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Revert "KVM: x86/pmu: Accept 0 for absent PMU MSRs when host-initiated if !enable_pmu"

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Eating reads and writes to all "PMU" MSRs when there is no PMU is wildly
broken as it results in allowing accesses to _any_ MSR on Intel CPUs
as intel_is_valid_msr() returns true for all host_initiated accesses.

A revert of commit d1c88a4020 ("KVM: x86: always allow host-initiated
writes to PMU MSRs") will soon follow.

This reverts commit 8e6a58e28b.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-06-11 00:57:51 +00:00 committed by Paolo Bonzini
parent 0f4a718527
commit 5d4283df5a
2 changed files with 1 additions and 18 deletions
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8
arch/x86/kvm/pmu.c
View File

@ -442,19 +442,11 @@ static void kvm_pmu_mark_pmc_in_use(struct kvm_vcpu *vcpu, u32 msr)
int kvm_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
if (msr_info->host_initiated && !vcpu->kvm->arch.enable_pmu) {
msr_info->data = 0;
return 0;
}
return static_call(kvm_x86_pmu_get_msr)(vcpu, msr_info);
}
int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
if (msr_info->host_initiated && !vcpu->kvm->arch.enable_pmu)
return !!msr_info->data;
kvm_pmu_mark_pmc_in_use(vcpu, msr_info->index);
return static_call(kvm_x86_pmu_set_msr)(vcpu, msr_info);
}

11
arch/x86/kvm/svm/pmu.c
View File

@ -182,16 +182,7 @@ static struct kvm_pmc *amd_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu,
static bool amd_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr, bool host_initiated)
{
/* All MSRs refer to exactly one PMC, so msr_idx_to_pmc is enough. */
if (!host_initiated)
return false;
switch (msr) {
case MSR_K7_EVNTSEL0 ... MSR_K7_PERFCTR3:
case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:
return true;
default:
return false;
}
return false;
}
static struct kvm_pmc *amd_msr_idx_to_pmc(struct kvm_vcpu *vcpu, u32 msr)