WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [PATCH] libxc: set CPUID topology leaf as unsupported fo

To: "David Vrabel" <david.vrabel@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] libxc: set CPUID topology leaf as unsupported for PV guests
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Fri, 15 Jul 2011 09:41:54 +0100
Cc: Keir Fraser <keir.xen@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Fri, 15 Jul 2011 01:42:41 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4E1EFC75.6080500@xxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <CA44AE04.1DDBE%keir.xen@xxxxxxxxx> <4E1EFC75.6080500@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>>> On 14.07.11 at 16:25, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
> On 14/07/11 14:30, Keir Fraser wrote:
>> On 14/07/2011 12:50, "David Vrabel" <david.vrabel@xxxxxxxxxx> wrote:
>> 
>>> libxc: set CPUID topology leaf as unsupported for PV guests
>>>
>>> The result of a CPUID Extended Topology Enumeration leaf for PV guests
>>> is invalid as the level in ECX is ignored.  This can cause some guests
>>> to loop endlessly when trying to enumerate the topology.
>>>
>>> Since the physical topology isn't useful to PV guests set the topology
>>> leaf as unsupported.
>> 
>> For future reference, you also need to modify
>> xen/arch/x86/traps.c:pv_cpuid(), for dom0.
> 
> Looking at the code it looks like dom0 would at least see valid data for
> the the topology leaf.  But I guess the info makes no sense to dom0 as
> well as domU guests.  Patch sent if you've not already fixed it up.

It may make limited sense to Dom0 if "dom0_vcpus_pin" is in effect.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel