RE: [Xen-ia64-devel] XEN_HYPER_ITC_D and XEN_HYPER_ITC_I in vhpt_miss

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Magenheimer, Dan (HP Labs Fort Collins)
>Sent: 2006年5月23日 22:40
>> > > > May it be that XEN_HYPER_ITC_D and XEN_HYPER_ITC_I are
>in
>> > >
>> > > the reverse
>> > >
>> > > > order?
>> > >
>> > > Good catch.
>> > >
>> > > Feel free to send a patch.
>> >
>> > Does this code ever get executed?  The VHPT is pinned by
>> > a TR, correct?
>
>Oops, Xen's VHPT is pinned, the guest's isn't pinned.
>
>> For sure it is strange we never hit this bug ;-)
>
>Yes, it looks like the faulty code should get executed.
>Maybe it quickly
>fixes itself because the wrong vtlb gets inserted,
>then another miss immediately occurs which is not
>a VHPT fault so the correct vtlb gets inserted.

Definitely. The key point is that vhpt entry is inserted after above bogus 
place and then TLB miss immediately happens after resuming with 
hardware triggered to walk vhpt table by inserting desired mapping. 
Above two insertions are only optimization code which don't hurt 
anything even not being there.

>
>Anyway, yes, please submit a patch!
>
>Dan
>

Yes, patch is needed.

Thanks,
Kevin

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