KVM: x86 emulator: Use opcode::execute for Group 9 instruction

Group 9: 0F C7

Rename em_grp9() to em_cmpxchg8b() and register it.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/emulate.c

@@ -1784,7 +1784,7 @@ static int em_grp45(struct x86_emulate_ctxt *ctxt)
 	return rc;
 }
 
-static int em_grp9(struct x86_emulate_ctxt *ctxt)
+static int em_cmpxchg8b(struct x86_emulate_ctxt *ctxt)
 {
 	u64 old = ctxt->dst.orig_val64;
 
@@ -3261,7 +3261,7 @@ static struct opcode group8[] = {
 };
 
 static struct group_dual group9 = { {
-	N, D(DstMem64 | ModRM | Lock | PageTable), N, N, N, N, N, N,
+	N, I(DstMem64 | ModRM | Lock | PageTable, em_cmpxchg8b), N, N, N, N, N, N,
 }, {
 	N, N, N, N, N, N, N, N,
 } };
@@ -4202,9 +4202,6 @@ twobyte_insn:
 		ctxt->dst.val = (ctxt->op_bytes == 4) ? (u32) ctxt->src.val :
 							(u64) ctxt->src.val;
 		break;
-	case 0xc7:		/* Grp9 (cmpxchg8b) */
-		rc = em_grp9(ctxt);
-		break;
 	default:
 		goto cannot_emulate;
 	}