Current IPI process in guest VM will virtualize the writing to interrupt
command register(ICR) of the local APIC which will cause VM-exit anyway
on source vCPU. Frequent VM-exit could induce much overhead accumulated
if running IPI intensive task.
IPI virtualization as a new VT-x feature targets to eliminate VM-exits
when issuing IPI on source vCPU. It introduces a new VM-execution
control - "IPI virtualization"(bit4) in the tertiary processor-based
VM-exection controls and a new data structure - "PID-pointer table
address" and "Last PID-pointer index" referenced by the VMCS. When "IPI
virtualization" is enabled, processor emulateds following kind of writes
to APIC registers that would send IPIs, moreover without causing VM-exits.
- Memory-mapped ICR writes
- MSR-mapped ICR writes
- SENDUIPI execution
This patch series implement IPI virtualization support in KVM.
Patches 1-4 add tertiary processor-based VM-execution support
framework.
Patch 5 implement interrupt dispatch support in x2APIC mode with
APIC-write VM exit. In previous platform, no CPU would produce
APIC-write VM exit with exit qulification 300H when the "virtual x2APIC
mode" VM-execution control was 1.
Patch 6 implement IPI virtualization related function including
feature enabling through tertiary processor-based VM-execution in
various scenario of VMCS configuration, PID table setup in vCPU creation
and vCPU block consideration.
Document for IPI virtualization is now available at the latest "Intel
Architecture Instruction Set Extensions Programming Reference".
Document Link:
https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html
We did experiment to measure average time sending IPI from source vCPU
to the target vCPU completing the IPI handling by kvm unittest w/ and
w/o IPI virtualization. When IPI virtualizatin enabled, it will reduce
22.21% and 15.98% cycles consuming in xAPIC mode and x2APIC mode
respectly.
KMV unittest:vmexit/ipi, 2 vCPU, AP was modified to run in idle loop
instead of halt to ensure no VM exit impact on target vCPU.
Cycles of IPI
xAPIC mode x2APIC mode
test w/o IPIv w/ IPIv w/o IPIv w/ IPIv
1 6106 4816 4265 3768
2 6244 4656 4404 3546
3 6165 4658 4233 3474
4 5992 4710 4363 3430
5 6083 4741 4215 3551
6 6238 4904 4304 3547
7 6164 4617 4263 3709
8 5984 4763 4518 3779
9 5931 4712 4645 3667
10 5955 4530 4332 3724
11 5897 4673 4283 3569
12 6140 4794 4178 3598
13 6183 4728 4363 3628
14 5991 4994 4509 3842
15 5866 4665 4520 3739
16 6032 4654 4229 3701
17 6050 4653 4185 3726
18 6004 4792 4319 3746
19 5961 4626 4196 3392
20 6194 4576 4433 3760
Average cycles 6059 4713.1 4337.85 3644.8
%Reduction -22.21% -15.98%
--------------------------------------
IPI microbenchmark:
(https://lore.kernel.org/kvm/[email protected])
2 vCPUs, 1:1 pin vCPU to pCPU, guest VM runs with idle=poll, x2APIC mode
Result with IPIv enabled:
Dry-run: 0, 272798 ns
Self-IPI: 5094123, 11114037 ns
Normal IPI: 131697087, 173321200 ns
Broadcast IPI: 0, 155649075 ns
Broadcast lock: 0, 161518031 ns
Result with IPIv disabled:
Dry-run: 0, 272766 ns
Self-IPI: 5091788, 11123699 ns
Normal IPI: 145215772, 174558920 ns
Broadcast IPI: 0, 175785384 ns
Broadcast lock: 0, 149076195 ns
As IPIv can benefit unicast IPI to other CPU, Noraml IPI test case gain
about 9.73% time saving on average out of 15 test runs when IPIv is
enabled.
w/o IPIv w/ IPIv
Normal IPI: 145944306.6 ns 131742993.1 ns
%Reduction -9.73%
--------------------------------------
hackbench:
8 vCPUs, guest VM free run, x2APIC mode
./hackbench -p -l 100000
w/o IPIv w/ IPIv
Time: 91.887 74.605
%Reduction: -18.808%
96 vCPUs, guest VM free run, x2APIC mode
./hackbench -p -l 1000000
w/o IPIv w/ IPIv
Time: 287.504 235.185
%Reduction: -18.198%
--------------------------------------
v1 -> v2:
1. Refine the IPIv enabling logic for VM.
Remove ipiv_active definition per vCPU.
Gao Chao (1):
KVM: VMX: enable IPI virtualization
Robert Hoo (4):
x86/feat_ctl: Add new VMX feature, Tertiary VM-Execution control
KVM: VMX: Extend BUILD_CONTROLS_SHADOW macro to support 64-bit
variation
KVM: VMX: Detect Tertiary VM-Execution control when setup VMCS config
KVM: VMX: dump_vmcs() reports tertiary_exec_control field as well
Zeng Guang (1):
KVM: x86: Support interrupt dispatch in x2APIC mode with APIC-write VM
exit
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/include/asm/vmx.h | 11 +++
arch/x86/include/asm/vmxfeatures.h | 5 +-
arch/x86/kernel/cpu/feat_ctl.c | 9 +++
arch/x86/kvm/lapic.c | 9 ++-
arch/x86/kvm/vmx/capabilities.h | 14 ++++
arch/x86/kvm/vmx/evmcs.c | 2 +
arch/x86/kvm/vmx/evmcs.h | 1 +
arch/x86/kvm/vmx/posted_intr.c | 22 ++++--
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmx.c | 116 +++++++++++++++++++++++++++--
arch/x86/kvm/vmx/vmx.h | 27 ++++---
12 files changed, 194 insertions(+), 24 deletions(-)
--
2.25.1
From: Robert Hoo <[email protected]>
New VMX capability MSR IA32_VMX_PROCBASED_CTLS3 conresponse to this new
VM-Execution control field. And it is 64bit allow-1 semantics, not like
previous capability MSRs 32bit allow-0 and 32bit allow-1. So with Tertiary
VM-Execution control field introduced, 2 vmx_feature leaves are introduced,
TERTIARY_CTLS_LOW and TERTIARY_CTLS_HIGH.
