linux-kernel - Re: [PATCH] KVM: SVM: compile out AVIC if !CONFIG_X86_LOCAL

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Message-ID: <573935ff-2310-b64f-d3c9-260a89de6752@amd.com>
Date:	Tue, 14 Jun 2016 13:20:30 -0500
From:	Suravee Suthikulanit <suravee.suthikulpanit@....com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC:	<rkrcmar@...hat.com>
Subject: Re: [PATCH] KVM: SVM: compile out AVIC if !CONFIG_X86_LOCAL_APIC

Hi Paolo,

On 6/14/2016 11:40 AM, Paolo Bonzini wrote:
> AVIC needs __default_cpu_present_to_apicid.  Stub out all functions
> that use it, and disable the module parameter, if Linux is
> compiled without local APIC support.

I think you are right that we should disable AVIC #ifndef 
CONFIG_X86_LOCAL_APIC. However, do you think we should just use 
default_cpu_present_to_apicid() instead of the 
__default_cpu_present_to_apicid()?  This way, we can avoid having #ifdef 
CONFIG_X86_LOCAL_APIC in multiple places.

As for disabling AVIC, I think we can also do:

     if (!IS_ENABLED(CONFIG_X86_LOCAL_APIC))
         avic = false;

What do you think?

Thanks,
Suravee