* KVM: limit lapic periodic timer frequency
@ 2009-07-28 2:41 Marcelo Tosatti
2009-08-03 12:11 ` Avi Kivity
0 siblings, 1 reply; 2+ messages in thread
From: Marcelo Tosatti @ 2009-07-28 2:41 UTC (permalink / raw)
To: kvm; +Cc: Avi Kivity
Otherwise its possible to starve the host by programming lapic timer
with a very high frequency.
Cc: stable@kernel.org
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Index: kvm/arch/x86/kvm/lapic.c
===================================================================
--- kvm.orig/arch/x86/kvm/lapic.c
+++ kvm/arch/x86/kvm/lapic.c
@@ -667,6 +667,15 @@ static void start_apic_timer(struct kvm_
if (!apic->lapic_timer.period)
return;
+ /*
+ * Do not allow the guest to program periodic timers with small
+ * interval, since the hrtimers are not throttled by the host
+ * scheduler.
+ */
+ if (apic_lvtt_period(apic)) {
+ if (apic->lapic_timer.period < NSEC_PER_MSEC/2)
+ apic->lapic_timer.period = NSEC_PER_MSEC/2;
+ }
hrtimer_start(&apic->lapic_timer.timer,
ktime_add_ns(now, apic->lapic_timer.period),
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: KVM: limit lapic periodic timer frequency
2009-07-28 2:41 KVM: limit lapic periodic timer frequency Marcelo Tosatti
@ 2009-08-03 12:11 ` Avi Kivity
0 siblings, 0 replies; 2+ messages in thread
From: Avi Kivity @ 2009-08-03 12:11 UTC (permalink / raw)
To: Marcelo Tosatti; +Cc: kvm
On 07/28/2009 05:41 AM, Marcelo Tosatti wrote:
> Otherwise its possible to starve the host by programming lapic timer
> with a very high frequency.
>
Applied, thanks.
--
error compiling committee.c: too many arguments to function
^ permalink raw reply [flat|nested] 2+ messages in thread
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