KVM: SVM: Coalesce userspace/kernel irqchip interrupt injection logic

Start to use interrupt/exception queues like VMX does.
This also fix the bug that if exit was caused by a guest
internal exception access to IDT the exception was not
reinjected.

Use EVENTINJ to inject interrupts.  Use VINT only for detecting when IRQ
windows is open again.  EVENTINJ ensures
the interrupt is injected immediately and not delayed.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/svm.c

@@ -70,7 +70,6 @@ module_param(npt, int, S_IRUGO);
 static int nested = 0;
 module_param(nested, int, S_IRUGO);
 
-static void kvm_reput_irq(struct vcpu_svm *svm);
 static void svm_flush_tlb(struct kvm_vcpu *vcpu);
 
 static int nested_svm_exit_handled(struct vcpu_svm *svm, bool kvm_override);
@@ -199,9 +198,7 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
 
 static bool svm_exception_injected(struct kvm_vcpu *vcpu)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
-
-	return !(svm->vmcb->control.exit_int_info & SVM_EXITINTINFO_VALID);
+	return false;
 }
 
 static int is_external_interrupt(u32 info)
@@ -978,12 +975,9 @@ static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
 
 static int svm_get_irq(struct kvm_vcpu *vcpu)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
-	u32 exit_int_info = svm->vmcb->control.exit_int_info;
-
-	if (is_external_interrupt(exit_int_info))
-		return exit_int_info & SVM_EVTINJ_VEC_MASK;
+	if (!vcpu->arch.interrupt.pending)
 		return -1;
+	return vcpu->arch.interrupt.nr;
 }
 
 static void load_host_msrs(struct kvm_vcpu *vcpu)
@@ -1090,17 +1084,8 @@ static void svm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long value,
 
 static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 {
-	u32 exit_int_info = svm->vmcb->control.exit_int_info;
-	struct kvm *kvm = svm->vcpu.kvm;
 	u64 fault_address;
 	u32 error_code;
-	bool event_injection = false;
-
-	if (!irqchip_in_kernel(kvm) &&
-	    is_external_interrupt(exit_int_info)) {
-		event_injection = true;
-		kvm_push_irq(&svm->vcpu, exit_int_info & SVM_EVTINJ_VEC_MASK);
-	}
 
 	fault_address  = svm->vmcb->control.exit_info_2;
 	error_code = svm->vmcb->control.exit_info_1;
@@ -1120,9 +1105,11 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
 	 */
 	if (npt_enabled)
 		svm_flush_tlb(&svm->vcpu);
-
-	if (!npt_enabled && event_injection)
+	else {
+		if (svm->vcpu.arch.interrupt.pending ||
+				svm->vcpu.arch.exception.pending)
 			kvm_mmu_unprotect_page_virt(&svm->vcpu, fault_address);
+	}
 	return kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code);
 }
 
@@ -2196,7 +2183,6 @@ static int handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 		}
 	}
 
-	kvm_reput_irq(svm);
 
 	if (svm->vmcb->control.exit_code == SVM_EXIT_ERR) {
 		kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
@@ -2259,13 +2245,19 @@ static inline void svm_inject_irq(struct vcpu_svm *svm, int irq)
 		((/*control->int_vector >> 4*/ 0xf) << V_INTR_PRIO_SHIFT);
 }
 
+static void svm_queue_irq(struct vcpu_svm *svm, unsigned nr)
+{
+	svm->vmcb->control.event_inj = nr |
+		SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR;
+}
+
 static void svm_set_irq(struct kvm_vcpu *vcpu, int irq)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	nested_svm_intr(svm);
 
-	svm_inject_irq(svm, irq);
+	svm_queue_irq(svm, irq);
 }
 
 static void update_cr8_intercept(struct kvm_vcpu *vcpu)
@@ -2298,98 +2290,47 @@ static int svm_interrupt_allowed(struct kvm_vcpu *vcpu)
 		(svm->vcpu.arch.hflags & HF_GIF_MASK);
 }
 
-static void svm_intr_assist(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+static void enable_irq_window(struct kvm_vcpu *vcpu)
 {
-	struct vcpu_svm *svm = to_svm(vcpu);
-	struct vmcb *vmcb = svm->vmcb;
-	int intr_vector = -1;
-
-	if ((vmcb->control.exit_int_info & SVM_EVTINJ_VALID) &&
-	    ((vmcb->control.exit_int_info & SVM_EVTINJ_TYPE_MASK) == 0)) {
-		intr_vector = vmcb->control.exit_int_info &
-			      SVM_EVTINJ_VEC_MASK;
-		vmcb->control.exit_int_info = 0;
-		svm_inject_irq(svm, intr_vector);
-		goto out;
-	}
-
-	if (vmcb->control.int_ctl & V_IRQ_MASK)
-		goto out;
-
-	if (!kvm_cpu_has_interrupt(vcpu))
-		goto out;
-
-	if (nested_svm_intr(svm))
-		goto out;
-
-	if (!(svm->vcpu.arch.hflags & HF_GIF_MASK))
-		goto out;
-
-	if (!(vmcb->save.rflags & X86_EFLAGS_IF) ||
-	    (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK) ||
-	    (vmcb->control.event_inj & SVM_EVTINJ_VALID)) {
-		/* unable to deliver irq, set pending irq */
-		svm_set_vintr(svm);
-		svm_inject_irq(svm, 0x0);
-		goto out;
-	}
-	/* Okay, we can deliver the interrupt: grab it and update PIC state. */
-	intr_vector = kvm_cpu_get_interrupt(vcpu);
-	svm_inject_irq(svm, intr_vector);
-out:
-	update_cr8_intercept(vcpu);
+	svm_set_vintr(to_svm(vcpu));
+	svm_inject_irq(to_svm(vcpu), 0x0);
 }
 
