[PATCH v4 17/22] qapi: introduce x-query-cmma QMP command

["Daniel P. Berrangé" <berrange@redhat.com>]

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.

This command is unable to use the pre-existing HumanReadableText,
because if 'common.json' is included into 'machine-target.json'
the static marshalling method for HumanReadableText will be reported
as unused by the compiler on all architectures except s390x.

Possible options were

 1 Support 'if' conditionals on 'include' statements in QAPI
 2 Add further commands to 'machine-target.json' that use
   HumanReadableText, such that it has at least one usage
   on all architecture targets.
 3 Duplicate HumanReadableText as TargetHumanReadableText
   adding conditions

This patch takes option (3) in the belief that we will eventually
get to a point where option (2) happens, and TargetHumanReadableText
can be removed again.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 hw/s390x/s390-stattrib.c | 56 +++++++++++++++++++++++++++-------------
 qapi/machine-target.json | 14 ++++++++++
 2 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/hw/s390x/s390-stattrib.c b/hw/s390x/s390-stattrib.c
index 9eda1c3b2a..d8f5867a5f 100644
--- a/hw/s390x/s390-stattrib.c
+++ b/hw/s390x/s390-stattrib.c
@@ -17,6 +17,8 @@
 #include "qemu/error-report.h"
 #include "exec/ram_addr.h"
 #include "qapi/error.h"
+#include "qapi/qapi-commands-machine-target.h"
+#include "qapi/type-helpers.h"
 #include "qapi/qmp/qdict.h"
 
 /* 512KiB cover 2GB of guest memory */
@@ -67,41 +69,59 @@ void hmp_migrationmode(Monitor *mon, const QDict *qdict)
     }
 }
 
-void hmp_info_cmma(Monitor *mon, const QDict *qdict)
+HumanReadableText *qmp_x_query_cmma(int64_t addr,
+                                    bool has_count,
+                                    int64_t count,
+                                    Error **errp)
 {
+    g_autoptr(GString) buf = g_string_new("");
     S390StAttribState *sas = s390_get_stattrib_device();
     S390StAttribClass *sac = S390_STATTRIB_GET_CLASS(sas);
-    uint64_t addr = qdict_get_int(qdict, "addr");
-    uint64_t buflen = qdict_get_try_int(qdict, "count", 8);
-    uint8_t *vals;
+    g_autofree uint8_t *vals = NULL;
     int cx, len;
 
-    vals = g_try_malloc(buflen);
+    vals = g_try_malloc(count);
     if (!vals) {
-        monitor_printf(mon, "Error: %s\n", strerror(errno));
-        return;
+        error_setg_errno(errp, errno, "cannot allocate CMMA attribute values");
+        return NULL;
     }
 
-    len = sac->peek_stattr(sas, addr / TARGET_PAGE_SIZE, buflen, vals);
+    len = sac->peek_stattr(sas, addr / TARGET_PAGE_SIZE, count, vals);
     if (len < 0) {
-        monitor_printf(mon, "Error: %s", strerror(-len));
-        goto out;
+        error_setg_errno(errp, -len, "cannot peek at CMMA attribute values");
+        return NULL;
     }
 
-    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_printf(buf, "\n");
+
+    return human_readable_text_from_str(buf);
+}
+
+void hmp_info_cmma(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+    g_autoptr(HumanReadableText) info = NULL;
+    uint64_t addr = qdict_get_int(qdict, "addr");
+    uint64_t count = qdict_get_try_int(qdict, "count", 8);
+
+    info = qmp_x_query_cmma(addr, true, count, &err);
+    if (err) {
+        error_report_err(err);
+        return;
+    }
 
-out:
-    g_free(vals);
+    monitor_printf(mon, "%s", info->human_readable_text);
 }
 
 /* Migration support: */
diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 7d4e73462f..19e44987af 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -345,6 +345,20 @@
                    'TARGET_MIPS' ] } }
 
 
+##
+# @x-query-cmma:
+#
+# Query the values of the CMMA storage attributes for a range of pages
+#
+# Returns: CMMA storage attribute values
+#
+# Since: 6.2
+##
+{ 'command': 'x-query-cmma',
+  'data': { 'addr': 'int', '*count': 'int' },
+  'returns': 'HumanReadableText',
+  'if': 'TARGET_S390X' }
+
 ##
 # @x-query-skeys:
 #
-- 
2.31.1