x86emul: LOCK check adjustments

BT, being encoded as DstBitBase just like BT{C,R,S}, nevertheless does
not write its (register or memory) operand and hence also doesn't allow
a LOCK prefix to be used.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: f2d4f4ba80de8a03a1b0f300d271715a88a8433d
master date: 2017-01-20 14:37:33 +0100

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 651506cdf86d6ac0651c2ae33c1228aa308f9050..8e9d36cacfc80436ab4bdc8c42d72568c1f47d91 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -5065,6 +5065,7 @@ x86_emulate(
     }
 
     case X86EMUL_OPC(0x0f, 0xa3): bt: /* bt */
+        generate_exception_if(lock_prefix, EXC_UD, 0);
         emulate_2op_SrcV_nobyte("bt", src, dst, _regs.eflags);
         dst.type = OP_NONE;
         break;