xen: check EFER for NX before setting up GDT mapping
commitb75fe4e5b869f8dbebd36df64a7fcda0c5b318ed
authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Mon, 21 Sep 2009 20:34:06 +0000 (21 13:34 -0700)
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Mon, 21 Sep 2009 20:49:43 +0000 (21 13:49 -0700)
treecba533110e8514184ddc63ab2ea37c38dc8a1861
parent79b520e87e1214cfa107bdc8528b5d6c055a8b82
xen: check EFER for NX before setting up GDT mapping

x86-64 assumes NX is available by default, so we need to
explicitly check for it before using NX.  Some first-generation
Intel x86-64 processors didn't support NX, and even recent systems
allow it to be disabled in BIOS.

[ Impact: prevent Xen crash on NX-less 64-bit machines ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>
arch/x86/mm/Makefile
arch/x86/xen/enlighten.c