[PATCH v3 01/12] KVM: x86/pmu: Honor enable_vmware_backdoor for VMware pseudo-PMCs

[Zack Rusin <zack.rusin@broadcom.com>]

Check enable_vmware_backdoor before kvm_pmu_rdpmc() hands an RDPMC of a
VMware pseudo-PMC to the VMware emulation.

The pseudo-PMCs are part of the VMware backdoor, but only the
emulator's check for RDPMC at CPL3 with CR4.PCE clear honors
enable_vmware_backdoor.  An RDPMC that KVM intercepts at CPL0, or at
CPL3 with CR4.PCE set, returns the host TSC or time to any guest, even
with the backdoor disabled.  Inject #GP instead, as for any other
invalid PMC index.

Fixes: 2d7921c499af ("KVM: x86: Add support for VMware backdoor Pseudo-PMCs")
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
---
 arch/x86/kvm/pmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index eef2f792dc9e..ca6dfb44949f 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -759,7 +759,7 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
 	if (!pmu->version)
 		return 1;
 
-	if (is_vmware_backdoor_pmc(idx))
+	if (enable_vmware_backdoor && is_vmware_backdoor_pmc(idx))
 		return kvm_pmu_rdpmc_vmware(vcpu, idx, data);
 
 	pmc = kvm_pmu_call(rdpmc_ecx_to_pmc)(vcpu, idx, &mask);
-- 
2.53.0