From: Keir Fraser <keir.fraser@citrix.com>
Date: Tue, 22 Apr 2008 09:27:04 +0000 (+0100)
Subject: x86_emulate: BT instruction does not write to its 'destination' operand.
X-Git-Tag: 3.3.0-rc1~240^2~27
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=4195aba99fe3de6d3288e3d886ad268e71706657;p=xen.git

x86_emulate: BT instruction does not write to its 'destination' operand.

This fixes w2k3 guests occasionally writing back to read-only registers.

Signed-off-by: Xu Dongxiao <dongxiao.xu@intel.com>
---

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index b9bc790af1..2b7ddeffbb 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3041,6 +3041,7 @@ x86_emulate(
 
     case 0xa3: bt: /* bt */
         emulate_2op_SrcV_nobyte("bt", src, dst, _regs.eflags);
+        dst.type = OP_NONE;
         break;
 
     case 0xa4: /* shld imm8,r,r/m */