2020-07-16 03:44:59

by Sean Christopherson

Subject: [PATCH 0/3] KVM: VMX: Clean up RTIT MAXPHYADDR usage

Stop using cpuid_query_maxphyaddr() for a random RTIT MSR check and
unexport said function to discourage future use.

Sean Christopherson (3):
KVM: VMX: Use precomputed MAXPHYADDR for RTIT base MSR check
KVM: VMX: Replace MSR_IA32_RTIT_OUTPUT_BASE_MASK with helper function
KVM: x86: Unexport cpuid_query_maxphyaddr()

arch/x86/kvm/cpuid.c | 1 -
arch/x86/kvm/vmx/vmx.c | 11 +++++++----
2 files changed, 7 insertions(+), 5 deletions(-)

--
2.26.0

2020-07-16 03:47:30

by Sean Christopherson

Subject: [PATCH 2/3] KVM: VMX: Replace MSR_IA32_RTIT_OUTPUT_BASE_MASK with helper function

Replace the subtly not-a-constant MSR_IA32_RTIT_OUTPUT_BASE_MASK with a
proper helper function to check whether or not the specified base is
valid. Blindly referencing the local 'vcpu' is especially nasty.

Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/vmx/vmx.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 50b7e85d37352..cf3c3562e843c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -145,9 +145,6 @@ module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO);
RTIT_STATUS_ERROR | RTIT_STATUS_STOPPED | \
RTIT_STATUS_BYTECNT))

-#define MSR_IA32_RTIT_OUTPUT_BASE_MASK \
- (~((1UL << cpuid_maxphyaddr(vcpu)) - 1) | 0x7f)
-
/*
* These 2 parameters are used to config the controls for Pause-Loop Exiting:
* ple_gap: upper bound on the amount of time between two successive
@@ -1036,6 +1033,12 @@ static inline bool pt_can_write_msr(struct vcpu_vmx *vmx)
!(vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN);
}

+static inline bool pt_output_base_valid(struct kvm_vcpu *vcpu, u64 base)
+{
+ /* The base must be 128-byte aligned and a legal physical address. */
+ return !(base & (~((1UL << cpuid_maxphyaddr(vcpu)) - 1) | 0x7f));
+}
+
static inline void pt_load_msr(struct pt_ctx *ctx, u32 addr_range)
{
u32 i;
@@ -2193,7 +2196,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
!intel_pt_validate_cap(vmx->pt_desc.caps,
PT_CAP_single_range_output))
return 1;
- if (data & MSR_IA32_RTIT_OUTPUT_BASE_MASK)
+ if (!pt_output_base_valid(vcpu, data))
return 1;
vmx->pt_desc.guest.output_base = data;
break;
--
2.26.0

2020-07-16 03:47:51

by Sean Christopherson

Subject: [PATCH 3/3] KVM: x86: Unexport cpuid_query_maxphyaddr()

Stop exporting cpuid_query_maxphyaddr() now that it's not being abused
by VMX.

Signed-off-by: Sean Christopherson <[email protected]>
---
arch/x86/kvm/cpuid.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7d92854082a14..e4a8065fbddd7 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -188,7 +188,6 @@ int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu)
not_found:
return 36;
}
-EXPORT_SYMBOL_GPL(cpuid_query_maxphyaddr);

/* when an old userspace process fills a new kernel module */
int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
--
2.26.0