[Xen-devel] [PATCH] Make get_page_from_l1e refcount correctly on foreign pagetables.

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hypercalls from dom0 can end up doing resyncs on HVM guests' out-of-sync
shadow pagetables.  At that point the check against current->domain in 
get_page_from_l1e() triggers the typecount exemption for foreign mappings
and a writeable typecount gets lost. 

Make the foreign-domain check explicit by having get_page_from_l1e_for(),
which understands both the dom whose right are being used and the dom
whose pagetables are being updated.  Most callers of get_page_from_l1e() 
have both the same (instead of one hard-coded to current->domain as before).

Analysis and fix from David Lively.

Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>

Attachment: get-page-from-l1e-refcounts
Description: Text document

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