data;
+ break;
+ default:
+ WARN_ON(event_data != 0);
+ break;
+ }
+ }
+
+ if (event_id & INTR_INFO_DELIVER_CODE_MASK)
+ kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field));
+ else
kvm_requeue_exception(vcpu, vector);
break;
case INTR_TYPE_SOFT_INTR:
@@ -7255,18 +7298,12 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
{
- __vmx_complete_interrupts(&vmx->vcpu, vmx->idt_vectoring_info,
- VM_EXIT_INSTRUCTION_LEN,
- IDT_VECTORING_ERROR_CODE);
+ __vmx_complete_interrupts(&vmx->vcpu, true);
}
static void vmx_cancel_injection(struct kvm_vcpu *vcpu)
{
- __vmx_complete_interrupts(vcpu,
- vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),
- VM_ENTRY_INSTRUCTION_LEN,
- VM_ENTRY_EXCEPTION_ERROR_CODE);
-
+ __vmx_complete_interrupts(vcpu, false);
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);
}
@@ -7382,6 +7419,24 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
vmx_disable_fb_clear(vmx);
+ /*
+ * %cr2 needs to be saved after a VM exit and restored before a VM
+ * entry in case a VM exit happens immediately after delivery of a
+ * guest #PF but before guest reads %cr2.
+ *
+ * A FRED guest should read its #PF faulting linear address from
+ * the event data field in its FRED stack frame instead of %cr2.
+ * But the FRED 5.0 spec still requires a FRED CPU to update %cr2
+ * in the normal way, thus %cr2 is still updated even for a FRED
+ * guest.
+ *
+ * Note, an NMI could interrupt KVM:
+ * 1) after VM exit but before CR2 is saved.
+ * 2) after CR2 is restored but before VM entry.
+ * And a #PF could happen durng NMI handlng, which overwrites %cr2.
+ * Thus exc_nmi() should save and restore %cr2 upon entering and
+ * before leaving to make sure %cr2 not corrupted.
+ */
if (vcpu->arch.cr2 != native_read_cr2())
native_write_cr2(vcpu->arch.cr2);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 176ad39be406..d5738c5a4814 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -266,6 +266,7 @@ struct vcpu_vmx {
u32 exit_intr_info;
u32 idt_vectoring_info;
ulong rflags;
+ u64 fred_xfd_event_data;
/*
* User return MSRs are always emulated when enabled in the guest, but
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4e8d60f248e3..00c0062726ae 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -680,8 +680,14 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.injected = true;
if (WARN_ON_ONCE(has_payload)) {
/*
- * A reinjected event has already
- * delivered its payload.
+ * For a reinjected event, KVM delivers its
+ * payload through:
+ * #PF: save %cr2 into arch.cr2 immediately
+ * after VM exits.
+ * #DB: save %dr6 into arch.dr6 later in
+ * sync_dirty_debug_regs().
+ *
+ * For FRED guest, see __vmx_complete_interrupts().
*/
has_payload = false;
payload = 0;
--
2.43.0
Set VMX nested exception bit in the VM-entry interruption information
VMCS field when injecting a nested exception using FRED event delivery
to ensure:
1) The nested exception is injected on a correct stack level.
2) The nested bit defined in FRED stack frame is set.
The event stack level used by FRED event delivery depends on whether the
event was a nested exception encountered during delivery of another event,
because a nested exception is "regarded" as happening on ring 0. E.g.,
when #PF is configured to use stack level 1 in IA32_FRED_STKLVLS MSR:
- nested #PF will be delivered on stack level 1 when encountered in
ring 3.
- normal #PF will be delivered on stack level 0 when encountered in
ring 3.
The VMX nested-exception support ensures the correct event stack level is
chosen when a VM entry injects a nested exception.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Changes since v1:
* Set the nested flag when there is an original interrupt (Chao Gao).
---
arch/x86/include/asm/kvm_host.h | 6 +++--
arch/x86/include/asm/vmx.h | 5 ++--
arch/x86/kvm/svm/svm.c | 4 +--
arch/x86/kvm/vmx/vmx.c | 8 ++++--
arch/x86/kvm/x86.c | 46 ++++++++++++++++++++++++++-------
arch/x86/kvm/x86.h | 1 +
6 files changed, 53 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0d88873eba63..ef278ee0b6ca 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -736,6 +736,7 @@ struct kvm_queued_exception {
u32 error_code;
unsigned long payload;
bool has_payload;
+ bool nested;
};
struct kvm_vcpu_arch {
@@ -2060,8 +2061,9 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu);
void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested);
+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr,
+ u32 error_code, bool nested);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
struct x86_exception *fault);
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 6b796c5c9c2b..68af74e48788 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -134,7 +134,7 @@
#define VMX_BASIC_DUAL_MONITOR_TREATMENT BIT_ULL(49)
#define VMX_BASIC_INOUT BIT_ULL(54)
#define VMX_BASIC_TRUE_CTLS BIT_ULL(55)
-
+#define VMX_BASIC_NESTED_EXCEPTION BIT_ULL(58)
/* VMX_MISC bits and bitmasks */
#define VMX_MISC_INTEL_PT BIT_ULL(14)
@@ -407,8 +407,9 @@ enum vmcs_field {
#define INTR_INFO_INTR_TYPE_MASK 0x700 /* 10:8 */
#define INTR_INFO_DELIVER_CODE_MASK 0x800 /* 11 */
#define INTR_INFO_UNBLOCK_NMI 0x1000 /* 12 */
+#define INTR_INFO_NESTED_EXCEPTION_MASK 0x2000 /* 13 */
#define INTR_INFO_VALID_MASK 0x80000000 /* 31 */
-#define INTR_INFO_RESVD_BITS_MASK 0x7ffff000
+#define INTR_INFO_RESVD_BITS_MASK 0x7fffd000
#define VECTORING_INFO_VECTOR_MASK INTR_INFO_VECTOR_MASK
#define VECTORING_INFO_TYPE_MASK INTR_INFO_INTR_TYPE_MASK
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e90b429c84f1..c220b690a37c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4057,10 +4057,10 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu)
if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
u32 err = svm->vmcb->control.exit_int_info_err;
- kvm_requeue_exception_e(vcpu, vector, err);
+ kvm_requeue_exception_e(vcpu, vector, err, false);
} else
- kvm_requeue_exception(vcpu, vector);
+ kvm_requeue_exception(vcpu, vector, false);
break;
case SVM_EXITINTINFO_TYPE_INTR:
kvm_queue_interrupt(vcpu, vector, false);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f622fb90a098..1f265d526daf 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1891,6 +1891,8 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
event_data = to_vmx(vcpu)->fred_xfd_event_data;
vmcs_write64(INJECTED_EVENT_DATA, event_data);
+
+ intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
}
}
@@ -7281,9 +7283,11 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
}
if (event_id & INTR_INFO_DELIVER_CODE_MASK)
- kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field));
+ kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field),
+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
else
- kvm_requeue_exception(vcpu, vector);
+ kvm_requeue_exception(vcpu, vector,
+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
break;
case INTR_TYPE_SOFT_INTR:
vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 00c0062726ae..725819262085 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -645,7 +645,8 @@ static void kvm_leave_nested(struct kvm_vcpu *vcpu)
static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
unsigned nr, bool has_error, u32 error_code,
- bool has_payload, unsigned long payload, bool reinject)
+ bool has_payload, unsigned long payload,
+ bool reinject, bool nested)
{
u32 prev_nr;
int class1, class2;
@@ -696,6 +697,13 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.pending = true;
vcpu->arch.exception.injected = false;
}
+
+ vcpu->arch.exception.nested = vcpu->arch.exception.nested ||
+ (kvm_is_fred_enabled(vcpu) &&
+ ((reinject && nested) ||
+ vcpu->arch.nmi_injected ||
+ vcpu->arch.interrupt.injected));
+
vcpu->arch.exception.has_error_code = has_error;
vcpu->arch.exception.vector = nr;
vcpu->arch.exception.error_code = error_code;
@@ -725,8 +733,28 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.injected = false;
vcpu->arch.exception.pending = false;
+ /*
+ * A #DF is NOT a nested event per its definition, however per
+ * FRED spec 5.0 Appendix B, its delivery determines the new
+ * stack level as is done for events occurring when CPL = 0.
+ */
+ vcpu->arch.exception.nested = false;
+
kvm_queue_exception_e(vcpu, DF_VECTOR, 0);
} else {
+ /*
+ * FRED spec 5.0 Appendix B: delivery of a nested exception
+ * determines the new stack level as is done for events
+ * occurring when CPL = 0.
+ *
+ * IOW, FRED event delivery of an event encountered in ring 3
+ * normally uses stack level 0 unconditionally. However, if
+ * the event is an exception nested on any earlier event,
+ * delivery of the nested exception will consult the FRED MSR
+ * IA32_FRED_STKLVLS to determine which stack level to use.
+ */
+ vcpu->arch.exception.nested = kvm_is_fred_enabled(vcpu);
+
/* replace previous exception with a new one in a hope
that instruction re-execution will regenerate lost
exception */
@@ -736,20 +764,20 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
{
- kvm_multiple_exception(vcpu, nr, false, 0, false, 0, false);
+ kvm_multiple_exception(vcpu, nr, false, 0, false, 0, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception);
-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr)
+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested)
{
- kvm_multiple_exception(vcpu, nr, false, 0, false, 0, true);
+ kvm_multiple_exception(vcpu, nr, false, 0, false, 0, true, nested);
}
EXPORT_SYMBOL_GPL(kvm_requeue_exception);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr,
unsigned long payload)
{
- kvm_multiple_exception(vcpu, nr, false, 0, true, payload, false);
+ kvm_multiple_exception(vcpu, nr, false, 0, true, payload, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_p);
@@ -757,7 +785,7 @@ static void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr,
u32 error_code, unsigned long payload)
{
kvm_multiple_exception(vcpu, nr, true, error_code,
- true, payload, false);
+ true, payload, false, false);
}
int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err)
@@ -829,13 +857,13 @@ void kvm_inject_nmi(struct kvm_vcpu *vcpu)
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
{
- kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, false);
+ kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, false, false);
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_e);
-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code, bool nested)
{
- kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, true);
+ kvm_multiple_exception(vcpu, nr, true, error_code, false, 0, true, nested);
}
EXPORT_SYMBOL_GPL(kvm_requeue_exception_e);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 9a52016ebf5a..c1f1d5696080 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -108,6 +108,7 @@ static inline void kvm_clear_exception_queue(struct kvm_vcpu *vcpu)
{
vcpu->arch.exception.pending = false;
vcpu->arch.exception.injected = false;
+ vcpu->arch.exception.nested = false;
vcpu->arch.exception_vmexit.pending = false;
}
--
2.43.0
Add VMX FRED controls to nested VMX controls and set the VMX
nested-exception support bit (bit 58) in the nested IA32_VMX_BASIC MSR
when FRED is enabled.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
arch/x86/kvm/vmx/nested.c | 14 ++++++++++----
arch/x86/kvm/vmx/vmx.c | 1 +
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index f9c1fbeac302..04a9cdb0361f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1239,10 +1239,12 @@ static bool is_bitwise_subset(u64 superset, u64 subset, u64 mask)
#define VMX_BASIC_FEATURES_MASK \
(VMX_BASIC_DUAL_MONITOR_TREATMENT | \
VMX_BASIC_INOUT | \
- VMX_BASIC_TRUE_CTLS)
+ VMX_BASIC_TRUE_CTLS | \
+ VMX_BASIC_NESTED_EXCEPTION)
-#define VMX_BASIC_RESERVED_BITS \
- (GENMASK_ULL(63, 56) | GENMASK_ULL(47, 45) | BIT_ULL(31))
+#define VMX_BASIC_RESERVED_BITS \
+ (GENMASK_ULL(63, 59) | GENMASK_ULL(57, 56) | \
+ GENMASK_ULL(47, 45) | BIT_ULL(31))
static int vmx_restore_vmx_basic(struct vcpu_vmx *vmx, u64 data)
{
@@ -6988,7 +6990,8 @@ static void nested_vmx_setup_entry_ctls(struct vmcs_config *vmcs_conf,
#ifdef CONFIG_X86_64
VM_ENTRY_IA32E_MODE |
#endif
- VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_LOAD_BNDCFGS;
+ VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_LOAD_BNDCFGS |
+ VM_ENTRY_LOAD_IA32_FRED;
msrs->entry_ctls_high |=
(VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR | VM_ENTRY_LOAD_IA32_EFER |
VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL);
@@ -7147,6 +7150,9 @@ static void nested_vmx_setup_basic(struct nested_vmx_msrs *msrs)
if (cpu_has_vmx_basic_inout())
msrs->basic |= VMX_BASIC_INOUT;
+
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED))
+ msrs->basic |= VMX_BASIC_NESTED_EXCEPTION;
}
static void nested_vmx_setup_cr_fixed(struct nested_vmx_msrs *msrs)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fc808d599493..1005b6a57d23 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7915,6 +7915,7 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
entry = kvm_find_cpuid_entry_index(vcpu, 0x7, 1);
cr4_fixed1_update(X86_CR4_LAM_SUP, eax, feature_bit(LAM));
+ cr4_fixed1_update(X86_CR4_FRED, eax, feature_bit(FRED));
#undef cr4_fixed1_update
}
--
2.43.0
Enable the secondary VM exit controls to prepare for nested FRED.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Documentation/virt/kvm/x86/nested-vmx.rst | 1 +
arch/x86/kvm/vmx/capabilities.h | 1 +
arch/x86/kvm/vmx/nested.c | 15 ++++++++++++++-
arch/x86/kvm/vmx/vmcs12.c | 1 +
arch/x86/kvm/vmx/vmcs12.h | 2 ++
arch/x86/kvm/x86.h | 2 +-
6 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/Documentation/virt/kvm/x86/nested-vmx.rst b/Documentation/virt/kvm/x86/nested-vmx.rst
index ac2095d41f02..e64ef231f310 100644
--- a/Documentation/virt/kvm/x86/nested-vmx.rst
+++ b/Documentation/virt/kvm/x86/nested-vmx.rst
@@ -217,6 +217,7 @@ struct shadow_vmcs is ever changed.
u16 host_fs_selector;
u16 host_gs_selector;
u16 host_tr_selector;
+ u64 secondary_vm_exit_controls;
};
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 73bf6618c425..b41c2cde811d 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -38,6 +38,7 @@ struct nested_vmx_msrs {
u32 pinbased_ctls_high;
u32 exit_ctls_low;
u32 exit_ctls_high;
+ u64 secondary_exit_ctls;
u32 entry_ctls_low;
u32 entry_ctls_high;
u32 misc_low;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8a5fda04e2de..1132e360ff13 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1431,6 +1431,7 @@ int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
case MSR_IA32_VMX_PINBASED_CTLS:
case MSR_IA32_VMX_PROCBASED_CTLS:
case MSR_IA32_VMX_EXIT_CTLS:
+ case MSR_IA32_VMX_EXIT_CTLS2:
case MSR_IA32_VMX_ENTRY_CTLS:
/*
* The "non-true" VMX capability MSRs are generated from the
@@ -1509,6 +1510,9 @@ int vmx_get_vmx_msr(struct nested_vmx_msrs *msrs, u32 msr_index, u64 *pdata)
if (msr_index == MSR_IA32_VMX_EXIT_CTLS)
*pdata |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
break;
+ case MSR_IA32_VMX_EXIT_CTLS2:
+ *pdata = msrs->secondary_exit_ctls;
+ break;
case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
case MSR_IA32_VMX_ENTRY_CTLS:
*pdata = vmx_control_msr(
@@ -2443,6 +2447,11 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
exec_control &= ~VM_EXIT_LOAD_IA32_EFER;
vm_exit_controls_set(vmx, exec_control);
+ if (exec_control & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS) {
+ exec_control = __secondary_vm_exit_controls_get(vmcs01);
+ secondary_vm_exit_controls_set(vmx, exec_control);
+ }
+
/*
* Interrupt/Exception Fields
*/
@@ -6856,13 +6865,17 @@ static void nested_vmx_setup_exit_ctls(struct vmcs_config *vmcs_conf,
VM_EXIT_HOST_ADDR_SPACE_SIZE |
#endif
VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT |
- VM_EXIT_CLEAR_BNDCFGS;
+ VM_EXIT_CLEAR_BNDCFGS | VM_EXIT_ACTIVATE_SECONDARY_CONTROLS;
msrs->exit_ctls_high |=
VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
VM_EXIT_LOAD_IA32_EFER | VM_EXIT_SAVE_IA32_EFER |
VM_EXIT_SAVE_VMX_PREEMPTION_TIMER | VM_EXIT_ACK_INTR_ON_EXIT |
VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
+ /* secondary exit controls */
+ if (msrs->exit_ctls_high & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
+ rdmsrl(MSR_IA32_VMX_EXIT_CTLS2, msrs->secondary_exit_ctls);
+
/* We support free control of debug control saving. */
msrs->exit_ctls_low &= ~VM_EXIT_SAVE_DEBUG_CONTROLS;
}
diff --git a/arch/x86/kvm/vmx/vmcs12.c b/arch/x86/kvm/vmx/vmcs12.c
index 106a72c923ca..98457d7b2b23 100644
--- a/arch/x86/kvm/vmx/vmcs12.c
+++ b/arch/x86/kvm/vmx/vmcs12.c
@@ -73,6 +73,7 @@ const unsigned short vmcs12_field_offsets[] = {
FIELD(PAGE_FAULT_ERROR_CODE_MATCH, page_fault_error_code_match),
FIELD(CR3_TARGET_COUNT, cr3_target_count),
FIELD(VM_EXIT_CONTROLS, vm_exit_controls),
+ FIELD(SECONDARY_VM_EXIT_CONTROLS, secondary_vm_exit_controls),
FIELD(VM_EXIT_MSR_STORE_COUNT, vm_exit_msr_store_count),
FIELD(VM_EXIT_MSR_LOAD_COUNT, vm_exit_msr_load_count),
FIELD(VM_ENTRY_CONTROLS, vm_entry_controls),
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index 01936013428b..f50f897b9b5f 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -185,6 +185,7 @@ struct __packed vmcs12 {
u16 host_gs_selector;
u16 host_tr_selector;
u16 guest_pml_index;
+ u64 secondary_vm_exit_controls;
};
/*
@@ -358,6 +359,7 @@ static inline void vmx_check_vmcs12_offsets(void)
CHECK_OFFSET(host_gs_selector, 992);
CHECK_OFFSET(host_tr_selector, 994);
CHECK_OFFSET(guest_pml_index, 996);
+ CHECK_OFFSET(secondary_vm_exit_controls, 998);
}
extern const unsigned short vmcs12_field_offsets[];
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c1f1d5696080..498bb6090b1e 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -47,7 +47,7 @@ void kvm_spurious_fault(void);
* associated feature that KVM supports for nested virtualization.
*/
#define KVM_FIRST_EMULATED_VMX_MSR MSR_IA32_VMX_BASIC
-#define KVM_LAST_EMULATED_VMX_MSR MSR_IA32_VMX_VMFUNC
+#define KVM_LAST_EMULATED_VMX_MSR MSR_IA32_VMX_EXIT_CTLS2
#define KVM_DEFAULT_PLE_GAP 128
#define KVM_VMX_DEFAULT_PLE_WINDOW 4096
--
2.43.0
Add a prerequisite for accessing VMCS fields referenced in macros
SHADOW_FIELD_R[OW], because a VMCS field may not exist on some CPUs.
Signed-off-by: Xin Li <[email protected]>
---
arch/x86/kvm/vmx/nested.c | 70 ++++++++++++++++++------
arch/x86/kvm/vmx/vmcs_shadow_fields.h | 76 +++++++++++++--------------
2 files changed, 91 insertions(+), 55 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 1132e360ff13..94da6a0a2f81 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -53,14 +53,14 @@ struct shadow_vmcs_field {
u16 offset;
};
static struct shadow_vmcs_field shadow_read_only_fields[] = {
-#define SHADOW_FIELD_RO(x, y) { x, offsetof(struct vmcs12, y) },
+#define SHADOW_FIELD_RO(x, y, c) { x, offsetof(struct vmcs12, y) },
#include "vmcs_shadow_fields.h"
};
static int max_shadow_read_only_fields =
ARRAY_SIZE(shadow_read_only_fields);
static struct shadow_vmcs_field shadow_read_write_fields[] = {
-#define SHADOW_FIELD_RW(x, y) { x, offsetof(struct vmcs12, y) },
+#define SHADOW_FIELD_RW(x, y, c) { x, offsetof(struct vmcs12, y) },
#include "vmcs_shadow_fields.h"
};
static int max_shadow_read_write_fields =
@@ -83,6 +83,17 @@ static void init_vmcs_shadow_fields(void)
pr_err("Missing field from shadow_read_only_field %x\n",
field + 1);
+ switch (field) {
+#define SHADOW_FIELD_RO(x, y, c) \
+ case x: \
+ if (!(c)) \
+ continue; \
+ break;
+#include "vmcs_shadow_fields.h"
+ default:
+ break;
+ }
+
clear_bit(field, vmx_vmread_bitmap);
if (field & 1)
#ifdef CONFIG_X86_64
@@ -114,18 +125,12 @@ static void init_vmcs_shadow_fields(void)
* on bare metal.
*/
switch (field) {
- case GUEST_PML_INDEX:
- if (!cpu_has_vmx_pml())
- continue;
- break;
- case VMX_PREEMPTION_TIMER_VALUE:
- if (!cpu_has_vmx_preemption_timer())
- continue;
- break;
- case GUEST_INTR_STATUS:
- if (!cpu_has_vmx_apicv())
- continue;
+#define SHADOW_FIELD_RW(x, y, c) \
+ case x: \
+ if (!(c)) \
+ continue; \
break;
+#include "vmcs_shadow_fields.h"
default:
break;
}
@@ -1585,6 +1590,18 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
for (i = 0; i < max_shadow_read_write_fields; i++) {
field = shadow_read_write_fields[i];
+
+ switch (field.encoding) {
+#define SHADOW_FIELD_RW(x, y, c) \
+ case x: \
+ if (!(c)) \
+ continue; \
+ break;
+#include "vmcs_shadow_fields.h"
+ default:
+ break;
+ }
+
val = __vmcs_readl(field.encoding);
vmcs12_write_any(vmcs12, field.encoding, field.offset, val);
}
@@ -1619,6 +1636,23 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
for (q = 0; q < ARRAY_SIZE(fields); q++) {
for (i = 0; i < max_fields[q]; i++) {
field = fields[q][i];
+
+ switch (field.encoding) {
+#define SHADOW_FIELD_RO(x, y, c) \
+ case x: \
+ if (!(c)) \
+ continue; \
+ break;
+#define SHADOW_FIELD_RW(x, y, c) \
+ case x: \
+ if (!(c)) \
+ continue; \
+ break;
+#include "vmcs_shadow_fields.h"
+ default:
+ break;
+ }
+
val = vmcs12_read_any(vmcs12, field.encoding,
field.offset);
__vmcs_writel(field.encoding, val);
@@ -5492,9 +5526,10 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
static bool is_shadow_field_rw(unsigned long field)
{
switch (field) {
-#define SHADOW_FIELD_RW(x, y) case x:
+#define SHADOW_FIELD_RW(x, y, c) \
+ case x: \
+ return c;
#include "vmcs_shadow_fields.h"
- return true;
default:
break;
}
@@ -5504,9 +5539,10 @@ static bool is_shadow_field_rw(unsigned long field)
static bool is_shadow_field_ro(unsigned long field)
{
switch (field) {
-#define SHADOW_FIELD_RO(x, y) case x:
+#define SHADOW_FIELD_RO(x, y, c) \
+ case x: \
+ return c;
#include "vmcs_shadow_fields.h"
- return true;
default:
break;
}
diff --git a/arch/x86/kvm/vmx/vmcs_shadow_fields.h b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
index cad128d1657b..7f48056fe351 100644
--- a/arch/x86/kvm/vmx/vmcs_shadow_fields.h
+++ b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
@@ -3,10 +3,10 @@ BUILD_BUG_ON(1)
#endif
#ifndef SHADOW_FIELD_RO
-#define SHADOW_FIELD_RO(x, y)
+#define SHADOW_FIELD_RO(x, y, c)
#endif
#ifndef SHADOW_FIELD_RW
-#define SHADOW_FIELD_RW(x, y)
+#define SHADOW_FIELD_RW(x, y, c)
#endif
/*
@@ -32,48 +32,48 @@ BUILD_BUG_ON(1)
*/
/* 16-bits */
-SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status)
-SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index)
-SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector)
-SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector)
+SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status, cpu_has_vmx_apicv())
+SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index, cpu_has_vmx_pml())
+SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector, true)
+SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector, true)
/* 32-bits */
-SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason)
-SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info)
-SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len)
-SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field)
-SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code)
-SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code)
-SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes)
-SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes)
-SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control)
-SHADOW_FIELD_RW(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control)
-SHADOW_FIELD_RW(EXCEPTION_BITMAP, exception_bitmap)
-SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code)
-SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field)
-SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len)
-SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold)
-SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info)
-SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value)
+SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason, true)
+SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info, true)
+SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len, true)
+SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code, true)
+SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field, true)
+SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code, true)
+SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes, true)
+SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes, true)
+SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control, true)
+SHADOW_FIELD_RW(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control, true)
+SHADOW_FIELD_RW(EXCEPTION_BITMAP, exception_bitmap, true)
+SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code, true)
+SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field, true)
+SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len, true)
+SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold, true)
+SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info, true)
+SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value, cpu_has_vmx_preemption_timer())
/* Natural width */
-SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification)
-SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS, guest_linear_address)
-SHADOW_FIELD_RW(GUEST_RIP, guest_rip)
-SHADOW_FIELD_RW(GUEST_RSP, guest_rsp)
-SHADOW_FIELD_RW(GUEST_CR0, guest_cr0)
-SHADOW_FIELD_RW(GUEST_CR3, guest_cr3)
-SHADOW_FIELD_RW(GUEST_CR4, guest_cr4)
-SHADOW_FIELD_RW(GUEST_RFLAGS, guest_rflags)
-SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK, cr0_guest_host_mask)
-SHADOW_FIELD_RW(CR0_READ_SHADOW, cr0_read_shadow)
-SHADOW_FIELD_RW(CR4_READ_SHADOW, cr4_read_shadow)
-SHADOW_FIELD_RW(HOST_FS_BASE, host_fs_base)
-SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base)
+SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification, true)
+SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS, guest_linear_address, true)
+SHADOW_FIELD_RW(GUEST_RIP, guest_rip, true)
+SHADOW_FIELD_RW(GUEST_RSP, guest_rsp, true)
+SHADOW_FIELD_RW(GUEST_CR0, guest_cr0, true)
+SHADOW_FIELD_RW(GUEST_CR3, guest_cr3, true)
+SHADOW_FIELD_RW(GUEST_CR4, guest_cr4, true)
+SHADOW_FIELD_RW(GUEST_RFLAGS, guest_rflags, true)
+SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK, cr0_guest_host_mask, true)
+SHADOW_FIELD_RW(CR0_READ_SHADOW, cr0_read_shadow, true)
+SHADOW_FIELD_RW(CR4_READ_SHADOW, cr4_read_shadow, true)
+SHADOW_FIELD_RW(HOST_FS_BASE, host_fs_base, true)
+SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base, true)
/* 64-bit */
-SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address)
-SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address)
+SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address, true)
+SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address, true)
#undef SHADOW_FIELD_RO
#undef SHADOW_FIELD_RW
--
2.43.0
Allow FRED/LKGS/WRMSRNS to be exposed to guests, thus a guest OS could see
these features when the guest is configured with FRED/LKGS/WRMSRNS in Qemu.
