Intel hosts, without long mode, and with nx support disabled in the bios
have an efer that is readable but not writable.  This causes a lockup on
switch to guest mode (even though it should exit with reason 34 according
to the documentation).
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>