Signed-off-by: Robert Hoo <[email protected]>
Signed-off-by: Zeng Guang <[email protected]>
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/include/asm/vmxfeatures.h | 3 ++-
arch/x86/kernel/cpu/feat_ctl.c | 9 +++++++++
3 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index a7c413432b33..3df26e27b554 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -919,6 +919,7 @@
#define MSR_IA32_VMX_TRUE_EXIT_CTLS 0x0000048f
#define MSR_IA32_VMX_TRUE_ENTRY_CTLS 0x00000490
#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
diff --git a/arch/x86/include/asm/vmxfeatures.h b/arch/x86/include/asm/vmxfeatures.h
index d9a74681a77d..27e76eeca05b 100644
--- a/arch/x86/include/asm/vmxfeatures.h
+++ b/arch/x86/include/asm/vmxfeatures.h
@@ -5,7 +5,7 @@
/*
* Defines VMX CPU feature bits
*/
-#define NVMXINTS 3 /* N 32-bit words worth of info */
+#define NVMXINTS 5 /* N 32-bit words worth of info */
/*
* Note: If the comment begins with a quoted string, that string is used
@@ -43,6 +43,7 @@
#define VMX_FEATURE_RDTSC_EXITING ( 1*32+ 12) /* "" VM-Exit on RDTSC */
#define VMX_FEATURE_CR3_LOAD_EXITING ( 1*32+ 15) /* "" VM-Exit on writes to CR3 */
#define VMX_FEATURE_CR3_STORE_EXITING ( 1*32+ 16) /* "" VM-Exit on reads from CR3 */
+#define VMX_FEATURE_TER_CONTROLS (1*32 + 17) /* "" Enable Tertiary VM-Execution Controls */
#define VMX_FEATURE_CR8_LOAD_EXITING ( 1*32+ 19) /* "" VM-Exit on writes to CR8 */
#define VMX_FEATURE_CR8_STORE_EXITING ( 1*32+ 20) /* "" VM-Exit on reads from CR8 */
#define VMX_FEATURE_VIRTUAL_TPR ( 1*32+ 21) /* "vtpr" TPR virtualization, a.k.a. TPR shadow */
diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index da696eb4821a..2e0272d127e4 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -15,6 +15,8 @@ enum vmx_feature_leafs {
MISC_FEATURES = 0,
PRIMARY_CTLS,
SECONDARY_CTLS,
+ TERTIARY_CTLS_LOW,
+ TERTIARY_CTLS_HIGH,
NR_VMX_FEATURE_WORDS,
};
@@ -42,6 +44,13 @@ static void init_vmx_capabilities(struct cpuinfo_x86 *c)
rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS2, &ign, &supported);
c->vmx_capability[SECONDARY_CTLS] = supported;
+ /*
+ * For tertiary execution controls MSR, it's actually a 64bit allowed-1.
+ */
+ rdmsr_safe(MSR_IA32_VMX_PROCBASED_CTLS3, &ign, &supported);
+ c->vmx_capability[TERTIARY_CTLS_LOW] = ign;
+ c->vmx_capability[TERTIARY_CTLS_HIGH] = supported;
+
rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported);
rdmsr_safe(MSR_IA32_VMX_VMFUNC, &ign, &funcs);
--
2.25.1
From: Robert Hoo <[email protected]>
The Tertiary VM-Exec Control, different from previous control fields, is 64
bit. So extend BUILD_CONTROLS_SHADOW() by adding a 'bit' parameter, to
support both 32 bit and 64 bit fields' auxiliary functions building.
Also, define the auxiliary functions for Tertiary control field here, using
the new BUILD_CONTROLS_SHADOW().
Suggested-by: Sean Christopherson <[email protected]>
Signed-off-by: Robert Hoo <[email protected]>
---
arch/x86/kvm/vmx/vmx.h | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 3979a947933a..945c6639ce24 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -413,31 +413,32 @@ static inline u8 vmx_get_rvi(void)
return vmcs_read16(GUEST_INTR_STATUS) & 0xff;
}
-#define BUILD_CONTROLS_SHADOW(lname, uname) \
-static inline void lname##_controls_set(struct vcpu_vmx *vmx, u32 val) \
+#define BUILD_CONTROLS_SHADOW(lname, uname, bits) \
+static inline void lname##_controls_set(struct vcpu_vmx *vmx, u##bits val) \
{ \
if (vmx->loaded_vmcs->controls_shadow.lname != val) { \
- vmcs_write32(uname, val); \
+ vmcs_write##bits(uname, val); \
vmx->loaded_vmcs->controls_shadow.lname = val; \
} \
} \
-static inline u32 lname##_controls_get(struct vcpu_vmx *vmx) \
+static inline u##bits lname##_controls_get(struct vcpu_vmx *vmx) \
{ \
return vmx->loaded_vmcs->controls_shadow.lname; \
} \
-static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u32 val) \
+static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u##bits val) \
{ \
lname##_controls_set(vmx, lname##_controls_get(vmx) | val); \
} \
-static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u32 val) \
+static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u##bits val) \
{ \
lname##_controls_set(vmx, lname##_controls_get(vmx) & ~val); \
}
-BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS)
-BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS)
-BUILD_CONTROLS_SHADOW(pin, PIN_BASED_VM_EXEC_CONTROL)
-BUILD_CONTROLS_SHADOW(exec, CPU_BASED_VM_EXEC_CONTROL)
-BUILD_CONTROLS_SHADOW(secondary_exec, SECONDARY_VM_EXEC_CONTROL)
+BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS, 32)
+BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS, 32)
+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)
+BUILD_CONTROLS_SHADOW(tertiary_exec, TERTIARY_VM_EXEC_CONTROL, 64)
static inline void vmx_register_cache_reset(struct kvm_vcpu *vcpu)
{
--
2.25.1
From: Robert Hoo <[email protected]>
Check VMX feature on tertiary execution control in VMCS config setup.
