6.6-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson seanjc@google.com
commit 0ea9494be9c931ddbc084ad5e11fda91b554cf47 upstream.
WARN and don't restart the hrtimer if KVM's callback runs with the guest's APIC timer in periodic mode but with a period of '0', as not advancing the hrtimer's deadline would put the CPU into an infinite loop of hrtimer events. Observing a period of '0' should be impossible, even when the hrtimer is running on a different CPU than the vCPU, as KVM is supposed to cancel the hrtimer before changing (or zeroing) the period, e.g. when switching from periodic to one-shot.
Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20251113205114.1647493-2-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2855,7 +2855,7 @@ static enum hrtimer_restart apic_timer_f
apic_timer_expired(apic, true);
- if (lapic_is_periodic(apic)) { + if (lapic_is_periodic(apic) && !WARN_ON_ONCE(!apic->lapic_timer.period)) { advance_periodic_target_expiration(apic); hrtimer_add_expires_ns(&ktimer->timer, ktimer->period); return HRTIMER_RESTART;