tree 51b3b999b061f20b92cbd8b8eb8bf1695fb35838
parent 64c98e7f49100b637cd20a6c63508caed6bbba7a
author David Vrabel <david.vrabel@citrix.com> 1441642448 +0100
committer David Vrabel <david.vrabel@citrix.com> 1444136060 +0100

x86/xen/p2m: hint at the last populated P2M entry

With commit 633d6f17cd91ad5bf2370265946f716e42d388c6 (x86/xen: prepare
p2m list for memory hotplug) the P2M may be sized to accomdate a much
larger amount of memory than the domain currently has.

When saving a domain, the toolstack must scan all the P2M looking for
populated pages.  This results in a performance regression due to the
unnecessary scanning.

Instead of reporting (via shared_info) the maximum possible size of
the P2M, hint at the last PFN which might be populated.  This hint is
increased as new leaves are added to the P2M (in the expectation that
they will be used for populated entries).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: <stable@vger.kernel.org> # 4.0+