Commit 5d4283df authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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 d1c88a40 ("KVM: x86: always allow host-initiated
writes to PMU MSRs") will soon follow.

This reverts commit 8e6a58e2.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220611005755.753273-4-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0f4a7185

arch/x86/kvm/pmu.c

+0 −8
Original line number Diff line number Diff line
@@ -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);

}

arch/x86/kvm/svm/pmu.c

+1 −10
Original line number Diff line number Diff line
@@ -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;

	}

}



static struct kvm_pmc *amd_msr_idx_to_pmc(struct kvm_vcpu *vcpu, u32 msr)