KVM: x86: Raise #GP when guest vCPU do not support PMU

Before this change, reading a VMware pseduo PMC will succeed even when
PMU is not supported by guest. This can easily be seen by running
kvm-unit-test vmware_backdoors with "-cpu host,-pmu" option.

Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 58ead7d..e397419 100644 (file)
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -281,9 +281,13 @@ static int kvm_pmu_rdpmc_vmware(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
 int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
 {
        bool fast_mode = idx & (1u << 31);
+       struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
        struct kvm_pmc *pmc;
        u64 ctr_val;
 
+       if (!pmu->version)
+               return 1;
+
        if (is_vmware_backdoor_pmc(idx))
                return kvm_pmu_rdpmc_vmware(vcpu, idx, data);