From 006a0f0607e1504950dd8fa3b6ca8e438ec6c9d2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 9 Dec 2021 14:10:04 -0500 Subject: KVM: x86: avoid out of bounds indices for fixed performance counters Because IceLake has 4 fixed performance counters but KVM only supports 3, it is possible for reprogram_fixed_counters to pass to reprogram_fixed_counter an index that is out of bounds for the fixed_pmc_events array. Ultimately intel_find_fixed_event, which is the only place that uses fixed_pmc_events, handles this correctly because it checks against the size of fixed_pmc_events anyway. Every other place operates on the fixed_counters[] array which is sized according to INTEL_PMC_MAX_FIXED. However, it is cleaner if the unsupported performance counters are culled early on in reprogram_fixed_counters. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/pmu_intel.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/vmx') diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 1b7456b2177b..d33e9799276e 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -91,7 +91,7 @@ static unsigned intel_find_fixed_event(int idx) u32 event; size_t size = ARRAY_SIZE(fixed_pmc_events); - if (idx >= size) + if (WARN_ON_ONCE(idx >= size)) return PERF_COUNT_HW_MAX; event = fixed_pmc_events[array_index_nospec(idx, size)]; @@ -500,8 +500,9 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) pmu->nr_arch_fixed_counters = 0; } else { pmu->nr_arch_fixed_counters = - min_t(int, edx.split.num_counters_fixed, - x86_pmu.num_counters_fixed); + min3(ARRAY_SIZE(fixed_pmc_events), + (size_t) edx.split.num_counters_fixed, + (size_t) x86_pmu.num_counters_fixed); edx.split.bit_width_fixed = min_t(int, edx.split.bit_width_fixed, x86_pmu.bit_width_fixed); pmu->counter_bitmask[KVM_PMC_FIXED] = -- cgit v1.2.3