This is a counterpart to the HMP "info cmma" command. It is being
added with an "x-" prefix because this QMP command is intended as an
adhoc debugging tool and will thus not be modelled in QAPI as fully
structured data, nor will it have long term guaranteed stability.
The existing HMP command is rewritten to call the QMP command.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 qapi/machine.json        | 20 ++++++++++++++++++++
 hw/s390x/s390-stattrib.c | 28 ++++++++++++++++++----------
 hmp-commands-info.hx     |  2 +-
 3 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/qapi/machine.json b/qapi/machine.json
index 6da72f2585..a56b7572b1 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -1905,3 +1905,23 @@
   'data': { 'json-args': 'str'},
   'returns': 'HumanReadableText',
   'features': [ 'unstable' ]}
+
+##
+# @x-query-s390x-cmma:
+#
+# Query information on s390x CMMA storage attributes
+#
+# @json-args: HMP arguments encoded as JSON string.
+#
+# Features:
+#
+# @unstable: This command is meant for debugging.
+#
+# Returns: s390x CMMA storage attributes information
+#
+# Since: 9.1
+##
+{ 'command': 'x-query-s390x-cmma',
+  'data': { 'json-args': 'str'},
+  'returns': 'HumanReadableText',
+  'features': [ 'unstable' ]}
diff --git a/hw/s390x/s390-stattrib.c b/hw/s390x/s390-stattrib.c
index 9b4b8d8d0c..8c2372bd71 100644
--- a/hw/s390x/s390-stattrib.c
+++ b/hw/s390x/s390-stattrib.c
@@ -19,6 +19,9 @@
 #include "exec/ram_addr.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
+#include "qapi/qapi-commands-machine.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/type-helpers.h"
 #include "monitor/hmp-target.h"
 #include "monitor/monitor.h"
 #include "cpu.h"
@@ -73,10 +76,12 @@ void hmp_migrationmode(Monitor *mon, const QDict *qdict)
     }
 }
 
-void hmp_info_cmma(Monitor *mon, const QDict *qdict)
+HumanReadableText *qmp_x_query_s390x_cmma(const char *json_args, Error **errp)
 {
+    g_autoptr(GString) buf = g_string_new("");
     S390StAttribState *sas = s390_get_stattrib_device();
     S390StAttribClass *sac = S390_STATTRIB_GET_CLASS(sas);
+    QDict *qdict = qobject_to(QDict, qobject_from_json(json_args, &error_abort));
     uint64_t addr = qdict_get_int(qdict, "addr");
     uint64_t buflen = qdict_get_try_int(qdict, "count", 8);
     uint8_t *vals;
@@ -84,30 +89,33 @@ void hmp_info_cmma(Monitor *mon, const QDict *qdict)
 
     vals = g_try_malloc(buflen);
     if (!vals) {
-        monitor_printf(mon, "Error: %s\n", strerror(errno));
-        return;
+        error_setg(errp, "Failed to allocate memory");
+        return NULL;
     }
 
     len = sac->peek_stattr(sas, addr / TARGET_PAGE_SIZE, buflen, vals);
     if (len < 0) {
-        monitor_printf(mon, "Error: %s", strerror(-len));
+        error_setg_errno(errp, -len, "Could not get attributes");
         goto out;
     }
 
-    monitor_printf(mon, "  CMMA attributes, "
-                   "pages %" PRIu64 "+%d (0x%" PRIx64 "):\n",
-                   addr / TARGET_PAGE_SIZE, len, addr & ~TARGET_PAGE_MASK);
+    g_string_append_printf(buf, "  CMMA attributes, "
+                           "pages %" PRIu64 "+%d (0x%" PRIx64 "):\n",
+                           addr / TARGET_PAGE_SIZE, len,
+                           addr & ~TARGET_PAGE_MASK);
     for (cx = 0; cx < len; cx++) {
         if (cx % 8 == 7) {
-            monitor_printf(mon, "%02x\n", vals[cx]);
+            g_string_append_printf(buf, "%02x\n", vals[cx]);
         } else {
-            monitor_printf(mon, "%02x", vals[cx]);
+            g_string_append_printf(buf, "%02x", vals[cx]);
         }
     }
-    monitor_printf(mon, "\n");
+    g_string_append_c(buf, '\n');
 
 out:
+    qobject_unref(qdict);
     g_free(vals);
+    return human_readable_text_from_str(buf);
 }
 
 /* Migration support: */
diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index cfd4ad5651..0a944e43ce 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -720,7 +720,7 @@ ERST
         .args_type  = "addr:l,count:l?",
         .params     = "address [count]",
         .help       = "Display the values of the CMMA storage attributes for a range of pages",
-        .cmd        = hmp_info_cmma,
+        .cmd_info_hrt = qmp_x_query_s390x_cmma,
     },
 #endif
 
-- 
2.41.0