Explicitly check for attempts to read unsupported PMC types instead of letting the bounds check fail. Functionally, letting the check fail is ok, but it's unnecessarily subtle and does a poor job of documenting the architectural behavior that KVM is emulating. Opportunistically add macros for the type vs. index to further document what is going on. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/vmx/pmu_intel.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 644de27bd48a..bd4f4bdf5419 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -23,6 +23,9 @@ /* Perf's "BASE" is wildly misleading, this is a single-bit flag, not a base. */ #define INTEL_RDPMC_FIXED INTEL_PMC_FIXED_RDPMC_BASE +#define INTEL_RDPMC_TYPE_MASK GENMASK(31, 16) +#define INTEL_RDPMC_INDEX_MASK GENMASK(15, 0) + #define MSR_PMC_FULL_WIDTH_BIT (MSR_IA32_PMC0 - MSR_IA32_PERFCTR0) static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data) @@ -82,9 +85,13 @@ static struct kvm_pmc *intel_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu, /* * Fixed PMCs are supported on all architectural PMUs. Note, KVM only * emulates fixed PMCs for PMU v2+, but the flag itself is still valid, - * i.e. let RDPMC fail due to accessing a non-existent counter. + * i.e. let RDPMC fail due to accessing a non-existent counter. Reject + * attempts to read all other types, which are unknown/unsupported. */ - idx &= ~INTEL_RDPMC_FIXED; + if (idx & INTEL_RDPMC_TYPE_MASK & ~INTEL_RDPMC_FIXED) + return NULL; + + idx &= INTEL_RDPMC_INDEX_MASK; if (fixed) { counters = pmu->fixed_counters; num_counters = pmu->nr_arch_fixed_counters; -- 2.43.0.rc2.451.g8631bc7472-goog