KVM: x86 emulator: fix byte-sized MOVZX/MOVSX

Commit 2adb5ad9 removed ByteOp from MOVZX/MOVSX, replacing them by
SrcMem8, but neglected to fix the dependency in the emulation code
on ByteOp.  This caused the instruction not to have any effect in
some circumstances.

Fix by replacing the check for ByteOp with the equivalent src.op_bytes == 1.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/emulate.c

@@ -4517,12 +4517,12 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 		break;
 	case 0xb6 ... 0xb7:	/* movzx */
 		ctxt->dst.bytes = ctxt->op_bytes;
-		ctxt->dst.val = (ctxt->d & ByteOp) ? (u8) ctxt->src.val
+		ctxt->dst.val = (ctxt->src.bytes == 1) ? (u8) ctxt->src.val
 						       : (u16) ctxt->src.val;
 		break;
 	case 0xbe ... 0xbf:	/* movsx */
 		ctxt->dst.bytes = ctxt->op_bytes;
-		ctxt->dst.val = (ctxt->d & ByteOp) ? (s8) ctxt->src.val :
+		ctxt->dst.val = (ctxt->src.bytes == 1) ? (s8) ctxt->src.val :
 							(s16) ctxt->src.val;
 		break;
 	case 0xc0 ... 0xc1:	/* xadd */