From e3d1f2826da68c763cba1f29dba5cc81d3fdaaee Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 6 Aug 2025 12:56:37 -0700 Subject: [PATCH] KVM: SVM: Check pmu->version, not enable_pmu, when getting PMC MSRs Gate access to PMC MSRs based on pmu->version, not on kvm->arch.enable_pmu, to more accurately reflect KVM's behavior. This is a glorified nop, as pmu->version and pmu->nr_arch_gp_counters can only be non-zero if amd_pmu_refresh() is reached, kvm_pmu_refresh() invokes amd_pmu_refresh() if and only if kvm->arch.enable_pmu is true, and amd_pmu_refresh() forces pmu->version to be 1 or 2. I.e. the following holds true: !pmu->nr_arch_gp_counters || kvm->arch.enable_pmu == (pmu->version > 0) and so the only way for amd_pmu_get_pmc() to return a non-NULL value is if both kvm->arch.enable_pmu and pmu->version evaluate to true. No real functional change intended. Reviewed-by: Sandipan Das Tested-by: Xudong Hao Link: https://lore.kernel.org/r/20250806195706.1650976-16-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/pmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c index aa4379e46e969..f3163237286f7 100644 --- a/arch/x86/kvm/svm/pmu.c +++ b/arch/x86/kvm/svm/pmu.c @@ -41,7 +41,7 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu); unsigned int idx; - if (!vcpu->kvm->arch.enable_pmu) + if (!pmu->version) return NULL; switch (msr) { -- 2.47.3