Queued for loongarch-kvm, thanks.
Huacai
On Tue, Jan 30, 2024 at 3:22 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
>
> SW timer is enabled when vcpu thread is scheduled out, and it is
> to wake up vcpu from blocked queue. If vcpu thread is scheduled out
> however is not blocked, such as it is preempted by other threads,
> it is not necessary to enable SW timer. Since vcpu thread is still
> on running queue if preempted and SW timer is only to wake up vcpu
> on blocking queue, so SW timer is not useful in this situation.
>
> This patch enables SW timer only when vcpu is scheduled out and
> is blocking.
>
> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> ---
> arch/loongarch/kvm/timer.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c
> index 111328f60872..a9125f0a12d1 100644
> --- a/arch/loongarch/kvm/timer.c
> +++ b/arch/loongarch/kvm/timer.c
> @@ -93,7 +93,8 @@ void kvm_restore_timer(struct kvm_vcpu *vcpu)
> /*
> * Freeze the soft-timer and sync the guest stable timer with it.
> */
> - hrtimer_cancel(&vcpu->arch.swtimer);
> + if (kvm_vcpu_is_blocking(vcpu))
> + hrtimer_cancel(&vcpu->arch.swtimer);
>
> /*
> * From LoongArch Reference Manual Volume 1 Chapter 7.6.2
> @@ -168,26 +169,19 @@ static void _kvm_save_timer(struct kvm_vcpu *vcpu)
> * Here judge one-shot timer fired by checking whether TVAL is larger
> * than TCFG
> */
> - if (ticks < cfg) {
> + if (ticks < cfg)
> delta = tick_to_ns(vcpu, ticks);
> - expire = ktime_add_ns(ktime_get(), delta);
> - vcpu->arch.expire = expire;
> + else
> + delta = 0;
> + expire = ktime_add_ns(ktime_get(), delta);
> + vcpu->arch.expire = expire;
> + if (kvm_vcpu_is_blocking(vcpu)) {
>
> /*
> * HRTIMER_MODE_PINNED is suggested since vcpu may run in
> * the same physical cpu in next time
> */
> hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED);
> - } else if (vcpu->stat.generic.blocking) {
> - /*
> - * Inject timer interrupt so that halt polling can dectect and exit.
> - * VCPU is scheduled out already and sleeps in rcuwait queue and
> - * will not poll pending events again. kvm_queue_irq() is not enough,
> - * hrtimer swtimer should be used here.
> - */
> - expire = ktime_add_ns(ktime_get(), 10);
> - vcpu->arch.expire = expire;
> - hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED);
> }
> }
>
> --
> 2.39.3
>
