[Xen-changelog] [xen-unstable] x86_emulate: BT instruction does not write to its 'destination' operand.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1208856424 -3600
# Node ID d9a74b8e9b1a345cc3d82efb837014e5658522c2
# Parent  da261c25f160ae3cddea1a4e5d1b045cceb7e03b
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@xxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c |    1 +
 1 files changed, 1 insertion(+)

diff -r da261c25f160 -r d9a74b8e9b1a xen/arch/x86/x86_emulate/x86_emulate.c
--- a/xen/arch/x86/x86_emulate/x86_emulate.c    Tue Apr 22 10:20:05 2008 +0100
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c    Tue Apr 22 10:27:04 2008 +0100
@@ -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 */

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