A qemu patch is required to expose FRED/LKGS/WRMSRNS to KVM guests.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
arch/x86/kvm/cpuid.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index adba49afb5fe..afc1316d78ad 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -676,8 +676,8 @@ void kvm_set_cpu_caps(void)
kvm_cpu_cap_mask(CPUID_7_1_EAX,
F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) |
- F(FZRM) | F(FSRS) | F(FSRC) |
- F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
+ F(FZRM) | F(FSRS) | F(FSRC) | F(FRED) | F(LKGS) |
+ F(WRMSRNS) | F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
);
kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
--
2.43.0
Run another round of debug_regs test with FRED enabled if FRED is
available.
Signed-off-by: Xin Li <[email protected]>
---
.../selftests/kvm/include/x86_64/processor.h | 4 ++
.../testing/selftests/kvm/x86_64/debug_regs.c | 50 ++++++++++++++-----
2 files changed, 41 insertions(+), 13 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index a84863503fcb..bc5cd8628a20 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -48,6 +48,7 @@ extern bool host_cpu_is_amd;
#define X86_CR4_SMEP (1ul << 20)
#define X86_CR4_SMAP (1ul << 21)
#define X86_CR4_PKE (1ul << 22)
+#define X86_CR4_FRED (1ul << 32)
struct xstate_header {
u64 xstate_bv;
@@ -164,6 +165,9 @@ struct kvm_x86_cpu_feature {
#define X86_FEATURE_SPEC_CTRL KVM_X86_CPU_FEATURE(0x7, 0, EDX, 26)
#define X86_FEATURE_ARCH_CAPABILITIES KVM_X86_CPU_FEATURE(0x7, 0, EDX, 29)
#define X86_FEATURE_PKS KVM_X86_CPU_FEATURE(0x7, 0, ECX, 31)
+#define X86_FEATURE_FRED KVM_X86_CPU_FEATURE(0x7, 1, EAX, 17)
+#define X86_FEATURE_LKGS KVM_X86_CPU_FEATURE(0x7, 1, EAX, 18)
+#define X86_FEATURE_WRMSRNS KVM_X86_CPU_FEATURE(0x7, 1, EAX, 19)
#define X86_FEATURE_XTILECFG KVM_X86_CPU_FEATURE(0xD, 0, EAX, 17)
#define X86_FEATURE_XTILEDATA KVM_X86_CPU_FEATURE(0xD, 0, EAX, 18)
#define X86_FEATURE_XSAVES KVM_X86_CPU_FEATURE(0xD, 1, EAX, 3)
diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c
index f6b295e0b2d2..69055e764f15 100644
--- a/tools/testing/selftests/kvm/x86_64/debug_regs.c
+++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c
@@ -20,7 +20,7 @@ uint32_t guest_value;
extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start;
-static void guest_code(void)
+static void guest_test_code(void)
{
/* Create a pending interrupt on current vCPU */
x2apic_enable();
@@ -61,6 +61,15 @@ static void guest_code(void)
/* DR6.BD test */
asm volatile("bd_start: mov %%dr0, %%rax" : : : "rax");
+}
+
+static void guest_code(void)
+{
+ guest_test_code();
+
+ if (get_cr4() & X86_CR4_FRED)
+ guest_test_code();
+
GUEST_DONE();
}
@@ -75,19 +84,15 @@ static void vcpu_skip_insn(struct kvm_vcpu *vcpu, int insn_len)
vcpu_regs_set(vcpu, ®s);
}
-int main(void)
+void run_test(struct kvm_vcpu *vcpu)
{
struct kvm_guest_debug debug;
+ struct kvm_run *run = vcpu->run;
unsigned long long target_dr6, target_rip;
- struct kvm_vcpu *vcpu;
- struct kvm_run *run;
- struct kvm_vm *vm;
- struct ucall uc;
- uint64_t cmd;
int i;
/* Instruction lengths starting at ss_start */
int ss_size[6] = {
- 1, /* sti*/
+ 1, /* sti */
2, /* xor */
2, /* cpuid */
5, /* mov */
@@ -95,11 +100,6 @@ int main(void)
1, /* cli */
};
- TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_GUEST_DEBUG));
-
- vm = vm_create_with_one_vcpu(&vcpu, guest_code);
- run = vcpu->run;
-
/* Test software BPs - int3 */
memset(&debug, 0, sizeof(debug));
debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
@@ -202,6 +202,30 @@ int main(void)
/* Disable all debug controls, run to the end */
memset(&debug, 0, sizeof(debug));
vcpu_guest_debug_set(vcpu, &debug);
+}
+
+int main(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ struct ucall uc;
+ uint64_t cmd;
+
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_GUEST_DEBUG));
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+ run_test(vcpu);
+
+ if (kvm_cpu_has(X86_FEATURE_FRED)) {
+ struct kvm_sregs sregs;
+
+ vcpu_sregs_get(vcpu, &sregs);
+ sregs.cr4 |= X86_CR4_FRED;
+ vcpu_sregs_set(vcpu, &sregs);
+
+ run_test(vcpu);
+ }
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
--
2.43.0
Add FRED VMCS fields to nested VMX context management.
Todo: change VMCS12_REVISION, as struct vmcs12 is changed.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
Change since v1:
* Remove hyperv TLFS related changes (Jeremi Piotrowski).
* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
---
Documentation/virt/kvm/x86/nested-vmx.rst | 18 +++++
arch/x86/kvm/vmx/nested.c | 91 +++++++++++++++++++----
arch/x86/kvm/vmx/vmcs12.c | 18 +++++
arch/x86/kvm/vmx/vmcs12.h | 36 +++++++++
arch/x86/kvm/vmx/vmcs_shadow_fields.h | 4 +
5 files changed, 152 insertions(+), 15 deletions(-)
diff --git a/Documentation/virt/kvm/x86/nested-vmx.rst b/Documentation/virt/kvm/x86/nested-vmx.rst
index e64ef231f310..87fa9f3877ab 100644
--- a/Documentation/virt/kvm/x86/nested-vmx.rst
+++ b/Documentation/virt/kvm/x86/nested-vmx.rst
@@ -218,6 +218,24 @@ struct shadow_vmcs is ever changed.
u16 host_gs_selector;
u16 host_tr_selector;
u64 secondary_vm_exit_controls;
+ u64 guest_ia32_fred_config;
+ u64 guest_ia32_fred_rsp1;
+ u64 guest_ia32_fred_rsp2;
+ u64 guest_ia32_fred_rsp3;
+ u64 guest_ia32_fred_stklvls;
+ u64 guest_ia32_fred_ssp1;
+ u64 guest_ia32_fred_ssp2;
+ u64 guest_ia32_fred_ssp3;
+ u64 host_ia32_fred_config;
+ u64 host_ia32_fred_rsp1;
+ u64 host_ia32_fred_rsp2;
+ u64 host_ia32_fred_rsp3;
+ u64 host_ia32_fred_stklvls;
+ u64 host_ia32_fred_ssp1;
+ u64 host_ia32_fred_ssp2;
+ u64 host_ia32_fred_ssp3;
+ u64 injected_event_data;
+ u64 original_event_data;
};
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 94da6a0a2f81..f9c1fbeac302 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -686,6 +686,9 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
MSR_KERNEL_GS_BASE, MSR_TYPE_RW);
+
+ nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
+ MSR_IA32_FRED_RSP0, MSR_TYPE_RW);
#endif
nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
MSR_IA32_SPEC_CTRL, MSR_TYPE_RW);
@@ -2498,6 +2501,8 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
vmcs12->vm_entry_instruction_len);
vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
vmcs12->guest_interruptibility_info);
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED))
+ vmcs_write64(INJECTED_EVENT_DATA, vmcs12->injected_event_data);
vmx->loaded_vmcs->nmi_known_unmasked =
!(vmcs12->guest_interruptibility_info & GUEST_INTR_STATE_NMI);
} else {
@@ -2548,6 +2553,17 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base);
vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base);
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs_write64(GUEST_IA32_FRED_CONFIG, vmcs12->guest_ia32_fred_config);
+ vmcs_write64(GUEST_IA32_FRED_RSP1, vmcs12->guest_ia32_fred_rsp1);
+ vmcs_write64(GUEST_IA32_FRED_RSP2, vmcs12->guest_ia32_fred_rsp2);
+ vmcs_write64(GUEST_IA32_FRED_RSP3, vmcs12->guest_ia32_fred_rsp3);
+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, vmcs12->guest_ia32_fred_stklvls);
+ vmcs_write64(GUEST_IA32_FRED_SSP1, vmcs12->guest_ia32_fred_ssp1);
+ vmcs_write64(GUEST_IA32_FRED_SSP2, vmcs12->guest_ia32_fred_ssp2);
+ vmcs_write64(GUEST_IA32_FRED_SSP3, vmcs12->guest_ia32_fred_ssp3);
+ }
+
vmx->segment_cache.bitmask = 0;
}
@@ -3835,6 +3851,22 @@ vmcs12_guest_cr4(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
vcpu->arch.cr4_guest_owned_bits));
}
+static inline unsigned long
+nested_vmx_get_event_data(struct kvm_vcpu *vcpu, bool for_ex_vmexit)
+{
+ struct kvm_queued_exception *ex = for_ex_vmexit ?
+ &vcpu->arch.exception_vmexit : &vcpu->arch.exception;
+
+ if (ex->has_payload)
+ return ex->payload;
+ else if (ex->vector == PF_VECTOR)
+ return vcpu->arch.cr2;
+ else if (ex->vector == DB_VECTOR)
+ return (vcpu->arch.dr6 & ~DR6_BT) ^ DR6_ACTIVE_LOW;
+ else
+ return 0;
+}
+
static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12,
u32 vm_exit_reason, u32 exit_intr_info)
@@ -3842,6 +3874,8 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
u32 idt_vectoring;
unsigned int nr;
+ vmcs12->original_event_data = 0;
+
/*
* Per the SDM, VM-Exits due to double and triple faults are never
* considered to occur during event delivery, even if the double/triple
@@ -3880,6 +3914,12 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
vcpu->arch.exception.error_code;
}
+ idt_vectoring |= vcpu->arch.exception.nested ?
+ INTR_INFO_NESTED_EXCEPTION_MASK : 0;
+
+ vmcs12->original_event_data =
+ nested_vmx_get_event_data(vcpu, false);
+
vmcs12->idt_vectoring_info_field = idt_vectoring;
} else if (vcpu->arch.nmi_injected) {
vmcs12->idt_vectoring_info_field =
@@ -3970,19 +4010,7 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu)
struct kvm_queued_exception *ex = &vcpu->arch.exception_vmexit;
u32 intr_info = ex->vector | INTR_INFO_VALID_MASK;
struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
- unsigned long exit_qual;
-
- if (ex->has_payload) {
- exit_qual = ex->payload;
- } else if (ex->vector == PF_VECTOR) {
- exit_qual = vcpu->arch.cr2;
- } else if (ex->vector == DB_VECTOR) {
- exit_qual = vcpu->arch.dr6;
- exit_qual &= ~DR6_BT;
- exit_qual ^= DR6_ACTIVE_LOW;
- } else {
- exit_qual = 0;
- }
+ unsigned long exit_qual = nested_vmx_get_event_data(vcpu, true);
/*
* Unlike AMD's Paged Real Mode, which reports an error code on #PF
@@ -4003,10 +4031,12 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu)
intr_info |= INTR_INFO_DELIVER_CODE_MASK;
}
- if (kvm_exception_is_soft(ex->vector))
+ if (kvm_exception_is_soft(ex->vector)) {
intr_info |= INTR_TYPE_SOFT_EXCEPTION;
- else
+ } else {
intr_info |= INTR_TYPE_HARD_EXCEPTION;
+ intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
+ }
if (!(vmcs12->idt_vectoring_info_field & VECTORING_INFO_VALID_MASK) &&
vmx_get_nmi_mask(vcpu))
@@ -4352,6 +4382,14 @@ static bool is_vmcs12_ext_field(unsigned long field)
case GUEST_TR_BASE:
case GUEST_GDTR_BASE:
case GUEST_IDTR_BASE:
+ case GUEST_IA32_FRED_CONFIG:
+ case GUEST_IA32_FRED_RSP1:
+ case GUEST_IA32_FRED_RSP2:
+ case GUEST_IA32_FRED_RSP3:
+ case GUEST_IA32_FRED_STKLVLS:
+ case GUEST_IA32_FRED_SSP1:
+ case GUEST_IA32_FRED_SSP2:
+ case GUEST_IA32_FRED_SSP3:
case GUEST_PENDING_DBG_EXCEPTIONS:
case GUEST_BNDCFGS:
return true;
@@ -4401,6 +4439,18 @@ static void sync_vmcs02_to_vmcs12_rare(struct kvm_vcpu *vcpu,
vmcs12->guest_tr_base = vmcs_readl(GUEST_TR_BASE);
vmcs12->guest_gdtr_base = vmcs_readl(GUEST_GDTR_BASE);
vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
+
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs12->guest_ia32_fred_config = vmcs_read64(GUEST_IA32_FRED_CONFIG);
+ vmcs12->guest_ia32_fred_rsp1 = vmcs_read64(GUEST_IA32_FRED_RSP1);
+ vmcs12->guest_ia32_fred_rsp2 = vmcs_read64(GUEST_IA32_FRED_RSP2);
+ vmcs12->guest_ia32_fred_rsp3 = vmcs_read64(GUEST_IA32_FRED_RSP3);
+ vmcs12->guest_ia32_fred_stklvls = vmcs_read64(GUEST_IA32_FRED_STKLVLS);
+ vmcs12->guest_ia32_fred_ssp1 = vmcs_read64(GUEST_IA32_FRED_SSP1);
+ vmcs12->guest_ia32_fred_ssp2 = vmcs_read64(GUEST_IA32_FRED_SSP2);
+ vmcs12->guest_ia32_fred_ssp3 = vmcs_read64(GUEST_IA32_FRED_SSP3);
+ }
+
vmcs12->guest_pending_dbg_exceptions =
vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
@@ -4625,6 +4675,17 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
vmcs_write32(GUEST_IDTR_LIMIT, 0xFFFF);
vmcs_write32(GUEST_GDTR_LIMIT, 0xFFFF);
+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
+ vmcs_write64(GUEST_IA32_FRED_CONFIG, vmcs12->host_ia32_fred_config);
+ vmcs_write64(GUEST_IA32_FRED_RSP1, vmcs12->host_ia32_fred_rsp1);
+ vmcs_write64(GUEST_IA32_FRED_RSP2, vmcs12->host_ia32_fred_rsp2);
+ vmcs_write64(GUEST_IA32_FRED_RSP3, vmcs12->host_ia32_fred_rsp3);
+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, vmcs12->host_ia32_fred_stklvls);
+ vmcs_write64(GUEST_IA32_FRED_SSP1, vmcs12->host_ia32_fred_ssp1);
+ vmcs_write64(GUEST_IA32_FRED_SSP2, vmcs12->host_ia32_fred_ssp2);
+ vmcs_write64(GUEST_IA32_FRED_SSP3, vmcs12->host_ia32_fred_ssp3);
+ }
+
/* If not VM_EXIT_CLEAR_BNDCFGS, the L2 value propagates to L1. */
if (vmcs12->vm_exit_controls & VM_EXIT_CLEAR_BNDCFGS)
vmcs_write64(GUEST_BNDCFGS, 0);
diff --git a/arch/x86/kvm/vmx/vmcs12.c b/arch/x86/kvm/vmx/vmcs12.c
index 98457d7b2b23..59f17fdfad11 100644
--- a/arch/x86/kvm/vmx/vmcs12.c
+++ b/arch/x86/kvm/vmx/vmcs12.c
@@ -80,6 +80,7 @@ const unsigned short vmcs12_field_offsets[] = {
FIELD(VM_ENTRY_MSR_LOAD_COUNT, vm_entry_msr_load_count),
FIELD(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field),
FIELD(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code),
+ FIELD(INJECTED_EVENT_DATA, injected_event_data),
FIELD(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len),
FIELD(TPR_THRESHOLD, tpr_threshold),
FIELD(SECONDARY_VM_EXEC_CONTROL, secondary_vm_exec_control),
@@ -89,6 +90,7 @@ const unsigned short vmcs12_field_offsets[] = {
FIELD(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code),
FIELD(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field),
FIELD(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code),
+ FIELD(ORIGINAL_EVENT_DATA, original_event_data),
FIELD(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len),
FIELD(VMX_INSTRUCTION_INFO, vmx_instruction_info),
FIELD(GUEST_ES_LIMIT, guest_es_limit),
@@ -152,5 +154,21 @@ const unsigned short vmcs12_field_offsets[] = {
FIELD(HOST_IA32_SYSENTER_EIP, host_ia32_sysenter_eip),
FIELD(HOST_RSP, host_rsp),
FIELD(HOST_RIP, host_rip),
+ FIELD(GUEST_IA32_FRED_CONFIG, guest_ia32_fred_config),
+ FIELD(GUEST_IA32_FRED_RSP1, guest_ia32_fred_rsp1),
+ FIELD(GUEST_IA32_FRED_RSP2, guest_ia32_fred_rsp2),
+ FIELD(GUEST_IA32_FRED_RSP3, guest_ia32_fred_rsp3),
+ FIELD(GUEST_IA32_FRED_STKLVLS, guest_ia32_fred_stklvls),
+ FIELD(GUEST_IA32_FRED_SSP1, guest_ia32_fred_ssp1),
+ FIELD(GUEST_IA32_FRED_SSP2, guest_ia32_fred_ssp2),
+ FIELD(GUEST_IA32_FRED_SSP3, guest_ia32_fred_ssp3),
+ FIELD(HOST_IA32_FRED_CONFIG, host_ia32_fred_config),
+ FIELD(HOST_IA32_FRED_RSP1, host_ia32_fred_rsp1),
+ FIELD(HOST_IA32_FRED_RSP2, host_ia32_fred_rsp2),
+ FIELD(HOST_IA32_FRED_RSP3, host_ia32_fred_rsp3),
+ FIELD(HOST_IA32_FRED_STKLVLS, host_ia32_fred_stklvls),
+ FIELD(HOST_IA32_FRED_SSP1, host_ia32_fred_ssp1),
+ FIELD(HOST_IA32_FRED_SSP2, host_ia32_fred_ssp2),
+ FIELD(HOST_IA32_FRED_SSP3, host_ia32_fred_ssp3),
};
const unsigned int nr_vmcs12_fields = ARRAY_SIZE(vmcs12_field_offsets);
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index f50f897b9b5f..edf7fcef8ccf 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -186,6 +186,24 @@ struct __packed vmcs12 {
u16 host_tr_selector;
u16 guest_pml_index;
u64 secondary_vm_exit_controls;
+ u64 guest_ia32_fred_config;
+ u64 guest_ia32_fred_rsp1;
+ u64 guest_ia32_fred_rsp2;
+ u64 guest_ia32_fred_rsp3;
+ u64 guest_ia32_fred_stklvls;
+ u64 guest_ia32_fred_ssp1;
+ u64 guest_ia32_fred_ssp2;
+ u64 guest_ia32_fred_ssp3;
+ u64 host_ia32_fred_config;
+ u64 host_ia32_fred_rsp1;
+ u64 host_ia32_fred_rsp2;
+ u64 host_ia32_fred_rsp3;
+ u64 host_ia32_fred_stklvls;
+ u64 host_ia32_fred_ssp1;
+ u64 host_ia32_fred_ssp2;
+ u64 host_ia32_fred_ssp3;
+ u64 injected_event_data;
+ u64 original_event_data;
};
/*
@@ -360,6 +378,24 @@ static inline void vmx_check_vmcs12_offsets(void)
CHECK_OFFSET(host_tr_selector, 994);
CHECK_OFFSET(guest_pml_index, 996);
CHECK_OFFSET(secondary_vm_exit_controls, 998);
+ CHECK_OFFSET(guest_ia32_fred_config, 1006);
+ CHECK_OFFSET(guest_ia32_fred_rsp1, 1014);
+ CHECK_OFFSET(guest_ia32_fred_rsp2, 1022);
+ CHECK_OFFSET(guest_ia32_fred_rsp3, 1030);
+ CHECK_OFFSET(guest_ia32_fred_stklvls, 1038);
+ CHECK_OFFSET(guest_ia32_fred_ssp1, 1046);
+ CHECK_OFFSET(guest_ia32_fred_ssp2, 1054);
+ CHECK_OFFSET(guest_ia32_fred_ssp3, 1062);
+ CHECK_OFFSET(host_ia32_fred_config, 1070);
+ CHECK_OFFSET(host_ia32_fred_rsp1, 1078);
+ CHECK_OFFSET(host_ia32_fred_rsp2, 1086);
+ CHECK_OFFSET(host_ia32_fred_rsp3, 1094);
+ CHECK_OFFSET(host_ia32_fred_stklvls, 1102);
+ CHECK_OFFSET(host_ia32_fred_ssp1, 1110);
+ CHECK_OFFSET(host_ia32_fred_ssp2, 1118);
+ CHECK_OFFSET(host_ia32_fred_ssp3, 1126);
+ CHECK_OFFSET(injected_event_data, 1134);
+ CHECK_OFFSET(original_event_data, 1142);
}
extern const unsigned short vmcs12_field_offsets[];
diff --git a/arch/x86/kvm/vmx/vmcs_shadow_fields.h b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
index 7f48056fe351..3885a3e0fbe8 100644
--- a/arch/x86/kvm/vmx/vmcs_shadow_fields.h
+++ b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
@@ -74,6 +74,10 @@ SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base, true)
/* 64-bit */
SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address, true)
SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address, true)
+SHADOW_FIELD_RO(ORIGINAL_EVENT_DATA, original_event_data, kvm_cpu_cap_has(X86_FEATURE_FRED))
+SHADOW_FIELD_RO(ORIGINAL_EVENT_DATA_HIGH, original_event_data, kvm_cpu_cap_has(X86_FEATURE_FRED))
+SHADOW_FIELD_RW(INJECTED_EVENT_DATA, injected_event_data, kvm_cpu_cap_has(X86_FEATURE_FRED))
+SHADOW_FIELD_RW(INJECTED_EVENT_DATA_HIGH, injected_event_data, kvm_cpu_cap_has(X86_FEATURE_FRED))
#undef SHADOW_FIELD_RO
#undef SHADOW_FIELD_RW
--
2.43.0
Add tests for FRED event data and VMX nested-exception.
FRED is designed to save a complete event context in its stack frame,
e.g., FRED saves the faulting linear address of a #PF into a 64-bit
event data field defined in FRED stack frame. As such, FRED VMX adds
event data handling during VMX transitions.
Besides, FRED introduces event stack levels to dispatch an event handler
onto a stack baesd on current stack level and stack levels defined in
IA32_FRED_STKLVLS MSR for each exception vector. VMX nested-exception
support ensures a correct event stack level is chosen when a VM entry
injects a nested exception, which is regarded as occurred in ring 0.
To fully test the underlying FRED VMX code, this test should be run one
more round with EPT disabled to inject page faults as nested exceptions.
