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

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
[sean: massage changelog]
Link: https://lore.kernel.org/r/20230603011058.1038821-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Like Xu
2023-06-02 18:10:55 -07:00
committed by Sean Christopherson
parent d338d8789e
commit 1c2bf8a6b0
1 changed files with 3 additions and 0 deletions
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arch/x86/kvm/svm/pmu.c
+3
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@@ -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;