xen: mask _PAGE_PCD from ptes
authorJeremy Fitzhardinge <jeremy@goop.org>
Thu, 29 Nov 2007 00:21:20 +0000 (16:21 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 29 Nov 2007 17:24:52 +0000 (09:24 -0800)
commit2c80b01beae3db9f99a161ec216405dd694bc4c2
treeaea1b56634dad1467eca5a53a81b6a08d7b619b5
parentc06869d660ceffec7dc0fca19ed9646ed5845c7f
xen: mask _PAGE_PCD from ptes

_PAGE_PCD maps a page with caching disabled, which is typically used for
mapping harware registers.  Xen never allows it to be set on a mapping, and
unprivileged guests never need it since they can't see the real underlying
hardware.  However, some uncached mappings are made early when probing the
(non-existent) APIC, and its OK to mask off the PCD flag in these cases.

This became necessary because Xen started checking for this bit, rather
than silently masking it off.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/x86/xen/mmu.c