qmp: Add qom_path field to query-cpus command

This will allow clients to query additional information directly using
qom-get on the CPU objects.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

cpus.c

@@ -1435,6 +1435,7 @@ CpuInfoList *qmp_query_cpus(Error **errp)
         info->value->CPU = cpu->cpu_index;
         info->value->current = (cpu == first_cpu);
         info->value->halted = cpu->halted;
+        info->value->qom_path = object_get_canonical_path(OBJECT(cpu));
         info->value->thread_id = cpu->thread_id;
 #if defined(TARGET_I386)
         info->value->has_pc = true;

qapi-schema.json

@@ -679,6 +679,8 @@
 # @halted: true if the virtual CPU is in the halt state.  Halt usually refers
 #          to a processor specific low power mode.
 #
+# @qom_path: path to the CPU object in the QOM tree (since 2.4)
+#
 # @pc: #optional If the target is i386 or x86_64, this is the 64-bit instruction
 #                pointer.
 #                If the target is Sparc, this is the PC component of the
@@ -699,8 +701,10 @@
 #        data is sent to the client, the guest may no longer be halted.
 ##
 { 'struct': 'CpuInfo',
-  'data': {'CPU': 'int', 'current': 'bool', 'halted': 'bool', '*pc': 'int',
-           '*nip': 'int', '*npc': 'int', '*PC': 'int', 'thread_id': 'int'} }
+  'data': {'CPU': 'int', 'current': 'bool', 'halted': 'bool',
+           'qom_path': 'str',
+           '*pc': 'int', '*nip': 'int', '*npc': 'int', '*PC': 'int',
+           'thread_id': 'int'} }
 
 ##
 # @query-cpus:

qmp-commands.hx

@@ -2569,6 +2569,7 @@ Return a json-array. Each CPU is represented by a json-object, which contains:
 - "CPU": CPU index (json-int)
 - "current": true if this is the current CPU, false otherwise (json-bool)
 - "halted": true if the cpu is halted, false otherwise (json-bool)
+- "qom_path": path to the CPU object in the QOM tree (json-str)
 - Current program counter. The key's name depends on the architecture:
      "pc": i386/x86_64 (json-int)
      "nip": PPC (json-int)
@@ -2585,14 +2586,16 @@ Example:
             "CPU":0,
             "current":true,
             "halted":false,
-            "pc":3227107138
+            "qom_path":"/machine/unattached/device[0]",
+            "pc":3227107138,
             "thread_id":3134
          },
          {
             "CPU":1,
             "current":false,
             "halted":true,
-            "pc":7108165
+            "qom_path":"/machine/unattached/device[2]",
+            "pc":7108165,
             "thread_id":3135
          }
       ]