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 217ed595e7c4 ("KVM: x86: always allow host-initiated
writes to PMU MSRs") will soon follow.

This reverts commit e6a4f3f1441f0babfc5cd7dc8e6872ab576a4fe6.

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 6a32092460d3fe55143ac9af912096012679517d..87483e503c46cdfd8ffde8887b382baf876af1ff 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 fe520b2649b59f88ce851dac308f35a5b168500c..256244b8f89cc2cb3949da40e6b0ff48a31efac4 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)