linux-kernel - [PATCH v13 12/12] KVM: x86: Disable Intel PT when VMXON in L1 guest

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Date:   Wed, 24 Oct 2018 16:05:16 +0800
From:   Luwei Kang <luwei.kang@...el.com>
To:     kvm@...r.kernel.org, x86@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        pbonzini@...hat.com, rkrcmar@...hat.com, joro@...tes.org,
        songliubraving@...com, peterz@...radead.org,
        alexander.shishkin@...ux.intel.com, kstewart@...uxfoundation.org,
        gregkh@...uxfoundation.org, thomas.lendacky@....com,
        konrad.wilk@...cle.com, mattst88@...il.com,
        Janakarajan.Natarajan@....com, dwmw@...zon.co.uk,
        jpoimboe@...hat.com, marcorr@...gle.com, ubizjak@...il.com,
        sean.j.christopherson@...el.com, jmattson@...gle.com,
        linux-kernel@...r.kernel.org, Luwei Kang <luwei.kang@...el.com>
Subject: [PATCH v13 12/12] KVM: x86: Disable Intel PT when VMXON in L1 guest

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@...el.com>
---
 arch/x86/kvm/vmx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed247dd..5001049 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4556,7 +4556,8 @@ 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));
@@ -8760,6 +8761,11 @@ 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;
+		pt_set_intercept_for_msr(vmx, 1);
+	}
+
 	return nested_vmx_succeed(vcpu);
 }
 
-- 
1.8.3.1