diff --git a/monitor.c b/monitor.c
index aa641de..e0a4b67 100644
--- a/monitor.c
+++ b/monitor.c
@@ -801,9 +801,24 @@ static int get_str(char *buf, int buf_size, const char **pp)
 
 #define MAX_ARGS 16
 
-/* NOTE: this parser is an approximate form of the real command parser */
+/*
+ * Parse the command line to get valid args.
+ * @cmdline: command line to be parsed.
+ * @pnb_args: location to store the number of args, must NOT be NULL.
+ * @args: location to store the args, which should be freed by caller, must
+ *        NOT be NULL.
+ * @args_cmdline: location to store char position in @cmdline correspond to
+ *                @args include '\0', can be NULL.
+ *
+ * For example, if @cmdline = " ab" and @args_cmdline != NULL, result will be:
+ * pnb_args = 1, args[0] = "ab", args_cmdline[0] = "ab",
+ * args_cmdline[1] = "\0".
+ *
+ * NOTE: this parser is an approximate form of the real command parser. Number
+ *       of args have a limit of MAX_ARGS.
+ */
 static void parse_cmdline(const char *cmdline,
-                         int *pnb_args, char **args)
+                         int *pnb_args, char **args, const char **args_cmdline)
 {
     const char *p;
     int nb_args, ret;
@@ -811,14 +826,14 @@ static void parse_cmdline(const char *cmdline,
 
     p = cmdline;
     nb_args = 0;
-    for (;;) {
+    while (nb_args < MAX_ARGS) {
         while (qemu_isspace(*p)) {
             p++;
         }
-        if (*p == '\0') {
-            break;
+        if (args_cmdline) {
+            args_cmdline[nb_args] = p;
         }
-        if (nb_args >= MAX_ARGS) {
+        if (*p == '\0') {
             break;
         }
         ret = get_str(buf, sizeof(buf), &p);
@@ -888,7 +903,7 @@ static void help_cmd(Monitor *mon, const char *name)
             return;
         }
 
-        parse_cmdline(name, &nb_args, args);
+        parse_cmdline(name, &nb_args, args, NULL);
         if (nb_args >= MAX_ARGS) {
             goto cleanup;
         }
@@ -4179,17 +4194,18 @@ static const char *next_arg_type(const char *typestr)
     return (p != NULL ? ++p : typestr);
 }
 
-static void monitor_find_completion(Monitor *mon,
-                                    const char *cmdline)
+static void monitor_find_completion_by_table(Monitor *mon,
+                                             const mon_cmd_t *cmd_table,
+                                             const char *cmdline)
 {
-    const char *cmdname;
+    const char *cmdname, *args_cmdline[MAX_ARGS];
     char *args[MAX_ARGS];
     int nb_args, i, len;
     const char *ptype, *str;
     const mon_cmd_t *cmd;
     MonitorBlockComplete mbs;
 
-    parse_cmdline(cmdline, &nb_args, args);
+    parse_cmdline(cmdline, &nb_args, args, args_cmdline);
 #ifdef DEBUG_COMPLETION
     for(i = 0; i < nb_args; i++) {
         monitor_printf(mon, "arg%d = '%s'\n", i, (char *)args[i]);
@@ -4212,12 +4228,12 @@ static void monitor_find_completion(Monitor *mon,
         else
             cmdname = args[0];
         readline_set_completion_index(mon->rs, strlen(cmdname));
-        for (cmd = mon->cmd_table; cmd->name != NULL; cmd++) {
+        for (cmd = cmd_table; cmd->name != NULL; cmd++) {
             cmd_completion(mon, cmdname, cmd->name);
         }
     } else {
         /* find the command */
-        for (cmd = mon->cmd_table; cmd->name != NULL; cmd++) {
+        for (cmd = cmd_table; cmd->name != NULL; cmd++) {
             if (compare_cmd(args[0], cmd->name)) {
                 break;
             }
@@ -4226,6 +4242,12 @@ static void monitor_find_completion(Monitor *mon,
             goto cleanup;
         }
 
+        if (cmd->sub_table) {
+            monitor_find_completion_by_table(mon, cmd->sub_table,
+                                             args_cmdline[1]);
+            goto cleanup;
+        }
+
         ptype = next_arg_type(cmd->args_type);
         for(i = 0; i < nb_args - 2; i++) {
             if (*ptype != '\0') {
@@ -4252,13 +4274,7 @@ static void monitor_find_completion(Monitor *mon,
             bdrv_iterate(block_completion_it, &mbs);
             break;
         case 's':
-            /* XXX: more generic ? */
-            if (!strcmp(cmd->name, "info")) {
-                readline_set_completion_index(mon->rs, strlen(str));
-                for(cmd = info_cmds; cmd->name != NULL; cmd++) {
-                    cmd_completion(mon, str, cmd->name);
-                }
-            } else if (!strcmp(cmd->name, "sendkey")) {
+            if (!strcmp(cmd->name, "sendkey")) {
                 char *sep = strrchr(str, '-');
                 if (sep)
                     str = sep + 1;
@@ -4284,6 +4300,12 @@ cleanup:
     }
 }
 
+static void monitor_find_completion(Monitor *mon,
+                                    const char *cmdline)
+{
+    return monitor_find_completion_by_table(mon, mon->cmd_table, cmdline);
+}
+
 static int monitor_can_read(void *opaque)
 {
     Monitor *mon = opaque;