Originally-by: Shan Kang <[email protected]>
Signed-off-by: Xin Li <[email protected]>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/processor.h | 32 ++
.../testing/selftests/kvm/x86_64/fred_test.c | 297 ++++++++++++++++++
3 files changed, 330 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/fred_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 492e937fab00..eaac13a605f2 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -67,6 +67,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features
TEST_GEN_PROGS_x86_64 += x86_64/exit_on_emulation_failure_test
TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_test
TEST_GEN_PROGS_x86_64 += x86_64/hwcr_msr_test
+TEST_GEN_PROGS_x86_64 += x86_64/fred_test
TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
TEST_GEN_PROGS_x86_64 += x86_64/hyperv_evmcs
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index bc5cd8628a20..ef7aaab790e0 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -1275,4 +1275,36 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
#define PFERR_GUEST_PAGE_MASK BIT_ULL(PFERR_GUEST_PAGE_BIT)
#define PFERR_IMPLICIT_ACCESS BIT_ULL(PFERR_IMPLICIT_ACCESS_BIT)
+/*
+ * FRED related data structures and functions
+ */
+
+#define FRED_SSX_NMI BIT_ULL(18)
+
+struct fred_stack {
+ u64 r15;
+ u64 r14;
+ u64 r13;
+ u64 r12;
+ u64 bp;
+ u64 bx;
+ u64 r11;
+ u64 r10;
+ u64 r9;
+ u64 r8;
+ u64 ax;
+ u64 cx;
+ u64 dx;
+ u64 si;
+ u64 di;
+ u64 error_code;
+ u64 ip;
+ u64 csx;
+ u64 flags;
+ u64 sp;
+ u64 ssx;
+ u64 event_data;
+ u64 reserved;
+};
+
#endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/x86_64/fred_test.c b/tools/testing/selftests/kvm/x86_64/fred_test.c
new file mode 100644
index 000000000000..412afa919568
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/fred_test.c
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * FRED nested exception tests
+ *
+ * Copyright (C) 2023, Intel, Inc.
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <asm/msr-index.h>
+
+#include "apic.h"
+#include "kvm_util.h"
+#include "test_util.h"
+#include "guest_modes.h"
+#include "processor.h"
+
+#define IRQ_VECTOR 0xAA
+
+#define FRED_STKLVL(v,l) (_AT(unsigned long, l) << (2 * (v)))
+#define FRED_CONFIG_ENTRYPOINT(p) _AT(unsigned long, (p))
+
+/* This address is already mapped in guest page table. */
+#define FRED_VALID_RSP 0x8000
+
+/*
+ * The following addresses are not yet mapped in both EPT and guest page
+ * tables at the beginning. As a result, it causes an EPT violation VM
+ * exit with an original guest #PF to access any of them for the first
+ * time.
+ *
+ * Use these addresses as guest FRED RSP0 to generate nested #PFs to test
+ * if event data are properly virtualized.
+ */
+static unsigned long fred_invalid_rsp[4] = {
+ 0x0,
+ 0xf0000000,
+ 0xe0000000,
+ 0xd0000000,
+};
+
+extern char asm_user_nop[];
+extern char asm_user_ud[];
+extern char asm_done_fault[];
+
+extern void asm_test_fault(int test);
+
+/*
+ * user level code for triggering faults.
+ */
+asm(".pushsection .text\n"
+ ".align 4096\n"
+
+ ".type asm_user_nop, @function\n"
+ "asm_user_nop:\n"
+ "1: .byte 0x90\n"
+ "jmp 1b\n"
+
+ ".fill asm_user_ud - ., 1, 0xcc\n"
+
+ ".type asm_user_ud, @function\n"
+ ".org asm_user_nop + 16\n"
+ "asm_user_ud:\n"
+ /* Trigger a #UD */
+ "ud2\n"
+
+ ".align 4096, 0xcc\n"
+ ".popsection");
+
+/* Send current stack level and #PF address */
+#define GUEST_SYNC_CSL_FA(__stage, __pf_address) \
+ GUEST_SYNC_ARGS(__stage, __pf_address, 0, 0, 0)
+
+void fred_entry_from_user(struct fred_stack *stack)
+{
+ u32 current_stack_level = rdmsr(MSR_IA32_FRED_CONFIG) & 0x3;
+
+ GUEST_SYNC_CSL_FA(current_stack_level, stack->event_data);
+
+ /* Do NOT go back to user level, continue the next test instead */
+ stack->ssx = 0x18;
+ stack->csx = 0x10;
+ stack->ip = (u64)&asm_done_fault;
+}
+
+void fred_entry_from_kernel(struct fred_stack *stack)
+{
+ /*
+ * Keep NMI blocked to delay the delivery of the next NMI until
+ * returning to user level.
+ * */
+ stack->ssx &= ~FRED_SSX_NMI;
+}
+
+#define PUSH_REGS \
+ "push %rdi\n" \
+ "push %rsi\n" \
+ "push %rdx\n" \
+ "push %rcx\n" \
+ "push %rax\n" \
+ "push %r8\n" \
+ "push %r9\n" \
+ "push %r10\n" \
+ "push %r11\n" \
+ "push %rbx\n" \
+ "push %rbp\n" \
+ "push %r12\n" \
+ "push %r13\n" \
+ "push %r14\n" \
+ "push %r15\n"
+
+#define POP_REGS \
+ "pop %r15\n" \
+ "pop %r14\n" \
+ "pop %r13\n" \
+ "pop %r12\n" \
+ "pop %rbp\n" \
+ "pop %rbx\n" \
+ "pop %r11\n" \
+ "pop %r10\n" \
+ "pop %r9\n" \
+ "pop %r8\n" \
+ "pop %rax\n" \
+ "pop %rcx\n" \
+ "pop %rdx\n" \
+ "pop %rsi\n" \
+ "pop %rdi\n"
+
+/*
+ * FRED entry points.
+ */
+asm(".pushsection .text\n"
+ ".type asm_fred_entrypoint_user, @function\n"
+ ".align 4096\n"
+ "asm_fred_entrypoint_user:\n"
+ "endbr64\n"
+ PUSH_REGS
+ "movq %rsp, %rdi\n"
+ "call fred_entry_from_user\n"
+ POP_REGS
+ /* Do NOT go back to user level, continue the next test instead */
+ ".byte 0xf2,0x0f,0x01,0xca\n" /* ERETS */
+
+ ".fill asm_fred_entrypoint_kernel - ., 1, 0xcc\n"
+
+ ".type asm_fred_entrypoint_kernel, @function\n"
+ ".org asm_fred_entrypoint_user + 256\n"
+ "asm_fred_entrypoint_kernel:\n"
+ "endbr64\n"
+ PUSH_REGS
+ "movq %rsp, %rdi\n"
+ "call fred_entry_from_kernel\n"
+ POP_REGS
+ ".byte 0xf2,0x0f,0x01,0xca\n" /* ERETS */
+ ".align 4096, 0xcc\n"
+ ".popsection");
+
+extern char asm_fred_entrypoint_user[];
+
+/*
+ * Prepare a FRED stack frame for ERETU to return to user level code,
+ * nop or ud2.
+ *
+ * Because FRED RSP0 is deliberately not mapped in guest page table,
+ * the delivery of interrupt/NMI or #UD from ring 3 causes a nested
+ * #PF, which is then delivered on FRED RSPx (x is 1, 2 or 3,
+ * determinated by MSR FRED_STKLVL[PF_VECTOR]).
+ */
+asm(".pushsection .text\n"
+ ".type asm_test_fault, @function\n"
+ ".align 4096\n"
+ "asm_test_fault:\n"
+ "endbr64\n"
+ "push %rbp\n"
+ "mov %rsp, %rbp\n"
+ "and $(~0x3f), %rsp\n"
+ "push $0\n"
+ "push $0\n"
+ "mov $0x2b, %rax\n"
+ /* Unblock NMI */
+ "bts $18, %rax\n"
+ /* Set long mode bit */
+ "bts $57, %rax\n"
+ "push %rax\n"
+ /* No stack required for the FRED user level test code */
+ "push $0\n"
+ "pushf\n"
+ "pop %rax\n"
+ /* Allow external interrupts */
+ "bts $9, %rax\n"
+ "push %rax\n"
+ "mov $0x33, %rax\n"
+ "push %rax\n"
+ "cmp $0, %edi\n"
+ "jne 1f\n"
+ "lea asm_user_nop(%rip), %rax\n"
+ "jmp 2f\n"
+ "1: lea asm_user_ud(%rip), %rax\n"
+ "2: push %rax\n"
+ "push $0\n"
+ /* ERETU to user level code to allow event delivery immediately */
+ ".byte 0xf3,0x0f,0x01,0xca\n"
+ "asm_done_fault:\n"
+ "mov %rbp, %rsp\n"
+ "pop %rbp\n"
+ "ret\n"
+ ".align 4096, 0xcc\n"
+ ".popsection");
+
+/*
+ * To fully test the underlying FRED VMX code, this test should be run one
+ * more round with EPT disabled to inject page faults as nested exceptions.
+ */
+static void guest_code(void)
+{
+ wrmsr(MSR_IA32_FRED_CONFIG,
+ FRED_CONFIG_ENTRYPOINT(asm_fred_entrypoint_user));
+
+ wrmsr(MSR_IA32_FRED_RSP1, FRED_VALID_RSP);
+ wrmsr(MSR_IA32_FRED_RSP2, FRED_VALID_RSP);
+ wrmsr(MSR_IA32_FRED_RSP3, FRED_VALID_RSP);
+
+ /* Enable FRED */
+ set_cr4(get_cr4() | X86_CR4_FRED);
+
+ x2apic_enable();
+
+ wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 1));
+ wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[1]);
+ /* 1: ud2 to generate #UD */
+ asm_test_fault(1);
+
+ wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 2));
+ wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[2]);
+ asm volatile("cli");
+ /* Create a pending interrupt on current vCPU */
+ x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
+ APIC_DM_FIXED | IRQ_VECTOR);
+ /* Return to ring 3 */
+ asm_test_fault(0);
+ x2apic_write_reg(APIC_EOI, 0);
+
+ wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 3));
+ wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[3]);
+ /*
+ * The first NMI is just to have NMI blocked in ring 0, because
+ * fred_entry_from_kernel() deliberately clears the NMI bit in
+ * FRED stack frame.
+ */
+ x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
+ APIC_DM_NMI | NMI_VECTOR);
+ /* The second NMI will be delivered after returning to ring 3 */
+ x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
+ APIC_DM_NMI | NMI_VECTOR);
+ /* Return to ring 3 */
+ asm_test_fault(0);
+
+ GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ struct ucall uc;
+ uint64_t expected_current_stack_level = 1;
+
+ TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_FRED));
+
+ vm = __vm_create_with_vcpus(VM_SHAPE(VM_MODE_PXXV48_4K_USER), 1, 0,
+ guest_code, &vcpu);
+
+ while (true) {
+ uint64_t r;
+
+ vcpu_run(vcpu);
+
+ r = get_ucall(vcpu, &uc);
+
+ if (r == UCALL_DONE)
+ break;
+
+ if (r == UCALL_SYNC) {
+ TEST_ASSERT((uc.args[1] == expected_current_stack_level) &&
+ (uc.args[2] == fred_invalid_rsp[expected_current_stack_level] - 1),
+ "Incorrect stack level %lx and #PF address %lx\n",
+ uc.args[1], uc.args[2]);
+ expected_current_stack_level++;
+ }
+ }
+
+ kvm_vm_free(vm);
+ return 0;
+}
--
2.43.0
Add FRED related VMCS fields checkings.
As real hardware, nested VMX performs checks on various VMCS fields,
including both controls and guest/host states. With the introduction
of VMX FRED, add FRED related VMCS fields checkings.
Signed-off-by: Xin Li <[email protected]>
Tested-by: Shan Kang <[email protected]>
---
arch/x86/kvm/vmx/nested.c | 80 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 79 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 04a9cdb0361f..ef0bd46eb0ce 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2933,6 +2933,8 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
+ bool fred_enabled = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) &&
+ (vmcs12->guest_cr4 & X86_CR4_FRED);
if (CC(!vmx_control_verify(vmcs12->vm_entry_controls,
vmx->nested.msrs.entry_ctls_low,
@@ -2951,6 +2953,7 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
u32 intr_type = intr_info & INTR_INFO_INTR_TYPE_MASK;
bool has_error_code = intr_info & INTR_INFO_DELIVER_CODE_MASK;
bool should_have_error_code;
+ bool has_nested_exception = vmx->nested.msrs.basic & VMX_BASIC_NESTED_EXCEPTION;
bool urg = nested_cpu_has2(vmcs12,
SECONDARY_EXEC_UNRESTRICTED_GUEST);
bool prot_mode = !urg || vmcs12->guest_cr0 & X86_CR0_PE;
@@ -2964,7 +2967,9 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
/* VM-entry interruption-info field: vector */
if (CC(intr_type == INTR_TYPE_NMI_INTR && vector != NMI_VECTOR) ||
CC(intr_type == INTR_TYPE_HARD_EXCEPTION && vector > 31) ||
- CC(intr_type == INTR_TYPE_OTHER_EVENT && vector != 0))
+ CC(intr_type == INTR_TYPE_OTHER_EVENT &&
+ ((!fred_enabled && vector > 0) ||
+ (fred_enabled && vector > 2))))
return -EINVAL;
/* VM-entry interruption-info field: deliver error code */
@@ -2983,6 +2988,15 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
if (CC(intr_info & INTR_INFO_RESVD_BITS_MASK))
return -EINVAL;
+ /*
+ * When the CPU enumerates VMX nested-exception support, bit 13
+ * (set to indicate a nested exception) of the intr info field
+ * may have value 1. Otherwise bit 13 is reserved.
+ */
+ if (CC(!has_nested_exception &&
+ (intr_info & INTR_INFO_NESTED_EXCEPTION_MASK)))
+ return -EINVAL;
+
/* VM-entry instruction length */
switch (intr_type) {
case INTR_TYPE_SOFT_EXCEPTION:
@@ -2992,6 +3006,12 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
CC(vmcs12->vm_entry_instruction_len == 0 &&
CC(!nested_cpu_has_zero_length_injection(vcpu))))
return -EINVAL;
+ break;
+ case INTR_TYPE_OTHER_EVENT:
+ if (fred_enabled && (vector == 1 || vector == 2))
+ if (CC(vmcs12->vm_entry_instruction_len > 15))
+ return -EINVAL;
+ break;
}
}
@@ -3054,9 +3074,30 @@ static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu,
if (ia32e) {
if (CC(!(vmcs12->host_cr4 & X86_CR4_PAE)))
return -EINVAL;
+ if (vmcs12->vm_exit_controls & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS &&
+ vmcs12->secondary_vm_exit_controls & SECONDARY_VM_EXIT_LOAD_IA32_FRED) {
+ /* Bit 11, bits 5:4, and bit 2 of the IA32_FRED_CONFIG must be zero */
+ if (CC(vmcs12->host_ia32_fred_config &
+ (BIT_ULL(11) | GENMASK_ULL(5, 4) | BIT_ULL(2))) ||
+ CC(vmcs12->host_ia32_fred_rsp1 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->host_ia32_fred_rsp2 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->host_ia32_fred_rsp3 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->host_ia32_fred_ssp1 & GENMASK_ULL(2, 0)) ||
+ CC(vmcs12->host_ia32_fred_ssp2 & GENMASK_ULL(2, 0)) ||
+ CC(vmcs12->host_ia32_fred_ssp3 & GENMASK_ULL(2, 0)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_config & PAGE_MASK, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_rsp1, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_rsp2, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_rsp3, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_ssp1, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_ssp2, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->host_ia32_fred_ssp3, vcpu)))
+ return -EINVAL;
+ }
} else {
if (CC(vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) ||
CC(vmcs12->host_cr4 & X86_CR4_PCIDE) ||
+ CC(vmcs12->host_cr4 & X86_CR4_FRED) ||
CC((vmcs12->host_rip) >> 32))
return -EINVAL;
}
@@ -3200,6 +3241,43 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu,
CC((vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD))))
return -EINVAL;
+ if (ia32e) {
+ if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_FRED) {
+ /* Bit 11, bits 5:4, and bit 2 of the IA32_FRED_CONFIG must be zero */
+ if (CC(vmcs12->guest_ia32_fred_config &
+ (BIT_ULL(11) | GENMASK_ULL(5, 4) | BIT_ULL(2))) ||
+ CC(vmcs12->guest_ia32_fred_rsp1 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->guest_ia32_fred_rsp2 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->guest_ia32_fred_rsp3 & GENMASK_ULL(5, 0)) ||
+ CC(vmcs12->guest_ia32_fred_ssp1 & GENMASK_ULL(2, 0)) ||
+ CC(vmcs12->guest_ia32_fred_ssp2 & GENMASK_ULL(2, 0)) ||
+ CC(vmcs12->guest_ia32_fred_ssp3 & GENMASK_ULL(2, 0)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_config & PAGE_MASK, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_rsp1, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_rsp2, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_rsp3, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_ssp1, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_ssp2, vcpu)) ||
+ CC(is_noncanonical_address(vmcs12->guest_ia32_fred_ssp3, vcpu)))
+ return -EINVAL;
+ }
+ if (vmcs12->guest_cr4 & X86_CR4_FRED) {
+ unsigned int ss_dpl = VMX_AR_DPL(vmcs12->guest_ss_ar_bytes);
+ if (CC(ss_dpl == 1 || ss_dpl == 2))
+ return -EINVAL;
+ if (ss_dpl == 0 &&
+ CC(!(vmcs12->guest_cs_ar_bytes & VMX_AR_L_MASK)))
+ return -EINVAL;
+ if (ss_dpl == 3 &&
+ (CC(vmcs12->guest_rflags & X86_EFLAGS_IOPL) ||
+ CC(vmcs12->guest_interruptibility_info & GUEST_INTR_STATE_STI)))
+ return -EINVAL;
+ }
+ } else {
+ if (CC(vmcs12->guest_cr4 & X86_CR4_FRED))
+ return -EINVAL;
+ }
+
if (nested_check_guest_non_reg_state(vmcs12))
return -EINVAL;
--
2.43.0
Add a new VM guest mode VM_MODE_PXXV48_4K_USER to set the user bit of
guest page table entries, thus allow user level code to run in guests.
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Xin Li <[email protected]>
---
.../testing/selftests/kvm/include/kvm_util_base.h | 1 +
tools/testing/selftests/kvm/lib/kvm_util.c | 5 ++++-
.../testing/selftests/kvm/lib/x86_64/processor.c | 15 ++++++++++-----
tools/testing/selftests/kvm/lib/x86_64/vmx.c | 4 ++--
4 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 9e5afc472c14..ea1a585ef6f4 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -187,6 +187,7 @@ enum vm_guest_mode {
VM_MODE_P36V48_16K,
VM_MODE_P36V48_64K,
VM_MODE_P36V47_16K,
+ VM_MODE_PXXV48_4K_USER, /* For 48bits VA but ANY bits PA with USER bit set */
NUM_VM_MODES,
};
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index e066d584c656..8b4761836b3e 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -163,6 +163,7 @@ const char *vm_guest_mode_string(uint32_t i)
[VM_MODE_P36V48_16K] = "PA-bits:36, VA-bits:48, 16K pages",
[VM_MODE_P36V48_64K] = "PA-bits:36, VA-bits:48, 64K pages",
[VM_MODE_P36V47_16K] = "PA-bits:36, VA-bits:47, 16K pages",
+ [VM_MODE_PXXV48_4K_USER] = "PA-bits:ANY, VA-bits:48, 4K user pages",
};
_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
"Missing new mode strings?");
@@ -189,6 +190,7 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
[VM_MODE_P36V48_16K] = { 36, 48, 0x4000, 14 },
[VM_MODE_P36V48_64K] = { 36, 48, 0x10000, 16 },
[VM_MODE_P36V47_16K] = { 36, 47, 0x4000, 14 },
+ [VM_MODE_PXXV48_4K_USER] = { 0, 0, 0x1000, 12 },
};
_Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct vm_guest_mode_params) == NUM_VM_MODES,
"Missing new mode params?");
@@ -263,6 +265,7 @@ struct kvm_vm *____vm_create(struct vm_shape shape)
vm->pgtable_levels = 3;
break;
case VM_MODE_PXXV48_4K:
+ case VM_MODE_PXXV48_4K_USER:
#ifdef __x86_64__
kvm_get_cpu_address_width(&vm->pa_bits, &vm->va_bits);
/*
@@ -278,7 +281,7 @@ struct kvm_vm *____vm_create(struct vm_shape shape)
vm->pgtable_levels = 4;
vm->va_bits = 48;
#else
- TEST_FAIL("VM_MODE_PXXV48_4K not supported on non-x86 platforms");
+ TEST_FAIL("VM_MODE_PXXV48_4K(_USER) not supported on non-x86 platforms");
#endif
break;
case VM_MODE_P47V64_4K:
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index d8288374078e..a8e60641df53 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -124,8 +124,8 @@ bool kvm_is_tdp_enabled(void)
void virt_arch_pgd_alloc(struct kvm_vm *vm)
{
- TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
- "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
+ TEST_ASSERT((vm->mode == VM_MODE_PXXV48_4K) || (vm->mode == VM_MODE_PXXV48_4K_USER),
+ "Attempt to use unknown or unsupported guest mode, mode: 0x%x", vm->mode);
/* If needed, create page map l4 table. */
if (!vm->pgd_created) {
@@ -159,6 +159,8 @@ static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
if (!(*pte & PTE_PRESENT_MASK)) {
*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK;
+ if (vm->mode == VM_MODE_PXXV48_4K_USER)
+ *pte |= PTE_USER_MASK;
if (current_level == target_level)
*pte |= PTE_LARGE_MASK | (paddr & PHYSICAL_PAGE_MASK);
else
@@ -185,7 +187,7 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
uint64_t *pml4e, *pdpe, *pde;
uint64_t *pte;
- TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K,
+ TEST_ASSERT((vm->mode == VM_MODE_PXXV48_4K) || (vm->mode == VM_MODE_PXXV48_4K_USER),
"Unknown or unsupported guest mode, mode: 0x%x", vm->mode);
TEST_ASSERT((vaddr % pg_size) == 0,
@@ -222,6 +224,8 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
TEST_ASSERT(!(*pte & PTE_PRESENT_MASK),
"PTE already present for 4k page at vaddr: 0x%lx\n", vaddr);
*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK | (paddr & PHYSICAL_PAGE_MASK);
+ if (vm->mode == VM_MODE_PXXV48_4K_USER)
+ *pte |= PTE_USER_MASK;
}
void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
@@ -268,8 +272,8 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
TEST_ASSERT(*level >= PG_LEVEL_NONE && *level < PG_LEVEL_NUM,
"Invalid PG_LEVEL_* '%d'", *level);
- TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
- "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
+ TEST_ASSERT((vm->mode == VM_MODE_PXXV48_4K) || (vm->mode == VM_MODE_PXXV48_4K_USER),
+ "Attempt to use unknown or unsupported guest mode, mode: 0x%x", vm->mode);
TEST_ASSERT(sparsebit_is_set(vm->vpages_valid,
(vaddr >> vm->page_shift)),
"Invalid virtual address, vaddr: 0x%lx",
@@ -536,6 +540,7 @@ static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
switch (vm->mode) {
case VM_MODE_PXXV48_4K:
+ case VM_MODE_PXXV48_4K_USER:
sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
diff --git a/tools/testing/selftests/kvm/lib/x86_64/vmx.c b/tools/testing/selftests/kvm/lib/x86_64/vmx.c
index 59d97531c9b1..65147de6f9c0 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/vmx.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/vmx.c
@@ -403,8 +403,8 @@ void __nested_pg_map(struct vmx_pages *vmx, struct kvm_vm *vm,
struct eptPageTableEntry *pt = vmx->eptp_hva, *pte;
uint16_t index;
- TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
- "unknown or unsupported guest mode, mode: 0x%x", vm->mode);
+ TEST_ASSERT((vm->mode == VM_MODE_PXXV48_4K) || (vm->mode == VM_MODE_PXXV48_4K_USER),
+ "Attempt to use unknown or unsupported guest mode, mode: 0x%x", vm->mode);
TEST_ASSERT((nested_paddr >> 48) == 0,
"Nested physical address 0x%lx requires 5-level paging",
--
2.43.0
Set VMX CPU capabilities before initializing nested instead of after,
as it needs to check VMX CPU capabilities to setup the VMX basic MSR
for nested.
Signed-off-by: Xin Li <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e3409607122d..fc808d599493 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8912,6 +8912,8 @@ static __init int hardware_setup(void)
setup_default_sgx_lepubkeyhash();
+ vmx_set_cpu_caps();
+
if (nested) {
nested_vmx_setup_ctls_msrs(&vmcs_config, vmx_capability.ept);
@@ -8920,8 +8922,6 @@ static __init int hardware_setup(void)
return r;
}
- vmx_set_cpu_caps();
-
r = alloc_kvm_area();
if (r && nested)
nested_vmx_hardware_unsetup();
--
2.43.0
On Wed, 2024-02-07 at 09:26 -0800, Xin Li wrote:
> This patch set enables the Intel flexible return and event delivery
> (FRED) architecture with KVM VMX to allow guests to utilize FRED.
>
We tested this FRED KVM patch set on a 7th Intel(R) Core(TM) CPU and the Intel
Simics® Simulator with the following four configurations:
The first config is the baseline on bare metal.
The second config is the baseline on Intel Simics® Simulator.
The third config enables host FRED, but disables guest FRED.
The last config enables both host and guest FRED.
Following are the Kselftest results on KVM guests.
+---------------------------------------------+-------+-------+-------+-------+
| Config | Pass | Fail | Skip | Hang |
+---------------------------------------------+-------+-------+-------+-------+
|the 7th Intel(R) Core(TM) CPU | | | | |
| L0: 6.8.0-rc3+ w/ FRED native/KVM patch set| 1775 | 526 | 332 | 6 |
| L1: 6.8.0-rc3+ | | | | |
+---------------------------------------------+-------+-------+-------+-------+
|Intel Simics® Simulator w/o FRED model | | | | |
| L0: 6.8.0-rc3+ w/ FRED native/KVM patch set| 1770 | 526 | 331 | 12 |
| L1: 6.8.0-rc3+ w/ FRED native/KVM patch set| | | | |
+---------------------------------------------+-------+-------+-------+-------+
|Intel Simics® Simulator w/ FRED model | | | | |
| L0: 6.8.0-rc3+ w/ FRED native/KVM patch set| 1770 | 526 | 331 | 12 |
| L1: 6.8.0-rc3+ w/ FRED native/KVM patch set| | | | |
| but FRED disabled | | | | |
+---------------------------------------------+-------+-------+-------+-------+
|Intel Simics® Simulator w/ FRED model | | | | |
| L0: 6.8.0-rc3+ w/ FRED native/KVM patch set| 1769 | 528 | 330 | 12 |
| L1: 6.8.0-rc3+ w/ FRED native/KVM patch set| | | | |
+---------------------------------------------+-------+-------+-------+-------+
First of all we don't see any major issue. One major differences come from
perf tests. Another variances are from timer tests due to Intel Simics®
emulator's slowness.
