New QMP command query-cpu-max and HMP command cpu_max

These commands return the maximum number of CPUs supported by the
currently running emulator instance, as defined in its QEMUMachine
struct.

Signed-off-by: Michal Novotny <minovotn@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

hmp-commands.hx

@@ -1643,6 +1643,8 @@ show qdev device model list
 show roms
 @item info tpm
 show the TPM device
+@item info cpu_max
+show the number of CPUs supported by the machine being emulated.
 @end table
 ETEXI
 

hmp.c

@@ -748,6 +748,14 @@ void hmp_ringbuf_read(Monitor *mon, const QDict *qdict)
     g_free(data);
 }
 
+void hmp_query_cpu_max(Monitor *mon, const QDict *qdict)
+{
+    int cpu_max;
+
+    cpu_max = qmp_query_cpu_max(NULL);
+    monitor_printf(mon, "Maximum number of CPUs is %d\n", cpu_max);
+}
+
 static void hmp_cont_cb(void *opaque, int err)
 {
     if (!err) {

hmp.h

@@ -42,6 +42,7 @@ void hmp_stop(Monitor *mon, const QDict *qdict);
 void hmp_system_reset(Monitor *mon, const QDict *qdict);
 void hmp_system_powerdown(Monitor *mon, const QDict *qdict);
 void hmp_cpu(Monitor *mon, const QDict *qdict);
+void hmp_query_cpu_max(Monitor *mon, const QDict *qdict);
 void hmp_memsave(Monitor *mon, const QDict *qdict);
 void hmp_pmemsave(Monitor *mon, const QDict *qdict);
 void hmp_ringbuf_write(Monitor *mon, const QDict *qdict);

monitor.c

@@ -2745,6 +2745,13 @@ static mon_cmd_t info_cmds[] = {
         .help       = "show the TPM device",
         .mhandler.cmd = hmp_info_tpm,
     },
+    {
+        .name       = "cpu_max",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Get maximum number of VCPUs supported by machine",
+        .mhandler.cmd = hmp_query_cpu_max,
+    },
     {
         .name       = NULL,
     },

qapi-schema.json

@@ -1831,6 +1831,17 @@
 ##
 { 'command': 'query-migrate-cache-size', 'returns': 'int' }
 
+##
+## @query-cpu-max
+##
+## query maximum number of CPUs supported by machine
+##
+## Returns: number of CPUs
+##
+## Since: 1.5
+###
+{ 'command': 'query-cpu-max', 'returns': 'int' }
+
 ##
 # @ObjectPropertyInfo:
 #

qmp-commands.hx

@@ -382,6 +382,28 @@ Example:
 
 Note: CPUs' indexes are obtained with the 'query-cpus' command.
 
+EQMP
+
+    {
+        .name       = "query-cpu-max",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_query_cpu_max,
+    },
+
+SQMP
+query-cpu-max
+-------------
+
+Get the maximum CPUs supported by the machine being currently
+emulated.
+
+Returns json-int.
+
+Example:
+
+-> { "execute": "query-cpu-max" }
+<- { "return": 255 }
+
 EQMP
 
     {

vl.c

@@ -662,6 +662,11 @@ StatusInfo *qmp_query_status(Error **errp)
     return info;
 }
 
+int64_t qmp_query_cpu_max(Error **errp)
+{
+    return current_machine->max_cpus;
+}
+
 /***********************************************************/
 /* real time host monotonic timer */