linux-kernel - Re: [PATCH] x86, AMD: Correct F15h IC aliasing issue

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Message-ID: <4E2F0498.8050005@zytor.com>
Date:	Tue, 26 Jul 2011 11:16:56 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...64.org>
CC:	Avi Kivity <avi@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	"Przywara, Andre" <Andre.Przywara@....com>,
	"Pohlack, Martin" <Martin.Pohlack@....com>
Subject: Re: [PATCH] x86, AMD: Correct F15h IC aliasing issue

On 07/26/2011 11:13 AM, Borislav Petkov wrote:
> Hi Avi,
> 
> On Tue, Jul 26, 2011 at 01:59:04PM -0400, Avi Kivity wrote:
>>> This change leaves virtual region address allocation on other families
>>> and/or vendors unaffected.
>>>
>>
>> Is it possible to derive the bit positions (and the need to mask them) 
>> from the cpuid description of the cache topology and sizes?
> 
> As far as I understand your question, there's no need for deriving the
> bit positions because they're not special. You just have to have bits
> [14:12] the same across all processes - we simply opted for clearing
> them in order to keep the patch as simple as possible. But we could just
> as well hashed the library name and generated the bits from it and thus
> keep them same per library (we have that version too, btw. :)).
> 
> FWIW, in both cases, the patch should fix even the virtualization
> scenario with and without KSM.
> 
> Does that answer your question?
> 

I think the question was the width (and position) for the mask... i.e.
your [14:12] above which *is* magic.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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