-static void kvm_reput_irq(struct vcpu_svm *svm)
+static void svm_intr_inject(struct kvm_vcpu *vcpu)
 {
-	struct vmcb_control_area *control = &svm->vmcb->control;
-
-	if ((control->int_ctl & V_IRQ_MASK)
-	    && !irqchip_in_kernel(svm->vcpu.kvm)) {
-		control->int_ctl &= ~V_IRQ_MASK;
-		kvm_push_irq(&svm->vcpu, control->int_vector);
+	/* try to reinject previous events if any */
+	if (vcpu->arch.interrupt.pending) {
+		svm_queue_irq(to_svm(vcpu), vcpu->arch.interrupt.nr);
+		return;
 	}
 
-	svm->vcpu.arch.interrupt_window_open =
-		!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
-		 (svm->vcpu.arch.hflags & HF_GIF_MASK);
-}
-
-static void svm_do_inject_vector(struct vcpu_svm *svm)
-{
-	svm_inject_irq(svm, kvm_pop_irq(&svm->vcpu));
+	/* try to inject new event if pending */
+	if (kvm_cpu_has_interrupt(vcpu)) {
+		if (vcpu->arch.interrupt_window_open) {
+			kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu));
+			svm_queue_irq(to_svm(vcpu), vcpu->arch.interrupt.nr);
+		}
+	}
 }
 
-static void do_interrupt_requests(struct kvm_vcpu *vcpu,
-				       struct kvm_run *kvm_run)
+static void svm_intr_assist(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	struct vmcb_control_area *control = &svm->vmcb->control;
+	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
+		kvm_run->request_interrupt_window;
 
 	if (nested_svm_intr(svm))
-		return;
+		goto out;
 
-	svm->vcpu.arch.interrupt_window_open =
-		(!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
-		 (svm->vmcb->save.rflags & X86_EFLAGS_IF) &&
-		 (svm->vcpu.arch.hflags & HF_GIF_MASK));
+	svm->vcpu.arch.interrupt_window_open = svm_interrupt_allowed(vcpu);
 
-	if (svm->vcpu.arch.interrupt_window_open &&
-	    kvm_cpu_has_interrupt(&svm->vcpu))
-		/*
-		 * If interrupts enabled, and not blocked by sti or mov ss. Good.
-		 */
-		svm_do_inject_vector(svm);
+	svm_intr_inject(vcpu);
 
-	/*
-	 * Interrupts blocked.  Wait for unblock.
-	 */
-	if (!svm->vcpu.arch.interrupt_window_open &&
-	    (kvm_cpu_has_interrupt(&svm->vcpu) ||
-	     kvm_run->request_interrupt_window))
-		svm_set_vintr(svm);
-	else
-		svm_clear_vintr(svm);
+	if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
+		enable_irq_window(vcpu);
+
+out:
+	update_cr8_intercept(vcpu);
 }
 
 static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr)
@@ -2429,6 +2370,46 @@ static inline void sync_lapic_to_cr8(struct kvm_vcpu *vcpu)
 	svm->vmcb->control.int_ctl |= cr8 & V_TPR_MASK;
 }
 
+static void svm_complete_interrupts(struct vcpu_svm *svm)
+{
+	u8 vector;
+	int type;
+	u32 exitintinfo = svm->vmcb->control.exit_int_info;
+
+	svm->vcpu.arch.nmi_injected = false;
+	kvm_clear_exception_queue(&svm->vcpu);
+	kvm_clear_interrupt_queue(&svm->vcpu);
+
+	if (!(exitintinfo & SVM_EXITINTINFO_VALID))
+		return;
+
+	vector = exitintinfo & SVM_EXITINTINFO_VEC_MASK;
+	type = exitintinfo & SVM_EXITINTINFO_TYPE_MASK;
+
+	switch (type) {
+	case SVM_EXITINTINFO_TYPE_NMI:
+		svm->vcpu.arch.nmi_injected = true;
+		break;
+	case SVM_EXITINTINFO_TYPE_EXEPT:
+		/* In case of software exception do not reinject an exception
+		   vector, but re-execute and instruction instead */
+		if (vector == BP_VECTOR || vector == OF_VECTOR)
+			break;
+		if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
+			u32 err = svm->vmcb->control.exit_int_info_err;
+			kvm_queue_exception_e(&svm->vcpu, vector, err);
+
+		} else
+			kvm_queue_exception(&svm->vcpu, vector);
+		break;
+	case SVM_EXITINTINFO_TYPE_INTR:
+		kvm_queue_interrupt(&svm->vcpu, vector);
+		break;
+	default:
+		break;
+	}
+}
+
 #ifdef CONFIG_X86_64
 #define R "r"
 #else
@@ -2557,6 +2538,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	sync_cr8_to_lapic(vcpu);
 
 	svm->next_rip = 0;
+
+	svm_complete_interrupts(svm);
 }
 
 #undef R
@@ -2678,7 +2661,7 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.queue_exception = svm_queue_exception,
 	.exception_injected = svm_exception_injected,
 	.inject_pending_irq = svm_intr_assist,
-	.inject_pending_vectors = do_interrupt_requests,
+	.inject_pending_vectors = svm_intr_assist,
 	.interrupt_allowed = svm_interrupt_allowed,
 
 	.set_tss_addr = svm_set_tss_addr,