Patch "kaiser: Set _PAGE_NX only if supported" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    kaiser: Set _PAGE_NX only if supported

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kaiser-set-_page_nx-only-if-supported.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ytht.net@gmail.com  Sat Jan 13 15:46:36 2018
From: Lepton Wu <ytht.net@gmail.com>
Date: Fri, 12 Jan 2018 13:42:56 -0800
Subject: kaiser: Set _PAGE_NX only if supported
To: stable@vger.kernel.org
Cc: gregkh@linuxfoundation.org, groeck@chromium.org, hshan@google.com, Lepton Wu <ytht.net@gmail.com>
Message-ID: <20180112214256.257463-1-ytht.net@gmail.com>

From: Lepton Wu <ytht.net@gmail.com>

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 <groeck@chromium.org>
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/mm/kaiser.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -197,6 +197,8 @@ static int kaiser_add_user_map(const voi
 	 * 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);


Patches currently in stable-queue which might be from ytht.net@gmail.com are

queue-4.9/kaiser-set-_page_nx-only-if-supported.patch