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 checksand , _and_ there has been at least one attempt to add a _third_ flavor. Link: https://lore.kernel.org/all/Yk4ugOETeo%2FqDRbW@xxxxxxxxxx Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/vmx/pmu_intel.c | 4 ++-- arch/x86/kvm/vmx/vmx.h | 12 ++++++++++++ 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 5b85320fc9f1..6ce3b066f7d9 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -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); @@ -208,7 +208,7 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr, bool host_initiat case MSR_CORE_PERF_GLOBAL_OVF_CTRL: if (host_initiated) return true; - return pmu->version > 1; + return intel_pmu_has_perf_global_ctrl(pmu); break; case MSR_IA32_PEBS_ENABLE: if (host_initiated) diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 576fed7e33de..215f17eb6732 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -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) -- 2.36.1.255.ge46751e96f-goog
