KVM: Avoid infinite-frequency local apic timer

If the local apic initial count is zero, don't start a an hrtimer with infinite
frequency, locking up the host.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2cbee9479ce4..68a6b1511934 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -647,6 +647,10 @@ static void start_apic_timer(struct kvm_lapic *apic)
         apic->timer.period = apic_get_reg(apic, APIC_TMICT) *
                     APIC_BUS_CYCLE_NS * apic->timer.divide_count;
         atomic_set(&apic->timer.pending, 0);
+
+        if (!apic->timer.period)
+                return;
+
         hrtimer_start(&apic->timer.dev,
                       ktime_add_ns(now, apic->timer.period),
                       HRTIMER_MODE_ABS);