The tests "x86:sysret_rip_64" and "x86:sigreturn_32" fail on the last config,
because they are not valid tests for FRED:
https://lore.kernel.org/lkml/[email protected]/T/#u
https://lore.kernel.org/lkml/[email protected]/
NB: Some tests pass on Intel Simics® emulator, but not bare metal. If needed,
we can share the data.
We conducted local live migration tests with LKGS/FRED/WRMSRNS enabled/disabled
on Intel Simics® Simulator, and see no problems.
We also tested KVM Kselftest on a nested FRED KVM guest, 48 out of 83 cases
passed and the rest cases failed due to the slowness of Intel Simics® emulator.
Detailed report upon request.
On 2/7/24 10:26 PM, Xin Li wrote:
> Add tests for FRED event data and VMX nested-exception.
>
> FRED is designed to save a complete event context in its stack frame,
> e.g., FRED saves the faulting linear address of a #PF into a 64-bit
> event data field defined in FRED stack frame. As such, FRED VMX adds
> event data handling during VMX transitions.
>
> Besides, FRED introduces event stack levels to dispatch an event handler
> onto a stack baesd on current stack level and stack levels defined in
> IA32_FRED_STKLVLS MSR for each exception vector. VMX nested-exception
> support ensures a correct event stack level is chosen when a VM entry
> injects a nested exception, which is regarded as occurred in ring 0.
>
> To fully test the underlying FRED VMX code, this test should be run one
> more round with EPT disabled to inject page faults as nested exceptions.
>
> Originally-by: Shan Kang <[email protected]>
> Signed-off-by: Xin Li <[email protected]>
Thank you for the new test patch. We have been trying to ensure TAP
conformance for tests which cannot be achieved if new tests aren't using
TAP already. Please make your test TAP compliant.
> ---
> tools/testing/selftests/kvm/Makefile | 1 +
> .../selftests/kvm/include/x86_64/processor.h | 32 ++
> .../testing/selftests/kvm/x86_64/fred_test.c | 297 ++++++++++++++++++
Add generated binary object to .gitignore.
> 3 files changed, 330 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/x86_64/fred_test.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 492e937fab00..eaac13a605f2 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -67,6 +67,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features
> TEST_GEN_PROGS_x86_64 += x86_64/exit_on_emulation_failure_test
> TEST_GEN_PROGS_x86_64 += x86_64/fix_hypercall_test
> TEST_GEN_PROGS_x86_64 += x86_64/hwcr_msr_test
> +TEST_GEN_PROGS_x86_64 += x86_64/fred_test
> TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
> TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
> TEST_GEN_PROGS_x86_64 += x86_64/hyperv_evmcs
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index bc5cd8628a20..ef7aaab790e0 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -1275,4 +1275,36 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> #define PFERR_GUEST_PAGE_MASK BIT_ULL(PFERR_GUEST_PAGE_BIT)
> #define PFERR_IMPLICIT_ACCESS BIT_ULL(PFERR_IMPLICIT_ACCESS_BIT)
>
> +/*
> + * FRED related data structures and functions
> + */
> +
> +#define FRED_SSX_NMI BIT_ULL(18)
> +
> +struct fred_stack {
> + u64 r15;
> + u64 r14;
> + u64 r13;
> + u64 r12;
> + u64 bp;
> + u64 bx;
> + u64 r11;
> + u64 r10;
> + u64 r9;
> + u64 r8;
> + u64 ax;
> + u64 cx;
> + u64 dx;
> + u64 si;
> + u64 di;
> + u64 error_code;
> + u64 ip;
> + u64 csx;
> + u64 flags;
> + u64 sp;
> + u64 ssx;
> + u64 event_data;
> + u64 reserved;
> +};
> +
> #endif /* SELFTEST_KVM_PROCESSOR_H */
> diff --git a/tools/testing/selftests/kvm/x86_64/fred_test.c b/tools/testing/selftests/kvm/x86_64/fred_test.c
> new file mode 100644
> index 000000000000..412afa919568
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/fred_test.c
> @@ -0,0 +1,297 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * FRED nested exception tests
> + *
> + * Copyright (C) 2023, Intel, Inc.
> + */
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +#include <asm/msr-index.h>
> +
> +#include "apic.h"
> +#include "kvm_util.h"
> +#include "test_util.h"
> +#include "guest_modes.h"
> +#include "processor.h"
> +
> +#define IRQ_VECTOR 0xAA
> +
> +#define FRED_STKLVL(v,l) (_AT(unsigned long, l) << (2 * (v)))
> +#define FRED_CONFIG_ENTRYPOINT(p) _AT(unsigned long, (p))
> +
> +/* This address is already mapped in guest page table. */
> +#define FRED_VALID_RSP 0x8000
> +
> +/*
> + * The following addresses are not yet mapped in both EPT and guest page
> + * tables at the beginning. As a result, it causes an EPT violation VM
> + * exit with an original guest #PF to access any of them for the first
> + * time.
> + *
> + * Use these addresses as guest FRED RSP0 to generate nested #PFs to test
> + * if event data are properly virtualized.
> + */
> +static unsigned long fred_invalid_rsp[4] = {
> + 0x0,
> + 0xf0000000,
> + 0xe0000000,
> + 0xd0000000,
> +};
> +
> +extern char asm_user_nop[];
> +extern char asm_user_ud[];
> +extern char asm_done_fault[];
> +
> +extern void asm_test_fault(int test);
> +
> +/*
> + * user level code for triggering faults.
> + */
> +asm(".pushsection .text\n"
> + ".align 4096\n"
> +
> + ".type asm_user_nop, @function\n"
> + "asm_user_nop:\n"
> + "1: .byte 0x90\n"
> + "jmp 1b\n"
> +
> + ".fill asm_user_ud - ., 1, 0xcc\n"
> +
> + ".type asm_user_ud, @function\n"
> + ".org asm_user_nop + 16\n"
> + "asm_user_ud:\n"
> + /* Trigger a #UD */
> + "ud2\n"
> +
> + ".align 4096, 0xcc\n"
> + ".popsection");
> +
> +/* Send current stack level and #PF address */
> +#define GUEST_SYNC_CSL_FA(__stage, __pf_address) \
> + GUEST_SYNC_ARGS(__stage, __pf_address, 0, 0, 0)
> +
> +void fred_entry_from_user(struct fred_stack *stack)
> +{
> + u32 current_stack_level = rdmsr(MSR_IA32_FRED_CONFIG) & 0x3;
> +
> + GUEST_SYNC_CSL_FA(current_stack_level, stack->event_data);
> +
> + /* Do NOT go back to user level, continue the next test instead */
> + stack->ssx = 0x18;
> + stack->csx = 0x10;
> + stack->ip = (u64)&asm_done_fault;
> +}
> +
> +void fred_entry_from_kernel(struct fred_stack *stack)
> +{
> + /*
> + * Keep NMI blocked to delay the delivery of the next NMI until
> + * returning to user level.
> + * */
> + stack->ssx &= ~FRED_SSX_NMI;
> +}
> +
> +#define PUSH_REGS \
> + "push %rdi\n" \
> + "push %rsi\n" \
> + "push %rdx\n" \
> + "push %rcx\n" \
> + "push %rax\n" \
> + "push %r8\n" \
> + "push %r9\n" \
> + "push %r10\n" \
> + "push %r11\n" \
> + "push %rbx\n" \
> + "push %rbp\n" \
> + "push %r12\n" \
> + "push %r13\n" \
> + "push %r14\n" \
> + "push %r15\n"
> +
> +#define POP_REGS \
> + "pop %r15\n" \
> + "pop %r14\n" \
> + "pop %r13\n" \
> + "pop %r12\n" \
> + "pop %rbp\n" \
> + "pop %rbx\n" \
> + "pop %r11\n" \
> + "pop %r10\n" \
> + "pop %r9\n" \
> + "pop %r8\n" \
> + "pop %rax\n" \
> + "pop %rcx\n" \
> + "pop %rdx\n" \
> + "pop %rsi\n" \
> + "pop %rdi\n"
> +
> +/*
> + * FRED entry points.
> + */
> +asm(".pushsection .text\n"
> + ".type asm_fred_entrypoint_user, @function\n"
> + ".align 4096\n"
> + "asm_fred_entrypoint_user:\n"
> + "endbr64\n"
> + PUSH_REGS
> + "movq %rsp, %rdi\n"
> + "call fred_entry_from_user\n"
> + POP_REGS
> + /* Do NOT go back to user level, continue the next test instead */
> + ".byte 0xf2,0x0f,0x01,0xca\n" /* ERETS */
> +
> + ".fill asm_fred_entrypoint_kernel - ., 1, 0xcc\n"
> +
> + ".type asm_fred_entrypoint_kernel, @function\n"
> + ".org asm_fred_entrypoint_user + 256\n"
> + "asm_fred_entrypoint_kernel:\n"
> + "endbr64\n"
> + PUSH_REGS
> + "movq %rsp, %rdi\n"
> + "call fred_entry_from_kernel\n"
> + POP_REGS
> + ".byte 0xf2,0x0f,0x01,0xca\n" /* ERETS */
> + ".align 4096, 0xcc\n"
> + ".popsection");
> +
> +extern char asm_fred_entrypoint_user[];
> +
> +/*
> + * Prepare a FRED stack frame for ERETU to return to user level code,
> + * nop or ud2.
> + *
> + * Because FRED RSP0 is deliberately not mapped in guest page table,
> + * the delivery of interrupt/NMI or #UD from ring 3 causes a nested
> + * #PF, which is then delivered on FRED RSPx (x is 1, 2 or 3,
> + * determinated by MSR FRED_STKLVL[PF_VECTOR]).
> + */
> +asm(".pushsection .text\n"
> + ".type asm_test_fault, @function\n"
> + ".align 4096\n"
> + "asm_test_fault:\n"
> + "endbr64\n"
> + "push %rbp\n"
> + "mov %rsp, %rbp\n"
> + "and $(~0x3f), %rsp\n"
> + "push $0\n"
> + "push $0\n"
> + "mov $0x2b, %rax\n"
> + /* Unblock NMI */
> + "bts $18, %rax\n"
> + /* Set long mode bit */
> + "bts $57, %rax\n"
> + "push %rax\n"
> + /* No stack required for the FRED user level test code */
> + "push $0\n"
> + "pushf\n"
> + "pop %rax\n"
> + /* Allow external interrupts */
> + "bts $9, %rax\n"
> + "push %rax\n"
> + "mov $0x33, %rax\n"
> + "push %rax\n"
> + "cmp $0, %edi\n"
> + "jne 1f\n"
> + "lea asm_user_nop(%rip), %rax\n"
> + "jmp 2f\n"
> + "1: lea asm_user_ud(%rip), %rax\n"
> + "2: push %rax\n"
> + "push $0\n"
> + /* ERETU to user level code to allow event delivery immediately */
> + ".byte 0xf3,0x0f,0x01,0xca\n"
> + "asm_done_fault:\n"
> + "mov %rbp, %rsp\n"
> + "pop %rbp\n"
> + "ret\n"
> + ".align 4096, 0xcc\n"
> + ".popsection");
> +
> +/*
> + * To fully test the underlying FRED VMX code, this test should be run one
> + * more round with EPT disabled to inject page faults as nested exceptions.
> + */
> +static void guest_code(void)
> +{
> + wrmsr(MSR_IA32_FRED_CONFIG,
> + FRED_CONFIG_ENTRYPOINT(asm_fred_entrypoint_user));
> +
> + wrmsr(MSR_IA32_FRED_RSP1, FRED_VALID_RSP);
> + wrmsr(MSR_IA32_FRED_RSP2, FRED_VALID_RSP);
> + wrmsr(MSR_IA32_FRED_RSP3, FRED_VALID_RSP);
> +
> + /* Enable FRED */
> + set_cr4(get_cr4() | X86_CR4_FRED);
> +
> + x2apic_enable();
> +
> + wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 1));
> + wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[1]);
> + /* 1: ud2 to generate #UD */
> + asm_test_fault(1);
> +
> + wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 2));
> + wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[2]);
> + asm volatile("cli");
> + /* Create a pending interrupt on current vCPU */
> + x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
> + APIC_DM_FIXED | IRQ_VECTOR);
> + /* Return to ring 3 */
> + asm_test_fault(0);
> + x2apic_write_reg(APIC_EOI, 0);
> +
> + wrmsr(MSR_IA32_FRED_STKLVLS, FRED_STKLVL(PF_VECTOR, 3));
> + wrmsr(MSR_IA32_FRED_RSP0, fred_invalid_rsp[3]);
> + /*
> + * The first NMI is just to have NMI blocked in ring 0, because
> + * fred_entry_from_kernel() deliberately clears the NMI bit in
> + * FRED stack frame.
> + */
> + x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
> + APIC_DM_NMI | NMI_VECTOR);
> + /* The second NMI will be delivered after returning to ring 3 */
> + x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |
> + APIC_DM_NMI | NMI_VECTOR);
> + /* Return to ring 3 */
> + asm_test_fault(0);
> +
> + GUEST_DONE();
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + struct kvm_vcpu *vcpu;
> + struct kvm_vm *vm;
> + struct ucall uc;
> + uint64_t expected_current_stack_level = 1;
> +
> + TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_FRED));
> +
> + vm = __vm_create_with_vcpus(VM_SHAPE(VM_MODE_PXXV48_4K_USER), 1, 0,
> + guest_code, &vcpu);
> +
> + while (true) {
> + uint64_t r;
> +
> + vcpu_run(vcpu);
> +
> + r = get_ucall(vcpu, &uc);
> +
> + if (r == UCALL_DONE)
> + break;
> +
> + if (r == UCALL_SYNC) {
> + TEST_ASSERT((uc.args[1] == expected_current_stack_level) &&
> + (uc.args[2] == fred_invalid_rsp[expected_current_stack_level] - 1),
> + "Incorrect stack level %lx and #PF address %lx\n",
> + uc.args[1], uc.args[2]);
> + expected_current_stack_level++;
> + }
> + }
> +
> + kvm_vm_free(vm);
> + return 0;
> +}
--
BR,
Muhammad Usama Anjum
> This patch set enables the Intel flexible return and event delivery
> (FRED) architecture with KVM VMX to allow guests to utilize FRED.
>
<snip>
>
> Intel VMX architecture is extended to run FRED guests, and the major changes
> are:
>
> 1) New VMCS fields for FRED context management, which includes two new
> event data VMCS fields, eight new guest FRED context VMCS fields and eight new
> host FRED context VMCS fields.
>
> 2) VMX nested-exception support for proper virtualization of stack levels
> introduced with FRED architecture.
>
<snip>
>
> Patch 1-2 are cleanups to VMX basic and misc MSRs, which were sent out earlier
> as a preparation for FRED changes:
> https://lore.kernel.org/kvm/[email protected]/T/#u
Obviously I will drop the 2 clean patches in the next iteration.
> Patch 3-15 add FRED support to VMX.
> Patch 16-21 add FRED support to nested VMX.
> Patch 22 exposes FRED and its baseline features to KVM guests.
> Patch 23-25 add FRED selftests.
Please help to review and comment on the FRED KVM/VMX patches.
Thanks!
Xin
On Wed, Feb 07, 2024 at 09:26:23AM -0800, Xin Li wrote:
>Enable the secondary VM exit controls to prepare for FRED enabling.
>
>The activation of the secondary VM exit controls is off now, and it
>will be switched on when a VMX feature needing it is enabled.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
Reviewed-by: Chao Gao <[email protected]>
On Wed, Feb 07, 2024 at 09:26:24AM -0800, Xin Li wrote:
>The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when a guest
>enumerates FRED, otherwise it is still a reserved bit.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
Reviewed-by: Chao Gao <[email protected]>
On Wed, Feb 07, 2024 at 09:26:25AM -0800, Xin Li wrote:
>Setup the global vmcs_config for FRED:
>1) Add VM_ENTRY_LOAD_IA32_FRED to KVM_OPTIONAL_VMX_VM_ENTRY_CONTROLS to
> have a FRED CPU load guest FRED MSRs from VMCS upon VM entry.
>2) Add SECONDARY_VM_EXIT_SAVE_IA32_FRED to
> KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU save
> guest FRED MSRs to VMCS during VM exit.
>3) add SECONDARY_VM_EXIT_LOAD_IA32_FRED to
> KVM_OPTIONAL_VMX_SECONDARY_VM_EXIT_CONTROLS to have a FRED CPU load
> host FRED MSRs from VMCS during VM exit.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
Reviewed-by: Chao Gao <[email protected]>
On Wed, Feb 07, 2024 at 09:26:26AM -0800, Xin Li wrote:
>Clear FRED VM entry/exit controls when initializing a vCPU, and set
>these controls only if FRED is enumerated after set CPUID.
>
>FRED VM entry/exit controls need to be set to establish context
>sufficient to support FRED event delivery immediately after VM entry
>and exit. However it is not required to save/load FRED MSRs for
>a non-FRED guest, which aren't supposed to access FRED MSRs.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
Reviewed-by: Chao Gao <[email protected]>
On Wed, Feb 07, 2024 at 09:26:27AM -0800, Xin Li wrote:
>Add FRED MSRs to the valid passthrough MSR list and set FRED MSRs intercept
>based on FRED enumeration.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
Reviewed-by: Chao Gao <[email protected]>
two nits below.
>---
>
>Change since v1:
>* Enable FRED MSRs intercept if FRED is no longer enumerated in CPUID
> (Chao Gao).
>---
> arch/x86/kvm/vmx/vmx.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index 34b6676f60d8..d58ed2d3d379 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -693,6 +693,9 @@ static bool is_valid_passthrough_msr(u32 msr)
> case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 8:
> /* LBR MSRs. These are handled in vmx_update_intercept_for_lbr_msrs() */
> return true;
>+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
>+ /* FRED MSRs should be passthrough to FRED guests only */
This comment sounds weird. It sounds like the code will be something like:
if guest supports FRED
return true
else
return false
how about "FRED MSRs are pass-thru'd to guests which enumerate FRED"?
Or to align with above comment for LBR MSRs, just say
/* FRED MSRs. These are handled in vmx_vcpu_config_fred_after_set_cpuid() */
>+ return true;
> }
>
> r = possible_passthrough_msr_slot(msr) != -ENOENT;
>@@ -7774,10 +7777,12 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
> static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
>+ bool fred_enumerated;
>
> kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
>+ fred_enumerated = guest_can_use(vcpu, X86_FEATURE_FRED);
>
>- if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
>+ if (fred_enumerated) {
> vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
> secondary_vm_exit_controls_setbit(vmx,
> SECONDARY_VM_EXIT_SAVE_IA32_FRED |
>@@ -7788,6 +7793,16 @@ static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> SECONDARY_VM_EXIT_LOAD_IA32_FRED);
> }
>+
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP0, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP1, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP2, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP3, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_STKLVLS, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP1, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP2, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP3, MSR_TYPE_RW, !fred_enumerated);
>+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_CONFIG, MSR_TYPE_RW, !fred_enumerated);
Use a for-loop here? e.g.,
for (i = MSR_IA32_FRED_RSP0; i <= MSR_IA32_FRED_CONFIG; i++)
> }
>
> static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
>--
>2.43.0
>
>
On Wed, Feb 07, 2024 at 09:26:28AM -0800, Xin Li wrote:
>Initialize host VMCS FRED fields with host FRED MSRs' value and
>guest VMCS FRED fields to 0.
>
>FRED CPU states are managed in 9 new FRED MSRs, as well as a few
>existing CPU registers and MSRs, e.g., CR4.FRED. To support FRED
>context management, new VMCS fields corresponding to most of FRED
>CPU state MSRs are added to both the host-state and guest-state
>areas of VMCS.
>
>Specifically no VMCS fields are added for FRED RSP0 and SSP0 MSRs,
>because the 2 FRED MSRs are used during ring 3 event delivery only,
>thus KVM, running on ring 0, can run safely even with guest FRED
>RSP0 and SSP0. It can be deferred to load host FRED RSP0 and SSP0
>until before returning to user level.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
>---
>
>Changes since v1:
>* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() to decouple
> KVM's capability to virtualize a feature and host's enabling of a
> feature (Chao Gao).
>* Move guest FRED states init into __vmx_vcpu_reset() (Chao Gao).
>---
> arch/x86/include/asm/vmx.h | 16 ++++++++++++++++
> arch/x86/kvm/vmx/vmx.c | 34 ++++++++++++++++++++++++++++++++++
> 2 files changed, 50 insertions(+)
>
>diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
>index cb14f7e315f5..4889754415b5 100644
>--- a/arch/x86/include/asm/vmx.h
>+++ b/arch/x86/include/asm/vmx.h
>@@ -280,12 +280,28 @@ enum vmcs_field {
> GUEST_BNDCFGS_HIGH = 0x00002813,
> GUEST_IA32_RTIT_CTL = 0x00002814,
> GUEST_IA32_RTIT_CTL_HIGH = 0x00002815,
>+ GUEST_IA32_FRED_CONFIG = 0x0000281a,
>+ GUEST_IA32_FRED_RSP1 = 0x0000281c,
>+ GUEST_IA32_FRED_RSP2 = 0x0000281e,
>+ GUEST_IA32_FRED_RSP3 = 0x00002820,
>+ GUEST_IA32_FRED_STKLVLS = 0x00002822,
>+ GUEST_IA32_FRED_SSP1 = 0x00002824,
>+ GUEST_IA32_FRED_SSP2 = 0x00002826,
>+ GUEST_IA32_FRED_SSP3 = 0x00002828,
> HOST_IA32_PAT = 0x00002c00,
> HOST_IA32_PAT_HIGH = 0x00002c01,
> HOST_IA32_EFER = 0x00002c02,
> HOST_IA32_EFER_HIGH = 0x00002c03,
> HOST_IA32_PERF_GLOBAL_CTRL = 0x00002c04,
> HOST_IA32_PERF_GLOBAL_CTRL_HIGH = 0x00002c05,
>+ HOST_IA32_FRED_CONFIG = 0x00002c08,
>+ HOST_IA32_FRED_RSP1 = 0x00002c0a,
>+ HOST_IA32_FRED_RSP2 = 0x00002c0c,
>+ HOST_IA32_FRED_RSP3 = 0x00002c0e,
>+ HOST_IA32_FRED_STKLVLS = 0x00002c10,
>+ HOST_IA32_FRED_SSP1 = 0x00002c12,
>+ HOST_IA32_FRED_SSP2 = 0x00002c14,
>+ HOST_IA32_FRED_SSP3 = 0x00002c16,
> PIN_BASED_VM_EXEC_CONTROL = 0x00004000,
> CPU_BASED_VM_EXEC_CONTROL = 0x00004002,
> EXCEPTION_BITMAP = 0x00004004,
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index d58ed2d3d379..b7b772183ee4 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -1470,6 +1470,18 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
> (unsigned long)(cpu_entry_stack(cpu) + 1));
> }
>
>+#ifdef CONFIG_X86_64
is this #ifdeffery neccesary?
I assume kvm_cpu_cap_has(X86_FEATURE_FRED) is always false for !CONFIG_X86_64.
Looks most of FRED changes in core kernel don't have such #ifdeffery.
>+ /* Per-CPU FRED MSRs */
Please explain why these six MSRs are updated here and why only they are updated in this
comment.
>+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
>+ vmcs_write64(HOST_IA32_FRED_RSP1, read_msr(MSR_IA32_FRED_RSP1));
>+ vmcs_write64(HOST_IA32_FRED_RSP2, read_msr(MSR_IA32_FRED_RSP2));
>+ vmcs_write64(HOST_IA32_FRED_RSP3, read_msr(MSR_IA32_FRED_RSP3));
>+ vmcs_write64(HOST_IA32_FRED_SSP1, read_msr(MSR_IA32_FRED_SSP1));
>+ vmcs_write64(HOST_IA32_FRED_SSP2, read_msr(MSR_IA32_FRED_SSP2));
>+ vmcs_write64(HOST_IA32_FRED_SSP3, read_msr(MSR_IA32_FRED_SSP3));
>+ }
>+#endif
>+
> vmx->loaded_vmcs->cpu = cpu;
> }
> }
>@@ -4321,6 +4333,15 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
> */
> vmcs_write16(HOST_DS_SELECTOR, 0);
> vmcs_write16(HOST_ES_SELECTOR, 0);
>+
>+ /*
>+ * FRED MSRs are per-cpu, however FRED CONFIG and STKLVLS MSRs
>+ * are the same on all CPUs, thus they are initialized here.
