4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiko Carstens <heiko.carstens@xxxxxxxxxx> 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. Fixes: 95ca2cb57985 ("KVM: s390: Add sthyi emulation") Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx> Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/kvm/sthyi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/s390/kvm/sthyi.c +++ b/arch/s390/kvm/sthyi.c @@ -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; }