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

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>

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 6a32092..87483e5 100644 (file)
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -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);
 }

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index fe520b2..256244b 100644 (file)
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -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)