[PATCH v7 13/13] KVM: x86: Disable Intel Processor Trace when VMXON in L1 guest

Luwei Kang
2018-05-03T12:13:28Z

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 <luwei.kang@intel.com>
---
arch/x86/kvm/vmx.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c125fb1..1e800d0 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3952,7 +3952,8 @@ 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);
pt_set_intercept_for_msr(vmx, !(data & RTIT_CTL_TRACEEN));
@@ -8029,6 +8030,12 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
if (ret)
return ret;

+ if (pt_mode == PT_MODE_HOST_GUEST) {
+ vmx->pt_desc.guest.ctl = 0;
+ vmcs_write64(GUEST_IA32_RTIT_CTL, 0);
+ pt_set_intercept_for_msr(vmx, 1);
+ }
+
nested_vmx_succeed(vcpu);
return kvm_skip_emulated_instruction(vcpu);
}
--
1.8.3.1