KVM: x86: Disable Intel PT when VMXON in L1 guest

Luwei Kang · bonzini · commit ee85dec2fe9c · 2018-12-21T11:28:38.000+01:00
Currently, Intel Processor Trace do not support tracing in L1 guest
VMX operation(IA32_VMX_MISC[bit 14] is 0). As mentioned in SDM,
on these type of processors, execution of the VMXON instruction will
clears IA32_RTIT_CTL.TraceEn and any attempt to write IA32_RTIT_CTL
causes a general-protection exception (#GP).

Signed-off-by: Luwei Kang &lt;luwei.kang@intel.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
@@ -4167,6 +4167,12 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
 
 	vmx->nested.vmcs02_initialized = false;
 	vmx->nested.vmxon = true;
+
+	if (pt_mode == PT_MODE_HOST_GUEST) {
+		vmx->pt_desc.guest.ctl = 0;
+		pt_update_intercept_for_msr(vmx);
+	}
+
 	return 0;
 
 out_shadow_vmcs:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
@@ -1926,7 +1926,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_RTIT_CTL:
 		if ((pt_mode != PT_MODE_HOST_GUEST) ||
-			vmx_rtit_ctl_check(vcpu, data))
+			vmx_rtit_ctl_check(vcpu, data) ||
+			vmx->nested.vmxon)
 			return 1;
 		vmcs_write64(GUEST_IA32_RTIT_CTL, data);
 		vmx->pt_desc.guest.ctl = data;
