KVM: Non-atomic interrupt injection

Change the interrupt injection code to work from preemptible, interrupts
enabled context.  This works by adding a ->cancel_injection() operation
that undoes an injection in case we were not able to actually enter the guest
(this condition could never happen with atomic injection).

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 16 insertions, 20 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e7198036db61..a465bd29f381 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5005,7 +5005,6 @@ 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))
@@ -5041,6 +5040,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
         if (unlikely(r))
                 goto out;
 
+        if (kvm_check_request(KVM_REQ_EVENT, vcpu) || 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);
+
+                if (kvm_lapic_enabled(vcpu)) {
+                        update_cr8_intercept(vcpu);
+                        kvm_lapic_sync_to_vapic(vcpu);
+                }
+        }
+
         preempt_disable();
 
         kvm_x86_ops->prepare_guest_switch(vcpu);
@@ -5053,35 +5067,17 @@ 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();
                 preempt_enable();
+                kvm_x86_ops->cancel_injection(vcpu);
                 r = 1;
                 goto out;
         }
 
-        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);
-
-                if (kvm_lapic_enabled(vcpu)) {
-                        update_cr8_intercept(vcpu);
-                        kvm_lapic_sync_to_vapic(vcpu);
-                }
-        }
-
         srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 
         kvm_guest_enter();