linux-kernel - Re: [PATCH] x86/amd: fix crash as Xen Dom0 on AMD Trinity systems

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Date:	Wed, 30 May 2012 07:58:23 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...en8.de>,
	Andre Przywara <andre.przywara@....com>, mingo@...e.hu,
	tglx@...utronix.de, konrad.wilk@...cle.com, jeremy@...p.org,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	stable@...r.kernel.org.#.3.4+
Subject: Re: [PATCH] x86/amd: fix crash as Xen Dom0 on AMD Trinity systems

On 05/30/2012 07:55 AM, Borislav Petkov wrote:
> On Wed, May 30, 2012 at 07:42:27AM -0700, H. Peter Anvin wrote:
>> On 05/30/2012 06:10 AM, Andre Przywara wrote:
>>> Because we are behind a family check before tweaking the topology
>>> bit, we can use the standard rd/wrmsr variants for the CPUID feature
>>> register.
>>
>> That is not what the *msr*_amd*() functions do.
>>
>> NAK.  This is a totally bogus patch.
> 
> The *msr*_amd*() variants were used instead of the normal *msrl_safe
> variants although the AMD variants weren't needed there at all.
> 
> This has no issue on baremetal but breaks xen and this is how we caught
> this.
> 
> So the patch corrects the original patch so that xen is happy too.
> 

If so, then fix the description to match reality and we can take the patch.

	-hpa

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