Patch "KVM: s390: sthyi: fix sthyi inline assembly" has been added to the 4.9-stable tree

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

KVM: s390: sthyi: fix sthyi inline assembly

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:
kvm-s390-sthyi-fix-sthyi-inline-assembly.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 <[email protected]> know about it.

From: Heiko Carstens <[email protected]>
Date: Thu, 3 Aug 2017 13:05:11 +0200
Subject: KVM: s390: sthyi: fix sthyi inline assembly

From: Heiko Carstens <[email protected]>

commit 4a4eefcd0e49f9f339933324c1bde431186a0a7d upstream.

The sthyi inline assembly misses register r3 within the clobber list. The sthyi instruction will always write a return code to register "R2+1", which in this case would be r3. Due to that we may have register corruption and see host crashes or data corruption depending on how gcc decided to allocate and use registers during compile time.

---
 arch/s390/kvm/sthyi.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -394,7 +394,7 @@ static int sthyi(u64 vaddr)
 		"srl     %[cc],28\n"
 		: [cc] "=d" (cc)
 		: [code] "d" (code), [addr] "a" (addr)
-		: "memory", "cc");
+		: "3", "memory", "cc");
 	return cc;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/kvm-s390-sthyi-fix-specification-exception-detection.patch queue-4.9/kvm-s390-sthyi-fix-sthyi-inline-assembly.patch