From 52d939a0bf44081bc9f69b4fbdc9e7f416df27c7 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 30 Dec 2008 15:55:06 -0200 Subject: KVM: PIT: provide an option to disable interrupt reinjection Certain clocks (such as TSC) in older 2.6 guests overaccount for lost ticks, causing severe time drift. Interrupt reinjection magnifies the problem. Provide an option to disable it. [avi: allow room for expansion in case we want to disable reinjection of other timers] Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/i8254.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/kvm/i8254.c') diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 72bd275a9b5c..528daadeba49 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -201,6 +201,9 @@ static int __pit_timer_fn(struct kvm_kpit_state *ps) if (!atomic_inc_and_test(&pt->pending)) set_bit(KVM_REQ_PENDING_TIMER, &vcpu0->requests); + if (!pt->reinject) + atomic_set(&pt->pending, 1); + if (vcpu0 && waitqueue_active(&vcpu0->wq)) wake_up_interruptible(&vcpu0->wq); @@ -580,6 +583,7 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm) pit_state->irq_ack_notifier.gsi = 0; pit_state->irq_ack_notifier.irq_acked = kvm_pit_ack_irq; kvm_register_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier); + pit_state->pit_timer.reinject = true; mutex_unlock(&pit->pit_state.lock); kvm_pit_reset(pit); -- cgit v1.2.3