Commit 1444885a authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
Browse files

KVM: limit lapic periodic timer frequency 



Otherwise its possible to starve the host by programming lapic timer
with a very high frequency.

Cc: stable@kernel.org
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 5f0269f5

arch/x86/kvm/lapic.c

+9 −0
Original line number Diff line number Diff line
@@ -670,6 +670,15 @@ static void start_apic_timer(struct kvm_lapic *apic) 


	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),