KVM: x86 emulator: do not munge rep prefix

Currently we store a rep prefix as 1 or 2 depending on whether it is a REPE or
REPNE.  Since sse instructions depend on the prefix value, store it as the
original opcode to simplify things further on.
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_emulate.h

@@ -249,8 +249,8 @@ struct x86_emulate_ctxt {
 };
 
 /* Repeat String Operation Prefix */
-#define REPE_PREFIX	1
-#define REPNE_PREFIX	2
+#define REPE_PREFIX	0xf3
+#define REPNE_PREFIX	0xf2
 
 /* Execution mode, passed to the emulator. */
 #define X86EMUL_MODE_REAL     0	/* Real mode.             */

arch/x86/kvm/emulate.c

@@ -2692,10 +2692,8 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
 			c->lock_prefix = 1;
 			break;
 		case 0xf2:	/* REPNE/REPNZ */
-			c->rep_prefix = REPNE_PREFIX;
-			break;
 		case 0xf3:	/* REP/REPE/REPZ */
-			c->rep_prefix = REPE_PREFIX;
+			c->rep_prefix = c->b;
 			break;
 		default:
 			goto done_prefixes;