Currently it's not supported for hyper-v and disabled for now.
Signed-off-by: Robert Hoo <[email protected]>
Signed-off-by: Zeng Guang <[email protected]>
---
arch/x86/include/asm/vmx.h | 3 +++
arch/x86/kvm/vmx/capabilities.h | 7 ++++++
arch/x86/kvm/vmx/evmcs.c | 2 ++
arch/x86/kvm/vmx/evmcs.h | 1 +
arch/x86/kvm/vmx/vmcs.h | 1 +
arch/x86/kvm/vmx/vmx.c | 44 ++++++++++++++++++++++++++++++++-
arch/x86/kvm/vmx/vmx.h | 1 +
7 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 0ffaa3156a4e..15652047f2db 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -31,6 +31,7 @@
#define CPU_BASED_RDTSC_EXITING VMCS_CONTROL_BIT(RDTSC_EXITING)
#define CPU_BASED_CR3_LOAD_EXITING VMCS_CONTROL_BIT(CR3_LOAD_EXITING)
#define CPU_BASED_CR3_STORE_EXITING VMCS_CONTROL_BIT(CR3_STORE_EXITING)
+#define CPU_BASED_ACTIVATE_TERTIARY_CONTROLS VMCS_CONTROL_BIT(TER_CONTROLS)
#define CPU_BASED_CR8_LOAD_EXITING VMCS_CONTROL_BIT(CR8_LOAD_EXITING)
#define CPU_BASED_CR8_STORE_EXITING VMCS_CONTROL_BIT(CR8_STORE_EXITING)
#define CPU_BASED_TPR_SHADOW VMCS_CONTROL_BIT(VIRTUAL_TPR)
@@ -221,6 +222,8 @@ enum vmcs_field {
ENCLS_EXITING_BITMAP_HIGH = 0x0000202F,
TSC_MULTIPLIER = 0x00002032,
TSC_MULTIPLIER_HIGH = 0x00002033,
+ TERTIARY_VM_EXEC_CONTROL = 0x00002034,
+ TERTIARY_VM_EXEC_CONTROL_HIGH = 0x00002035,
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 4705ad55abb5..38d414f64e61 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -59,6 +59,7 @@ struct vmcs_config {
u32 pin_based_exec_ctrl;
u32 cpu_based_exec_ctrl;
u32 cpu_based_2nd_exec_ctrl;
+ u64 cpu_based_3rd_exec_ctrl;
u32 vmexit_ctrl;
u32 vmentry_ctrl;
struct nested_vmx_msrs nested;
@@ -131,6 +132,12 @@ static inline bool cpu_has_secondary_exec_ctrls(void)
CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
}
+static inline bool cpu_has_tertiary_exec_ctrls(void)
+{
+ return vmcs_config.cpu_based_exec_ctrl &
+ CPU_BASED_ACTIVATE_TERTIARY_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/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index 896b2a50b4aa..03c15e1e5807 100644
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c
@@ -299,8 +299,10 @@ const unsigned int nr_evmcs_1_fields = ARRAY_SIZE(vmcs_field_to_evmcs_1);
__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf)
{
+ vmcs_conf->cpu_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_EXEC_CTRL;
vmcs_conf->pin_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_PINCTRL;
vmcs_conf->cpu_based_2nd_exec_ctrl &= ~EVMCS1_UNSUPPORTED_2NDEXEC;
+ vmcs_conf->cpu_based_3rd_exec_ctrl = 0;
vmcs_conf->vmexit_ctrl &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
vmcs_conf->vmentry_ctrl &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index 2ec9b46f0d0c..8a20295f4f0f 100644
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h
@@ -50,6 +50,7 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
*/
#define EVMCS1_UNSUPPORTED_PINCTRL (PIN_BASED_POSTED_INTR | \
PIN_BASED_VMX_PREEMPTION_TIMER)
+#define EVMCS1_UNSUPPORTED_EXEC_CTRL (CPU_BASED_ACTIVATE_TERTIARY_CONTROLS)
#define EVMCS1_UNSUPPORTED_2NDEXEC \
(SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY | \
SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES | \
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
index 4b9957e2bf5b..83e2065a955d 100644
--- a/arch/x86/kvm/vmx/vmcs.h
+++ b/arch/x86/kvm/vmx/vmcs.h
@@ -48,6 +48,7 @@ struct vmcs_controls_shadow {
u32 pin;
u32 exec;
u32 secondary_exec;
+ u64 tertiary_exec;
};
/*
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 927a552393b9..728873971913 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2391,6 +2391,23 @@ static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
return 0;
}
+static __init int adjust_vmx_controls_64(u64 ctl_min, u64 ctl_opt,
+ u32 msr, u64 *result)
+{
+ u64 vmx_msr;
+ u64 ctl = ctl_min | ctl_opt;
+
+ rdmsrl(msr, vmx_msr);
+ ctl &= vmx_msr; /* bit == 1 means it can be set */
+
+ /* Ensure minimum (required) set of control bits are supported. */
+ if (ctl_min & ~ctl)
+ return -EIO;
+
+ *result = ctl;
+ return 0;
+}
+
static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
struct vmx_capability *vmx_cap)
{
@@ -2399,6 +2416,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
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;
@@ -2420,7 +2438,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
opt = CPU_BASED_TPR_SHADOW |
CPU_BASED_USE_MSR_BITMAPS |
- CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
+ CPU_BASED_ACTIVATE_SECONDARY_CONTROLS |
+ CPU_BASED_ACTIVATE_TERTIARY_CONTROLS;
if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_PROCBASED_CTLS,
&_cpu_based_exec_control) < 0)
return -EIO;
@@ -2494,6 +2513,16 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
"1-setting enable VPID VM-execution control\n");
}
+ if (_cpu_based_exec_control & CPU_BASED_ACTIVATE_TERTIARY_CONTROLS) {
+ u64 opt3 = 0;
+ u64 min3 = 0;
+
+ if (adjust_vmx_controls_64(min3, opt3,
+ MSR_IA32_VMX_PROCBASED_CTLS3,
