On Tue, Mar 25, 2025 at 01:13:50PM +0900, Suleiman Souhlal wrote:
> When the host resumes from a suspend, the guest thinks any task
> that was running during the suspend ran for a long time, even though
> the effective run time was much shorter, which can end up having
> negative effects with scheduling.
>
> [...]
>
> Signed-off-by: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Saw the corresponding host suspended time has been compensated in
update_rq_clock_task():
Tested-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
With 1 minor comment:
Reviewed-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
> @@ -917,8 +918,13 @@ struct kvm_vcpu_arch {
>
> struct {
> u8 preempted;
> + bool host_suspended;
Use it in bool manner.
> +static void wait_for_resume(struct kvm_vcpu *vcpu)
> +{
> + wait_event_interruptible(vcpu->arch.st.resume_waitq,
> + vcpu->arch.st.host_suspended == 0);
E.g.: !vcpu->arch.st.host_suspended.
> @@ -6939,6 +6954,19 @@ static int kvm_arch_suspend_notifier(struct kvm *kvm)
>
> mutex_lock(&kvm->lock);
> kvm_for_each_vcpu(i, vcpu, kvm) {
> + vcpu->arch.st.last_suspend = ktime_get_boottime_ns();
> + /*
> + * Tasks get thawed before the resume notifier has been called
> + * so we need to block vCPUs until the resume notifier has run.
> + * Otherwise, suspend steal time might get applied too late,
> + * and get accounted to the wrong guest task.
> + * This also ensures that the guest paused bit set below
> + * doesn't get checked and cleared before the host actually
> + * suspends.
> + */
> + vcpu->arch.st.host_suspended = 1;
E.g.: true.
> +static int kvm_arch_resume_notifier(struct kvm *kvm)
> +{
> + struct kvm_vcpu *vcpu;
> + unsigned long i;
> +
> + mutex_lock(&kvm->lock);
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + vcpu->arch.st.host_suspended = 0;
E.g.: false.
