[PATCH] paravirt: fix missing pte update

The function ptep_get_and_clear uses an atomic instruction sequence to get and
clear an active pte.  Rather than add such an atomic operator to all virtual
machine implementations in paravirt-ops, it is easier to support the raw
atomic sequence and use either a trapping writable pagetable approach, or a
post-update notification.  For the post update notification, we require the
pte_update function to be called after the access.  Combine the 2-level and
3-level paging operators into one common function which does the post-update
notification, and rename the actual atomic sequences to raw_ptep_xxx
operators.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>