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>

1 files changed, 32 insertions, 9 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3ff0a8ff275c..e7198036db61 100644
--- a/arch/x86/kvm/x86.c
+++ b/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 @@ done:
 
         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);