+ &_cpu_based_3rd_exec_control))
+ return -EIO;
+ }
+
min = VM_EXIT_SAVE_DEBUG_CONTROLS | VM_EXIT_ACK_INTR_ON_EXIT;
#ifdef CONFIG_X86_64
min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
@@ -2581,6 +2610,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
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;
+ vmcs_conf->cpu_based_3rd_exec_ctrl = _cpu_based_3rd_exec_control;
vmcs_conf->vmexit_ctrl = _vmexit_control;
vmcs_conf->vmentry_ctrl = _vmentry_control;
@@ -4204,6 +4234,13 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control,
#define vmx_adjust_sec_exec_exiting(vmx, exec_control, lname, uname) \
vmx_adjust_sec_exec_control(vmx, exec_control, lname, uname, uname##_EXITING, true)
+static void vmx_compute_tertiary_exec_control(struct vcpu_vmx *vmx)
+{
+ u32 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
+
+ vmx->tertiary_exec_control = exec_control;
+}
+
static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
{
struct kvm_vcpu *vcpu = &vmx->vcpu;
@@ -4319,6 +4356,11 @@ static void init_vmcs(struct vcpu_vmx *vmx)
secondary_exec_controls_set(vmx, vmx->secondary_exec_control);
}
+ if (cpu_has_tertiary_exec_ctrls()) {
+ vmx_compute_tertiary_exec_control(vmx);
+ tertiary_exec_controls_set(vmx, vmx->tertiary_exec_control);
+ }
+
if (kvm_vcpu_apicv_active(&vmx->vcpu)) {
vmcs_write64(EOI_EXIT_BITMAP0, 0);
vmcs_write64(EOI_EXIT_BITMAP1, 0);
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 945c6639ce24..c356ceebe84c 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -266,6 +266,7 @@ struct vcpu_vmx {
u32 msr_ia32_umwait_control;
u32 secondary_exec_control;
+ u64 tertiary_exec_control;
/*
* loaded_vmcs points to the VMCS currently used in this vcpu. For a
--
2.25.1
Since IA x86 platform introduce features of IPI virtualization and
User Interrupts, new behavior applies to the execution of WRMSR ICR
register that causes APIC-write VM exit instead of MSR-write VM exit
in x2APIC mode.
This requires KVM to emulate writing 64-bit value to offset 300H on
the virtual-APIC page(VICR) for guest running in x2APIC mode when
APIC-wrtie VM exit occurs. Prevoisely KVM doesn't consider this
situation as CPU never produce APIC-write VM exit in x2APIC mode before.
Signed-off-by: Zeng Guang <[email protected]>
---
arch/x86/kvm/lapic.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ba5a27879f1d..0b0f0ce96679 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2188,7 +2188,14 @@ void kvm_apic_write_nodecode(struct kvm_vcpu *vcpu, u32 offset)
/* hw has done the conditional check and inst decode */
offset &= 0xff0;
- kvm_lapic_reg_read(vcpu->arch.apic, offset, 4, &val);
+ if (apic_x2apic_mode(vcpu->arch.apic) && (offset == APIC_ICR)) {
+ u64 icr_val = *((u64 *)(vcpu->arch.apic->regs + offset));
+
+ kvm_lapic_reg_write(vcpu->arch.apic, APIC_ICR2, (u32)(icr_val>>32));
+ val = (u32)icr_val;
+ } else {
+ kvm_lapic_reg_read(vcpu->arch.apic, offset, 4, &val);
+ }
/* TODO: optimize to just emulate side effect w/o one more write */
kvm_lapic_reg_write(vcpu->arch.apic, offset, val);
--
2.25.1
From: Robert Hoo <[email protected]>
Add tertiary_exec_control field report in dump_vmcs()
Signed-off-by: Robert Hoo <[email protected]>
Signed-off-by: Zeng Guang <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 728873971913..820fc131d258 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5749,6 +5749,7 @@ 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 = 0;
unsigned long cr4;
int efer_slot;
@@ -5766,6 +5767,9 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
if (cpu_has_secondary_exec_ctrls())
secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
+ if (cpu_has_tertiary_exec_ctrls())
+ tertiary_exec_control = vmcs_read64(TERTIARY_VM_EXEC_CONTROL);
+
pr_err("VMCS %p, last attempted VM-entry on CPU %d\n",
vmx->loaded_vmcs->vmcs, vcpu->arch.last_vmentry_cpu);
pr_err("*** Guest State ***\n");
@@ -5864,8 +5868,9 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
vmx_dump_msrs("host autoload", &vmx->msr_autoload.host);
pr_err("*** Control State ***\n");
- pr_err("PinBased=%08x CPUBased=%08x SecondaryExec=%08x\n",
- pin_based_exec_ctrl, cpu_based_exec_ctrl, secondary_exec_control);
+ pr_err("PinBased=0x%08x CPUBased=0x%08x SecondaryExec=0x%08x TertiaryExec=0x%016llx\n",
+ pin_based_exec_ctrl, cpu_based_exec_ctrl, secondary_exec_control,
+ tertiary_exec_control);
pr_err("EntryControls=%08x ExitControls=%08x\n", vmentry_ctl, vmexit_ctl);
pr_err("ExceptionBitmap=%08x PFECmask=%08x PFECmatch=%08x\n",
vmcs_read32(EXCEPTION_BITMAP),
--
2.25.1
From: Gao Chao <[email protected]>
With IPI virtualization enabled, the processor emulates writes
to APIC registers that would send IPIs. The processor sets the
bit corresponding to the vector in target vCPU's PIR and may send
a notification (IPI) specified by NDST and NV fields in target vCPU's
PID. It is similar to what IOMMU engine does when dealing with posted
interrupt from devices.
