[PATCH 6.12 221/567] KVM: x86: Explicitly set new periodic hrtimer expiration in apic_timer_fn()

Greg Kroah-Hartman
2026-01-06T17:26:24Z

From: fuqiang wang <fuqiang.wng@gmail.com>

commit 9633f180ce994ab293ce4924a9b7aaf4673aa114 upstream.

When restarting an hrtimer to emulate a the guest's APIC timer in periodic
mode, explicitly set the expiration using the target expiration computed
by advance_periodic_target_expiration() instead of adding the period to
the existing timer. This will allow making adjustments to the expiration,
e.g. to deal with expirations far in the past, without having to implement
the same logic in both advance_periodic_target_expiration() and
apic_timer_fn().

Cc: stable@vger.kernel.org
Signed-off-by: fuqiang wang <fuqiang.wng@gmail.com>
[sean: split to separate patch, write changelog]
Link: https://patch.msgid.link/20251113205114.1647493-3-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
@@ -2871,7 +2871,7 @@ static enum hrtimer_restart apic_timer_f

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);
+ hrtimer_set_expires(&ktimer->timer, ktimer->target_expiration);
return HRTIMER_RESTART;
} else
return HRTIMER_NORESTART;