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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2009-07-28 04:41:01 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-09-10 07:33:17 +0200 |
| commit | 1444885a045fe3b1905a14ea1b52540bf556578b (patch) | |
| tree | 204bbcfa479942245d957fd9d2dbe94ecbcfbc9d | |
| parent | KVM: Align cr8 threshold when userspace changes cr8 (diff) | |
| download | linux-1444885a045fe3b1905a14ea1b52540bf556578b.tar.xz linux-1444885a045fe3b1905a14ea1b52540bf556578b.zip | |
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: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | 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 66122bfc74a9..5b9d1ae09cad 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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), |