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>
xen-unstable changeset:   17492:d9a74b8e9b1a345cc3d82efb837014e5658522c2
xen-unstable date:        Tue Apr 22 10:27:04 2008 +0100

diff --git a/xen/arch/x86/x86_emulate.c b/xen/arch/x86/x86_emulate.c
index 61645bf827e22cc33fe55c35a10da6cde8eb8ce8..a7870eca2dcc6ba935beb7721ccd43adceeed65e 100644 (file)
--- a/xen/arch/x86/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate.c
@@ -2154,6 +2154,7 @@ x86_emulate(
 
     case 0xa3: bt: /* bt */
         emulate_2op_SrcV_nobyte("bt", src, dst, _regs.eflags);
+        dst.type = OP_NONE;
         break;
 
     case 0xb3: btr: /* btr */