KVM: x86: VMX: synthesize invalid VM exit when emulating invalid guest state

Since no actual VM entry happened, the VM exit information is stale.
To avoid this, synthesize an invalid VM guest state VM exit.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210913140954.165665-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -6622,10 +6622,21 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
 		     vmx->loaded_vmcs->soft_vnmi_blocked))
 		vmx->loaded_vmcs->entry_time = ktime_get();
 
-	/* Don't enter VMX if guest state is invalid, let the exit handler
-	   start emulation until we arrive back to a valid state */
-	if (vmx->emulation_required)
+	/*
+	 * Don't enter VMX if guest state is invalid, let the exit handler
+	 * start emulation until we arrive back to a valid state.  Synthesize a
+	 * consistency check VM-Exit due to invalid guest state and bail.
+	 */
+	if (unlikely(vmx->emulation_required)) {
+		vmx->fail = 0;
+		vmx->exit_reason.full = EXIT_REASON_INVALID_STATE;
+		vmx->exit_reason.failed_vmentry = 1;
+		kvm_register_mark_available(vcpu, VCPU_EXREG_EXIT_INFO_1);
+		vmx->exit_qualification = ENTRY_FAIL_DEFAULT;
+		kvm_register_mark_available(vcpu, VCPU_EXREG_EXIT_INFO_2);
+		vmx->exit_intr_info = 0;
 		return EXIT_FASTPATH_NONE;
+	}
 
 	trace_kvm_entry(vcpu);