[Qemu-devel] [PATCH v4 1/2] QMP: add query-hotpluggable-cpus

[Igor Mammedov <imammedo@redhat.com>]

it will allow mgmt to query present and hotpluggable
CPU objects, it is required from a target platform that
wish to support command to implement and set
 MachineClass.query_hotpluggable_cpus
callback, which will return a list of possible CPU objects
with options that would be needed for hotplugging possible
CPU objects.

There are:
'type': 'str' - QOM CPU object type for usage with device_add
'vcpus-count': 'int' - number of logical VCPU threads per
                        CPU object (mgmt needs to know)

and a set of optional fields that are to used for hotplugging
a CPU objects and would allows mgmt tools to know what/where
it could be hotplugged;
[node],[socket],[core],[thread]

For present CPUs there is a 'qom-path' field which
would allow mgmt to inspect whatever object/abstraction
the target platform considers as CPU object.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
v4:
 - add MachineClass method to get CPU object list
v3:
 - add 'vcpus-count' field, pkrempa@redhat.com
 - s/CpuInstanceProps/CpuInstanceProperties/
 - use '#optional' marker
 - make "props" as always present even if it's empty
 - fix JSON examples
 - fix minor typos
---
 include/hw/boards.h |  5 +++++
 monitor.c           | 13 +++++++++++++
 qapi-schema.json    | 41 +++++++++++++++++++++++++++++++++++++++++
 qmp-commands.hx     | 43 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 102 insertions(+)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 8efce0f..a8f7dba 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -82,6 +82,10 @@ typedef struct {
  *    Returns an array of @CPUArchId architecture-dependent CPU IDs
  *    which includes CPU IDs for present and possible to hotplug CPUs.
  *    Caller is responsible for freeing returned list.
+ * @query_hotpluggable_cpus:
+ *    Returns a @HotpluggableCPUList, which describes CPUs objects which
+ *    could be added with -device/device_add.
+ *    Caller is responsible for freeing returned list.
  */
 struct MachineClass {
     /*< private >*/
@@ -124,6 +128,7 @@ struct MachineClass {
                                            DeviceState *dev);
     unsigned (*cpu_index_to_socket_id)(unsigned cpu_index);
     CPUArchIdList *(*possible_cpu_arch_ids)(MachineState *machine);
+    HotpluggableCPUList *(*query_hotpluggable_cpus)(MachineState *machine);
 };
 
 /**
diff --git a/monitor.c b/monitor.c
index 4c02f0f..490e214 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4257,4 +4257,17 @@ void qmp_dump_skeys(const char *filename, Error **errp)
 {
     error_setg(errp, QERR_FEATURE_DISABLED, "dump-skeys");
 }
+
+HotpluggableCPUList *qmp_query_hotpluggable_cpus(Error **errp)
+{
+    MachineState *ms = MACHINE(qdev_get_machine());
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+
+    if (!mc->query_hotpluggable_cpus) {
+        error_setg(errp, QERR_FEATURE_DISABLED, "query-hotpluggable-cpus");
+        return NULL;
+    }
+
+    return mc->query_hotpluggable_cpus(ms);
+}
 #endif
diff --git a/qapi-schema.json b/qapi-schema.json
index 88f9b81..71e20e1 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4126,3 +4126,44 @@
 ##
 { 'enum': 'ReplayMode',
   'data': [ 'none', 'record', 'play' ] }
+
+##
+# CpuInstanceProperties
+#
+# @node: NUMA node ID the CPU belongs to, optional
+# @socket: #optional socket number within node/board the CPU belongs to
+# @core: #optional core number within socket the CPU belongs to
+# @thread: #optional thread number within core the CPU belongs to
+#
+# Since: 2.7
+{ 'struct': 'CpuInstanceProperties',
+  'data': { '*node': 'int',
+            '*socket': 'int',
+            '*core': 'int',
+            '*thread': 'int'
+  }
+}
+
+##
+# @HotpluggableCPU
+#
+# @type: CPU object type for usage with device_add command
+# @props: list of properties to be used for hotplugging CPU
+# @vcpus-count: number of logical VCPU threads @HotpluggableCPU provides
+# @qom-path: #optional link to existing CPU object if CPU is present or
+#            omitted if CPU is not present.
+#
+# Since: 2.7
+{ 'struct': 'HotpluggableCPU',
+  'data': { 'type': 'str',
+            'vcpus-count': 'int',
+            'props': 'CpuInstanceProperties',
+            '*qom-path': 'str'
+          }
+}
+
+##
+# @query-hotpluggable-cpus
+#
+# Since: 2.7
+{ 'command': 'query-hotpluggable-cpus', 'returns': ['HotpluggableCPU'] }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 9e05365..85ffba3 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4853,3 +4853,46 @@ Example:
                  {"type": 0, "out-pport": 0, "pport": 0, "vlan-id": 3840,
                   "pop-vlan": 1, "id": 251658240}
    ]}
+
+EQMP
+
+    {
+        .name       = "query-hotpluggable-cpus",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_query_hotpluggable_cpus,
+    },
+
+SQMP
+Show  existing/possible CPUs
+-------------------------------
+
+Arguments: None.
+
+Example for x86 target started with -smp 2,sockets=2,cores=1,threads=3,maxcpus=6:
+
+-> { "execute": "query-hotpluggable-cpus" }
+<- {"return": [
+     { "props": { "core": 0, "socket": 1, "thread": 2},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1 },
+     { "props": { "core": 0, "socket": 1, "thread": 1},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1 },
+     { "props": { "core": 0, "socket": 1, "thread": 0},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1 },
+     { "props": { "core": 0, "socket": 0, "thread": 2},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1 },
+     { "props": { "core": 0, "socket": 0, "thread": 1},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1,
+       "qom-path": "/machine/unattached/device[3]"},
+     { "props": { "core": 0, "socket": 0, "thread": 0},
+       "type": "qemu64-x86_64-cpu", "vcpus-count": 1,
+       "qom-path": "/machine/unattached/device[0]"}
+   ]}'
+
+Example for SPAPR target started with -smp 2,cores=2,maxcpus=4:
+
+-> { "execute": "query-hotpluggable-cpus" }
+<- {"return": [
+     { "props": { "core": 1 }, "type": "spapr-cpu-core", "vcpus-count": 1 },
+     { "props": { "core": 0 }, "type": "spapr-cpu-core", "vcpus-count": 1,
+       "qom-path": "/machine/unattached/device[0]"}
+   ]}'
-- 
1.8.3.1