2.6.31-stable review patch. If anyone has any objections, please let us know. ------------------ From: Marcelo Tosatti commit 1444885a045fe3b1905a14ea1b52540bf556578b upstream. Otherwise its possible to starve the host by programming lapic timer with a very high frequency. Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/lapic.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -573,6 +573,15 @@ 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), -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/