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LoongArch: KVM: Reload one-shot TVAL on migration destination

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kvm_restore_timer() rebuilds the remaining timer countdown value from
vcpu->arch.expire, which is host-internal and is not part of the
migrated vCPU state. On the migration destination it is still 0, so for
a one-shot timer that has not expired yet the computed delta is 0 and
write_gcsr_timertick(0) injects the timer interrupt immediately instead
of after the remaining time.

The expired one-shot case (TVAL = -1) is already handled earlier. When
expire has not been set (i.e. on the migration destination), reload the
remaining countdown value from the migrated TVAL. This covers both one-
shot and periodic timers. The regular preempt/resume path on the source,
where expire is valid, is unchanged.

Fixes: a5857b9ff6 ("LoongArch: KVM: Implement vcpu timer operations")
Suggested-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Tao Cui 2026-08-10 12:21:50 +08:00 committed by Huacai Chen
parent a5518ad7ef
commit fe41c0759b
1 changed files with 12 additions and 0 deletions
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12
arch/loongarch/kvm/timer.c
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@ -119,6 +119,18 @@ void kvm_restore_timer(struct kvm_vcpu *vcpu)
delta = 0;
now = ktime_get();
expire = vcpu->arch.expire;
if (!expire) {
/*
* vcpu->arch.expire is host-internal and is not migrated,
* so it is 0 after migration. Reload the remaining countdown
* from the migrated TVAL. This covers both one-shot and
* periodic timers.
*/
if (ticks < cfg)
delta = tick_to_ns(vcpu, ticks);
expire = ktime_add_ns(now, delta);
}
if (ktime_before(now, expire))
delta = ktime_to_tick(vcpu, ktime_sub(expire, now));
else if (cfg & CSR_TCFG_PERIOD) {