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>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 58ead7db71a3..e39741997893 100644
--- 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);