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>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e719803..a465bd2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5005,7 +5005,6 @@
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))
@@ -5041,33 +5040,7 @@
if (unlikely(r))
goto out;
- preempt_disable();
-
- kvm_x86_ops->prepare_guest_switch(vcpu);
- if (vcpu->fpu_active)
- kvm_load_guest_fpu(vcpu);
- kvm_load_guest_xcr0(vcpu);
-
- atomic_set(&vcpu->guest_mode, 1);
- smp_wmb();
-
- 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();
- r = 1;
- goto out;
- }
-
- if (req_event || req_int_win) {
+ if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
inject_pending_event(vcpu);
/* enable NMI/IRQ window open exits if needed */
@@ -5082,6 +5055,29 @@
}
}
+ preempt_disable();
+
+ kvm_x86_ops->prepare_guest_switch(vcpu);
+ if (vcpu->fpu_active)
+ kvm_load_guest_fpu(vcpu);
+ kvm_load_guest_xcr0(vcpu);
+
+ atomic_set(&vcpu->guest_mode, 1);
+ smp_wmb();
+
+ local_irq_disable();
+
+ if (!atomic_read(&vcpu->guest_mode) || vcpu->requests
+ || need_resched() || signal_pending(current)) {
+ atomic_set(&vcpu->guest_mode, 0);
+ smp_wmb();
+ local_irq_enable();
+ preempt_enable();
+ kvm_x86_ops->cancel_injection(vcpu);
+ r = 1;
+ goto out;
+ }
+
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
kvm_guest_enter();