linux-kernel - Re: [PATCH 2/2] cpu: intel, amd: mask cleared cpuid features

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Message-ID: <f743f40a-ca5a-42aa-8086-4d7d2224cf95@email.android.com>
Date:	Wed, 25 Jul 2012 07:13:46 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vladimir Davydov <vdavydov@...allels.com>
CC:	Borislav Petkov <bp@...64.org>,
	Andre Przywara <andre.przywara@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Borislav Petkov <borislav.petkov@....com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: [PATCH 2/2] cpu: intel, amd: mask cleared cpuid features

With the necessary infrastructure, yes.  Trap and emulate is montrivial work.

Vladimir Davydov <vdavydov@...allels.com> wrote:

>On 07/25/2012 04:57 AM, H. Peter Anvin wrote:
>> On 07/24/2012 04:09 AM, Vladimir Davydov wrote:
>>> We have not encountered this situation in our environments and I
>hope we
>>> won't :-)
>>>
>>> But look, these CPUID functions cover majority of CPU features,
>don't
>>> they? So, most of "normal" apps inside VM will survive migration.
>>> Perhaps, some low-level utils won't. I guess that's why there are no
>>> MSRs for other levels provided by vendors.
>>>
>> You will once Ivy Bridge becomes common.
>
>Ivy Bridge has CPUID faulting, which allows masking all CPUID 
>levels/functions.
>
>> 	-hpa
>>

-- 
Sent from my mobile phone. Please excuse brevity and lack of formatting.
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