spapr: handle cpu core unplug via hotplug handler chain

Factor out cpu core unplug into separate function from
spapr_core_release(). Then use generic hotplug_handler_unplug() to trigger
cpu core unplug, which would call spapr_machine_device_unplug() ->
spapr_core_unplug() in the end.

This way unplug operation is not buried in spapr internals and located
in the same place like in other targets, following similar
logic/call chain across targets.
Acked-by: NIgor Mammedov <imammedo@redhat.com>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -3416,7 +3416,15 @@ static void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
 /* Callback to be called during DRC release. */
 void spapr_core_release(DeviceState *dev)
 {
-    MachineState *ms = MACHINE(qdev_get_hotplug_handler(dev));
+    HotplugHandler *hotplug_ctrl = qdev_get_hotplug_handler(dev);
+
+    /* Call the unplug handler chain. This can never fail. */
+    hotplug_handler_unplug(hotplug_ctrl, dev, &error_abort);
+}
+
+static void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev)
+{
+    MachineState *ms = MACHINE(hotplug_dev);
     sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(ms);
     CPUCore *cc = CPU_CORE(dev);
     CPUArchId *core_slot = spapr_find_cpu_slot(ms, cc->core_id, NULL);
@@ -3598,6 +3606,8 @@ static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
 {
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         spapr_memory_unplug(hotplug_dev, dev);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
+        spapr_core_unplug(hotplug_dev, dev);
     }
 }