From: Sean Christopherson <seanjc@xxxxxxxxxx>
[ Upstream commit b663f0b5f3d665c261256d1f76e98f077c6e56af ]
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@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20220722224409.1336532-4-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@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 2cbd5f183ab5..8bd154f8c966 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -98,7 +98,7 @@ 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);
@@ -215,7 +215,7 @@ 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;
default:
ret = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0) ||
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 1e7f9453894b..93aa1f3ea01e 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -92,6 +92,18 @@ 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)
--
2.35.1
