From: Jan Beulich <jbeulich@suse.com>
Date: Thu, 19 May 2016 10:06:33 +0000 (+0200)
Subject: x86emul: suppress writeback upon unsuccessful MMX/SSE/AVX insn emulation
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~1105
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=2bb230972c5ddb1ca823f47750b5d46a9d302d0e;p=xen.git

x86emul: suppress writeback upon unsuccessful MMX/SSE/AVX insn emulation

This in particular prevents updating guest IP when handling the retry
needed to forward the memory access to qemu.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
---

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 621332bcbd..d7c6d90cd6 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4178,6 +4178,8 @@ x86_emulate(
         if ( !rc && (b & 1) && (ea.type == OP_MEM) )
             rc = ops->write(ea.mem.seg, ea.mem.off, mmvalp,
                             ea.bytes, ctxt);
+        if ( rc )
+            goto done;
         dst.type = OP_NONE;
         break;
     }
@@ -4430,6 +4432,8 @@ x86_emulate(
         if ( !rc && (b != 0x6f) && (ea.type == OP_MEM) )
             rc = ops->write(ea.mem.seg, ea.mem.off, mmvalp,
                             ea.bytes, ctxt);
+        if ( rc )
+            goto done;
         dst.type = OP_NONE;
         break;
     }