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[Xen-devel] Re: [PATCH] xen: mask XSAVE in cpuid since we don't allow gu

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] xen: mask XSAVE in cpuid since we don't allow guests to use it
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Sun, 08 Mar 2009 09:13:16 +0000
Cc: Boris Derzhavets <bderzhavets@xxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Marc - A. Dahlhaus \[ Administration | Westermann GmbH \]" <mad@xxxxxx>
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On 08/03/2009 05:31, "Jeremy Fitzhardinge" <jeremy@xxxxxxxx> wrote:

> Mask X86_FEATURE_XSAVE in cpuid leaf 1, ecx, as we don't allow guests to
> use it (by setting cr4.OSXSAVE).
> 
> This prevents crashes in pvops dom0 kernels, as new versions of Linux try
> to use this feature.
> 
> (This patch deals with dom0 cpuid; I'm not sure where the right place to
> set up the default mask for domU is.)

Thanks, the whole problem stems from blacklisting rather than whitelisting
feature bits. I might try and do a more comprehensive job for xen-unstable
at least. This is good for 3.3.

 -- Keir



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