A PID-pointer table is used by the processor to locate the PID of a
vCPU with the vCPU's APIC ID.
Like VT-d PI, if a vCPU goes to blocked state, VMM needs to switch its
notification vector to wakeup vector. This can ensure that when an IPI
for blocked vCPUs arrives, VMM can get control and wake up blocked
vCPUs. And if a VCPU is preempted, its posted interrupt notification
is suppressed.
Note that IPI virtualization can only virualize physical-addressing,
flat mode, unicast IPIs. Sending other IPIs would still cause a
VM exit and need to be handled by VMM.
Signed-off-by: Gao Chao <[email protected]>
Signed-off-by: Zeng Guang <[email protected]>
---
arch/x86/include/asm/vmx.h | 8 ++++
arch/x86/include/asm/vmxfeatures.h | 2 +
arch/x86/kvm/vmx/capabilities.h | 7 ++++
arch/x86/kvm/vmx/posted_intr.c | 22 +++++++---
arch/x86/kvm/vmx/vmx.c | 65 ++++++++++++++++++++++++++++--
arch/x86/kvm/vmx/vmx.h | 3 ++
6 files changed, 98 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 15652047f2db..e97cf7b9ff12 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -76,6 +76,11 @@
#define SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE VMCS_CONTROL_BIT(USR_WAIT_PAUSE)
#define SECONDARY_EXEC_BUS_LOCK_DETECTION VMCS_CONTROL_BIT(BUS_LOCK_DETECTION)
+/*
+ * Definitions of Tertiary Processor-Based VM-Execution Controls.
+ */
+#define TERTIARY_EXEC_IPI_VIRT VMCS_CONTROL_BIT(IPI_VIRT)
+
#define PIN_BASED_EXT_INTR_MASK VMCS_CONTROL_BIT(INTR_EXITING)
#define PIN_BASED_NMI_EXITING VMCS_CONTROL_BIT(NMI_EXITING)
#define PIN_BASED_VIRTUAL_NMIS VMCS_CONTROL_BIT(VIRTUAL_NMIS)
@@ -159,6 +164,7 @@ static inline int vmx_misc_mseg_revid(u64 vmx_misc)
enum vmcs_field {
VIRTUAL_PROCESSOR_ID = 0x00000000,
POSTED_INTR_NV = 0x00000002,
+ LAST_PID_POINTER_INDEX = 0x00000008,
GUEST_ES_SELECTOR = 0x00000800,
GUEST_CS_SELECTOR = 0x00000802,
GUEST_SS_SELECTOR = 0x00000804,
@@ -224,6 +230,8 @@ enum vmcs_field {
TSC_MULTIPLIER_HIGH = 0x00002033,
TERTIARY_VM_EXEC_CONTROL = 0x00002034,
TERTIARY_VM_EXEC_CONTROL_HIGH = 0x00002035,
+ PID_POINTER_TABLE = 0x00002042,
+ PID_POINTER_TABLE_HIGH = 0x00002043,
GUEST_PHYSICAL_ADDRESS = 0x00002400,
GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
VMCS_LINK_POINTER = 0x00002800,
diff --git a/arch/x86/include/asm/vmxfeatures.h b/arch/x86/include/asm/vmxfeatures.h
index 27e76eeca05b..e821e8126097 100644
--- a/arch/x86/include/asm/vmxfeatures.h
+++ b/arch/x86/include/asm/vmxfeatures.h
@@ -86,4 +86,6 @@
#define VMX_FEATURE_ENCLV_EXITING ( 2*32+ 28) /* "" VM-Exit on ENCLV (leaf dependent) */
#define VMX_FEATURE_BUS_LOCK_DETECTION ( 2*32+ 30) /* "" VM-Exit when bus lock caused */
+/* Tertiary Processor-Based VM-Execution Controls, word 3 */
+#define VMX_FEATURE_IPI_VIRT ( 3*32 + 4) /* "" Enable IPI virtualization */
#endif /* _ASM_X86_VMXFEATURES_H */
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 38d414f64e61..78b0525dd991 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -12,6 +12,7 @@ extern bool __read_mostly enable_ept;
extern bool __read_mostly enable_unrestricted_guest;
extern bool __read_mostly enable_ept_ad_bits;
extern bool __read_mostly enable_pml;
+extern bool __read_mostly enable_ipiv;
extern int __read_mostly pt_mode;
#define PT_MODE_SYSTEM 0
@@ -283,6 +284,12 @@ static inline bool cpu_has_vmx_apicv(void)
cpu_has_vmx_posted_intr();
}
+static inline bool cpu_has_vmx_ipiv(void)
+{
+ return vmcs_config.cpu_based_3rd_exec_ctrl &
+ TERTIARY_EXEC_IPI_VIRT;
+}
+
static inline bool cpu_has_vmx_flexpriority(void)
{
return cpu_has_vmx_tpr_shadow() &&
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 5f81ef092bd4..8c1400aaa1e7 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -81,9 +81,12 @@ void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
- if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (!kvm_vcpu_apicv_active(vcpu))
+ return;
+
+ if ((!kvm_arch_has_assigned_device(vcpu->kvm) ||
+ !irq_remapping_cap(IRQ_POSTING_CAP)) &&
+ !enable_ipiv)
return;
/* Set SN when the vCPU is preempted */
@@ -141,9 +144,16 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
struct pi_desc old, new;
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
- if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
- !irq_remapping_cap(IRQ_POSTING_CAP) ||
- !kvm_vcpu_apicv_active(vcpu))
+ if (!kvm_vcpu_apicv_active(vcpu))
+ return 0;
+
+ /* Put vCPU into a list and set NV to wakeup vector if it is
+ * one of the following cases:
+ * 1. any assigned device is in use.
