linux-kernel - Re: [PATCH] KVM: X86: Add missing KVM

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Date:   Mon, 8 Oct 2018 14:52:46 +0000
From:   "Singh, Brijesh" <brijesh.singh@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Guenter Roeck <linux@...ck-us.net>
CC:     "Singh, Brijesh" <brijesh.singh@....com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH] KVM: X86: Add missing KVM_AMD dependency



On 10/08/2018 06:27 AM, Paolo Bonzini wrote:
> On 06/10/2018 22:43, Guenter Roeck wrote:
>>>
>>>>> Maybe this works as well?  I haven't tested it yet:
>>>>>
>>>> I am sure there are many possible solutions. I would personally
>>>> prefer one
>>>> that enforces KVM_AMD=m with CRYPTO_DEV_CCP_DD=m, but that is just me.
>>>
>>> Well, KVM_AMD=y is a relatively unusual choice to begin with.  The
>>
>> It is common enough that we are not the only ones affected. Also, even a
>> "relatively unusual choice" should, in my opinion, not result in a build
>> error.
> 
> Of course not!  The question is whether to solve it by disabling
> KVM_AMD_SEV (which is what the current code attempts to do, and my patch
> should fix that) or KVM_AMD (your patch).


IMHO, Paolo's patch make sense; it removes all the SEV specific code
when KVM_AMD_SEV=n. It saves ~4K in text section.

Paolo,

Does it make sense to move all the SEV specific code in svm-sev.c ?
I am looking to add SEV migration support very soon, and can see
myself adding more SEV command handling which will grow svm.c further.

-Brijesh