linux-kernel - Re: [PATCH v2 1/2] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch

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Message-ID: <CANRm+Cz0S7DwojGkGOuyygGnZb8xz1T-fOCjQm5pzf5tCadPvg@mail.gmail.com>
Date:   Thu, 19 May 2022 16:50:36 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v2 1/2] KVM: LAPIC: Disarm LAPIC timer includes pending
 timer around TSC deadline switch

ping,
On Wed, 11 May 2022 at 10:39, Wanpeng Li <kernellwp@...il.com> wrote:
>
> From: Wanpeng Li <wanpengli@...cent.com>
>
> The timer is disarmed when switching between TSC deadline and other modes,
> however, the pending timer is still in-flight, so let's accurately set
> everything to a disarmed state, this patch does it by clearing pending
> when canceling the timer.
>
> Fixes: 4427593258 (KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch)
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
> v1 -> v2:
>  * clear pending in cancel_apic_timer
>
>  arch/x86/kvm/lapic.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 66b0eb0bda94..6268880c8eed 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1548,6 +1548,7 @@ static void cancel_apic_timer(struct kvm_lapic *apic)
>         if (apic->lapic_timer.hv_timer_in_use)
>                 cancel_hv_timer(apic);
>         preempt_enable();
> +       atomic_set(&apic->lapic_timer.pending, 0);
>  }
>
>  static void apic_update_lvtt(struct kvm_lapic *apic)
> --
> 2.25.1
>