+ * 2. IPI virtualization is enabled.
+ */
+ if ((!kvm_arch_has_assigned_device(vcpu->kvm) ||
+ !irq_remapping_cap(IRQ_POSTING_CAP)) && !enable_ipiv)
return 0;
WARN_ON(irqs_disabled());
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 820fc131d258..077474c52380 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -104,6 +104,9 @@ module_param(fasteoi, bool, S_IRUGO);
module_param(enable_apicv, bool, S_IRUGO);
+bool __read_mostly enable_ipiv = 1;
+module_param(enable_ipiv, bool, S_IRUGO);
+
/*
* If nested=1, nested virtualization is supported, i.e., guests may use
* VMX and be a hypervisor for its own guests. If nested=0, guests may not
@@ -225,6 +228,7 @@ static const struct {
};
#define L1D_CACHE_ORDER 4
+#define PID_TABLE_ORDER get_order(KVM_MAX_VCPU_ID << 3)
static void *vmx_l1d_flush_pages;
static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
@@ -2514,7 +2518,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
}
if (_cpu_based_exec_control & CPU_BASED_ACTIVATE_TERTIARY_CONTROLS) {
- u64 opt3 = 0;
+ u64 opt3 = enable_ipiv ? TERTIARY_EXEC_IPI_VIRT : 0;
u64 min3 = 0;
if (adjust_vmx_controls_64(min3, opt3,
@@ -3870,6 +3874,8 @@ static void vmx_update_msr_bitmap_x2apic(struct kvm_vcpu *vcpu, u8 mode)
vmx_enable_intercept_for_msr(vcpu, X2APIC_MSR(APIC_TMCCT), MSR_TYPE_RW);
vmx_disable_intercept_for_msr(vcpu, X2APIC_MSR(APIC_EOI), MSR_TYPE_W);
vmx_disable_intercept_for_msr(vcpu, X2APIC_MSR(APIC_SELF_IPI), MSR_TYPE_W);
+ vmx_set_intercept_for_msr(vcpu, X2APIC_MSR(APIC_ICR),
+ MSR_TYPE_RW, !enable_ipiv);
}
}
@@ -4138,14 +4144,21 @@ static void vmx_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
pin_controls_set(vmx, vmx_pin_based_exec_ctrl(vmx));
if (cpu_has_secondary_exec_ctrls()) {
- if (kvm_vcpu_apicv_active(vcpu))
+ if (kvm_vcpu_apicv_active(vcpu)) {
secondary_exec_controls_setbit(vmx,
SECONDARY_EXEC_APIC_REGISTER_VIRT |
SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
- else
+ if (cpu_has_tertiary_exec_ctrls() && enable_ipiv)
+ tertiary_exec_controls_setbit(vmx,
+ TERTIARY_EXEC_IPI_VIRT);
+ } else {
secondary_exec_controls_clearbit(vmx,
SECONDARY_EXEC_APIC_REGISTER_VIRT |
SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
+ if (cpu_has_tertiary_exec_ctrls())
+ tertiary_exec_controls_clearbit(vmx,
+ TERTIARY_EXEC_IPI_VIRT);
+ }
}
if (cpu_has_vmx_msr_bitmap())
@@ -4236,8 +4249,12 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control,
static void vmx_compute_tertiary_exec_control(struct vcpu_vmx *vmx)
{
+ struct kvm_vcpu *vcpu = &vmx->vcpu;
u32 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
+ if (!kvm_vcpu_apicv_active(vcpu))
+ exec_control &= ~TERTIARY_EXEC_IPI_VIRT;
+
vmx->tertiary_exec_control = exec_control;
}
@@ -4332,6 +4349,17 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
#define VMX_XSS_EXIT_BITMAP 0
+static void install_pid(struct vcpu_vmx *vmx)
+{
+ struct kvm_vmx *kvm_vmx = to_kvm_vmx(vmx->vcpu.kvm);
+
+ BUG_ON(vmx->vcpu.vcpu_id > kvm_vmx->pid_last_index);
+ /* Bit 0 is the valid bit */
+ kvm_vmx->pid_table[vmx->vcpu.vcpu_id] = __pa(&vmx->pi_desc) | 1;
+ vmcs_write64(PID_POINTER_TABLE, __pa(kvm_vmx->pid_table));
+ vmcs_write16(LAST_PID_POINTER_INDEX, kvm_vmx->pid_last_index);
+}
+
/*
* Noting that the initialization of Guest-state Area of VMCS is in
* vmx_vcpu_reset().
