spapr: handle pc-dimm unplug via hotplug handler chain

Factor out memory unplug into separate function from spapr_lmb_release().
Then use generic hotplug_handler_unplug() to trigger memory unplug,
which will call spapr_machine_device_unplug() -> spapr_memory_unplug()
in the end.

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

hw/ppc/spapr.c

@@ -3299,7 +3299,8 @@ static sPAPRDIMMState *spapr_recover_pending_dimm_state(sPAPRMachineState *ms,
 /* Callback to be called during DRC release. */
 void spapr_lmb_release(DeviceState *dev)
 {
-    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_hotplug_handler(dev));
+    HotplugHandler *hotplug_ctrl = qdev_get_hotplug_handler(dev);
+    sPAPRMachineState *spapr = SPAPR_MACHINE(hotplug_ctrl);
     sPAPRDIMMState *ds = spapr_pending_dimm_unplugs_find(spapr, PC_DIMM(dev));
 
     /* This information will get lost if a migration occurs
@@ -3317,9 +3318,17 @@ void spapr_lmb_release(DeviceState *dev)
 
     /*
      * Now that all the LMBs have been removed by the guest, call the
-     * pc-dimm unplug handler to cleanup up the pc-dimm device.
+     * unplug handler chain. This can never fail.
      */
-    pc_dimm_memory_unplug(dev, MACHINE(spapr));
+    hotplug_handler_unplug(hotplug_ctrl, dev, &error_abort);
+}
+
+static void spapr_memory_unplug(HotplugHandler *hotplug_dev, DeviceState *dev)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(hotplug_dev);
+    sPAPRDIMMState *ds = spapr_pending_dimm_unplugs_find(spapr, PC_DIMM(dev));
+
+    pc_dimm_memory_unplug(dev, MACHINE(hotplug_dev));
     object_unparent(OBJECT(dev));
     spapr_pending_dimm_unplugs_remove(spapr, ds);
 }
@@ -3587,6 +3596,9 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
 static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
                                         DeviceState *dev, Error **errp)
 {
+    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
+        spapr_memory_unplug(hotplug_dev, dev);
+    }
 }
 
 static void spapr_machine_device_unplug_request(HotplugHandler *hotplug_dev,