linux-kernel - Re: [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire

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Message-ID: <87imri73dp.fsf@vitty.brq.redhat.com>
Date:   Wed, 31 Jul 2019 15:14:10 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <kernellwp@...il.com>
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: Don't need to wakeup vCPU twice afer timer fire

Paolo Bonzini <pbonzini@...hat.com> writes:

> On 31/07/19 13:27, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@...cent.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.
>

Hm, but kvm_set_pending_timer() currently looks like:

void kvm_set_pending_timer(struct kvm_vcpu *vcpu)
{
	kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu);
	kvm_vcpu_kick(vcpu);
}

-- 
Vitaly