RE: [Xen-ia64-devel] RE: Xen/ia64 - global or per VP VHPT

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

 >      The original design we shared with you has included 
> this. The VHPT miss will handle this. So don't worry for 
> this. If digging into much details of vMMU, an HV TLB/VHPT is 
> a must to support PMT (guest physical to machine physical). 
> (Oh, you may argu IA64 don't need PMT, if this is the case, 
> it deviates from X86 much more).

The current implementation does support guest physical to
machine physical translation.  But the translations are
put in the TLB and NOT into the VHPT.  If there is a TLB
miss on a guest physical address, resolving it is slow
(requiring a multi-level page table lookup),
but since physical addressing is used relatively infrequently
(and of course never used by applications), I suspect locality
is so low that putting guest physical addresses into the
VHPT won't help much.

Dan

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