x86emul: suppress general register update upon AVX gather failures

While destination and mask registers may indeed need updating in this
case, the rIP update in particular needs to be avoided, as well as e.g.
raising a single step trap.

Reported-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 74f299bbd7d5cc52325b5866c17b44dd0bd1c5a2
master date: 2019-04-03 10:14:32 +0200

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index e3b7e8c396b25f4bc9db074bbff8393e06eac005..651194a683dcf7476af4da92dd3dd99a587af1af 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -8549,6 +8549,9 @@ x86_emulate(
         invoke_stub("", "", "+m" (mask) : "a" (&mask));
         put_stub(stub);
 
+        if ( rc != X86EMUL_OKAY )
+            goto done;
+
         state->simd_size = simd_none;
         break;
     }