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    Subject[PATCH 5.19 1106/1157] Revert "KVM: x86/pmu: Accept 0 for absent PMU MSRs when host-initiated if !enable_pmu"
    Date
    From: Sean Christopherson <seanjc@google.com>

    [ Upstream commit 5d4283df5a0fc8299fba9443c33d219939eccc2d ]

    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 d1c88a402056 ("KVM: x86: always allow host-initiated
    writes to PMU MSRs") will soon follow.

    This reverts commit 8e6a58e28b34e8d247e772159b8fa8f6bae39192.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Message-Id: <20220611005755.753273-4-seanjc@google.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/pmu.c | 8 --------
    arch/x86/kvm/svm/pmu.c | 11 +----------
    2 files changed, 1 insertion(+), 18 deletions(-)

    diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
    index 2334ddfbbab2..3f868fed9114 100644
    --- a/arch/x86/kvm/pmu.c
    +++ b/arch/x86/kvm/pmu.c
    @@ -433,19 +433,11 @@ 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);
    }
    diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
    index d93ecb25fe17..136039fc6d01 100644
    --- a/arch/x86/kvm/svm/pmu.c
    +++ b/arch/x86/kvm/svm/pmu.c
    @@ -232,16 +232,7 @@ 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)
    {
    /* 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)
    --
    2.35.1


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