Re: [Xen-devel] Re: Next steps with pv_ops for Xen

[Derek Murray <Derek.Murray@xxxxxxxxxxxx>]

Keir Fraser wrote:
> You'd need to track pte->grant_handle mappings somewhere, but it could
> certainly be done this way, yes.
At the moment, blktap and gntdev provide struct pages to get_user_pages 
by smuggling them in the vm_private_data field of the relevant 
vm_area_struct. Could we use this field to get the handles to 
ptep_get_and_clear_full as well?
Only downside that I can see is that we would need to find the vma for 
each PTE that needs to be cleared this way (since we don't get this 
passed to ptep_get_and_clear_full), but this is mitigated by (i) it only 
happening in the erroneous, unclean-shutdown case, and (ii) getting a 
hit in the mm->mmap_cache for consecutive runs of mapped grants.
Regards,

Derek.

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