Re: [Xen-devel] [PATCH v2 0/3] VPMU fixes

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.12.15 at 11:46, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Thursday, December 03, 2015 6:36 PM
>> 
>> >>> On 03.12.15 at 07:16, <kevin.tian@xxxxxxxxx> wrote:
>> >>  From: Dietmar Hahn [mailto:dietmar.hahn@xxxxxxxxxxxxxx]
>> >> Sent: Wednesday, December 02, 2015 5:21 PM
>> >>
>> >> Am Mittwoch 02 Dezember 2015, 02:20:49 schrieb Tian, Kevin:
>> >> > > From: Boris Ostrovsky [mailto:boris.ostrovsky@xxxxxxxxxx]
>> >> > > Sent: Wednesday, December 02, 2015 12:50 AM
>> >> > >
>> >> > > * Limit VPMU support to PMU versions 2, 3 and 4 (emulated at version 
>> >> > > 3 
> level)
>> >> > > * Always implement family 6 VPMU quirk.
>> >> > >   ==>  Intel folks: is the quirk needed for all family 6 processors 
>> >> > > or can 
> we
>> >> > >                     limit it to certain models?
>> >> >
>> >> > Let me confirm this information internally. btw could you provide a link
>> >> > where you find out the original quirk information?
>> >>
>> >> http://old-list-archives.xenproject.org/xen-devel/2010-11/msg01157.html 
>> >> Dietmar.
>> >
>> > Looks there's no formal errata recorded from original thread. Since the
>> > patch sustains original behavior, I'm OK with this assumption.
>> 
>> Except that the Link Dietmar provided makes it even more
>> likely that this could be limited to certain models (since in that
>> original patch version it covered just two). See also the vague
>> statement in 75a92f551a ("Currently only a few Intel models
>> have VPMU workaround turned on. It").
> 
> Well, I'm not sure about the whole history. If you look at Boris's
> patch, the code already assumes quirk for all family 6 before his
> change. 

That's why I was referring you to the older patch (also by him),
which converted from a model specific workaround to a universal
one.

Jan


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