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SubjectRe: [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire
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On 31/07/19 13:27, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> kvm_set_pending_timer() will take care to wake up the sleeping vCPU which
> has pending timer, don't need to check this in apic_timer_expired() again.

No, it doesn't. kvm_make_request never kicks the vCPU.

Paolo

> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/lapic.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 0aa1586..685d17c 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1548,7 +1548,6 @@ static void kvm_apic_inject_pending_timer_irqs(struct kvm_lapic *apic)
> static void apic_timer_expired(struct kvm_lapic *apic)
> {
> struct kvm_vcpu *vcpu = apic->vcpu;
> - struct swait_queue_head *q = &vcpu->wq;
> struct kvm_timer *ktimer = &apic->lapic_timer;
>
> if (atomic_read(&apic->lapic_timer.pending))
> @@ -1566,13 +1565,6 @@ static void apic_timer_expired(struct kvm_lapic *apic)
>
> atomic_inc(&apic->lapic_timer.pending);
> kvm_set_pending_timer(vcpu);
> -
> - /*
> - * For x86, the atomic_inc() is serialized, thus
> - * using swait_active() is safe.
> - */
> - if (swait_active(q))
> - swake_up_one(q);
> }
>
> static void start_sw_tscdeadline(struct kvm_lapic *apic)
>

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