From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH] libxc: set CPUID topology leaf as unsupported
	for PV guests
Date: Thu, 14 Jul 2011 15:25:57 +0100
Message-ID: <4E1EFC75.6080500@citrix.com>
References: <CA44AE04.1DDBE%keir.xen@gmail.com>
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To: Keir Fraser <keir.xen@gmail.com>
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On 14/07/11 14:30, Keir Fraser wrote:
> On 14/07/2011 12:50, "David Vrabel" <david.vrabel@citrix.com> 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.

David