KVM: Check for pending events before attempting injection

Instead of blindly attempting to inject an event before each guest entry,
check for a possible event first in vcpu->requests.  Sites that can trigger
event injection are modified to set KVM_REQ_EVENT:

- interrupt, nmi window opening
- ppr updates
- i8259 output changes
- local apic irr changes
- rflags updates
- gif flag set
- event set on exit

This improves non-injecting entry performance, and sets the stage for
non-atomic injection.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/i8259.c

@@ -67,6 +67,7 @@ static void pic_unlock(struct kvm_pic *s)
 		if (!found)
 			return;
 
+		kvm_make_request(KVM_REQ_EVENT, found);
 		kvm_vcpu_kick(found);
 	}
 }

arch/x86/kvm/lapic.c

@@ -259,9 +259,10 @@ static inline int apic_find_highest_isr(struct kvm_lapic *apic)
 
 static void apic_update_ppr(struct kvm_lapic *apic)
 {
-	u32 tpr, isrv, ppr;
+	u32 tpr, isrv, ppr, old_ppr;
 	int isr;
 
+	old_ppr = apic_get_reg(apic, APIC_PROCPRI);
 	tpr = apic_get_reg(apic, APIC_TASKPRI);
 	isr = apic_find_highest_isr(apic);
 	isrv = (isr != -1) ? isr : 0;
@@ -274,7 +275,10 @@ static void apic_update_ppr(struct kvm_lapic *apic)
 	apic_debug("vlapic %p, ppr 0x%x, isr 0x%x, isrv 0x%x",
 		   apic, ppr, isr, isrv);
 
-	apic_set_reg(apic, APIC_PROCPRI, ppr);
+	if (old_ppr != ppr) {
+		apic_set_reg(apic, APIC_PROCPRI, ppr);
+		kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
+	}
 }
 
 static void apic_set_tpr(struct kvm_lapic *apic, u32 tpr)
@@ -391,6 +395,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 			break;
 		}
 
+		kvm_make_request(KVM_REQ_EVENT, vcpu);
 		kvm_vcpu_kick(vcpu);
 		break;
 
@@ -416,6 +421,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 				       "INIT on a runnable vcpu %d\n",
 				       vcpu->vcpu_id);
 			vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
+			kvm_make_request(KVM_REQ_EVENT, vcpu);
 			kvm_vcpu_kick(vcpu);
 		} else {
 			apic_debug("Ignoring de-assert INIT to vcpu %d\n",
@@ -430,6 +436,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 			result = 1;
 			vcpu->arch.sipi_vector = vector;
 			vcpu->arch.mp_state = KVM_MP_STATE_SIPI_RECEIVED;
+			kvm_make_request(KVM_REQ_EVENT, vcpu);
 			kvm_vcpu_kick(vcpu);
 		}
 		break;
@@ -475,6 +482,7 @@ static void apic_set_eoi(struct kvm_lapic *apic)
 		trigger_mode = IOAPIC_EDGE_TRIG;
 	if (!(apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI))
 		kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
+	kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
 }
 
 static void apic_send_ipi(struct kvm_lapic *apic)
@@ -1152,6 +1160,7 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu)
 	update_divide_count(apic);
 	start_apic_timer(apic);
 	apic->irr_pending = true;
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 }
 
 void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)

arch/x86/kvm/svm.c

@@ -2371,6 +2371,7 @@ static int stgi_interception(struct vcpu_svm *svm)
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
 	skip_emulated_instruction(&svm->vcpu);
+	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
 
 	enable_gif(svm);
 
@@ -2763,6 +2764,7 @@ static int interrupt_window_interception(struct vcpu_svm *svm)
 {
 	struct kvm_run *kvm_run = svm->vcpu.run;
 
+	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
 	svm_clear_vintr(svm);
 	svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
 	/*
@@ -3209,8 +3211,10 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
 
 	svm->int3_injected = 0;
 
-	if (svm->vcpu.arch.hflags & HF_IRET_MASK)
+	if (svm->vcpu.arch.hflags & HF_IRET_MASK) {
 		svm->vcpu.arch.hflags &= ~(HF_NMI_MASK | HF_IRET_MASK);
+		kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+	}
 
 	svm->vcpu.arch.nmi_injected = false;
 	kvm_clear_exception_queue(&svm->vcpu);
@@ -3219,6 +3223,8 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
 	if (!(exitintinfo & SVM_EXITINTINFO_VALID))
 		return;
 
+	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
+
 	vector = exitintinfo & SVM_EXITINTINFO_VEC_MASK;
 	type = exitintinfo & SVM_EXITINTINFO_TYPE_MASK;
 

arch/x86/kvm/vmx.c

@@ -3327,6 +3327,7 @@ static int handle_wrmsr(struct kvm_vcpu *vcpu)
 
 static int handle_tpr_below_threshold(struct kvm_vcpu *vcpu)
 {
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	return 1;
 }
 