@@ -4371,6 +4399,9 @@ static void init_vmcs(struct vcpu_vmx *vmx)
vmcs_write16(POSTED_INTR_NV, POSTED_INTR_VECTOR);
vmcs_write64(POSTED_INTR_DESC_ADDR, __pa((&vmx->pi_desc)));
+
+ if (enable_ipiv)
+ install_pid(vmx);
}
if (!kvm_pause_in_guest(vmx->vcpu.kvm)) {
@@ -6969,6 +7000,22 @@ static int vmx_vm_init(struct kvm *kvm)
break;
}
}
+
+ if (enable_ipiv) {
+ struct page *pages;
+
+ /* Allocate pages for PID table in order of PID_TABLE_ORDER
+ * depending on KVM_MAX_VCPU_ID. Each PID entry is 8 bytes.
+ */
+ pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, PID_TABLE_ORDER);
+
+ if (!pages)
+ return -ENOMEM;
+
+ to_kvm_vmx(kvm)->pid_table = (void *)page_address(pages);
+ to_kvm_vmx(kvm)->pid_last_index = KVM_MAX_VCPU_ID;
+ }
+
return 0;
}
@@ -7579,6 +7626,14 @@ static bool vmx_check_apicv_inhibit_reasons(ulong bit)
return supported & BIT(bit);
}
+static void vmx_vm_destroy(struct kvm *kvm)
+{
+ struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
+
+ if (kvm_vmx->pid_table)
+ free_pages((unsigned long)kvm_vmx->pid_table, PID_TABLE_ORDER);
+}
+
static struct kvm_x86_ops vmx_x86_ops __initdata = {
.hardware_unsetup = hardware_unsetup,
@@ -7589,6 +7644,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
.vm_size = sizeof(struct kvm_vmx),
.vm_init = vmx_vm_init,
+ .vm_destroy = vmx_vm_destroy,
.vcpu_create = vmx_create_vcpu,
.vcpu_free = vmx_free_vcpu,
@@ -7828,6 +7884,9 @@ static __init int hardware_setup(void)
vmx_x86_ops.sync_pir_to_irr = NULL;
}
+ if (!enable_apicv || !cpu_has_vmx_ipiv())
+ enable_ipiv = 0;
+
if (cpu_has_vmx_tsc_scaling()) {
kvm_has_tsc_control = true;
kvm_max_tsc_scaling_ratio = KVM_VMX_TSC_MULTIPLIER_MAX;
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index c356ceebe84c..cfab065661a8 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -352,6 +352,9 @@ struct kvm_vmx {
unsigned int tss_addr;
bool ept_identity_pagetable_done;
gpa_t ept_identity_map_addr;
+ /* PID table for IPI virtualization */
+ u64 *pid_table;
+ u16 pid_last_index;
};
bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
--
2.25.1
On Fri, 23 Jul 2021 at 13:41, Zeng Guang <[email protected]> wrote:
>
> Current IPI process in guest VM will virtualize the writing to interrupt
> command register(ICR) of the local APIC which will cause VM-exit anyway
> on source vCPU. Frequent VM-exit could induce much overhead accumulated
> if running IPI intensive task.
>
> IPI virtualization as a new VT-x feature targets to eliminate VM-exits
> when issuing IPI on source vCPU. It introduces a new VM-execution
> control - "IPI virtualization"(bit4) in the tertiary processor-based
> VM-exection controls and a new data structure - "PID-pointer table
> address" and "Last PID-pointer index" referenced by the VMCS. When "IPI
> virtualization" is enabled, processor emulateds following kind of writes
> to APIC registers that would send IPIs, moreover without causing VM-exits.
> - Memory-mapped ICR writes
> - MSR-mapped ICR writes
> - SENDUIPI execution
>
> This patch series implement IPI virtualization support in KVM.
>
> Patches 1-4 add tertiary processor-based VM-execution support
> framework.
>
> Patch 5 implement interrupt dispatch support in x2APIC mode with
> APIC-write VM exit. In previous platform, no CPU would produce
> APIC-write VM exit with exit qulification 300H when the "virtual x2APIC
> mode" VM-execution control was 1.
>
> Patch 6 implement IPI virtualization related function including
> feature enabling through tertiary processor-based VM-execution in
> various scenario of VMCS configuration, PID table setup in vCPU creation
> and vCPU block consideration.
>
> Document for IPI virtualization is now available at the latest "Intel
> Architecture Instruction Set Extensions Programming Reference".
>
> Document Link:
> https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html
>
> We did experiment to measure average time sending IPI from source vCPU
> to the target vCPU completing the IPI handling by kvm unittest w/ and
> w/o IPI virtualization. When IPI virtualizatin enabled, it will reduce
> 22.21% and 15.98% cycles consuming in xAPIC mode and x2APIC mode
> respectly.
>
> KMV unittest:vmexit/ipi, 2 vCPU, AP was modified to run in idle loop
> instead of halt to ensure no VM exit impact on target vCPU.
