3 files changed, 53 insertions, 4 deletions

diff --git a/monitor/hmp.c b/monitor/hmp.c
index d50c3124e1..b20737e63c 100644
--- a/monitor/hmp.c
+++ b/monitor/hmp.c
@@ -26,6 +26,7 @@
 #include <dirent.h>
 #include "hw/qdev-core.h"
 #include "monitor-internal.h"
+#include "monitor/hmp.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qnum.h"
@@ -1061,6 +1062,31 @@ fail:
     return NULL;
 }
 
+static void hmp_info_human_readable_text(Monitor *mon,
+                                         HumanReadableText *(*handler)(Error **))
+{
+    Error *err = NULL;
+    g_autoptr(HumanReadableText) info = handler(&err);
+
+    if (hmp_handle_error(mon, err)) {
+        return;
+    }
+
+    monitor_printf(mon, "%s", info->human_readable_text);
+}
+
+static void handle_hmp_command_exec(Monitor *mon,
+                                    const HMPCommand *cmd,
+                                    QDict *qdict)
+{
+    if (cmd->cmd_info_hrt) {
+        hmp_info_human_readable_text(mon,
+                                     cmd->cmd_info_hrt);
+    } else {
+        cmd->cmd(mon, qdict);
+    }
+}
+
 typedef struct HandleHmpCommandCo {
     Monitor *mon;
     const HMPCommand *cmd;
@@ -1071,7 +1097,7 @@ typedef struct HandleHmpCommandCo {
 static void handle_hmp_command_co(void *opaque)
 {
     HandleHmpCommandCo *data = opaque;
-    data->cmd->cmd(data->mon, data->qdict);
+    handle_hmp_command_exec(data->mon, data->cmd, data->qdict);
     monitor_set_cur(qemu_coroutine_self(), NULL);
     data->done = true;
 }
@@ -1089,7 +1115,7 @@ void handle_hmp_command(MonitorHMP *mon, const char *cmdline)
         return;
     }
 
-    if (!cmd->cmd) {
+    if (!cmd->cmd && !cmd->cmd_info_hrt) {
         /* FIXME: is it useful to try autoload modules here ??? */
         monitor_printf(&mon->common, "Command \"%.*s\" is not available.\n",
                        (int)(cmdline - cmd_start), cmd_start);
@@ -1109,7 +1135,7 @@ void handle_hmp_command(MonitorHMP *mon, const char *cmdline)
     if (!cmd->coroutine) {
         /* old_mon is non-NULL when called from qmp_human_monitor_command() */
         Monitor *old_mon = monitor_set_cur(qemu_coroutine_self(), &mon->common);
-        cmd->cmd(&mon->common, qdict);
+        handle_hmp_command_exec(&mon->common, cmd, qdict);
         monitor_set_cur(qemu_coroutine_self(), old_mon);
     } else {
         HandleHmpCommandCo data = {
diff --git a/monitor/misc.c b/monitor/misc.c
index c2d227a07c..0e124044d0 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -1964,7 +1964,7 @@ void monitor_register_hmp(const char *name, bool info,
 
     while (table->name != NULL) {
         if (strcmp(table->name, name) == 0) {
-            g_assert(table->cmd == NULL);
+            g_assert(table->cmd == NULL && table->cmd_info_hrt == NULL);
             table->cmd = cmd;
             return;
         }
@@ -1973,6 +1973,22 @@ void monitor_register_hmp(const char *name, bool info,
     g_assert_not_reached();
 }
 
+void monitor_register_hmp_info_hrt(const char *name,
+                                   HumanReadableText *(*handler)(Error **errp))
+{
+    HMPCommand *table = hmp_info_cmds;
+
+    while (table->name != NULL) {
+        if (strcmp(table->name, name) == 0) {
+            g_assert(table->cmd == NULL && table->cmd_info_hrt == NULL);
+            table->cmd_info_hrt = handler;
+            return;
+        }
+        table++;
+    }
+    g_assert_not_reached();
+}
+
 void monitor_init_globals(void)
 {
     monitor_init_globals_core();
diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h
index 9c3a09cb01..3da3f86c6a 100644
--- a/monitor/monitor-internal.h
+++ b/monitor/monitor-internal.h
@@ -74,6 +74,13 @@ typedef struct HMPCommand {
     const char *help;
     const char *flags; /* p=preconfig */
     void (*cmd)(Monitor *mon, const QDict *qdict);
+    /*
+     * If implementing a command that takes no arguments and simply
+     * prints formatted data, then leave @cmd NULL, and then set
+     * @cmd_info_hrt to the corresponding QMP handler that returns
+     * the formatted text.
+     */
+    HumanReadableText *(*cmd_info_hrt)(Error **errp);
     bool coroutine;
     /*
      * @sub_table is a list of 2nd level of commands. If it does not exist,