[PATCH] x86-64: x86_64 add NX mask for PTE entry

    If function change_page_attr_addr calls revert_page to revert
to original pte value, mk_pte_phys does not mask NX bit. If NX bit
is set on no NX hardware supported x86_64 machine, there is will
be RSVD type page fault and system will crash. This patch adds NX
mask bit for PTE entry.

Signed-off-by: bibo,mao <bibo.mao@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>