All of lore.kernel.org
 help / color / mirror / Atom feed
From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire
Date: Wed, 31 Jul 2019 14:56:57 +0200	[thread overview]
Message-ID: <ab8f8b07-e3f9-4831-c386-0bfa0314f9c3@redhat.com> (raw)
In-Reply-To: <1564572438-15518-1-git-send-email-wanpengli@tencent.com>

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)
> 


  parent reply	other threads:[~2019-07-31 12:57 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-31 11:27 [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire Wanpeng Li
2019-07-31 11:27 ` [PATCH 2/3] KVM: Check preempted_in_kernel for involuntary preemption Wanpeng Li
2019-07-31 11:27 ` [PATCH 3/3] KVM: Fix leak vCPU's VMCS value into other pCPU Wanpeng Li
2019-07-31 11:39   ` [PATCH v2 " Wanpeng Li
2019-07-31 12:55     ` Paolo Bonzini
2019-08-01  3:35       ` Wanpeng Li
2019-07-31 12:56 ` Paolo Bonzini [this message]
2019-07-31 13:14   ` [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire Vitaly Kuznetsov
2019-07-31 16:39     ` Paolo Bonzini

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=ab8f8b07-e3f9-4831-c386-0bfa0314f9c3@redhat.com \
    --to=pbonzini@redhat.com \
    --cc=kernellwp@gmail.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rkrcmar@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.