>+ */
>+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
>+ vmcs_write64(HOST_IA32_FRED_CONFIG, read_msr(MSR_IA32_FRED_CONFIG));
>+ vmcs_write64(HOST_IA32_FRED_STKLVLS, read_msr(MSR_IA32_FRED_STKLVLS));
>+ }
> #else
> vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
> vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
>@@ -4865,6 +4886,19 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
> */
> vmx->pi_desc.nv = POSTED_INTR_VECTOR;
> vmx->pi_desc.sn = 1;
>+
>+#ifdef CONFIG_X86_64
ditto
>+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
>+ vmcs_write64(GUEST_IA32_FRED_CONFIG, 0);
>+ vmcs_write64(GUEST_IA32_FRED_RSP1, 0);
>+ vmcs_write64(GUEST_IA32_FRED_RSP2, 0);
>+ vmcs_write64(GUEST_IA32_FRED_RSP3, 0);
>+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, 0);
>+ vmcs_write64(GUEST_IA32_FRED_SSP1, 0);
>+ vmcs_write64(GUEST_IA32_FRED_SSP2, 0);
>+ vmcs_write64(GUEST_IA32_FRED_SSP3, 0);
>+ }
>+#endif
> }
>
> static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>--
>2.43.0
>
>
On Wed, Feb 07, 2024 at 09:26:29AM -0800, Xin Li wrote:
>Switch MSR_IA32_FRED_RSP0 between host and guest in
>vmx_prepare_switch_to_{host,guest}().
>
>MSR_IA32_FRED_RSP0 is used during ring 3 event delivery only, thus
>KVM, running on ring 0, can run safely with guest FRED RSP0, i.e.,
>no need to switch between host/guest FRED RSP0 during VM entry and
>exit.
>
>KVM should switch to host FRED RSP0 before returning to user level,
>and switch to guest FRED RSP0 before entering guest mode.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
>---
>
>Changes since v1:
>* Don't use guest_cpuid_has() in vmx_prepare_switch_to_{host,guest}(),
> which are called from IRQ-disabled context (Chao Gao).
>* Reset msr_guest_fred_rsp0 in __vmx_vcpu_reset() (Chao Gao).
>---
> arch/x86/kvm/vmx/vmx.c | 17 +++++++++++++++++
> arch/x86/kvm/vmx/vmx.h | 2 ++
> 2 files changed, 19 insertions(+)
>
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index b7b772183ee4..264378c3b784 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -1337,6 +1337,16 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
> }
>
> wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
>+
>+ if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
>+ /*
>+ * MSR_IA32_FRED_RSP0 is top of task stack, which never changes.
>+ * Thus it should be initialized only once.
>+ */
>+ if (unlikely(vmx->msr_host_fred_rsp0 == 0))
>+ vmx->msr_host_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
can we just drop this and use "(unsigned long)task_stack_page(current) + THREAD_SIZE"
as host fred rsp0?
>+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_guest_fred_rsp0);
any reason to not use wrmsrns?
>+ }
> #else
> savesegment(fs, fs_sel);
> savesegment(gs, gs_sel);
>@@ -1381,6 +1391,11 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
> invalidate_tss_limit();
> #ifdef CONFIG_X86_64
> wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
>+
>+ if (guest_can_use(&vmx->vcpu, X86_FEATURE_FRED)) {
>+ vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
>+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_host_fred_rsp0);
same question.
>+ }
> #endif
> load_fixmap_gdt(raw_smp_processor_id());
> vmx->guest_state_loaded = false;
>@@ -4889,6 +4904,8 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
>
> #ifdef CONFIG_X86_64
> if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
>+ vmx->msr_guest_fred_rsp0 = 0;
>+
> vmcs_write64(GUEST_IA32_FRED_CONFIG, 0);
> vmcs_write64(GUEST_IA32_FRED_RSP1, 0);
> vmcs_write64(GUEST_IA32_FRED_RSP2, 0);
>diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>index 3ad52437f426..176ad39be406 100644
>--- a/arch/x86/kvm/vmx/vmx.h
>+++ b/arch/x86/kvm/vmx/vmx.h
>@@ -278,6 +278,8 @@ struct vcpu_vmx {
> #ifdef CONFIG_X86_64
> u64 msr_host_kernel_gs_base;
> u64 msr_guest_kernel_gs_base;
>+ u64 msr_host_fred_rsp0;
>+ u64 msr_guest_fred_rsp0;
> #endif
>
> u64 spec_ctrl;
>--
>2.43.0
>
>
> >+ if (unlikely(vmx->msr_host_fred_rsp0 == 0))
> >+ vmx->msr_host_fred_rsp0 =
> read_msr(MSR_IA32_FRED_RSP0);
>
> can we just drop this and use "(unsigned long)task_stack_page(current) +
> THREAD_SIZE"
> as host fred rsp0?
I thought about it, however, don't see a strong reason that it's better,
i.e., is RDMSR slower than reading 'stack' from current task_struct?
>
> >+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_guest_fred_rsp0);
>
> any reason to not use wrmsrns?
Good call!
> >+ }
> > #else
> > savesegment(fs, fs_sel);
> > savesegment(gs, gs_sel);
> >@@ -1381,6 +1391,11 @@ static void vmx_prepare_switch_to_host(struct
> vcpu_vmx *vmx)
> > invalidate_tss_limit();
> > #ifdef CONFIG_X86_64
> > wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
> >+
> >+ if (guest_can_use(&vmx->vcpu, X86_FEATURE_FRED)) {
> >+ vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
> >+ wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_host_fred_rsp0);
>
> same question.
Will do!
Thanks!
Xin
> >+#ifdef CONFIG_X86_64
>
> is this #ifdeffery neccesary?
Yes, otherwise build fails on 32 bit.
>
> I assume kvm_cpu_cap_has(X86_FEATURE_FRED) is always false
> for !CONFIG_X86_64.
> Looks most of FRED changes in core kernel don't have such #ifdeffery.
Because it's not a compile time false, instead false from runtime.
>
> >+ /* Per-CPU FRED MSRs */
>
> Please explain why these six MSRs are updated here and why only they are updated in
> this comment.
The explanation is kind of implicit "per-CPU", I will make it more explicit
Thanks!
Xin
> >+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
> >+ /* FRED MSRs should be passthrough to FRED guests only */
>
> This comment sounds weird. It sounds like the code will be something like:
> if guest supports FRED
> return true
> else
> return false
>
> how about "FRED MSRs are pass-thru'd to guests which enumerate FRED"?
>
> Or to align with above comment for LBR MSRs, just say
>
> /* FRED MSRs. These are handled in vmx_vcpu_config_fred_after_set_cpuid() */
>
Maybe both to not confuse people at all ????
> >+ return true;
> > }
> >
> > r = possible_passthrough_msr_slot(msr) != -ENOENT; @@ -7774,10
> >+7777,12 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
> >static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> >{
> > struct vcpu_vmx *vmx = to_vmx(vcpu);
> >+ bool fred_enumerated;
> >
> > kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
> >+ fred_enumerated = guest_can_use(vcpu, X86_FEATURE_FRED);
> >
> >- if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
> >+ if (fred_enumerated) {
> > vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
> > secondary_vm_exit_controls_setbit(vmx,
> >
> SECONDARY_VM_EXIT_SAVE_IA32_FRED | @@ -7788,6 +7793,16 @@
> >static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> >
> SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> >
> SECONDARY_VM_EXIT_LOAD_IA32_FRED);
> > }
> >+
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP0,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP1,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP2,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP3,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_STKLVLS,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP1,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP2,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP3,
> MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_CONFIG, MSR_TYPE_RW,
> >+!fred_enumerated);
>
> Use a for-loop here? e.g.,
> for (i = MSR_IA32_FRED_RSP0; i <= MSR_IA32_FRED_CONFIG; i++)
> > }
Yeah, let me try.
On Sat, Mar 30, 2024, Muhammad Usama Anjum wrote:
> On 2/7/24 10:26 PM, Xin Li wrote:
> > Add tests for FRED event data and VMX nested-exception.
> >
> > FRED is designed to save a complete event context in its stack frame,
> > e.g., FRED saves the faulting linear address of a #PF into a 64-bit
> > event data field defined in FRED stack frame. As such, FRED VMX adds
> > event data handling during VMX transitions.
> >
> > Besides, FRED introduces event stack levels to dispatch an event handler
> > onto a stack baesd on current stack level and stack levels defined in
> > IA32_FRED_STKLVLS MSR for each exception vector. VMX nested-exception
> > support ensures a correct event stack level is chosen when a VM entry
> > injects a nested exception, which is regarded as occurred in ring 0.
> >
> > To fully test the underlying FRED VMX code, this test should be run one
> > more round with EPT disabled to inject page faults as nested exceptions.
> >
> > Originally-by: Shan Kang <[email protected]>
> > Signed-off-by: Xin Li <[email protected]>
> Thank you for the new test patch. We have been trying to ensure TAP
> conformance for tests which cannot be achieved if new tests aren't using
> TAP already.
Who is "we"?
> Please make your test TAP compliant.
This isn't entirely reasonable feedback. I'm all for getting KVM selftests
TAP-friendly, but the current reality is that the KVM selftests infrastructure
doesn't make it easy to be TAP compliant. We're working on improving things,
i.e. I do hope/want to get to a state where it's a hard requirement for KVM
selftests to be TAP compliant, but we aren't there yet.
If you have specific feedback on _how_ to make a test TAP compliant, then by all
means provide that feedback. But a drive-by "make your test TAP compliant" isn't
super helpful.
> > ---
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../selftests/kvm/include/x86_64/processor.h | 32 ++
> > .../testing/selftests/kvm/x86_64/fred_test.c | 297 ++++++++++++++++++
> Add generated binary object to .gitignore.
This should be unnecessary (though I haven't actually verified by building), as
KVM selftests ignore most everything by default since commit 43e96957e8b8
("KVM: selftests: Use pattern matching in .gitignore").
On Thu, Feb 08, 2024 at 01:26:30AM +0800, Xin Li wrote:
>Handle host initiated FRED MSR access requests to allow FRED context
>to be set/get from user level.
>
The changelog isn't accurate because guest accesses are also handled
by this patch, specifically in the "else" branch.
>+ if (host_initiated) {
>+ if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
>+ return 1;
>+ } else {
> void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
>@@ -2019,6 +2037,33 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> case MSR_KERNEL_GS_BASE:
> msr_info->data = vmx_read_guest_kernel_gs_base(vmx);
> break;
>+ case MSR_IA32_FRED_RSP0:
>+ msr_info->data = vmx_read_guest_fred_rsp0(vmx);
>+ break;
>+ case MSR_IA32_FRED_RSP1:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP1);
>+ break;
>+ case MSR_IA32_FRED_RSP2:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP2);
>+ break;
>+ case MSR_IA32_FRED_RSP3:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_RSP3);
>+ break;
>+ case MSR_IA32_FRED_STKLVLS:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_STKLVLS);
>+ break;
>+ case MSR_IA32_FRED_SSP1:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP1);
>+ break;
>+ case MSR_IA32_FRED_SSP2:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP2);
>+ break;
>+ case MSR_IA32_FRED_SSP3:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_SSP3);
>+ break;
>+ case MSR_IA32_FRED_CONFIG:
>+ msr_info->data = vmcs_read64(GUEST_IA32_FRED_CONFIG);
>+ break;
how about adding a helper function to convert MSR index to the VMCS field id?
Then do:
case MSR_IA32_FRED_RSP1 ... MSR_IA32_FRED_STKLVLS:
case MSR_IA32_FRED_SSP1 ... MSR_IA32_FRED_CONFIG:
msr_info->data = vmcs_read64(msr_to_vmcs(index));
break;
and ...
> #endif
> case MSR_EFER:
> return kvm_get_msr_common(vcpu, msr_info);
>@@ -2226,6 +2271,33 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> vmx_update_exception_bitmap(vcpu);
> }
> break;
>+ case MSR_IA32_FRED_RSP0:
>+ vmx_write_guest_fred_rsp0(vmx, data);
>+ break;
>+ case MSR_IA32_FRED_RSP1:
>+ vmcs_write64(GUEST_IA32_FRED_RSP1, data);
>+ break;
>+ case MSR_IA32_FRED_RSP2:
>+ vmcs_write64(GUEST_IA32_FRED_RSP2, data);
>+ break;
>+ case MSR_IA32_FRED_RSP3:
>+ vmcs_write64(GUEST_IA32_FRED_RSP3, data);
>+ break;
>+ case MSR_IA32_FRED_STKLVLS:
>+ vmcs_write64(GUEST_IA32_FRED_STKLVLS, data);
>+ break;
>+ case MSR_IA32_FRED_SSP1:
>+ vmcs_write64(GUEST_IA32_FRED_SSP1, data);
>+ break;
>+ case MSR_IA32_FRED_SSP2:
>+ vmcs_write64(GUEST_IA32_FRED_SSP2, data);
>+ break;
>+ case MSR_IA32_FRED_SSP3:
>+ vmcs_write64(GUEST_IA32_FRED_SSP3, data);
>+ break;
>+ case MSR_IA32_FRED_CONFIG:
>+ vmcs_write64(GUEST_IA32_FRED_CONFIG, data);
>+ break;
case MSR_IA32_FRED_RSP1 ... MSR_IA32_FRED_STKLVLS:
case MSR_IA32_FRED_SSP1 ... MSR_IA32_FRED_CONFIG:
vmcs_write64(msr_to_vmcs(index), data);
break;
The code will be more compact and generate less instructions. I believe CET
series can do the same change [*]. Performance here isn't critical. I just
think it looks cumbersome to repeat the same pattern for 8 (and more with
CET considered) MSRs.
[*]: https://lore.kernel.org/kvm/[email protected]/
> #endif
> case MSR_IA32_SYSENTER_CS:
> if (is_guest_mode(vcpu))
>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>index 363b1c080205..4e8d60f248e3 100644
>--- a/arch/x86/kvm/x86.c
>+++ b/arch/x86/kvm/x86.c
>@@ -1451,6 +1451,9 @@ static const u32 msrs_to_save_base[] = {
> MSR_STAR,
> #ifdef CONFIG_X86_64
> MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
>+ MSR_IA32_FRED_RSP0, MSR_IA32_FRED_RSP1, MSR_IA32_FRED_RSP2,
>+ MSR_IA32_FRED_RSP3, MSR_IA32_FRED_STKLVLS, MSR_IA32_FRED_SSP1,
>+ MSR_IA32_FRED_SSP2, MSR_IA32_FRED_SSP3, MSR_IA32_FRED_CONFIG,
> #endif
> MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
> MSR_IA32_FEAT_CTL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
>@@ -1892,6 +1895,30 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data,
> return 1;
>
> data = (u32)data;
>+ break;
>+ case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
>+ if (index != MSR_IA32_FRED_STKLVLS && is_noncanonical_address(data, vcpu))
>+ return 1;
>+ if ((index >= MSR_IA32_FRED_RSP0 && index <= MSR_IA32_FRED_RSP3) &&
>+ (data & GENMASK_ULL(5, 0)))
>+ return 1;
>+ if ((index >= MSR_IA32_FRED_SSP1 && index <= MSR_IA32_FRED_SSP3) &&
>+ (data & GENMASK_ULL(2, 0)))
>+ return 1;
>+
>+ if (host_initiated) {
>+ if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
>+ return 1;
Should be:
if (!kvm_cpu_cap_has(X86_FEATURE_FRED) && data)
KVM ABI allows userspace to write only 0 if guests cannot enumerate the
feature. And even better, your next version can be on top of Sean's series
https://lore.kernel.org/kvm/[email protected]/T/#md00be687770e1e658fc9fe0eac20b5f0bd230e4c
this way, you can get rid of the "host_initiated" check.
On Thu, Feb 08, 2024 at 01:26:31AM +0800, Xin Li wrote:
>Add kvm_is_fred_enabled() to get if FRED is enabled on a vCPU.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
>---
>
>Change since v1:
>* Explain why it is ok to only check CR4.FRED (Chao Gao).
>---
> arch/x86/kvm/kvm_cache_regs.h | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
>diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
>index 75eae9c4998a..1d431c703fdf 100644
>--- a/arch/x86/kvm/kvm_cache_regs.h
>+++ b/arch/x86/kvm/kvm_cache_regs.h
>@@ -187,6 +187,23 @@ static __always_inline bool kvm_is_cr4_bit_set(struct kvm_vcpu *vcpu,
> return !!kvm_read_cr4_bits(vcpu, cr4_bit);
> }
>
>+/*
>+ * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
>+ * a vCPU is running with FRED enabled, because:
>+ * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
>+ * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
>+ *
>+ * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
>+ */
I think we can give more context here, e.g.,
Although FRED architecture applies to 64-bit mode only, there is no need to
check if the CPU is in 64-bit mode (i.e., IA32_EFER.LMA and CS.L) to tell if
FRED is enabled because CR4.FRED=1 implies the CPU is in 64-bit mode.
Specifically,
1) ..
2) ..
>index ee61d2c25cb0..f622fb90a098 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -1871,9 +1871,29 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
> vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
> vmx->vcpu.arch.event_exit_inst_len);
> intr_info |= INTR_TYPE_SOFT_EXCEPTION;
>- } else
>+ } else {
> intr_info |= INTR_TYPE_HARD_EXCEPTION;
>
>+ if (kvm_is_fred_enabled(vcpu)) {
>+ u64 event_data = 0;
>+
>+ if (is_debug(intr_info))
>+ /*
>+ * Compared to DR6, FRED #DB event data saved on
>+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
>+ * inverted, i.e.,
>+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
>+ */
>+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
>+ else if (is_page_fault(intr_info))
>+ event_data = vcpu->arch.cr2;
>+ else if (is_nm_fault(intr_info))
>+ event_data = to_vmx(vcpu)->fred_xfd_event_data;
>+
IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
and event_data field to B (!=A) when injecting #PF.
And this approach cannot be extended to handle a (future) exception whose
event_data isn't tied to a dedicated register like CR2/DR6.
Adding a new field fred_xfd_event_data in struct vcpu has problems too:
fred_xfd_event_data gets lost during migration; strickly speaking, event_data
is tied to an exception rather than a CPU. e.g., the CPU may detect a nested
exception when delivering one and both have their own event_data.
I think we can make event_data a property of exceptions. i.e., add a payload2
to struct kvm_queued_exception. and add new APIs to kvm_queue_exception* family
to accept a payload2 and in VMX code, just program payload2 to the VMCS
event_data field if FRED is enabled. KVM ABI should be extended as well to pass
payload2 to userspace like how the payload is handled in
kvm_vcpu_ioctl_x86_get/put_vcpu_events.
On Thu, Feb 08, 2024 at 01:26:33AM +0800, Xin Li wrote:
>Set VMX nested exception bit in the VM-entry interruption information
>VMCS field when injecting a nested exception using FRED event delivery
>to ensure:
> 1) The nested exception is injected on a correct stack level.
> 2) The nested bit defined in FRED stack frame is set.
>
>The event stack level used by FRED event delivery depends on whether the
>event was a nested exception encountered during delivery of another event,
>because a nested exception is "regarded" as happening on ring 0. E.g.,
>when #PF is configured to use stack level 1 in IA32_FRED_STKLVLS MSR:
> - nested #PF will be delivered on stack level 1 when encountered in
> ring 3.
> - normal #PF will be delivered on stack level 0 when encountered in
> ring 3.
>
>The VMX nested-exception support ensures the correct event stack level is
>chosen when a VM entry injects a nested exception.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
>---
>
>Changes since v1:
>* Set the nested flag when there is an original interrupt (Chao Gao).
>---
> arch/x86/include/asm/kvm_host.h | 6 +++--
> arch/x86/include/asm/vmx.h | 5 ++--
> arch/x86/kvm/svm/svm.c | 4 +--
> arch/x86/kvm/vmx/vmx.c | 8 ++++--
> arch/x86/kvm/x86.c | 46 ++++++++++++++++++++++++++-------
> arch/x86/kvm/x86.h | 1 +
> 6 files changed, 53 insertions(+), 17 deletions(-)
>
>diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>index 0d88873eba63..ef278ee0b6ca 100644
>--- a/arch/x86/include/asm/kvm_host.h
>+++ b/arch/x86/include/asm/kvm_host.h
>@@ -736,6 +736,7 @@ struct kvm_queued_exception {
> u32 error_code;
> unsigned long payload;
> bool has_payload;
>+ bool nested;
"nested" may be lost after migration.
> };
>
> struct kvm_vcpu_arch {
>@@ -2060,8 +2061,9 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu);
> void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
> void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
> void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
>-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
>-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
>+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested);
>+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr,
>+ u32 error_code, bool nested);
> void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
> void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
> struct x86_exception *fault);
>diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
>index 6b796c5c9c2b..68af74e48788 100644
>--- a/arch/x86/include/asm/vmx.h
>+++ b/arch/x86/include/asm/vmx.h
>@@ -134,7 +134,7 @@
> #define VMX_BASIC_DUAL_MONITOR_TREATMENT BIT_ULL(49)
> #define VMX_BASIC_INOUT BIT_ULL(54)
> #define VMX_BASIC_TRUE_CTLS BIT_ULL(55)
>-
>+#define VMX_BASIC_NESTED_EXCEPTION BIT_ULL(58)
this definition is not used in this patch.
>
> /* VMX_MISC bits and bitmasks */
> #define VMX_MISC_INTEL_PT BIT_ULL(14)
>@@ -407,8 +407,9 @@ enum vmcs_field {
> #define INTR_INFO_INTR_TYPE_MASK 0x700 /* 10:8 */
> #define INTR_INFO_DELIVER_CODE_MASK 0x800 /* 11 */
> #define INTR_INFO_UNBLOCK_NMI 0x1000 /* 12 */
>+#define INTR_INFO_NESTED_EXCEPTION_MASK 0x2000 /* 13 */
> #define INTR_INFO_VALID_MASK 0x80000000 /* 31 */
>-#define INTR_INFO_RESVD_BITS_MASK 0x7ffff000
>+#define INTR_INFO_RESVD_BITS_MASK 0x7fffd000
>
> #define VECTORING_INFO_VECTOR_MASK INTR_INFO_VECTOR_MASK
> #define VECTORING_INFO_TYPE_MASK INTR_INFO_INTR_TYPE_MASK
>diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>index e90b429c84f1..c220b690a37c 100644
>--- a/arch/x86/kvm/svm/svm.c
>+++ b/arch/x86/kvm/svm/svm.c
>@@ -4057,10 +4057,10 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu)
>
> if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
> u32 err = svm->vmcb->control.exit_int_info_err;
>- kvm_requeue_exception_e(vcpu, vector, err);
>+ kvm_requeue_exception_e(vcpu, vector, err, false);
>
> } else
>- kvm_requeue_exception(vcpu, vector);
>+ kvm_requeue_exception(vcpu, vector, false);
> break;
> case SVM_EXITINTINFO_TYPE_INTR:
> kvm_queue_interrupt(vcpu, vector, false);
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index f622fb90a098..1f265d526daf 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -1891,6 +1891,8 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
> event_data = to_vmx(vcpu)->fred_xfd_event_data;
>
> vmcs_write64(INJECTED_EVENT_DATA, event_data);
>+
>+ intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
> }
> }
>
>@@ -7281,9 +7283,11 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
> }
>
> if (event_id & INTR_INFO_DELIVER_CODE_MASK)
>- kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field));
>+ kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field),
>+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
> else
>- kvm_requeue_exception(vcpu, vector);
>+ kvm_requeue_exception(vcpu, vector,
>+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
> break;
> case INTR_TYPE_SOFT_INTR:
> vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>index 00c0062726ae..725819262085 100644
>--- a/arch/x86/kvm/x86.c
>+++ b/arch/x86/kvm/x86.c
>@@ -645,7 +645,8 @@ static void kvm_leave_nested(struct kvm_vcpu *vcpu)
>
> static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> unsigned nr, bool has_error, u32 error_code,
>- bool has_payload, unsigned long payload, bool reinject)
>+ bool has_payload, unsigned long payload,
>+ bool reinject, bool nested)
> {
> u32 prev_nr;
> int class1, class2;
>@@ -696,6 +697,13 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.pending = true;
> vcpu->arch.exception.injected = false;
> }
>+
>+ vcpu->arch.exception.nested = vcpu->arch.exception.nested ||
>+ (kvm_is_fred_enabled(vcpu) &&
>+ ((reinject && nested) ||
>+ vcpu->arch.nmi_injected ||
>+ vcpu->arch.interrupt.injected));
You can set the nested flag regardless of FRED because the sole place using
such information (vmx_inject_exception()) is guarded by kvm_is_fred_enabled()
already.
I would also drop the check about @reinject to make @reinject and @nested
orthogonal (i.e., avoid the artifical rule that nested interrupts should be
queued by "reinject" only)
so, how about:
if (vcpu->arch.nmi_injected || vcpu->arch.interrupt.injected ||
nested)
vcpu->arch.exception.nested = true;
>+
> vcpu->arch.exception.has_error_code = has_error;
> vcpu->arch.exception.vector = nr;
> vcpu->arch.exception.error_code = error_code;
>@@ -725,8 +733,28 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.injected = false;
> vcpu->arch.exception.pending = false;
>
>+ /*
>+ * A #DF is NOT a nested event per its definition, however per
>+ * FRED spec 5.0 Appendix B, its delivery determines the new
>+ * stack level as is done for events occurring when CPL = 0.
>+ */
>+ vcpu->arch.exception.nested = false;
>+
> kvm_queue_exception_e(vcpu, DF_VECTOR, 0);
> } else {
>+ /*
>+ * FRED spec 5.0 Appendix B: delivery of a nested exception
>+ * determines the new stack level as is done for events
>+ * occurring when CPL = 0.
>+ *
>+ * IOW, FRED event delivery of an event encountered in ring 3
>+ * normally uses stack level 0 unconditionally. However, if
>+ * the event is an exception nested on any earlier event,
>+ * delivery of the nested exception will consult the FRED MSR
>+ * IA32_FRED_STKLVLS to determine which stack level to use.
>+ */
>+ vcpu->arch.exception.nested = kvm_is_fred_enabled(vcpu);
as said above, nested flag can be set regardless of FRED.
