From: Zhao Liu <zhao1.liu@intel.com>

Convert CPU to topology device then its parent topology devices could
count the number of CPUs when new CPUs are added into topology tree.

Note since CPUs are created from *_init_cpus() in MachineClass.init() or
added from hotplug way, it depends on board initialization. Thus CPU
topology device isn't marked as DEVICE_CATEGORY_CPU_DEF and it will only
be created after board initialization.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 accel/kvm/kvm-all.c   |  4 ++--
 hw/core/cpu-common.c  | 25 +++++++++++++++++++++----
 include/hw/core/cpu.h |  8 ++++++--
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index e39a810a4e92..2eee3eb95907 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3953,7 +3953,7 @@ static void query_stats(StatsResultList **result, StatsTarget target,
         break;
     case STATS_TARGET_VCPU:
         add_stats_entry(result, STATS_PROVIDER_KVM,
-                        cpu->parent_obj.canonical_path,
+                        DEVICE(cpu)->canonical_path,
                         stats_list);
         break;
     default:
@@ -4045,7 +4045,7 @@ static void query_stats_cb(StatsResultList **result, StatsTarget target,
         stats_args.names = names;
         stats_args.errp = errp;
         CPU_FOREACH(cpu) {
-            if (!apply_str_list_filter(cpu->parent_obj.canonical_path, targets)) {
+            if (!apply_str_list_filter(DEVICE(cpu)->canonical_path, targets)) {
                 continue;
             }
             query_stats_vcpu(cpu, &stats_args);
diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index 82dae51a550b..e9ed84ff5386 100644
--- a/hw/core/cpu-common.c
+++ b/hw/core/cpu-common.c
@@ -195,6 +195,16 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
 {
     CPUState *cpu = CPU(dev);
     Object *machine = qdev_get_machine();
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    /*
+     * The parent topology realize() must be completed before cpu_resume()
+     * where the CPU starts to run.
+     */
+    cc->parent_realize(dev, errp);
+    if (*errp) {
+        return;
+    }
 
     /* qdev_get_machine() can return something that's not TYPE_MACHINE
      * if this is one of the user-only emulators; in that case there's
@@ -225,6 +235,7 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
 static void cpu_common_unrealizefn(DeviceState *dev)
 {
     CPUState *cpu = CPU(dev);
+    CPUClass *cc = CPU_GET_CLASS(cpu);
 
     /* Call the plugin hook before clearing the cpu is fully unrealized */
     if (tcg_enabled()) {
@@ -233,6 +244,7 @@ static void cpu_common_unrealizefn(DeviceState *dev)
 
     /* NOTE: latest generic point before the cpu is fully unrealized */
     cpu_exec_unrealizefn(cpu);
+    cc->parent_unrealize(dev);
 }
 
 static void cpu_common_initfn(Object *obj)
@@ -275,6 +287,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     ResettableClass *rc = RESETTABLE_CLASS(klass);
+    CPUTopoClass *tc = CPU_TOPO_CLASS(klass);
     CPUClass *k = CPU_CLASS(klass);
 
     k->parse_features = cpu_common_parse_features;
@@ -282,9 +295,6 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     k->has_work = cpu_common_has_work;
     k->gdb_read_register = cpu_common_gdb_read_register;
     k->gdb_write_register = cpu_common_gdb_write_register;
-    set_bit(DEVICE_CATEGORY_CPU, dc->categories);
-    dc->realize = cpu_common_realizefn;
-    dc->unrealize = cpu_common_unrealizefn;
     rc->phases.hold = cpu_common_reset_hold;
     cpu_class_init_props(dc);
     /*
@@ -292,11 +302,18 @@ static void cpu_class_init(ObjectClass *klass, void *data)
      * IRQs, adding reset handlers, halting non-first CPUs, ...
      */
     dc->user_creatable = false;
+    /* CPU is the minimum granularity for hotplug. */
+    dc->hotpluggable = true;
+    device_class_set_parent_realize(dc, cpu_common_realizefn,
+                                    &k->parent_realize);
+    device_class_set_parent_unrealize(dc, cpu_common_unrealizefn,
+                                      &k->parent_unrealize);
+    tc->level = CPU_TOPO_THREAD;
 }
 
 static const TypeInfo cpu_type_info = {
     .name = TYPE_CPU,
-    .parent = TYPE_DEVICE,
+    .parent = TYPE_CPU_TOPO,
     .instance_size = sizeof(CPUState),
     .instance_init = cpu_common_initfn,
     .instance_finalize = cpu_common_finalize,
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index c0c8320413e5..a700f7c39140 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -20,6 +20,7 @@
 #ifndef QEMU_CPU_H
 #define QEMU_CPU_H
 
+#include "hw/core/cpu-topo.h"
 #include "hw/qdev-core.h"
 #include "disas/dis-asm.h"
 #include "exec/cpu-common.h"
@@ -146,7 +147,7 @@ struct SysemuCPUOps;
  */
 struct CPUClass {
     /*< private >*/
-    DeviceClass parent_class;
+    CPUTopoClass parent_class;
     /*< public >*/
 
     ObjectClass *(*class_by_name)(const char *cpu_model);
@@ -191,6 +192,9 @@ struct CPUClass {
     int reset_dump_flags;
     int gdb_num_core_regs;
     bool gdb_stop_before_watchpoint;
+
+    DeviceRealize parent_realize;
+    DeviceUnrealize parent_unrealize;
 };
 
 /*
@@ -456,7 +460,7 @@ struct qemu_work_item;
  */
 struct CPUState {
     /*< private >*/
-    DeviceState parent_obj;
+    CPUTopoState parent_obj;
     /* cache to avoid expensive CPU_GET_CLASS */
     CPUClass *cc;
     /*< public >*/
-- 
2.34.1