Commit 1c2bf8a6 authored by Like Xu's avatar Like Xu Committed by Sean Christopherson
Browse files

KVM: x86/pmu: Constrain the num of guest counters with kvm_pmu_cap 



Cap the number of general purpose counters enumerated on AMD to what KVM
actually supports, i.e. don't allow userspace to coerce KVM into thinking
there are more counters than actually exist, e.g. by enumerating
X86_FEATURE_PERFCTR_CORE in guest CPUID when its not supported.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarLike Xu <likexu@tencent.com>
[sean: massage changelog]
Link: https://lore.kernel.org/r/20230603011058.1038821-10-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent d338d878

arch/x86/kvm/svm/pmu.c

+3 −0
Original line number Diff line number Diff line
@@ -170,6 +170,9 @@ static void amd_pmu_refresh(struct kvm_vcpu *vcpu) 
	else

		pmu->nr_arch_gp_counters = AMD64_NUM_COUNTERS;



	pmu->nr_arch_gp_counters = min_t(unsigned int, pmu->nr_arch_gp_counters,

					 kvm_pmu_cap.num_counters_gp);



	pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << 48) - 1;

	pmu->reserved_bits = 0xfffffff000280000ull;

	pmu->raw_event_mask = AMD64_RAW_EVENT_MASK;