On Thu, Feb 08, 2024 at 01:26:34AM +0800, Xin Li wrote:
>Refuse to virtualize FRED if FRED consistency checks fail.
After reading this, I realize some consistency checks are missing in
setup_vmcs_config(). Actually Sean requested some infrastructure for
vmcs_entry_exit_pairs to deal with secondary_vmexit_ctrl.
https://lore.kernel.org/kvm/[email protected]/
On Thu, Feb 08, 2024 at 01:26:35AM +0800, Xin Li wrote:
>Add FRED related VMCS fields to dump_vmcs() to have it dump FRED context.
>
>Signed-off-by: Xin Li <[email protected]>
>Tested-by: Shan Kang <[email protected]>
>---
>
>Change since v1:
>* Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
>* Dump guest FRED states only if guest has FRED enabled (Nikolay Borisov).
>---
> arch/x86/kvm/vmx/vmx.c | 46 +++++++++++++++++++++++++++++++++++-------
> 1 file changed, 39 insertions(+), 7 deletions(-)
>
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index a484b9ac2400..e3409607122d 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -6392,7 +6392,7 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> u32 vmentry_ctl, vmexit_ctl;
> u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
>- u64 tertiary_exec_control;
>+ u64 tertiary_exec_control, secondary_vmexit_ctl;
> unsigned long cr4;
> int efer_slot;
>
>@@ -6403,6 +6403,8 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
>
> vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS);
> vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS);
>+ secondary_vmexit_ctl = cpu_has_secondary_vmexit_ctrls() ?
>+ vmcs_read64(SECONDARY_VM_EXIT_CONTROLS) : 0;
> cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
> pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
> cr4 = vmcs_readl(GUEST_CR4);
>@@ -6449,6 +6451,19 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
> vmx_dump_sel("LDTR:", GUEST_LDTR_SELECTOR);
> vmx_dump_dtsel("IDTR:", GUEST_IDTR_LIMIT);
> vmx_dump_sel("TR: ", GUEST_TR_SELECTOR);
>+#ifdef CONFIG_X86_64
>+ if (kvm_is_fred_enabled(vcpu)) {
FRED MSRs are accessible even if CR4.FRED isn't set and #ifdef is ugly, I think
you can simply do:
if (vmentry_ctrl & VM_ENTRY_LOAD_IA32_FRED)
just like below handling for EFER/PAT etc.
>+ pr_err("FRED guest: config=0x%016llx, stack levels=0x%016llx\n"
>+ "RSP0=0x%016lx, RSP1=0x%016llx\n"
>+ "RSP2=0x%016llx, RSP3=0x%016llx\n",
>+ vmcs_read64(GUEST_IA32_FRED_CONFIG),
>+ vmcs_read64(GUEST_IA32_FRED_STKLVLS),
>+ read_msr(MSR_IA32_FRED_RSP0),
>+ vmcs_read64(GUEST_IA32_FRED_RSP1),
>+ vmcs_read64(GUEST_IA32_FRED_RSP2),
>+ vmcs_read64(GUEST_IA32_FRED_RSP3));
>+ }
>+#endif
> efer_slot = vmx_find_loadstore_msr_slot(&vmx->msr_autoload.guest, MSR_EFER);
> if (vmentry_ctl & VM_ENTRY_LOAD_IA32_EFER)
> pr_err("EFER= 0x%016llx\n", vmcs_read64(GUEST_IA32_EFER));
>@@ -6496,6 +6511,19 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
> vmcs_readl(HOST_TR_BASE));
> pr_err("GDTBase=%016lx IDTBase=%016lx\n",
> vmcs_readl(HOST_GDTR_BASE), vmcs_readl(HOST_IDTR_BASE));
>+#ifdef CONFIG_X86_64
>+ if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
ditto
>+ pr_err("FRED host: config=0x%016llx, stack levels=0x%016llx\n"
>+ "RSP0=0x%016llx, RSP1=0x%016llx\n"
>+ "RSP2=0x%016llx, RSP3=0x%016llx\n",
>+ vmcs_read64(HOST_IA32_FRED_CONFIG),
>+ vmcs_read64(HOST_IA32_FRED_STKLVLS),
>+ vmx->msr_host_fred_rsp0,
>+ vmcs_read64(HOST_IA32_FRED_RSP1),
>+ vmcs_read64(HOST_IA32_FRED_RSP2),
>+ vmcs_read64(HOST_IA32_FRED_RSP3));
>+ }
>+#endif
> pr_err("CR0=%016lx CR3=%016lx CR4=%016lx\n",
> vmcs_readl(HOST_CR0), vmcs_readl(HOST_CR3),
> vmcs_readl(HOST_CR4));
>@@ -6517,25 +6545,29 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
> pr_err("*** Control State ***\n");
> pr_err("CPUBased=0x%08x SecondaryExec=0x%08x TertiaryExec=0x%016llx\n",
> cpu_based_exec_ctrl, secondary_exec_control, tertiary_exec_control);
>- pr_err("PinBased=0x%08x EntryControls=%08x ExitControls=%08x\n",
>- pin_based_exec_ctrl, vmentry_ctl, vmexit_ctl);
>+ pr_err("PinBased=0x%08x EntryControls=0x%08x\n",
>+ pin_based_exec_ctrl, vmentry_ctl);
>+ pr_err("ExitControls=0x%08x SecondaryExitControls=0x%016llx\n",
>+ vmexit_ctl, secondary_vmexit_ctl);
> pr_err("ExceptionBitmap=%08x PFECmask=%08x PFECmatch=%08x\n",
> vmcs_read32(EXCEPTION_BITMAP),
> vmcs_read32(PAGE_FAULT_ERROR_CODE_MASK),
> vmcs_read32(PAGE_FAULT_ERROR_CODE_MATCH));
>- pr_err("VMEntry: intr_info=%08x errcode=%08x ilen=%08x\n",
>+ pr_err("VMEntry: intr_info=%08x errcode=%08x ilen=%08x event data=%016llx\n",
s/event data/event_data/
> vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),
> vmcs_read32(VM_ENTRY_EXCEPTION_ERROR_CODE),
>- vmcs_read32(VM_ENTRY_INSTRUCTION_LEN));
>+ vmcs_read32(VM_ENTRY_INSTRUCTION_LEN),
>+ kvm_cpu_cap_has(X86_FEATURE_FRED) ? vmcs_read64(INJECTED_EVENT_DATA) : 0);
again, it is better to check some vmexit/vmentry ctrl bit.
> pr_err("VMExit: intr_info=%08x errcode=%08x ilen=%08x\n",
> vmcs_read32(VM_EXIT_INTR_INFO),
> vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
> vmcs_read32(VM_EXIT_INSTRUCTION_LEN));
> pr_err(" reason=%08x qualification=%016lx\n",
> vmcs_read32(VM_EXIT_REASON), vmcs_readl(EXIT_QUALIFICATION));
>- pr_err("IDTVectoring: info=%08x errcode=%08x\n",
>+ pr_err("IDTVectoring: info=%08x errcode=%08x event data=%016llx\n",
s/event data/event_data/
> vmcs_read32(IDT_VECTORING_INFO_FIELD),
>- vmcs_read32(IDT_VECTORING_ERROR_CODE));
>+ vmcs_read32(IDT_VECTORING_ERROR_CODE),
>+ kvm_cpu_cap_has(X86_FEATURE_FRED) ? vmcs_read64(ORIGINAL_EVENT_DATA) : 0);
ditto
> >+ if (kvm_is_fred_enabled(vcpu)) {
> >+ u64 event_data = 0;
> >+
> >+ if (is_debug(intr_info))
> >+ /*
> >+ * Compared to DR6, FRED #DB event data saved on
> >+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
> >+ * inverted, i.e.,
> >+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
> >+ */
> >+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
> >+ else if (is_page_fault(intr_info))
> >+ event_data = vcpu->arch.cr2;
> >+ else if (is_nm_fault(intr_info))
> >+ event_data =
> >+ to_vmx(vcpu)->fred_xfd_event_data;
> >+
>
> IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
> event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
> and event_data field to B (!=A) when injecting #PF.
VMM should guarantee a FRED guest _sees_ consistent values in CR6/DR6
and event data. If not it's just a VMM bug that we need to fix.
>
> And this approach cannot be extended to handle a (future) exception whose
> event_data isn't tied to a dedicated register like CR2/DR6.
See below.
> Adding a new field fred_xfd_event_data in struct vcpu has problems too:
> fred_xfd_event_data gets lost during migration;
I'm not bothered, because this is not hard to fix, right?
> strickly speaking, event_data is tied
> to an exception rather than a CPU. e.g., the CPU may detect a nested exception when
> delivering one and both have their own event_data.
No, don't get me wrong. An event data has to be _regenerated_ after
a nested exception is handled and the original instruction flow is
restarted.
sometimes the original event could be gone.
We don't say an event data is tied to an exception or a CPU, which
is just confusing, or misleading.
> I think we can make event_data a property of exceptions. i.e., add a payload2 to
> struct kvm_queued_exception. and add new APIs to kvm_queue_exception* family to
> accept a payload2 and in VMX code, just program payload2 to the VMCS event_data
> field if FRED is enabled. KVM ABI should be extended as well to pass
> payload2 to userspace like how the payload is handled in
> kvm_vcpu_ioctl_x86_get/put_vcpu_events.
Yes, it's very likely that we will need to add a payload2 in future,
but NOT now. 2 reasons:
1) The first-generation FRED is designed to NOT go too far from what
IDT can do. And FRED event data is conceptually an alias of CR2/DR6
in the latest FRED spec (not considering xfd event data for now).
And the existing payload is a nice match for now;
2) FRED is an extendable CPU architecture, which allows the structure
of event data to become way bigger and complicated. Let's not assume
anything and add a payload2 too early.
> >+/*
> >+ * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
> >+ * a vCPU is running with FRED enabled, because:
> >+ * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
> >+ * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
> >+ *
> >+ * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
> >+ */
>
> I think we can give more context here, e.g.,
>
> Although FRED architecture applies to 64-bit mode only, there is no need to check if
> the CPU is in 64-bit mode (i.e., IA32_EFER.LMA and CS.L) to tell if FRED is enabled
> because CR4.FRED=1 implies the CPU is in 64-bit mode.
What is "more context" here?
> Specifically,
On Sat, May 11, 2024 at 09:24:12AM +0800, Li, Xin3 wrote:
>> >+/*
>> >+ * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
>> >+ * a vCPU is running with FRED enabled, because:
>> >+ * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
>> >+ * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
>> >+ *
>> >+ * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
>> >+ */
>>
>> I think we can give more context here, e.g.,
>>
>> Although FRED architecture applies to 64-bit mode only, there is no need to check if
>> the CPU is in 64-bit mode (i.e., IA32_EFER.LMA and CS.L) to tell if FRED is enabled
>> because CR4.FRED=1 implies the CPU is in 64-bit mode.
>
>What is "more context" here?
e.g.,
why IA32_EFER.LMA and CPU mode are related to FRED here?
"it's enough to " implies something else is not necessary. what is it?
I don't think the original comment make them super clear.
>
>> Specifically,
>
>
On Fri, May 10, 2024 at 05:36:03PM +0800, Li, Xin3 wrote:
>> >+ if (kvm_is_fred_enabled(vcpu)) {
>> >+ u64 event_data = 0;
>> >+
>> >+ if (is_debug(intr_info))
>> >+ /*
>> >+ * Compared to DR6, FRED #DB event data saved on
>> >+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
>> >+ * inverted, i.e.,
>> >+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
>> >+ */
>> >+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
>> >+ else if (is_page_fault(intr_info))
>> >+ event_data = vcpu->arch.cr2;
>> >+ else if (is_nm_fault(intr_info))
>> >+ event_data =
>> >+ to_vmx(vcpu)->fred_xfd_event_data;
>> >+
>>
>> IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
>> event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
>> and event_data field to B (!=A) when injecting #PF.
>
>VMM should guarantee a FRED guest _sees_ consistent values in CR6/DR6
>and event data. If not it's just a VMM bug that we need to fix.
I don't get why VMM should.
I know the hardware will guarantee this. And likely KVM will also do this.
but I don't think it is necessary for KVM to assume L1 VMM will guarantee
this. because as long as L2 guest is enlightened to read event_data from stack
only, the ABI between L1 VMM and L2 guest can be: CR2/DR6 may be out of sync
with the event_data. I am not saying it is good that L1 VMM deviates from the
real hardware behavior. But how L1 VMM defines this ABI with L2 has nothing to
do with KVM as L0. KVM shouldn't make assumptions on that.
On Wed, Feb 07, 2024, Xin Li wrote:
> The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when a guest
> enumerates FRED, otherwise it is still a reserved bit.
This isn't quite correct, as __cr4_reserved_bits() is used with kvm_cpu_caps too,
i.e. to compute CR4 bits that are reserved from the host's perspective. And that
matters, because if this check was done _only_ on guest CPUID, then KVM would
allow CR4.FRED=1 before all of KVM support is in place.
> Signed-off-by: Xin Li <[email protected]>
> Tested-by: Shan Kang <[email protected]>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/x86.h | 2 ++
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index b5b2d0fde579..0d88873eba63 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -134,7 +134,7 @@
> | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
> | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
> | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP \
> - | X86_CR4_LAM_SUP))
> + | X86_CR4_LAM_SUP | X86_CR4_FRED))
>
> #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
>
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 2f7e19166658..9a52016ebf5a 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -532,6 +532,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type);
> __reserved_bits |= X86_CR4_PCIDE; \
> if (!__cpu_has(__c, X86_FEATURE_LAM)) \
> __reserved_bits |= X86_CR4_LAM_SUP; \
> + if (!__cpu_has(__c, X86_FEATURE_FRED)) \
> + __reserved_bits |= X86_CR4_FRED; \
> __reserved_bits; \
> })
>
> --
> 2.43.0
>
On Wed, Feb 07, 2024, Xin Li wrote:
> Clear FRED VM entry/exit controls when initializing a vCPU, and set
> these controls only if FRED is enumerated after set CPUID.
>
> FRED VM entry/exit controls need to be set to establish context
> sufficient to support FRED event delivery immediately after VM entry
> and exit. However it is not required to save/load FRED MSRs for
> a non-FRED guest, which aren't supposed to access FRED MSRs.
Does this actually provide a measurable performance boost? If not, just do the
unnecessary load/store on entry/exit.
Generally speaking, the only time KVM dynamically toggles entry/exit controls is
when KVM wants to run the guest with a host value, e.g. with the host's
PERF_GLOBAL_CTRL.
On Wed, Feb 07, 2024, Xin Li wrote:
> @@ -7774,10 +7777,12 @@ static void update_intel_pt_cfg(struct kvm_vcpu *vcpu)
> static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> + bool fred_enumerated;
>
> kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
> + fred_enumerated = guest_can_use(vcpu, X86_FEATURE_FRED);
"enumerated" isn't correct. Userspace can enumerate FRED to the guest even if
FRED is unsupported in KVM.
Planning for a future where this becomes guest_cpu_cap_has(), maybe "has_fred"?
> - if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
> + if (fred_enumerated) {
> vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
> secondary_vm_exit_controls_setbit(vmx,
> SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> @@ -7788,6 +7793,16 @@ static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> SECONDARY_VM_EXIT_LOAD_IA32_FRED);
> }
> +
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP0, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP1, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP2, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP3, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_STKLVLS, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP1, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP2, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP3, MSR_TYPE_RW, !fred_enumerated);
> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_CONFIG, MSR_TYPE_RW, !fred_enumerated);
> }
>
> static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
> --
> 2.43.0
>
On Fri, Apr 19, 2024, Chao Gao wrote:
> On Wed, Feb 07, 2024 at 09:26:27AM -0800, Xin Li wrote:
> >Add FRED MSRs to the valid passthrough MSR list and set FRED MSRs intercept
> >based on FRED enumeration.
This needs a *much* more verbose explanation. It's pretty darn obvious _what_
KVM is doing, but it's not at all clear _why_ KVM is passing through FRED MSRs.
E.g. why is FRED_SSP0 not included in the set of passthrough MSRs?
> > static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> > {
> > struct vcpu_vmx *vmx = to_vmx(vcpu);
> >+ bool fred_enumerated;
> >
> > kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_FRED);
> >+ fred_enumerated = guest_can_use(vcpu, X86_FEATURE_FRED);
> >
> >- if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
> >+ if (fred_enumerated) {
> > vm_entry_controls_setbit(vmx, VM_ENTRY_LOAD_IA32_FRED);
> > secondary_vm_exit_controls_setbit(vmx,
> > SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> >@@ -7788,6 +7793,16 @@ static void vmx_vcpu_config_fred_after_set_cpuid(struct kvm_vcpu *vcpu)
> > SECONDARY_VM_EXIT_SAVE_IA32_FRED |
> > SECONDARY_VM_EXIT_LOAD_IA32_FRED);
> > }
> >+
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP0, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP1, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP2, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_RSP3, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_STKLVLS, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP1, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP2, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_SSP3, MSR_TYPE_RW, !fred_enumerated);
> >+ vmx_set_intercept_for_msr(vcpu, MSR_IA32_FRED_CONFIG, MSR_TYPE_RW, !fred_enumerated);
>
> Use a for-loop here? e.g.,
> for (i = MSR_IA32_FRED_RSP0; i <= MSR_IA32_FRED_CONFIG; i++)
Hmm, I'd prefer to keep the open coded version. It's not pretty, but I don't
expect this to have much, if any, maintenance cost. And using a loop makes it
harder to both understand _exactly_ what's happening, and to search for relevant
code. E.g. it's quite difficult to see that FRED_SSP0 is still intercepted (see
my comment regarding the changelog).
On Wed, Feb 07, 2024, Xin Li wrote:
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d58ed2d3d379..b7b772183ee4 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1470,6 +1470,18 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
> (unsigned long)(cpu_entry_stack(cpu) + 1));
> }
>
> +#ifdef CONFIG_X86_64
Don't bother, practically no one cares about 32-bit KVM these days, and I highly
don't anyone that runs 32-bit KVM cares about the code footprint to this degree.
> + /* Per-CPU FRED MSRs */
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
> + vmcs_write64(HOST_IA32_FRED_RSP1, read_msr(MSR_IA32_FRED_RSP1));
> + vmcs_write64(HOST_IA32_FRED_RSP2, read_msr(MSR_IA32_FRED_RSP2));
> + vmcs_write64(HOST_IA32_FRED_RSP3, read_msr(MSR_IA32_FRED_RSP3));
> + vmcs_write64(HOST_IA32_FRED_SSP1, read_msr(MSR_IA32_FRED_SSP1));
> + vmcs_write64(HOST_IA32_FRED_SSP2, read_msr(MSR_IA32_FRED_SSP2));
> + vmcs_write64(HOST_IA32_FRED_SSP3, read_msr(MSR_IA32_FRED_SSP3));
That's a lot of RDMSRs to eat on every task migration. How hard would it be to
add a per-CPU cache for each of these? Or is there a pre-existing way to get at
the info that's faster than RDMSR?
> + }
> +#endif
> +
> vmx->loaded_vmcs->cpu = cpu;
> }
> }
> @@ -4321,6 +4333,15 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
> */
> vmcs_write16(HOST_DS_SELECTOR, 0);
> vmcs_write16(HOST_ES_SELECTOR, 0);
> +
> + /*
> + * FRED MSRs are per-cpu, however FRED CONFIG and STKLVLS MSRs
> + * are the same on all CPUs, thus they are initialized here.
Eh, just trim this to:
/* FRED CONFIG and STKLVLS are the same on all CPUs. */
> + */
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
> + vmcs_write64(HOST_IA32_FRED_CONFIG, read_msr(MSR_IA32_FRED_CONFIG));
> + vmcs_write64(HOST_IA32_FRED_STKLVLS, read_msr(MSR_IA32_FRED_STKLVLS));
> + }
> #else
> vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
> vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
> @@ -4865,6 +4886,19 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
> */
> vmx->pi_desc.nv = POSTED_INTR_VECTOR;
> vmx->pi_desc.sn = 1;
> +
> +#ifdef CONFIG_X86_64
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
> + vmcs_write64(GUEST_IA32_FRED_CONFIG, 0);
> + vmcs_write64(GUEST_IA32_FRED_RSP1, 0);
> + vmcs_write64(GUEST_IA32_FRED_RSP2, 0);
> + vmcs_write64(GUEST_IA32_FRED_RSP3, 0);
> + vmcs_write64(GUEST_IA32_FRED_STKLVLS, 0);
> + vmcs_write64(GUEST_IA32_FRED_SSP1, 0);
> + vmcs_write64(GUEST_IA32_FRED_SSP2, 0);
> + vmcs_write64(GUEST_IA32_FRED_SSP3, 0);
> + }
Somewhat of a moot point, but this belongs in init_vmcs(), not __vmx_vcpu_reset().
On Wed, Feb 07, 2024, Xin Li wrote:
> Switch MSR_IA32_FRED_RSP0 between host and guest in
> vmx_prepare_switch_to_{host,guest}().
>
> MSR_IA32_FRED_RSP0 is used during ring 3 event delivery only, thus
> KVM, running on ring 0, can run safely with guest FRED RSP0, i.e.,
> no need to switch between host/guest FRED RSP0 during VM entry and
> exit.
>
> KVM should switch to host FRED RSP0 before returning to user level,
> and switch to guest FRED RSP0 before entering guest mode.
Heh, if only KVM had a framework that was specifically designed for context
switching MSRs on return to userspace. Translation: please use the user_return_msr()
APIs.
> Signed-off-by: Xin Li <[email protected]>
> Tested-by: Shan Kang <[email protected]>
> ---
>
> Changes since v1:
> * Don't use guest_cpuid_has() in vmx_prepare_switch_to_{host,guest}(),
> which are called from IRQ-disabled context (Chao Gao).
> * Reset msr_guest_fred_rsp0 in __vmx_vcpu_reset() (Chao Gao).
> ---
> arch/x86/kvm/vmx/vmx.c | 17 +++++++++++++++++
> arch/x86/kvm/vmx/vmx.h | 2 ++
> 2 files changed, 19 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index b7b772183ee4..264378c3b784 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1337,6 +1337,16 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
> }
>
> wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
> +
> + if (guest_can_use(vcpu, X86_FEATURE_FRED)) {
> + /*
> + * MSR_IA32_FRED_RSP0 is top of task stack, which never changes.
> + * Thus it should be initialized only once.
Then grab the host value during vmx_hardware_setup(). And when you rebase on top
of the latest kvm-x86/next, there's a handy dandy "struct kvm_host_values kvm_host"
to track host MSR values (and similar state).
You could also use that for MSR_IA32_FRED_CONFIG and MSR_IA32_FRED_STKLVLS.
> + */
> + if (unlikely(vmx->msr_host_fred_rsp0 == 0))
> + vmx->msr_host_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
> + wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_guest_fred_rsp0);
> + }
> #else
> savesegment(fs, fs_sel);
> savesegment(gs, gs_sel);
> @@ -1381,6 +1391,11 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
> invalidate_tss_limit();
> #ifdef CONFIG_X86_64
> wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
> +
> + if (guest_can_use(&vmx->vcpu, X86_FEATURE_FRED)) {
> + vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
> + wrmsrl(MSR_IA32_FRED_RSP0, vmx->msr_host_fred_rsp0);
> + }
> #endif
> load_fixmap_gdt(raw_smp_processor_id());
> vmx->guest_state_loaded = false;
> @@ -4889,6 +4904,8 @@ static void __vmx_vcpu_reset(struct kvm_vcpu *vcpu)
>
> #ifdef CONFIG_X86_64
> if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
> + vmx->msr_guest_fred_rsp0 = 0;
Eh, I wouldn't bother. Arguably it's better to use __kvm_set_msr(), and "vmx"
is zero-allocated so this is unnecessary.
The GUEST_IA32_FRED_* VMCS fields need to be explicitly initialized because the
VMCS could (very theoretically) use a non-zero-based encoding scheme.
On Wed, Feb 07, 2024, Xin Li wrote:
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 264378c3b784..ee61d2c25cb0 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1420,6 +1420,24 @@ static void vmx_write_guest_kernel_gs_base(struct vcpu_vmx *vmx, u64 data)
> preempt_enable();
> vmx->msr_guest_kernel_gs_base = data;
> }
> +
> +static u64 vmx_read_guest_fred_rsp0(struct vcpu_vmx *vmx)
> +{
> + preempt_disable();
> + if (vmx->guest_state_loaded)
> + vmx->msr_guest_fred_rsp0 = read_msr(MSR_IA32_FRED_RSP0);
> + preempt_enable();
> + return vmx->msr_guest_fred_rsp0;
> +}
> +
> +static void vmx_write_guest_fred_rsp0(struct vcpu_vmx *vmx, u64 data)
> +{
> + preempt_disable();
> + if (vmx->guest_state_loaded)
> + wrmsrl(MSR_IA32_FRED_RSP0, data);
> + preempt_enable();
> + vmx->msr_guest_fred_rsp0 = data;
> +}
This should be unnecessary when you switch to the user return framework.
KERNEL_GS_BASE is a bit special because it needs to be reloaded if the kernel
switches to a different task, i.e. before an exit to userspace.
> @@ -1892,6 +1895,30 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data,
> return 1;
>
> data = (u32)data;
> + break;
> + case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
> + if (index != MSR_IA32_FRED_STKLVLS && is_noncanonical_address(data, vcpu))
> + return 1;
> + if ((index >= MSR_IA32_FRED_RSP0 && index <= MSR_IA32_FRED_RSP3) &&
> + (data & GENMASK_ULL(5, 0)))
> + return 1;
> + if ((index >= MSR_IA32_FRED_SSP1 && index <= MSR_IA32_FRED_SSP3) &&
> + (data & GENMASK_ULL(2, 0)))
> + return 1;
> +
> + if (host_initiated) {
> + if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
> + return 1;
> + } else {
> + /*
> + * Inject #GP upon FRED MSRs accesses from a non-FRED guest,
> + * which also ensures no malicious guest can write to FRED
> + * MSRs to corrupt host FRED MSRs.
