linux-kernel - [PATCH] KVM: nVMX: Add VM-Enter failed tracepoints for super early checks

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Date:   Wed, 12 Aug 2020 11:06:15 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: nVMX: Add VM-Enter failed tracepoints for super early checks

Add tracepoints for the early consistency checks in nested_vmx_run().
The "VMLAUNCH vs. VMRESUME" check in particular is useful to trace, as
there is no architectural way to check VMCS.LAUNCH_STATE, and subtle
bugs such as VMCLEAR on the wrong HPA can lead to confusing errors in
the L1 VMM.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/nested.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 23b58c28a1c92..fb37f0972e78a 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3468,11 +3468,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	if (evmptrld_status == EVMPTRLD_ERROR) {
 		kvm_queue_exception(vcpu, UD_VECTOR);
 		return 1;
-	} else if (evmptrld_status == EVMPTRLD_VMFAIL) {
+	} else if (CC(evmptrld_status == EVMPTRLD_VMFAIL)) {
 		return nested_vmx_failInvalid(vcpu);
 	}
 
-	if (!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull)
+	if (CC(!vmx->nested.hv_evmcs && vmx->nested.current_vmptr == -1ull))
 		return nested_vmx_failInvalid(vcpu);
 
 	vmcs12 = get_vmcs12(vcpu);
@@ -3483,7 +3483,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	 * rather than RFLAGS.ZF, and no error number is stored to the
 	 * VM-instruction error field.
 	 */
-	if (vmcs12->hdr.shadow_vmcs)
+	if (CC(vmcs12->hdr.shadow_vmcs))
 		return nested_vmx_failInvalid(vcpu);
 
 	if (vmx->nested.hv_evmcs) {
@@ -3504,10 +3504,10 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
 	 * for misconfigurations which will anyway be caught by the processor
 	 * when using the merged vmcs02.
 	 */
-	if (interrupt_shadow & KVM_X86_SHADOW_INT_MOV_SS)
+	if (CC(interrupt_shadow & KVM_X86_SHADOW_INT_MOV_SS))
 		return nested_vmx_fail(vcpu, VMXERR_ENTRY_EVENTS_BLOCKED_BY_MOV_SS);
 
-	if (vmcs12->launch_state == launch)
+	if (CC(vmcs12->launch_state == launch))
 		return nested_vmx_fail(vcpu,
 			launch ? VMXERR_VMLAUNCH_NONCLEAR_VMCS
 			       : VMXERR_VMRESUME_NONLAUNCHED_VMCS);
-- 
2.28.0