From 3d80840d96127401ba6aeadd813c3a15b84e70fe Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Fri, 11 Apr 2008 14:53:26 -0300 Subject: KVM: hlt emulation should take in-kernel APIC/PIT timers into account Timers that fire between guest hlt and vcpu_block's add_wait_queue() are ignored, possibly resulting in hangs. Also make sure that atomic_inc and waitqueue_active tests happen in the specified order, otherwise the following race is open: CPU0 CPU1 if (waitqueue_active(wq)) add_wait_queue() if (!atomic_read(pit_timer->pending)) schedule() atomic_inc(pit_timer->pending) Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/i8254.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/x86/kvm/i8254.c') diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 9f118e2f350d..ed1af80432b3 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -212,6 +212,16 @@ int __pit_timer_fn(struct kvm_kpit_state *ps) return (pt->period == 0 ? 0 : 1); } +int pit_has_pending_timer(struct kvm_vcpu *vcpu) +{ + struct kvm_pit *pit = vcpu->kvm->arch.vpit; + + if (pit && vcpu->vcpu_id == 0) + return atomic_read(&pit->pit_state.pit_timer.pending); + + return 0; +} + static enum hrtimer_restart pit_timer_fn(struct hrtimer *data) { struct kvm_kpit_state *ps; -- cgit v1.2.3