If a timer fires after kvm_inject_pending_timer_irqs() but before
local_irq_disable() the code will enter guest mode and only inject such
timer interrupt the next time an unrelated event causes an exit.
It would be simpler if the timer->pending irq conversion could be done
with IRQ's disabled, so that the above problem cannot happen.
For now introduce a new vcpu requests bit to cancel guest entry.
Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>
Index: kvm/arch/x86/kvm/i8254.c
===================================================================
--- kvm.orig/arch/x86/kvm/i8254.c
+++ kvm/arch/x86/kvm/i8254.c
@@ -200,9 +200,12 @@ static int __pit_timer_fn(struct kvm_kpi
atomic_inc(&pt->pending);
smp_mb__after_atomic_inc();
- if (vcpu0 && waitqueue_active(&vcpu0->wq)) {
- vcpu0->arch.mp_state = KVM_MP_STATE_RUNNABLE;
- wake_up_interruptible(&vcpu0->wq);
+ if (vcpu0) {
+ set_bit(KVM_REQ_PENDING_TIMER, &vcpu0->requests);
+ if (waitqueue_active(&vcpu0->wq)) {
+ vcpu0->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+ wake_up_interruptible(&vcpu0->wq);
+ }
}
pt->timer.expires = ktime_add_ns(pt->timer.expires, pt->period);
Index: kvm/arch/x86/kvm/lapic.c
===================================================================
--- kvm.orig/arch/x86/kvm/lapic.c
+++ kvm/arch/x86/kvm/lapic.c
@@ -946,6 +946,7 @@ static int __apic_timer_fn(struct kvm_la
wait_queue_head_t *q = &apic->vcpu->wq;
atomic_inc(&apic->timer.pending);
+ set_bit(KVM_REQ_PENDING_TIMER, &apic->vcpu->requests);
if (waitqueue_active(q)) {
apic->vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
wake_up_interruptible(q);
Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -2813,6 +2813,7 @@ again:
}
}
+ clear_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
kvm_inject_pending_timer_irqs(vcpu);
preempt_disable();
Index: kvm/include/linux/kvm_host.h
===================================================================
--- kvm.orig/include/linux/kvm_host.h
+++ kvm/include/linux/kvm_host.h
@@ -33,6 +33,7 @@
#define KVM_REQ_REPORT_TPR_ACCESS 2
#define KVM_REQ_MMU_RELOAD 3
#define KVM_REQ_TRIPLE_FAULT 4
+#define KVM_REQ_PENDING_TIMER 5
struct kvm_vcpu;
extern struct kmem_cache *kvm_vcpu_cache;
--
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