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KVM: VMX: Add helper to check if the guest PMU has PERF_GLOBAL_CTRL

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Add a helper to check of the guest PMU has PERF_GLOBAL_CTRL, which is
unintuitive _and_ diverges from Intel's architecturally defined behavior.
Even worse, KVM currently implements the check using two different (but
equivalent) checks, _and_ there has been at least one attempt to add a
_third_ flavor.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220722224409.1336532-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-07-22 22:44:07 +00:00 committed by Paolo Bonzini
parent 93255bf929
commit b663f0b5f3
2 changed files with 14 additions and 2 deletions
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4
arch/x86/kvm/vmx/pmu_intel.c
View File

@ -111,7 +111,7 @@ static bool intel_pmc_is_enabled(struct kvm_pmc *pmc)
{
struct kvm_pmu *pmu = pmc_to_pmu(pmc);
if (pmu->version < 2)
if (!intel_pmu_has_perf_global_ctrl(pmu))
return true;
return test_bit(pmc->idx, (unsigned long *)&pmu->global_ctrl);
@ -207,7 +207,7 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
case MSR_CORE_PERF_GLOBAL_STATUS:
case MSR_CORE_PERF_GLOBAL_CTRL:
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
ret = pmu->version > 1;
return intel_pmu_has_perf_global_ctrl(pmu);
break;
case MSR_IA32_PEBS_ENABLE:
ret = vcpu_get_perf_capabilities(vcpu) & PERF_CAP_PEBS_FORMAT;

12
arch/x86/kvm/vmx/vmx.h
View File

@ -91,6 +91,18 @@ union vmx_exit_reason {
u32 full;
};
static inline bool intel_pmu_has_perf_global_ctrl(struct kvm_pmu *pmu)
{
/*
* Architecturally, Intel's SDM states that IA32_PERF_GLOBAL_CTRL is
* supported if "CPUID.0AH: EAX[7:0] > 0", i.e. if the PMU version is
* greater than zero. However, KVM only exposes and emulates the MSR
* to/for the guest if the guest PMU supports at least "Architectural
* Performance Monitoring Version 2".
*/
return pmu->version > 1;
}
#define vcpu_to_lbr_desc(vcpu) (&to_vmx(vcpu)->lbr_desc)
#define vcpu_to_lbr_records(vcpu) (&to_vmx(vcpu)->lbr_desc.records)