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 b1f3b568ab6f8e2893f06843b5fc5ad3ff936982..28e1248d2fc7011202489f16d8178cac84cc85de 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -7746,6 +7746,9 @@ x86_emulate(
         invoke_stub("", "", "+m" (mask) : "a" (&mask));
         put_stub(stub);
 
+        if ( rc != X86EMUL_OKAY )
+            goto done;
+
         state->simd_size = simd_none;
         break;
     }