KVM: Emulate multibyte NOP

This is encountered when booting RHEL5.9 64-bit.  There is another bug
after this one that is not a simple emulation failure, but this one lets
the boot proceed a bit.

Cc: <stable@vger.kernel.org> # 3.9
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

arch/x86/kvm/emulate.c

@@ -3997,7 +3997,8 @@ static const struct opcode twobyte_table[256] = {
 	DI(ImplicitOps | Priv, invd), DI(ImplicitOps | Priv, wbinvd), N, N,
 	N, D(ImplicitOps | ModRM), N, N,
 	/* 0x10 - 0x1F */
-	N, N, N, N, N, N, N, N, D(ImplicitOps | ModRM), N, N, N, N, N, N, N,
+	N, N, N, N, N, N, N, N,
+	D(ImplicitOps | ModRM), N, N, N, N, N, N, D(ImplicitOps | ModRM),
 	/* 0x20 - 0x2F */
 	DIP(ModRM | DstMem | Priv | Op3264, cr_read, check_cr_read),
 	DIP(ModRM | DstMem | Priv | Op3264, dr_read, check_dr_read),
@@ -4836,6 +4837,7 @@ twobyte_insn:
 	case 0x08:		/* invd */
 	case 0x0d:		/* GrpP (prefetch) */
 	case 0x18:		/* Grp16 (prefetch/nop) */
+	case 0x1f:		/* nop */
 		break;
 	case 0x20: /* mov cr, reg */
 		ctxt->dst.val = ops->get_cr(ctxt, ctxt->modrm_reg);