diff options
| author | Marcelo Tosatti <mtosatti@redhat.com> | 2008-06-11 19:52:53 -0300 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-07-20 12:42:32 +0300 |
| commit | 622395a9e63bf87a16faecf555ed02375cbae5b7 (patch) | |
| tree | c4a8082660a4e4bf8f687a33921d292ae35f6394 /arch/x86/kvm/lapic.c | |
| parent | 7f39f8ac177db258200053074aa7a3d98656b1cf (diff) | |
KVM: only abort guest entry if timer count goes from 0->1
Only abort guest entry if the timer count went from 0->1, since for 1->2
or larger the bit will either be set already or a timer irq will have
been injected.
Using atomic_inc_and_test() for it also introduces an SMP barrier
to the LAPIC version (thought it was unecessary because of timer
migration, but guest can be scheduled to a different pCPU between exit
and kvm_vcpu_block(), so there is the possibility for a race).
Noticed by Avi.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch/x86/kvm/lapic.c')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 180ba7316da5..73f43de69f67 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -945,8 +945,8 @@ static int __apic_timer_fn(struct kvm_lapic *apic) int result = 0; wait_queue_head_t *q = &apic->vcpu->wq; - atomic_inc(&apic->timer.pending); - set_bit(KVM_REQ_PENDING_TIMER, &apic->vcpu->requests); + if(!atomic_inc_and_test(&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); |