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KVM: vmx/pmu: Add PMU_CAP_LBR_FMT check when guest LBR is enabled

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Usespace could set the bits [0, 5] of the IA32_PERF_CAPABILITIES
MSR which tells about the record format stored in the LBR records.

The LBR will be enabled on the guest if host perf supports LBR
(checked via x86_perf_get_lbr()) and the vcpu model is compatible
with the host one.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20210201051039.255478-4-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Like Xu 2021-02-01 13:10:31 +08:00 committed by Paolo Bonzini
parent 9c9520ce88
commit c646236344
4 changed files with 25 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
arch/x86/kvm/vmx/capabilities.h
View file

@ -387,7 +387,12 @@ static inline u64 vmx_get_perf_capabilities(void)
static inline u64 vmx_supported_debugctl(void)
{
return 0;
u64 debugctl = 0;
if (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT)
debugctl |= DEBUGCTLMSR_LBR;
return debugctl;
}
#endif /* __KVM_X86_VMX_CAPS_H */

7
arch/x86/kvm/vmx/pmu_intel.c
View file

@ -183,6 +183,13 @@ bool intel_pmu_lbr_is_compatible(struct kvm_vcpu *vcpu)
return boot_cpu_data.x86_model == guest_cpuid_model(vcpu);
}
bool intel_pmu_lbr_is_enabled(struct kvm_vcpu *vcpu)
{
struct x86_pmu_lbr *lbr = vcpu_to_lbr_records(vcpu);
return lbr->nr && (vcpu_get_perf_capabilities(vcpu) & PMU_CAP_LBR_FMT);
}
static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

12
arch/x86/kvm/vmx/vmx.c
View file

@ -1950,6 +1950,16 @@ static u64 nested_vmx_truncate_sysenter_addr(struct kvm_vcpu *vcpu,
return (unsigned long)data;
}
static u64 vcpu_supported_debugctl(struct kvm_vcpu *vcpu)
{
u64 debugctl = vmx_supported_debugctl();
if (!intel_pmu_lbr_is_enabled(vcpu))
debugctl &= ~DEBUGCTLMSR_LBR;
return debugctl;
}
/*
* Writes msr value into the appropriate "register".
* Returns 0 on success, non-0 otherwise.
@ -2001,7 +2011,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vmcs_writel(GUEST_SYSENTER_ESP, data);
break;
case MSR_IA32_DEBUGCTLMSR: {
u64 invalid = data & ~vmx_supported_debugctl();
u64 invalid = data & ~vcpu_supported_debugctl(vcpu);
if (invalid & (DEBUGCTLMSR_BTF|DEBUGCTLMSR_LBR)) {
if (report_ignored_msrs)
vcpu_unimpl(vcpu, "%s: BTF|LBR in IA32_DEBUGCTLMSR 0x%llx, nop\n",

1
arch/x86/kvm/vmx/vmx.h
View file

@ -97,6 +97,7 @@ union vmx_exit_reason {
#define vcpu_to_lbr_records(vcpu) (&to_vmx(vcpu)->lbr_desc.records)
bool intel_pmu_lbr_is_compatible(struct kvm_vcpu *vcpu);
bool intel_pmu_lbr_is_enabled(struct kvm_vcpu *vcpu);
struct lbr_desc {
/* Basic info about guest LBR records. */