Re: [PATCH 8/9] xen/arch/x86: use is_hardware_domain instead of domid == 0

Andrew Cooper
Fri, 12 Apr 2013 16:50:24 -0000

On 12/04/13 17:48, Andrew Cooper wrote:
> On 12/04/13 16:49, Ian Campbell wrote:
>> On Fri, 2013-04-12 at 16:41 +0100, Keir Fraser wrote:
>>> We could get rid of this not-always-faulting-cpuid hack in the
>>> hypervisor altogether, if we could provide a paravirtualised
interface
>>> that guarantees access to the real CPUID space, for the toolstack
to
>>> use.
>> Doesn''t XCP have a patch which allows access to the
non-levelled cpuid
>> values for the toolstacks benefit? Andy C CCd...
>>
>>
> XCP/XenServer has a specific patch which records the real CPUID values
> before applying the MSRs for feature masking, which can then subsequently
queried by the toolstack.

(Apologies - I sent mid-sentence)

~Andrew

>
> This allows the toolstack to recalculate the host level parity bits
> correctly whenever a host is added or removed from the pool, without
> suffering the problems of getting into a diminishing subset of features
> as slightly heterogeneous hardware is moved in and out of the pool.
>
> The patch is currently in the state of "Needing to be cleaned up for
> upstream" and is in my todo list (albeit quite far down given some
> recent Xen crashes found during stress testing)
>
> I can up its priority if there is a need for it.
>
> ~Andrew
>
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