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.
At the same time CLAC/STAC have no need to explicitly check lock_prefix
- this is being taken care of by generic code.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4668,8 +4668,7 @@ x86_emulate(
case 0xca: /* clac */
case 0xcb: /* stac */
vcpu_must_have(smap);
- generate_exception_if(lock_prefix || vex.pfx || !mode_ring0(),
- EXC_UD);
+ generate_exception_if(vex.pfx || !mode_ring0(), EXC_UD);
_regs._eflags &= ~EFLG_AC;
if ( modrm == 0xcb )
@@ -5475,6 +5474,7 @@ x86_emulate(
break;
case X86EMUL_OPC(0x0f, 0xa3): bt: /* bt */
+ generate_exception_if(lock_prefix, EXC_UD);
emulate_2op_SrcV_nobyte("bt", src, dst, _regs._eflags);
dst.type = OP_NONE;
break;
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.
At the same time CLAC/STAC have no need to explicitly check lock_prefix
- this is being taken care of by generic code.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4668,8 +4668,7 @@ x86_emulate(
case 0xca: /* clac */
case 0xcb: /* stac */
vcpu_must_have(smap);
- generate_exception_if(lock_prefix || vex.pfx || !mode_ring0(),
- EXC_UD);
+ generate_exception_if(vex.pfx || !mode_ring0(), EXC_UD);
_regs._eflags &= ~EFLG_AC;
if ( modrm == 0xcb )
@@ -5475,6 +5474,7 @@ x86_emulate(
break;
case X86EMUL_OPC(0x0f, 0xa3): bt: /* bt */
+ generate_exception_if(lock_prefix, EXC_UD);
emulate_2op_SrcV_nobyte("bt", src, dst, _regs._eflags);
dst.type = OP_NONE;
break;
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