From: Sean Christopherson Date: Fri, 22 Jul 2022 22:44:07 +0000 (+0000) Subject: KVM: VMX: Add helper to check if the guest PMU has PERF_GLOBAL_CTRL X-Git-Tag: baikal/mips/sdk6.1~5143^2~6^2~9 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=825db332ac1a23d0d50265b43090f7929d8d03ef;p=kernel.git KVM: VMX: Add helper to check if the guest PMU has PERF_GLOBAL_CTRL 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 Message-Id: <20220722224409.1336532-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 6e355c5d2f40a..78f2800fd8500 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); @@ -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; diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 286c88e285eaf..2a0b94e0fda73 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)