> + */
Drop the comment, if someone reading KVM code doesn't grok that attempting to
access MSRs that shouldn't exist results in #GP, then a comment probably isn't
going to save them.
This should also be bumped to the top, i.e. do the "does this exist check" first.
Lastly, the direction we are taking is to NOT exempt host-initiated writes, i.e.
userspace has to set CPUID before MSRs. If you base the next version on top of
this series, it should just work (and if it doesn't, I definitely want to know):
https://lore.kernel.org/all/[email protected]
> + if (!guest_can_use(vcpu, X86_FEATURE_FRED))
> + return 1;
> + }
> +
Uh, where does the value go? Oh, this is common code. Ah, and it's in common
code so that VMX can avoid having to make an extra function call for every MSR.
Neat.
> break;
> }
>
> @@ -1936,6 +1963,22 @@ int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
> !guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
> return 1;
> break;
> + case MSR_IA32_FRED_RSP0 ... MSR_IA32_FRED_CONFIG:
> + if (host_initiated) {
> + if (!kvm_cpu_cap_has(X86_FEATURE_FRED))
> + return 1;
> + } else {
> + /*
> + * Inject #GP upon FRED MSRs accesses from a non-FRED guest,
> + * which also ensures no malicious guest can write to FRED
> + * MSRs to corrupt host FRED MSRs.
> + */
> + if (!guest_can_use(vcpu, X86_FEATURE_FRED))
> + return 1;
> + }
Same comments here.
On Wed, Feb 07, 2024, Xin Li wrote:
> Add kvm_is_fred_enabled() to get if FRED is enabled on a vCPU.
>
> Signed-off-by: Xin Li <[email protected]>
> Tested-by: Shan Kang <[email protected]>
> ---
>
> Change since v1:
> * Explain why it is ok to only check CR4.FRED (Chao Gao).
> ---
> arch/x86/kvm/kvm_cache_regs.h | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
> index 75eae9c4998a..1d431c703fdf 100644
> --- a/arch/x86/kvm/kvm_cache_regs.h
> +++ b/arch/x86/kvm/kvm_cache_regs.h
> @@ -187,6 +187,23 @@ static __always_inline bool kvm_is_cr4_bit_set(struct kvm_vcpu *vcpu,
> return !!kvm_read_cr4_bits(vcpu, cr4_bit);
> }
>
> +/*
> + * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
> + * a vCPU is running with FRED enabled, because:
> + * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
> + * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
> + *
> + * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
> + */
> +static __always_inline bool kvm_is_fred_enabled(struct kvm_vcpu *vcpu)
Maybe just is_fred_enabled(), or even just is_fred()? Most helpers in x86.h that
wrap CR4/CR0 in similar ways omit the "kvm_", partly for brevity, but also because
the check is architectural, not KVM-defined (though the state obviously comes
from KVM).
> +{
> +#ifdef CONFIG_X86_64
> + return kvm_is_cr4_bit_set(vcpu, X86_CR4_FRED);
> +#else
> + return false;
> +#endif
> +}
> +
> static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu)
> {
> if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))
> --
> 2.43.0
>
On Wed, Feb 07, 2024, Xin Li wrote:
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 4889754415b5..6b796c5c9c2b 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -256,8 +256,12 @@ enum vmcs_field {
> PID_POINTER_TABLE_HIGH = 0x00002043,
> SECONDARY_VM_EXIT_CONTROLS = 0x00002044,
> SECONDARY_VM_EXIT_CONTROLS_HIGH = 0x00002045,
> + INJECTED_EVENT_DATA = 0x00002052,
> + INJECTED_EVENT_DATA_HIGH = 0x00002053,
> GUEST_PHYSICAL_ADDRESS = 0x00002400,
> GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
> + ORIGINAL_EVENT_DATA = 0x00002404,
> + ORIGINAL_EVENT_DATA_HIGH = 0x00002405,
Are these the actual names from the SDM? E.g. is there no FRED_ prefix to clue
in readers that they are FRED specific? (unless they aren't FRED specific?)
> VMCS_LINK_POINTER = 0x00002800,
> VMCS_LINK_POINTER_HIGH = 0x00002801,
> GUEST_IA32_DEBUGCTL = 0x00002802,
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index ee61d2c25cb0..f622fb90a098 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1871,9 +1871,29 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
> vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
> vmx->vcpu.arch.event_exit_inst_len);
> intr_info |= INTR_TYPE_SOFT_EXCEPTION;
> - } else
> + } else {
> intr_info |= INTR_TYPE_HARD_EXCEPTION;
>
> + if (kvm_is_fred_enabled(vcpu)) {
> + u64 event_data = 0;
> +
> + if (is_debug(intr_info))
> + /*
> + * Compared to DR6, FRED #DB event data saved on
> + * the stack frame have bits 4 ~ 11 and 16 ~ 31
> + * inverted, i.e.,
> + * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
> + */
> + event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
> + else if (is_page_fault(intr_info))
> + event_data = vcpu->arch.cr2;
> + else if (is_nm_fault(intr_info))
> + event_data = to_vmx(vcpu)->fred_xfd_event_data;
> +
> + vmcs_write64(INJECTED_EVENT_DATA, event_data);
> + }
> + }
> +
> vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
>
> vmx_clear_hlt(vcpu);
> @@ -7082,8 +7102,11 @@ static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu)
> *
> * Queuing exception is done in vmx_handle_exit. See comment there.
> */
> - if (vcpu->arch.guest_fpu.fpstate->xfd)
> + if (vcpu->arch.guest_fpu.fpstate->xfd) {
> rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
> + to_vmx(vcpu)->fred_xfd_event_data = vcpu->arch.cr0 & X86_CR0_TS
kvm_is_cr0_bit_set(), don't read vcpu->arch.cr0 directly.
> + ? 0 : vcpu->arch.guest_fpu.xfd_err;
Maybe this?
if (kvm_is_cr0_bit_set(vcpu, X86_CR0_TS))
to_vmx(vcpu)->fred_xfd_event_data = 0;
else
to_vmx(vcpu)->fred_xfd_event_data = vcpu->arch.guest_fpu.xfd_err;
Hmm, but why does this need to be cached _now_? I.e. why does fred_xfd_event_data
need to exist? Wouldn't it be simpler and more robust to use vcpu->arch.guest_fpu.xfd_err
directly in vmx_inject_exception()?
> + }
> }
>
> static void handle_exception_irqoff(struct vcpu_vmx *vmx)
> @@ -7199,29 +7222,28 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
> vmx->loaded_vmcs->entry_time));
> }
>
> -static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
> - u32 idt_vectoring_info,
> - int instr_len_field,
> - int error_code_field)
> +static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
> {
> - u8 vector;
> - int type;
> - bool idtv_info_valid;
> -
> - idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
> + u32 event_id = vectoring ? to_vmx(vcpu)->idt_vectoring_info
> + : vmcs_read32(VM_ENTRY_INTR_INFO_FIELD);
Preferred style for ternary operators is:
u32 event_id = vectoring ? to_vmx(vcpu)->idt_vectoring_info :
vmcs_read32(VM_ENTRY_INTR_INFO_FIELD);
That said, I don't think this is a net positive versus passing in all params.
The bare true/false is somewhat inscrutable, and in this code, it's hard to
understand why KVM looks at X instead of Y without the conext of the caller.
> + int instr_len_field = vectoring ? VM_EXIT_INSTRUCTION_LEN
> + : VM_ENTRY_INSTRUCTION_LEN;
> + int error_code_field = vectoring ? IDT_VECTORING_ERROR_CODE
> + : VM_ENTRY_EXCEPTION_ERROR_CODE;
> + int event_data_field = vectoring ? ORIGINAL_EVENT_DATA
> + : INJECTED_EVENT_DATA;
> + u8 vector = event_id & INTR_INFO_VECTOR_MASK;
> + int type = event_id & INTR_INFO_INTR_TYPE_MASK;
>
> vcpu->arch.nmi_injected = false;
> kvm_clear_exception_queue(vcpu);
> kvm_clear_interrupt_queue(vcpu);
>
> - if (!idtv_info_valid)
> + if (!(event_id & INTR_INFO_VALID_MASK))
> return;
>
> kvm_make_request(KVM_REQ_EVENT, vcpu);
>
> - vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
> - type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;
> -
> switch (type) {
> case INTR_TYPE_NMI_INTR:
> vcpu->arch.nmi_injected = true;
> @@ -7236,10 +7258,31 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu,
> vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
> fallthrough;
> case INTR_TYPE_HARD_EXCEPTION:
> - if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) {
> - u32 err = vmcs_read32(error_code_field);
> - kvm_requeue_exception_e(vcpu, vector, err);
> - } else
> + if (kvm_is_fred_enabled(vcpu)) {
> + /* Save event data for being used as injected-event data */
> + u64 event_data = vmcs_read64(event_data_field);
> +
> + switch (vector) {
> + case DB_VECTOR:
> + /* %dr6 should be equal to (event_data ^ DR6_RESERVED) */
DR6, no need to use assembly syntax, but I'd just drop this comment, as well as
the CR2 comment. They add no insight beyond what the code literally does.
> + vcpu->arch.dr6 = event_data ^ DR6_RESERVED;
> + break;
> + case NM_VECTOR:
> + to_vmx(vcpu)->fred_xfd_event_data = event_data;
> + break;
> + case PF_VECTOR:
> + /* %cr2 should be equal to event_data */
> + vcpu->arch.cr2 = event_data;
> + break;
> + default:
> + WARN_ON(event_data != 0);
> + break;
> + }
> + }
On Sat, May 11, 2024, Chao Gao wrote:
> On Fri, May 10, 2024 at 05:36:03PM +0800, Li, Xin3 wrote:
> >> >+ if (kvm_is_fred_enabled(vcpu)) {
> >> >+ u64 event_data = 0;
> >> >+
> >> >+ if (is_debug(intr_info))
> >> >+ /*
> >> >+ * Compared to DR6, FRED #DB event data saved on
> >> >+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
> >> >+ * inverted, i.e.,
> >> >+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
> >> >+ */
> >> >+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
> >> >+ else if (is_page_fault(intr_info))
> >> >+ event_data = vcpu->arch.cr2;
> >> >+ else if (is_nm_fault(intr_info))
> >> >+ event_data =
> >> >+ to_vmx(vcpu)->fred_xfd_event_data;
> >> >+
> >>
> >> IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
> >> event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
> >> and event_data field to B (!=A) when injecting #PF.
> >
> >VMM should guarantee a FRED guest _sees_ consistent values in CR6/DR6
> >and event data. If not it's just a VMM bug that we need to fix.
>
> I don't get why VMM should.
>
> I know the hardware will guarantee this. And likely KVM will also do this.
> but I don't think it is necessary for KVM to assume L1 VMM will guarantee
> this. because as long as L2 guest is enlightened to read event_data from stack
> only, the ABI between L1 VMM and L2 guest can be: CR2/DR6 may be out of sync
> with the event_data. I am not saying it is good that L1 VMM deviates from the
> real hardware behavior. But how L1 VMM defines this ABI with L2 has nothing to
> do with KVM as L0. KVM shouldn't make assumptions on that.
Right, but in that case the propagation of event_data would be from vmcs12 =>
vmcs02, which is handled by prepare_vmcs02_early().
For this flow, it specifically handles exception injection from _L0 KVM_, in which
case KVM should always follow the architectural behavior.
Ahh, but the code in with __vmx_complete_interrupts() is wrong. Overwriting
vcpu->arch.{dr6,cr2} is wrong, because theres no telling what was in vmcs02.
And even if vmcs02 holds DR6/CR2 values, those might be L2 values, i.e. shouldn't
clobber the vCPU state.
It's not clear to me that we need to do anything new for FRED in
__vmx_complete_interrupts(). The relevant VMCS fields should already hold the
correct values, there's no reason to clobber vCPU state. The reason KVM grabs
things like instruction length and error code is because that information is
visible to other aspects of injection, e.g. to adjust RIP and pushed the error
code on the stack.
On Tue, Apr 30, 2024, Chao Gao wrote:
> On Thu, Feb 08, 2024 at 01:26:35AM +0800, Xin Li wrote:
> >@@ -6449,6 +6451,19 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
> > vmx_dump_sel("LDTR:", GUEST_LDTR_SELECTOR);
> > vmx_dump_dtsel("IDTR:", GUEST_IDTR_LIMIT);
> > vmx_dump_sel("TR: ", GUEST_TR_SELECTOR);
> >+#ifdef CONFIG_X86_64
> >+ if (kvm_is_fred_enabled(vcpu)) {
>
> FRED MSRs are accessible even if CR4.FRED isn't set and #ifdef is ugly, I think
> you can simply do:
>
> if (vmentry_ctrl & VM_ENTRY_LOAD_IA32_FRED)
>
> just like below handling for EFER/PAT etc.
+1
> On Wed, Feb 07, 2024, Xin Li wrote:
> > The CR4.FRED bit, i.e., CR4[32], is no longer a reserved bit when a guest
> > enumerates FRED, otherwise it is still a reserved bit.
>
> This isn't quite correct, as __cr4_reserved_bits() is used with kvm_cpu_caps too,
> i.e. to compute CR4 bits that are reserved from the host's perspective. And that
> matters, because if this check was done _only_ on guest CPUID, then KVM would
> allow CR4.FRED=1 before all of KVM support is in place.
Ah, that means I didn't dig deep enough.
Thanks!
Xin
> On Wed, Feb 07, 2024, Xin Li wrote:
> > Clear FRED VM entry/exit controls when initializing a vCPU, and set
> > these controls only if FRED is enumerated after set CPUID.
> >
> > FRED VM entry/exit controls need to be set to establish context
> > sufficient to support FRED event delivery immediately after VM entry
> > and exit. However it is not required to save/load FRED MSRs for
> > a non-FRED guest, which aren't supposed to access FRED MSRs.
>
> Does this actually provide a measurable performance boost? If not, just do the
> unnecessary load/store on entry/exit.
No performance measurement yet. Will make the change.
>
> Generally speaking, the only time KVM dynamically toggles entry/exit controls is
> when KVM wants to run the guest with a host value, e.g. with the host's
> PERF_GLOBAL_CTRL.
Simple rule.
Thanks!
Xin
On Wed, Jun 12, 2024 at 04:31:35PM -0700, Sean Christopherson wrote:
>On Sat, May 11, 2024, Chao Gao wrote:
>> On Fri, May 10, 2024 at 05:36:03PM +0800, Li, Xin3 wrote:
>> >> >+ if (kvm_is_fred_enabled(vcpu)) {
>> >> >+ u64 event_data = 0;
>> >> >+
>> >> >+ if (is_debug(intr_info))
>> >> >+ /*
>> >> >+ * Compared to DR6, FRED #DB event data saved on
>> >> >+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
>> >> >+ * inverted, i.e.,
>> >> >+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
>> >> >+ */
>> >> >+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
>> >> >+ else if (is_page_fault(intr_info))
>> >> >+ event_data = vcpu->arch.cr2;
>> >> >+ else if (is_nm_fault(intr_info))
>> >> >+ event_data =
>> >> >+ to_vmx(vcpu)->fred_xfd_event_data;
>> >> >+
>> >>
>> >> IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
>> >> event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
>> >> and event_data field to B (!=A) when injecting #PF.
>> >
>> >VMM should guarantee a FRED guest _sees_ consistent values in CR6/DR6
>> >and event data. If not it's just a VMM bug that we need to fix.
>>
>> I don't get why VMM should.
>>
>> I know the hardware will guarantee this. And likely KVM will also do this.
>> but I don't think it is necessary for KVM to assume L1 VMM will guarantee
>> this. because as long as L2 guest is enlightened to read event_data from stack
>> only, the ABI between L1 VMM and L2 guest can be: CR2/DR6 may be out of sync
>> with the event_data. I am not saying it is good that L1 VMM deviates from the
>> real hardware behavior. But how L1 VMM defines this ABI with L2 has nothing to
>> do with KVM as L0. KVM shouldn't make assumptions on that.
>
>Right, but in that case the propagation of event_data would be from vmcs12 =>
>vmcs02, which is handled by prepare_vmcs02_early().
Yes. But delivering this event to L2 may cause VM-exit. So, L0 KVM may need to
re-inject this event ...
>
>For this flow, it specifically handles exception injection from _L0 KVM_, in which
>case KVM should always follow the architectural behavior.
... and go through this exception injection flow. For such an event, there is no
guarantee that the associated event data is consistent with the vCPU's
DR6/CR2/XFD_ERR.
>
>Ahh, but the code in with __vmx_complete_interrupts() is wrong. Overwriting
>vcpu->arch.{dr6,cr2} is wrong, because theres no telling what was in vmcs02.
>And even if vmcs02 holds DR6/CR2 values, those might be L2 values, i.e. shouldn't
>clobber the vCPU state.
Exactly.
>
>It's not clear to me that we need to do anything new for FRED in
>__vmx_complete_interrupts(). The relevant VMCS fields should already hold the
>correct values, there's no reason to clobber vCPU state. The reason KVM grabs
The whole point is to cache the ORIGINAL_EVENT_DATA VMCS field so that KVM can
set it back to the INJECTED_EVENT_DATA VMCS field when reinjecting the pending
event in IDT-vectoring information.
>things like instruction length and error code is because that information is
>visible to other aspects of injection, e.g. to adjust RIP and pushed the error
>code on the stack.
On Wed, Feb 07, 2024, Xin Li wrote:
> Add kvm_is_fred_enabled() to get if FRED is enabled on a vCPU.
>
> Signed-off-by: Xin Li <[email protected]>
> Tested-by: Shan Kang <[email protected]>
> ---
>
> Change since v1:
> * Explain why it is ok to only check CR4.FRED (Chao Gao).
> ---
> arch/x86/kvm/kvm_cache_regs.h | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
> index 75eae9c4998a..1d431c703fdf 100644
> --- a/arch/x86/kvm/kvm_cache_regs.h
> +++ b/arch/x86/kvm/kvm_cache_regs.h
> @@ -187,6 +187,23 @@ static __always_inline bool kvm_is_cr4_bit_set(struct kvm_vcpu *vcpu,
> return !!kvm_read_cr4_bits(vcpu, cr4_bit);
> }
>
> +/*
> + * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if
> + * a vCPU is running with FRED enabled, because:
> + * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1.
> + * 2) To leave IA-32e mode, CR4.FRED must be cleared first.
> + *
> + * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4.
Please don't reference specific sections/tables/fields in comments. They always
become stale. And the code+comments always reflect the current state, i.e. don't
need to worry about spec revisions and whatnot. If there is a spec change, then
there darn well needs to be a way for software to differentiate old vs. new, at
which point there will be accompanying code to capture the difference.
Even in changelogs, references specific specs by section number is usually
discouraged. Again, it shouldn't matter if its FRED spec 6.0 vs. spec 5.0,
because if there is a difference between those two, then the code better be
different too.
Instead, for the changelog, if it's really necessary/helpful, reference the section
by name and/or keyword, as those are much less likely to become stale.
> + */
> +static __always_inline bool kvm_is_fred_enabled(struct kvm_vcpu *vcpu)
This doesn't need to be __always_inline, it's not used from a noinstr section.
kvm_is_cr4_bit_set() is __always_inline so that @cr4_bit is guaranteed to be a
compile-time constant, otherwise the BUILD_BUG_ON() would fail.
On Wed, Feb 07, 2024, Xin Li wrote:
> @@ -7382,6 +7419,24 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
>
> vmx_disable_fb_clear(vmx);
>
> + /*
> + * %cr2 needs to be saved after a VM exit and restored before a VM
> + * entry in case a VM exit happens immediately after delivery of a
> + * guest #PF but before guest reads %cr2.
> + *
> + * A FRED guest should read its #PF faulting linear address from
> + * the event data field in its FRED stack frame instead of %cr2.
> + * But the FRED 5.0 spec still requires a FRED CPU to update %cr2
> + * in the normal way, thus %cr2 is still updated even for a FRED
> + * guest.
> + *
> + * Note, an NMI could interrupt KVM:
> + * 1) after VM exit but before CR2 is saved.
> + * 2) after CR2 is restored but before VM entry.
> + * And a #PF could happen durng NMI handlng, which overwrites %cr2.
> + * Thus exc_nmi() should save and restore %cr2 upon entering and
> + * before leaving to make sure %cr2 not corrupted.
> + */
This is 99.9% noise. What software does or does not do with respect to CR2 is
completely irrelevant. The *only* thing that matters is the architectural
behavior, and architecturally guest CR2 _must_ be up-to-date at all times because
CR2 accesses cannot be intercepted. So, just say:
/*
* Note, even though FRED delivers the faulting linear address via the
* event data field on the stack, CR2 is still updated.
*/
> if (vcpu->arch.cr2 != native_read_cr2())
> native_write_cr2(vcpu->arch.cr2);
>
On Wed, Feb 07, 2024, Xin Li wrote:
> @@ -725,8 +733,28 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.injected = false;
> vcpu->arch.exception.pending = false;
>
> + /*
> + * A #DF is NOT a nested event per its definition, however per
> + * FRED spec 5.0 Appendix B, its delivery determines the new
> + * stack level as is done for events occurring when CPL = 0.
> + */
Similar to my comments about CR2, this is mostly noise. Unless I'm missing a
patch, KVM is not responsible for emulating the stack level stuff, and so there
is zero reason to mention it, because it's not relevant to the KVM code. Simply
say that #DF is defined to not be a nested exception.
/* #DF is NOT a nested event, per its definition. */
> + vcpu->arch.exception.nested = false;
> +
> kvm_queue_exception_e(vcpu, DF_VECTOR, 0);
> } else {
> + /*
> + * FRED spec 5.0 Appendix B: delivery of a nested exception
> + * determines the new stack level as is done for events
> + * occurring when CPL = 0.
> + *
> + * IOW, FRED event delivery of an event encountered in ring 3
> + * normally uses stack level 0 unconditionally. However, if
> + * the event is an exception nested on any earlier event,
> + * delivery of the nested exception will consult the FRED MSR
> + * IA32_FRED_STKLVLS to determine which stack level to use.
> + */
And drop this entirely. The above does not help the reader understand _why_ KVM
sets nested=true for FRED. E.g. there's no CPL check here.
IMO, this code is entirely self-explanatory; KVM is quite obviously handling a
back-to-back exceptions, and it doesn't take a big mental leap to grok that FRED
tracks that information by describing the second exception as "nested".
> + vcpu->arch.exception.nested = kvm_is_fred_enabled(vcpu);
> +
> /* replace previous exception with a new one in a hope
> that instruction re-execution will regenerate lost
> exception */
On Thu, Jun 13, 2024, Chao Gao wrote:
> On Wed, Jun 12, 2024 at 04:31:35PM -0700, Sean Christopherson wrote:
> >On Sat, May 11, 2024, Chao Gao wrote:
> >> On Fri, May 10, 2024 at 05:36:03PM +0800, Li, Xin3 wrote:
> >> >> >+ if (kvm_is_fred_enabled(vcpu)) {
> >> >> >+ u64 event_data = 0;
> >> >> >+
> >> >> >+ if (is_debug(intr_info))
> >> >> >+ /*
> >> >> >+ * Compared to DR6, FRED #DB event data saved on
> >> >> >+ * the stack frame have bits 4 ~ 11 and 16 ~ 31
> >> >> >+ * inverted, i.e.,
> >> >> >+ * fred_db_event_data = dr6 ^ 0xFFFF0FF0UL
> >> >> >+ */
> >> >> >+ event_data = vcpu->arch.dr6 ^ DR6_RESERVED;
> >> >> >+ else if (is_page_fault(intr_info))
> >> >> >+ event_data = vcpu->arch.cr2;
> >> >> >+ else if (is_nm_fault(intr_info))
> >> >> >+ event_data =
> >> >> >+ to_vmx(vcpu)->fred_xfd_event_data;
> >> >> >+
> >> >>
> >> >> IMO, deriving an event_data from CR2/DR6 is a little short-sighted because the
> >> >> event_data and CR2/DR6 __can__ be different, e.g., L1 VMM __can__ set CR2 to A
> >> >> and event_data field to B (!=A) when injecting #PF.
> >> >
> >> >VMM should guarantee a FRED guest _sees_ consistent values in CR6/DR6
> >> >and event data. If not it's just a VMM bug that we need to fix.
> >>
> >> I don't get why VMM should.
> >>
> >> I know the hardware will guarantee this. And likely KVM will also do this.
> >> but I don't think it is necessary for KVM to assume L1 VMM will guarantee
> >> this. because as long as L2 guest is enlightened to read event_data from stack
> >> only, the ABI between L1 VMM and L2 guest can be: CR2/DR6 may be out of sync
> >> with the event_data. I am not saying it is good that L1 VMM deviates from the
> >> real hardware behavior. But how L1 VMM defines this ABI with L2 has nothing to
> >> do with KVM as L0. KVM shouldn't make assumptions on that.
> >
> >Right, but in that case the propagation of event_data would be from vmcs12 =>
> >vmcs02, which is handled by prepare_vmcs02_early().
>
> Yes. But delivering this event to L2 may cause VM-exit. So, L0 KVM may need to
> re-inject this event ...
>
> >
> >For this flow, it specifically handles exception injection from _L0 KVM_, in which
> >case KVM should always follow the architectural behavior.
>
> ... and go through this exception injection flow. For such an event, there is no
> guarantee that the associated event data is consistent with the vCPU's
> DR6/CR2/XFD_ERR.
