lkml.org 
[lkml]   [2009]   [Aug]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 38/46] KVM: limit lapic periodic timer frequency
    Date
    From: Marcelo Tosatti <mtosatti@redhat.com>

    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>
    Signed-off-by: Avi Kivity <avi@redhat.com>
    ---
    arch/x86/kvm/lapic.c | 9 +++++++++
    1 files changed, 9 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
    index fdddf48..ce195f8 100644
    --- a/arch/x86/kvm/lapic.c
    +++ b/arch/x86/kvm/lapic.c
    @@ -664,6 +664,15 @@ 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),
    --
    1.6.4.1


    \
     
     \ /
      Last update: 2009-08-23 14:27    [W:0.025 / U:150.552 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site