3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Lepton Wu <[email protected]>

This finally resolve crash if loaded under qemu + haxm. Haitao Shan pointed
out that the reason of that crash is that NX bit get set for page tables.
It seems we missed checking if _PAGE_NX is supported in kaiser_add_user_map

Link: https://www.spinics.net/lists/kernel/msg2689835.html

Reviewed-by: Guenter Roeck <[email protected]>
Signed-off-by: Lepton Wu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(backported from Greg K-H's 4.4 stable-queue)
Signed-off-by: Juerg Haefliger <[email protected]>
Signed-off-by: Ben Hutchings <[email protected]>
---
 arch/x86/mm/kaiser.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c
index 2d5ac54dbcee..7cb57d14ddc0 100644
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -195,6 +195,8 @@ static int kaiser_add_user_map(const void *__start_addr, 
unsigned long size,
         * requires that not to be #defined to 0): so mask it off here.
         */
        flags &= ~_PAGE_GLOBAL;
+       if (!(__supported_pte_mask & _PAGE_NX))
+               flags &= ~_PAGE_NX;
 
        for (; address < end_addr; address += PAGE_SIZE) {
                target_address = get_pa_from_mapping(address);

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