linux-kernel - Re: [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC

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Message-ID: <56E68955.5060401@amd.com>
Date:	Mon, 14 Mar 2016 16:50:13 +0700
From:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	Radim Krčmář <rkrcmar@...hat.com>
CC:	<joro@...tes.org>, <bp@...en8.de>, <gleb@...nel.org>,
	<alex.williamson@...hat.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <wei@...hat.com>,
	<sherry.hurwitz@....com>
Subject: Re: [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC

Hi,

On 03/09/2016 06:10 PM, Paolo Bonzini wrote:
>>>> +
>>>> >>>+	if (vcpu->mode == IN_GUEST_MODE) {
>>>> >>>+		wrmsrl(SVM_AVIC_DOORBELL,
>>>> >>>+		       __default_cpu_present_to_apicid(vcpu->cpu));
>>>> >>>+	} else {
>>>> >>>+		kvm_vcpu_kick(vcpu);
>>>> >>>+	}
 >> >
>> >And what about
>> >   [...]
>> >   else if (!vcpu->...->is_running)
>> >   	kvm_vcpu_kick(vcpu);
>> >
>> >?
>> >The kick isn't needed unless the VCPU is scheduled out.
>> >Or maybe just
>> >   if (vcpu->...->is_running)
>> >     wrmsrl()
>> >   else
>> >     kvm_vcpu_kick();
>> >?
>> >Which doesn't use the information we have on top AVIC, making our logic
>> >a bit simpler.
> Yes, both of this should work.  I like the latter.

Ok, I'll modify this to check the is_running bit of the AVIC Physical 
APIC ID table entry to determine if we should kick vcpu.

Thanks,
Suravee