KVM: x86: reset RVI upon system reset

A bug was reported as follows: when running Windows 7 32-bit guests on qemu-kvm,
sometimes the guests run into blue screen during reboot. The problem was that a
guest's RVI was not cleared when it rebooted. This patch has fixed the problem.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Tested-by: Rongrong Liu <rongrongx.liu@intel.com>, Da Chun <ngugc@qq.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -1714,6 +1714,9 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
 	apic->isr_count = kvm_apic_vid_enabled(vcpu->kvm) ?
 				1 : count_vectors(apic->regs + APIC_ISR);
 	apic->highest_isr_cache = -1;
+	if (kvm_x86_ops->hwapic_irr_update)
+		kvm_x86_ops->hwapic_irr_update(vcpu,
+				apic_find_highest_irr(apic));
 	kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic));
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	kvm_rtc_eoi_tracking_restore_one(vcpu);

arch/x86/kvm/vmx.c

@@ -7419,6 +7419,9 @@ static void vmx_set_rvi(int vector)
 	u16 status;
 	u8 old;
 
+	if (vector == -1)
+		vector = 0;
+
 	status = vmcs_read16(GUEST_INTR_STATUS);
 	old = (u8)status & 0xff;
 	if ((u8)vector != old) {
@@ -7430,22 +7433,23 @@ static void vmx_set_rvi(int vector)
 
 static void vmx_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
 {
-	if (max_irr == -1)
-		return;
-
-	/*
-	 * If a vmexit is needed, vmx_check_nested_events handles it.
-	 */
-	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
-		return;
-
 	if (!is_guest_mode(vcpu)) {
 		vmx_set_rvi(max_irr);
 		return;
 	}
 
+	if (max_irr == -1)
+		return;
+
 	/*
-	 * Fall back to pre-APICv interrupt injection since L2
+	 * In guest mode.  If a vmexit is needed, vmx_check_nested_events
+	 * handles it.
+	 */
+	if (nested_exit_on_intr(vcpu))
+		return;
+
+	/*
+	 * Else, fall back to pre-APICv interrupt injection since L2
 	 * is run without virtual interrupt delivery.
 	 */
 	if (!kvm_event_needs_reinjection(vcpu) &&