>
> >
> >Ahh, but the code in with __vmx_complete_interrupts() is wrong. Overwriting
> >vcpu->arch.{dr6,cr2} is wrong, because theres no telling what was in vmcs02.
> >And even if vmcs02 holds DR6/CR2 values, those might be L2 values, i.e. shouldn't
> >clobber the vCPU state.
>
> Exactly.
>
> >
> >It's not clear to me that we need to do anything new for FRED in
> >__vmx_complete_interrupts(). The relevant VMCS fields should already hold the
> >correct values, there's no reason to clobber vCPU state. The reason KVM grabs
>
> The whole point is to cache the ORIGINAL_EVENT_DATA VMCS field so that KVM can
> set it back to the INJECTED_EVENT_DATA VMCS field when reinjecting the pending
> event in IDT-vectoring information.
Hrm, right. I was thinking INJECTED_EVENT_DATA would already hold the correct
data, but that's only true when the VM-Exit occurred on an injected event, i.e.
when KVM already set the relevant fields. Ah, and not capturing the state would
lead to loss of data on migration.
I think the right way to handle this is to add kvm_queued_exception.event_data,
and then fill event_data during kvm_deliver_exception_payload() when injecting
an event for the first time, and set it directly when re-injecting an event. The
event data is effectively the same thing as the payload, it just happens to be
deliver on the event stack frame, not via architectural register state.
And I think we should also rework kvm_requeue_exception() to open code stuffing
vcpu->arch.exception instead of using kvm_multiple_exception(). The two flows
(injection vs. re-injection) don't actually have that much in common, and the
common parts are the super duper simple things, e.g. actually setting values and
requested KVM_REQ_EVENT.
Aha! And there is a pre-existing bug in handle_nm_fault_irqoff(), as it clobbers
guest XFD_ERR if CR0.TS=1.
Speaking of XFD_ERR, I think the best way to deal with that is to pass it along
as a payload, but then simply do nothing when delivering the payload... until
FRED comes along, and then kvm_deliver_exception_payload() can be responsible
for setting FRED's ex->event_data.
With that combination of tweaks, "normal" injection always sets event_data via
the payload, and because re-injected events never deliver payloads (already
delivered), KVM will naturally avoid clobbering ex->event_data with stale state
(and obviously doesn't need to overwrite CR2 or DR6).
Attached patches are compile-tested only. They're a subset of the overall series,
hopefully it's fairly easy to understand where they slot in.
On Tue, Apr 30, 2024, Chao Gao wrote:
> On Thu, Feb 08, 2024 at 01:26:34AM +0800, Xin Li wrote:
> >Refuse to virtualize FRED if FRED consistency checks fail.
>
> After reading this, I realize some consistency checks are missing in
> setup_vmcs_config(). Actually Sean requested some infrastructure for
> vmcs_entry_exit_pairs to deal with secondary_vmexit_ctrl.
Yeah, this belongs in setup_vmcs_config(), e.g. to guarantee that discrepancies
between CPUs are detected. I would also strongly prefer this be squashed with
the patch(es) that introduce recognition of the FRED fields, if only so that we
can avoid "consistency checks" in the shortlog (I thought this patch was going
to disable FRED if a VM-Enter consistency check failed, which would be... interesting).
> On Wed, Feb 07, 2024, Xin Li wrote:
> > @@ -7382,6 +7419,24 @@ static noinstr void vmx_vcpu_enter_exit(struct
> kvm_vcpu *vcpu,
> >
> > vmx_disable_fb_clear(vmx);
> >
> > + /*
> > + * %cr2 needs to be saved after a VM exit and restored before a VM
> > + * entry in case a VM exit happens immediately after delivery of a
> > + * guest #PF but before guest reads %cr2.
> > + *
> > + * A FRED guest should read its #PF faulting linear address from
> > + * the event data field in its FRED stack frame instead of %cr2.
> > + * But the FRED 5.0 spec still requires a FRED CPU to update %cr2
> > + * in the normal way, thus %cr2 is still updated even for a FRED
> > + * guest.
> > + *
> > + * Note, an NMI could interrupt KVM:
> > + * 1) after VM exit but before CR2 is saved.
> > + * 2) after CR2 is restored but before VM entry.
> > + * And a #PF could happen durng NMI handlng, which overwrites %cr2.
> > + * Thus exc_nmi() should save and restore %cr2 upon entering and
> > + * before leaving to make sure %cr2 not corrupted.
> > + */
>
> This is 99.9% noise. What software does or does not do with respect to CR2 is
> completely irrelevant. The *only* thing that matters is the architectural
> behavior, and architecturally guest CR2 _must_ be up-to-date at all times because
> CR2 accesses cannot be intercepted. So, just say:
>
> /*
> * Note, even though FRED delivers the faulting linear address via the
> * event data field on the stack, CR2 is still updated.
> */
Will do!
There is a reason for this comment because it won't be architectural:
https://lore.kernel.org/lkml/[email protected]/
FRED is designed to atomically save and restore _full_ supervisor/user
context upon event delivery and return. But unfortunately, KVM still has
to save/restore guest CR2 explicitly due to the issue mentioned above.
Thanks!
Xin
On Wed, Feb 07, 2024, Xin Li wrote:
> @@ -6856,13 +6865,17 @@ static void nested_vmx_setup_exit_ctls(struct vmcs_config *vmcs_conf,
> VM_EXIT_HOST_ADDR_SPACE_SIZE |
> #endif
> VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT |
> - VM_EXIT_CLEAR_BNDCFGS;
> + VM_EXIT_CLEAR_BNDCFGS | VM_EXIT_ACTIVATE_SECONDARY_CONTROLS;
> msrs->exit_ctls_high |=
> VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
> VM_EXIT_LOAD_IA32_EFER | VM_EXIT_SAVE_IA32_EFER |
> VM_EXIT_SAVE_VMX_PREEMPTION_TIMER | VM_EXIT_ACK_INTR_ON_EXIT |
> VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL;
>
> + /* secondary exit controls */
Drop the comment, it's pretty obvious what field is being setup.
> + if (msrs->exit_ctls_high & VM_EXIT_ACTIVATE_SECONDARY_CONTROLS)
> + rdmsrl(MSR_IA32_VMX_EXIT_CTLS2, msrs->secondary_exit_ctls);
This is wrong, the resulting msrs->secondary_exit_ctls needs to be sanitized
based on what KVM supports for nVMX.
On a very related topic, this should not do a raw RDMSR. One of the reasons why
KVM uses vmcs_config as the base is to avoid advertising features to L1 that KVM
itself doesn't support, e.g. because the expected entry+exit pairs aren't
supported.
And by pulling state from vmcs_conf->secondary_exit_ctls there's no need to check
the activation bit.
I.e. literaly just this:
msrs->secondary_exit_ctls = vmcs_conf->secondary_exit_ctls;
msrs->secondary_exit_ctls &= 0;
and then when nVMX FRED support is ready, it becomes:
msrs->secondary_exit_ctls = vmcs_conf->secondary_exit_ctls;
msrs->secondary_exit_ctls &= SECONDARY_VM_EXIT_SAVE_IA32_FRED |
SECONDARY_VM_EXIT_LOAD_IA32_FRED;
On Wed, Feb 07, 2024, Xin Li wrote:
> @@ -32,48 +32,48 @@ BUILD_BUG_ON(1)
> */
>
> /* 16-bits */
> -SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status)
> -SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index)
> -SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector)
> -SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector)
> +SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status, cpu_has_vmx_apicv())
> +SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index, cpu_has_vmx_pml())
> +SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector, true)
> +SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector, true)
>
> /* 32-bits */
> -SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason)
> -SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info)
> -SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len)
> -SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field)
> -SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code)
> -SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code)
> -SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes)
> -SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes)
> -SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control)
> -SHADOW_FIELD_RW(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control)
> -SHADOW_FIELD_RW(EXCEPTION_BITMAP, exception_bitmap)
> -SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code)
> -SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field)
> -SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len)
> -SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold)
> -SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info)
> -SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value)
> +SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason, true)
> +SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info, true)
> +SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len, true)
> +SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code, true)
> +SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field, true)
> +SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code, true)
> +SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes, true)
> +SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes, true)
> +SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control, true)
> +SHADOW_FIELD_RW(PIN_BASED_VM_EXEC_CONTROL, pin_based_vm_exec_control, true)
> +SHADOW_FIELD_RW(EXCEPTION_BITMAP, exception_bitmap, true)
> +SHADOW_FIELD_RW(VM_ENTRY_EXCEPTION_ERROR_CODE, vm_entry_exception_error_code, true)
> +SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field, true)
> +SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len, true)
> +SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold, true)
> +SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info, true)
> +SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value, cpu_has_vmx_preemption_timer())
>
> /* Natural width */
> -SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification)
> -SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS, guest_linear_address)
> -SHADOW_FIELD_RW(GUEST_RIP, guest_rip)
> -SHADOW_FIELD_RW(GUEST_RSP, guest_rsp)
> -SHADOW_FIELD_RW(GUEST_CR0, guest_cr0)
> -SHADOW_FIELD_RW(GUEST_CR3, guest_cr3)
> -SHADOW_FIELD_RW(GUEST_CR4, guest_cr4)
> -SHADOW_FIELD_RW(GUEST_RFLAGS, guest_rflags)
> -SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK, cr0_guest_host_mask)
> -SHADOW_FIELD_RW(CR0_READ_SHADOW, cr0_read_shadow)
> -SHADOW_FIELD_RW(CR4_READ_SHADOW, cr4_read_shadow)
> -SHADOW_FIELD_RW(HOST_FS_BASE, host_fs_base)
> -SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base)
> +SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification, true)
> +SHADOW_FIELD_RO(GUEST_LINEAR_ADDRESS, guest_linear_address, true)
> +SHADOW_FIELD_RW(GUEST_RIP, guest_rip, true)
> +SHADOW_FIELD_RW(GUEST_RSP, guest_rsp, true)
> +SHADOW_FIELD_RW(GUEST_CR0, guest_cr0, true)
> +SHADOW_FIELD_RW(GUEST_CR3, guest_cr3, true)
> +SHADOW_FIELD_RW(GUEST_CR4, guest_cr4, true)
> +SHADOW_FIELD_RW(GUEST_RFLAGS, guest_rflags, true)
> +SHADOW_FIELD_RW(CR0_GUEST_HOST_MASK, cr0_guest_host_mask, true)
> +SHADOW_FIELD_RW(CR0_READ_SHADOW, cr0_read_shadow, true)
> +SHADOW_FIELD_RW(CR4_READ_SHADOW, cr4_read_shadow, true)
> +SHADOW_FIELD_RW(HOST_FS_BASE, host_fs_base, true)
> +SHADOW_FIELD_RW(HOST_GS_BASE, host_gs_base, true)
>
> /* 64-bit */
> -SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address)
> -SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address)
> +SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS, guest_physical_address, true)
> +SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address, true)
This is not a net postive for readability or maintability. I don't hate the
idea, it just needs MOAR MACROs :-) E.g. add a layer for the common case where
the field unconditionally exists.
#ifndef __SHADOW_FIELD_RO
#define __SHADOW_FIELD_RO(x, y, c)
#endif
#ifndef __SHADOW_FIELD_RW
#define __SHADOW_FIELD_RW(x, y, c)
#endif
#define SHADOW_FIELD_RO(x, y) __SHADOW_FIELD_RO(x, y, true)
#define SHADOW_FIELD_RW(x, y) __SHADOW_FIELD_RW(x, y, true)
On Wed, Feb 07, 2024, Xin Li wrote:
> Add FRED VMCS fields to nested VMX context management.
>
> Todo: change VMCS12_REVISION, as struct vmcs12 is changed.
It actually doesn't, the comment is just stale. At this point, KVM must _never_
change VMCS12_REVISION as doing so will break backwards compatibility.
I'll post this once I've written a changelog:
---
arch/x86/kvm/vmx/vmcs12.h | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h
index edf7fcef8ccf..d67bebb9f1c2 100644
--- a/arch/x86/kvm/vmx/vmcs12.h
+++ b/arch/x86/kvm/vmx/vmcs12.h
@@ -207,11 +207,9 @@ struct __packed vmcs12 {
};
/*
- * VMCS12_REVISION is an arbitrary id that should be changed if the content or
- * layout of struct vmcs12 is changed. MSR_IA32_VMX_BASIC returns this id, and
- * VMPTRLD verifies that the VMCS region that L1 is loading contains this id.
+ * VMCS12_REVISION is KVM's arbitrary id for the layout of struct vmcs12.
*
- * IMPORTANT: Changing this value will break save/restore compatibility with
+ * DO NOT change this value, as it will break save/restore compatibility with
* older kvm releases.
*/
#define VMCS12_REVISION 0x11e57ed0
@@ -225,7 +223,8 @@ struct __packed vmcs12 {
#define VMCS12_SIZE KVM_STATE_NESTED_VMX_VMCS_SIZE
/*
- * For save/restore compatibility, the vmcs12 field offsets must not change.
+ * For save/restore compatibility, the vmcs12 field offsets must not change,
+ * although appending fields and/or filling gaps is obviously allowed.
*/
#define CHECK_OFFSET(field, loc) \
ASSERT_STRUCT_OFFSET(struct vmcs12, field, loc)
base-commit: 878fe4c2f7eead383f2b306cbafd300006dd518c
--
> Signed-off-by: Xin Li <[email protected]>
> Tested-by: Shan Kang <[email protected]>
> ---
>
> Change since v1:
> * Remove hyperv TLFS related changes (Jeremi Piotrowski).
> * Use kvm_cpu_cap_has() instead of cpu_feature_enabled() (Chao Gao).
> ---
> Documentation/virt/kvm/x86/nested-vmx.rst | 18 +++++
> arch/x86/kvm/vmx/nested.c | 91 +++++++++++++++++++----
> arch/x86/kvm/vmx/vmcs12.c | 18 +++++
> arch/x86/kvm/vmx/vmcs12.h | 36 +++++++++
> arch/x86/kvm/vmx/vmcs_shadow_fields.h | 4 +
> 5 files changed, 152 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/virt/kvm/x86/nested-vmx.rst b/Documentation/virt/kvm/x86/nested-vmx.rst
> index e64ef231f310..87fa9f3877ab 100644
> --- a/Documentation/virt/kvm/x86/nested-vmx.rst
> +++ b/Documentation/virt/kvm/x86/nested-vmx.rst
> @@ -218,6 +218,24 @@ struct shadow_vmcs is ever changed.
> u16 host_gs_selector;
> u16 host_tr_selector;
> u64 secondary_vm_exit_controls;
> + u64 guest_ia32_fred_config;
> + u64 guest_ia32_fred_rsp1;
> + u64 guest_ia32_fred_rsp2;
> + u64 guest_ia32_fred_rsp3;
> + u64 guest_ia32_fred_stklvls;
> + u64 guest_ia32_fred_ssp1;
> + u64 guest_ia32_fred_ssp2;
> + u64 guest_ia32_fred_ssp3;
> + u64 host_ia32_fred_config;
> + u64 host_ia32_fred_rsp1;
> + u64 host_ia32_fred_rsp2;
> + u64 host_ia32_fred_rsp3;
> + u64 host_ia32_fred_stklvls;
> + u64 host_ia32_fred_ssp1;
> + u64 host_ia32_fred_ssp2;
> + u64 host_ia32_fred_ssp3;
> + u64 injected_event_data;
> + u64 original_event_data;
> };
>
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 94da6a0a2f81..f9c1fbeac302 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -686,6 +686,9 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
>
> nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
> MSR_KERNEL_GS_BASE, MSR_TYPE_RW);
> +
> + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
> + MSR_IA32_FRED_RSP0, MSR_TYPE_RW);
> #endif
> nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,
> MSR_IA32_SPEC_CTRL, MSR_TYPE_RW);
> @@ -2498,6 +2501,8 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs0
> vmcs12->vm_entry_instruction_len);
> vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
> vmcs12->guest_interruptibility_info);
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED))
This is wrong, vmcs02 should be set from vmcs12 if and only if the field is enabled
in L1's VMX configuration, i.e. iff nested_cpu_has(vmcs12, ???).
Note, the ??? should be tied to whatever VMX MSR feature flag enumerates
INJECTED_EVENT_DATA. KVM's clearing of X86_FEATURE_FRED when one or more pieces
is missing is a software decision, i.e. not archictectural.
> + vmcs_write64(INJECTED_EVENT_DATA, vmcs12->injected_event_data);
> vmx->loaded_vmcs->nmi_known_unmasked =
> !(vmcs12->guest_interruptibility_info & GUEST_INTR_STATE_NMI);
> } else {
> @@ -2548,6 +2553,17 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
> vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base);
> vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base);
>
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
Same thing here.
> + vmcs_write64(GUEST_IA32_FRED_CONFIG, vmcs12->guest_ia32_fred_config);
> + vmcs_write64(GUEST_IA32_FRED_RSP1, vmcs12->guest_ia32_fred_rsp1);
> + vmcs_write64(GUEST_IA32_FRED_RSP2, vmcs12->guest_ia32_fred_rsp2);
> + vmcs_write64(GUEST_IA32_FRED_RSP3, vmcs12->guest_ia32_fred_rsp3);
> + vmcs_write64(GUEST_IA32_FRED_STKLVLS, vmcs12->guest_ia32_fred_stklvls);
> + vmcs_write64(GUEST_IA32_FRED_SSP1, vmcs12->guest_ia32_fred_ssp1);
> + vmcs_write64(GUEST_IA32_FRED_SSP2, vmcs12->guest_ia32_fred_ssp2);
> + vmcs_write64(GUEST_IA32_FRED_SSP3, vmcs12->guest_ia32_fred_ssp3);
> + }
> +
> vmx->segment_cache.bitmask = 0;
> }
>
> @@ -3835,6 +3851,22 @@ vmcs12_guest_cr4(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vcpu->arch.cr4_guest_owned_bits));
> }
>
> +static inline unsigned long
> +nested_vmx_get_event_data(struct kvm_vcpu *vcpu, bool for_ex_vmexit)
Heh, two form letters for the price of one:
#1
Do not use "inline" for functions that are visible only to the local compilation
unit. "inline" is just a hint, and modern compilers are smart enough to inline
functions when appropriate without a hint.
A longer explanation/rant here: https://lore.kernel.org/all/[email protected]
#2
Do not wrap before the function name. Linus has a nice explanation/rant on this[*].
[*] https://lore.kernel.org/all/CAHk-=wjoLAYG446ZNHfg=GhjSY6nFmuB_wA8fYd5iLBNXjo9Bw@mail.gmail.com
> +{
> + struct kvm_queued_exception *ex = for_ex_vmexit ?
> + &vcpu->arch.exception_vmexit : &vcpu->arch.exception;
> +
> + if (ex->has_payload)
> + return ex->payload;
> + else if (ex->vector == PF_VECTOR)
> + return vcpu->arch.cr2;
> + else if (ex->vector == DB_VECTOR)
> + return (vcpu->arch.dr6 & ~DR6_BT) ^ DR6_ACTIVE_LOW;
> + else
> + return 0;
I'll circle back to this on the next version, i.e. after it's reworked to account
for the suggested payload changes. I highly doubt it's correct as-is.
> static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12,
> u32 vm_exit_reason, u32 exit_intr_info)
> @@ -3842,6 +3874,8 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
> u32 idt_vectoring;
> unsigned int nr;
>
> + vmcs12->original_event_data = 0;
> +
> /*
> * Per the SDM, VM-Exits due to double and triple faults are never
> * considered to occur during event delivery, even if the double/triple
> @@ -3880,6 +3914,12 @@ static void vmcs12_save_pending_event(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.error_code;
> }
>
> + idt_vectoring |= vcpu->arch.exception.nested ?
> + INTR_INFO_NESTED_EXCEPTION_MASK : 0;
Please stop using ternary operators this way. It's less readable and the same
number of lines as:
if (vcpu->arch.exception.nested)
idt_vectoring |= INTR_INFO_NESTED_EXCEPTION_MASK;
> +
> + vmcs12->original_event_data =
> + nested_vmx_get_event_data(vcpu, false);
> +
> vmcs12->idt_vectoring_info_field = idt_vectoring;
> } else if (vcpu->arch.nmi_injected) {
> vmcs12->idt_vectoring_info_field =
> @@ -3970,19 +4010,7 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu)
> struct kvm_queued_exception *ex = &vcpu->arch.exception_vmexit;
> u32 intr_info = ex->vector | INTR_INFO_VALID_MASK;
> struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> - unsigned long exit_qual;
> -
> - if (ex->has_payload) {
> - exit_qual = ex->payload;
> - } else if (ex->vector == PF_VECTOR) {
> - exit_qual = vcpu->arch.cr2;
> - } else if (ex->vector == DB_VECTOR) {
> - exit_qual = vcpu->arch.dr6;
> - exit_qual &= ~DR6_BT;
> - exit_qual ^= DR6_ACTIVE_LOW;
> - } else {
> - exit_qual = 0;
> - }
> + unsigned long exit_qual = nested_vmx_get_event_data(vcpu, true);
This can't possibly be correct, EXIT_QUAL and EVENT_DATA aren't equivalent, e.g.
the former doesn't have XFD_ERR, but the latter does.
> /*
> * Unlike AMD's Paged Real Mode, which reports an error code on #PF
> @@ -4003,10 +4031,12 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu)
> intr_info |= INTR_INFO_DELIVER_CODE_MASK;
> }
>
> - if (kvm_exception_is_soft(ex->vector))
> + if (kvm_exception_is_soft(ex->vector)) {
> intr_info |= INTR_TYPE_SOFT_EXCEPTION;
> - else
> + } else {
> intr_info |= INTR_TYPE_HARD_EXCEPTION;
> + intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
Again,
if (ex->nested)
intr_info |= INTR_INFO_NESTED_EXCEPTION_MASK;
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
And here
> + vmcs12->guest_ia32_fred_config = vmcs_read64(GUEST_IA32_FRED_CONFIG);
> + vmcs12->guest_ia32_fred_rsp1 = vmcs_read64(GUEST_IA32_FRED_RSP1);
> + vmcs12->guest_ia32_fred_rsp2 = vmcs_read64(GUEST_IA32_FRED_RSP2);
> + vmcs12->guest_ia32_fred_rsp3 = vmcs_read64(GUEST_IA32_FRED_RSP3);
> + vmcs12->guest_ia32_fred_stklvls = vmcs_read64(GUEST_IA32_FRED_STKLVLS);
> + vmcs12->guest_ia32_fred_ssp1 = vmcs_read64(GUEST_IA32_FRED_SSP1);
> + vmcs12->guest_ia32_fred_ssp2 = vmcs_read64(GUEST_IA32_FRED_SSP2);
> + vmcs12->guest_ia32_fred_ssp3 = vmcs_read64(GUEST_IA32_FRED_SSP3);
> + }
> +
> vmcs12->guest_pending_dbg_exceptions =
> vmcs_readl(GUEST_PENDING_DBG_EXCEPTIONS);
>
> @@ -4625,6 +4675,17 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
> vmcs_write32(GUEST_IDTR_LIMIT, 0xFFFF);
> vmcs_write32(GUEST_GDTR_LIMIT, 0xFFFF);
>
> + if (kvm_cpu_cap_has(X86_FEATURE_FRED)) {
And here
On Wed, Feb 07, 2024, Xin Li wrote:
> Allow FRED/LKGS/WRMSRNS to be exposed to guests, thus a guest OS could see
> these features when the guest is configured with FRED/LKGS/WRMSRNS in Qemu.
(a) please describe what these features are, and (b) one patch per feature unless
they _must_ be bundled together, in which case there needs to be code to enforce
that.
> A qemu patch is required to expose FRED/LKGS/WRMSRNS to KVM guests.
Omit this, QEMU is not the only VMM that uses KVM.
On Wed, Mar 27, 2024, Shan Kang wrote:
> On Wed, 2024-02-07 at 09:26 -0800, Xin Li wrote:
> > This patch set enables the Intel flexible return and event delivery
> > (FRED) architecture with KVM VMX to allow guests to utilize FRED.
> >
> We tested this FRED KVM patch set on a 7th Intel(R) Core(TM) CPU and the Intel
> Simics® Simulator with the following four configurations:
That likely provides coverage for the happy cases, but I doubt it provides negative
testing, e.g. for VM-Enter consistency checks. KVM-Unit-Tests are currently the
best choice for concistency checks (unfortunately).
And given the insanity of event re-injection, KVM selftests needs a dedicated test
for that, and another for the interactions with nVMX, e.g. a la svm_nested_soft_inject_test.c.
I haven't looked too closely at the selftest that's already provided, but my
suspicion is that we'll want multiple tests, or alternatively one test that
uses KVM_ONE_VCPU_TEST_SUITE().
> On Wed, Mar 27, 2024, Shan Kang wrote:
> > On Wed, 2024-02-07 at 09:26 -0800, Xin Li wrote:
> > > This patch set enables the Intel flexible return and event delivery
> > > (FRED) architecture with KVM VMX to allow guests to utilize FRED.
> > >
> > We tested this FRED KVM patch set on a 7th Intel(R) Core(TM) CPU and
> > the Intel Simics® Simulator with the following four configurations:
>
> That likely provides coverage for the happy cases, but I doubt it provides negative
> testing, e.g. for VM-Enter consistency checks. KVM-Unit-Tests are currently the
> best choice for concistency checks (unfortunately).
>
> And given the insanity of event re-injection, KVM selftests needs a dedicated test
> for that, and another for the interactions with nVMX, e.g. a la
> svm_nested_soft_inject_test.c.
>
> I haven't looked too closely at the selftest that's already provided, but my
> suspicion is that we'll want multiple tests, or alternatively one test that uses
> KVM_ONE_VCPU_TEST_SUITE().
What about posting the FRED selftests in another new patch set?
Thanks!
Xin