linux-kernel - [PATCH V4 09/11] KVM: x86: Disable Intel Processor Trace when VMXON in L1 guest

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Date:   Mon, 11 Dec 2017 04:30:55 +0800
From:   Luwei Kang <luwei.kang@...el.com>
To:     kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, pbonzini@...hat.com, rkrcmar@...hat.com,
        linux-kernel@...r.kernel.org, joro@...tes.org,
        Luwei Kang <luwei.kang@...el.com>
Subject: [PATCH V4 09/11] KVM: x86: Disable Intel Processor Trace 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 xception (#GP).

Signed-off-by: Luwei Kang <luwei.kang@...el.com>
---
 arch/x86/kvm/vmx.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 7761c25..d2e64bf 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -948,6 +948,7 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu,
 static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked);
 static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12,
 					    u16 error_code);
+static void pt_disable_intercept_for_msr(bool flag);
 
 static DEFINE_PER_CPU(struct vmcs *, vmxarea);
 static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
@@ -2469,6 +2470,15 @@ static void vmx_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
 		vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, interruptibility);
 }
 
+static void vmx_set_rtit_ctl(struct kvm_vcpu *vcpu, u64 data)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	pt_disable_intercept_for_msr(data & RTIT_CTL_TRACEEN);
+	vmcs_write64(GUEST_IA32_RTIT_CTL, data);
+	vmx->pt_desc.guest.ctl = data;
+}
+
 static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 {
 	unsigned long rip;
@@ -7500,6 +7510,9 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
 	if (ret)
 		return ret;
 
+	if (pt_mode == PT_MODE_HOST_GUEST)
+		vmx_set_rtit_ctl(vcpu, 0);
+
 	nested_vmx_succeed(vcpu);
 	return kvm_skip_emulated_instruction(vcpu);
 }
-- 
1.8.3.1