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

["Boppuri, Navin" <Navin.Boppuri@xxxxxxx>]

Keir,

Sorry but the patch is against the latest tip of the xen unstable tree 
(changeset: 18646).

I understand that MWAIT is not mentioned in the whitelist for HVM policy. 
However, one could modify the guest config file and set the cpuid bit for 
monitor/mwait and enable this feature by force. I was able to do just this in 
my test configuration. This patch should cover such mods for cpuid in addition 
to the cpuid policy in libxc. 

Thank you.
-Navin

> -----Original Message-----
> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> Sent: Friday, May 22, 2009 11:40 AM
> To: Boppuri, Navin; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: XEN monitor/mwait patch for AMD SVM
> 
> 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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