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[Xen-devel] Re: XEN monitor/mwait patch for AMD SVM

To: "Boppuri, Navin" <Navin.Boppuri@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: XEN monitor/mwait patch for AMD SVM
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 22 May 2009 17:39:53 +0100
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On 22/05/2009 16:23, "Boppuri, Navin" <Navin.Boppuri@xxxxxxx> wrote:

> This patch clears the monitor/mwait bit in the cpuid intercept code for AMD¹s
> SVM. This is to disallow VM¹s that may try and use the monitor/mwait feature
> on AMD processors which is currently not supported in XEN.
>  
> Signed-off-by: Navin Boppuri <navin.boppuri@xxxxxxx>

What Xen version is this patch against? We already hide MWAIT from HVM
guests as far as I am aware. See
tools/libxc/xc_cpuid_x86.c:xc_cpuid_hvm_policy(), and note that features are
*whitelisted* and also that MWAIT is *not* mentioned.

So I think your patch is not needed, and also inappropriate since we
implement CPUID filtering policy in libxc these days.

 -- Keir



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