>
> Cycles of IPI
> xAPIC mode x2APIC mode
> test w/o IPIv w/ IPIv w/o IPIv w/ IPIv
> 1 6106 4816 4265 3768
> 2 6244 4656 4404 3546
> 3 6165 4658 4233 3474
> 4 5992 4710 4363 3430
> 5 6083 4741 4215 3551
> 6 6238 4904 4304 3547
> 7 6164 4617 4263 3709
> 8 5984 4763 4518 3779
> 9 5931 4712 4645 3667
> 10 5955 4530 4332 3724
> 11 5897 4673 4283 3569
> 12 6140 4794 4178 3598
> 13 6183 4728 4363 3628
> 14 5991 4994 4509 3842
> 15 5866 4665 4520 3739
> 16 6032 4654 4229 3701
> 17 6050 4653 4185 3726
> 18 6004 4792 4319 3746
> 19 5961 4626 4196 3392
> 20 6194 4576 4433 3760
>
> Average cycles 6059 4713.1 4337.85 3644.8
> %Reduction -22.21% -15.98%
>
> --------------------------------------
> IPI microbenchmark:
> (https://lore.kernel.org/kvm/[email protected])
>
> 2 vCPUs, 1:1 pin vCPU to pCPU, guest VM runs with idle=poll, x2APIC mode
Improve the performance for unicast ipi is as expected, however, I
wonder whether the broadcast performance is worse than PV
IPIs/Thomas's IPI shorthands(IPI shorthands are supported by upstream
linux apic/x2apic driver). The hardware acceleration is not always
outstanding on AMD(https://lore.kernel.org/kvm/CANRm+Cx597FNRUCyVz1D=B6Vs2GX3Sw57X7Muk+yMpi_hb+v1w@mail.gmail.com/),
how about your Intel guys? Please try a big VM at least 96 vCPUs as
below or more bigger.
>
> Result with IPIv enabled:
>
> Dry-run: 0, 272798 ns
> Self-IPI: 5094123, 11114037 ns
> Normal IPI: 131697087, 173321200 ns
> Broadcast IPI: 0, 155649075 ns
> Broadcast lock: 0, 161518031 ns
>
> Result with IPIv disabled:
>
> Dry-run: 0, 272766 ns
> Self-IPI: 5091788, 11123699 ns
> Normal IPI: 145215772, 174558920 ns
> Broadcast IPI: 0, 175785384 ns
> Broadcast lock: 0, 149076195 ns
>
>
> As IPIv can benefit unicast IPI to other CPU, Noraml IPI test case gain
> about 9.73% time saving on average out of 15 test runs when IPIv is
> enabled.
>
> w/o IPIv w/ IPIv
> Normal IPI: 145944306.6 ns 131742993.1 ns
> %Reduction -9.73%
>
> --------------------------------------
> hackbench:
>
> 8 vCPUs, guest VM free run, x2APIC mode
> ./hackbench -p -l 100000
>
> w/o IPIv w/ IPIv
> Time: 91.887 74.605
> %Reduction: -18.808%
>
> 96 vCPUs, guest VM free run, x2APIC mode
> ./hackbench -p -l 1000000
>
> w/o IPIv w/ IPIv
> Time: 287.504 235.185
> %Reduction: -18.198%
Good to know this.
Wanpeng
On 7/23/2021 2:11 PM, Wanpeng Li wrote:
> On Fri, 23 Jul 2021 at 13:41, Zeng Guang <[email protected]> wrote:
>
> --------------------------------------
> IPI microbenchmark:
> (https://lore.kernel.org/kvm/[email protected])
>
> 2 vCPUs, 1:1 pin vCPU to pCPU, guest VM runs with idle=poll, x2APIC mode
> Improve the performance for unicast ipi is as expected, however, I
> wonder whether the broadcast performance is worse than PV
> IPIs/Thomas's IPI shorthands(IPI shorthands are supported by upstream
> linux apic/x2apic driver). The hardware acceleration is not always
> outstanding on AMD(https://lore.kernel.org/kvm/CANRm+Cx597FNRUCyVz1D=B6Vs2GX3Sw57X7Muk+yMpi_hb+v1w@mail.gmail.com/),
> how about your Intel guys? Please try a big VM at least 96 vCPUs as
> below or more bigger.
Intel IPIv target to accelerate unicast ipi process, not benefit to
broadcast performance.
As to IPI benchmark, it's not big different to test with large or small
scale of vCPUs. In essential, Normal IPI test try
to send ipi to any other online CPU in sequence. The cost on IPI process
itself should be similar.
>> Result with IPIv enabled:
>>
>> Dry-run: 0, 272798 ns
>> Self-IPI: 5094123, 11114037 ns
>> Normal IPI: 131697087, 173321200 ns
>> Broadcast IPI: 0, 155649075 ns
>> Broadcast lock: 0, 161518031 ns
>>
>> Result with IPIv disabled:
>>
>> Dry-run: 0, 272766 ns
>> Self-IPI: 5091788, 11123699 ns
>> Normal IPI: 145215772, 174558920 ns
>> Broadcast IPI: 0, 175785384 ns
>> Broadcast lock: 0, 149076195 ns
>>
>>
>> As IPIv can benefit unicast IPI to other CPU, Noraml IPI test case gain
>> about 9.73% time saving on average out of 15 test runs when IPIv is
>> enabled.
>>
>> w/o IPIv w/ IPIv
>> Normal IPI: 145944306.6 ns 131742993.1 ns
>> %Reduction -9.73%
>>
>> --------------------------------------
>> hackbench:
>>
>> 8 vCPUs, guest VM free run, x2APIC mode
>> ./hackbench -p -l 100000
>>
>> w/o IPIv w/ IPIv
>> Time: 91.887 74.605
>> %Reduction: -18.808%
>>
>> 96 vCPUs, guest VM free run, x2APIC mode
>> ./hackbench -p -l 1000000
>>
>> w/o IPIv w/ IPIv
>> Time: 287.504 235.185
>> %Reduction: -18.198%
> Good to know this.
>
> Wanpeng