@@ -3339,6 +3340,8 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu)
 	cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
 	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	++vcpu->stat.irq_window_exits;
 
 	/*
@@ -3595,6 +3598,7 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu)
 	cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;
 	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
 	++vcpu->stat.nmi_window_exits;
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 
 	return 1;
 }
@@ -3828,6 +3832,8 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
 	if (!idtv_info_valid)
 		return;
 
+	kvm_make_request(KVM_REQ_EVENT, &vmx->vcpu);
+
 	vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
 	type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;
 

arch/x86/kvm/x86.c

@@ -284,6 +284,8 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
 	u32 prev_nr;
 	int class1, class2;
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	if (!vcpu->arch.exception.pending) {
 	queue:
 		vcpu->arch.exception.pending = true;
@@ -356,6 +358,7 @@ void kvm_propagate_fault(struct kvm_vcpu *vcpu)
 
 void kvm_inject_nmi(struct kvm_vcpu *vcpu)
 {
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	vcpu->arch.nmi_pending = 1;
 }
 EXPORT_SYMBOL_GPL(kvm_inject_nmi);
@@ -2418,6 +2421,7 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
 		return -ENXIO;
 
 	kvm_queue_interrupt(vcpu, irq->irq, false);
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 
 	return 0;
 }
@@ -2571,6 +2575,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
 	if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)
 		vcpu->arch.sipi_vector = events->sipi_vector;
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	return 0;
 }
 
@@ -4329,6 +4335,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 
 	toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility);
 	kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
 	kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);
 
@@ -4998,6 +5005,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	int r;
 	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
 		vcpu->run->request_interrupt_window;
+	bool req_event;
 
 	if (vcpu->requests) {
 		if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
@@ -5045,8 +5053,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 
 	local_irq_disable();
 
+	req_event = kvm_check_request(KVM_REQ_EVENT, vcpu);
+
 	if (!atomic_read(&vcpu->guest_mode) || vcpu->requests
 	    || need_resched() || signal_pending(current)) {
+		if (req_event)
+			kvm_make_request(KVM_REQ_EVENT, vcpu);
 		atomic_set(&vcpu->guest_mode, 0);
 		smp_wmb();
 		local_irq_enable();
@@ -5055,17 +5067,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		goto out;
 	}
 
-	inject_pending_event(vcpu);
+	if (req_event || req_int_win) {
+		inject_pending_event(vcpu);
 
-	/* enable NMI/IRQ window open exits if needed */
-	if (vcpu->arch.nmi_pending)
-		kvm_x86_ops->enable_nmi_window(vcpu);
-	else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
-		kvm_x86_ops->enable_irq_window(vcpu);
+		/* enable NMI/IRQ window open exits if needed */
+		if (vcpu->arch.nmi_pending)
+			kvm_x86_ops->enable_nmi_window(vcpu);
+		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
+			kvm_x86_ops->enable_irq_window(vcpu);
 
-	if (kvm_lapic_enabled(vcpu)) {
-		update_cr8_intercept(vcpu);
-		kvm_lapic_sync_to_vapic(vcpu);
+		if (kvm_lapic_enabled(vcpu)) {
+			update_cr8_intercept(vcpu);
+			kvm_lapic_sync_to_vapic(vcpu);
+		}
 	}
 
 	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
@@ -5305,6 +5319,8 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 
 	vcpu->arch.exception.pending = false;
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	return 0;
 }
 
@@ -5368,6 +5384,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
 	vcpu->arch.mp_state = mp_state->mp_state;
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	return 0;
 }
 
@@ -5389,6 +5406,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,
 	memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
 	kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);
 	kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 	return EMULATE_DONE;
 }
 EXPORT_SYMBOL_GPL(kvm_task_switch);
@@ -5459,6 +5477,8 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 	    !is_protmode(vcpu))
 		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	return 0;
 }
 
@@ -5691,6 +5711,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
 	vcpu->arch.dr6 = DR6_FIXED_1;
 	vcpu->arch.dr7 = DR7_FIXED_1;
 
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
+
 	return kvm_x86_ops->vcpu_reset(vcpu);
 }
 
@@ -6001,6 +6023,7 @@ void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
 	    kvm_is_linear_rip(vcpu, vcpu->arch.singlestep_rip))
 		rflags |= X86_EFLAGS_TF;
 	kvm_x86_ops->set_rflags(vcpu, rflags);
+	kvm_make_request(KVM_REQ_EVENT, vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_set_rflags);
 

include/linux/kvm_host.h

@@ -39,6 +39,7 @@
 #define KVM_REQ_KVMCLOCK_UPDATE    8
 #define KVM_REQ_KICK               9
 #define KVM_REQ_DEACTIVATE_FPU    10
+#define KVM_REQ_EVENT             11
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID	0