[RFC 34/41] hw/core/topo: Implement user-child to collect topology device from cli

[Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx>]

From: Zhao Liu <zhao1.liu@xxxxxxxxx>

Support user-child for topology devices.

This will affect these 2 aspects:
1. For the basic topology device (with DEVICE_CATEGORY_CPU_DEF
   category), user could specify "parent" to build the topology
   relationship from cli. And cpu-slot will collect all topology
   devices.

2. For the hotplug topology devices (ppc-core or CPUs of other arches),
   user-child could help to search the correct topology parent in
   topology tree with the index properties. This is compatible with
   the original behavior of inserting CPU/core from cli. And this
   requires arch to support QOM topology with a few arch-specific
   modifications, before this support, hotplugged CPUs/cores are
   inserted into cpu-slot by default.

Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
---
 hw/core/cpu-slot.c         | 44 ++++++++++++++++++++++++++++++++++++++
 hw/core/cpu-topo.c         | 38 ++++++++++++++++++++++++++++++++
 include/hw/core/cpu-slot.h |  3 +++
 include/hw/core/cpu-topo.h |  4 ++++
 4 files changed, 89 insertions(+)

diff --git a/hw/core/cpu-slot.c b/hw/core/cpu-slot.c
index 45b6aef0750a..413daa66aaad 100644
--- a/hw/core/cpu-slot.c
+++ b/hw/core/cpu-slot.c
@@ -559,3 +559,47 @@ bool machine_validate_cpu_topology(MachineState *ms, Error 
**errp)
 
     return true;
 }
+
+Object *cpu_slot_get_free_parent(CPUTopoState *child, Error **errp)
+{
+    MachineState *ms = MACHINE(qdev_get_machine());
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+    CPUTopoLevel level = CPU_TOPO_LEVEL(child);
+    CPUSlot *slot = ms->topo;
+
+    if (!slot) {
+        return NULL;
+    }
+
+    /*
+     * For CPUs and cores that support hotplug, the behavior is to specify
+     * some topology sub ids. This requires special handling.
+     */
+    if (level == mc->smp_props.possible_cpus_qom_granu) {
+        CPUTopoClass *child_tc = CPU_TOPO_GET_CLASS(child);
+
+        if (child_tc->search_parent_pre_plug) {
+            return child_tc->search_parent_pre_plug(child,
+                       CPU_TOPO(slot), errp);
+        }
+    }
+
+    /*
+     * For other topology devices, just collect them into CPU slot.
+     * The realize() of CPUTopoClass will check no "parent" option case.
+     */
+    return OBJECT(slot);
+}
+
+char *cpu_slot_name_future_child(CPUTopoState *child)
+{
+    MachineState *ms = MACHINE(qdev_get_machine());
+    CPUTopoLevel level = CPU_TOPO_LEVEL(child);
+    CPUSlot *slot = ms->topo;
+
+    if (!slot) {
+        return NULL;
+    }
+
+    return get_topo_global_name(&slot->stat, level);
+}
diff --git a/hw/core/cpu-topo.c b/hw/core/cpu-topo.c
index 351112ca7a73..143b0a148b17 100644
--- a/hw/core/cpu-topo.c
+++ b/hw/core/cpu-topo.c
@@ -20,8 +20,10 @@
 
 #include "qemu/osdep.h"
 
+#include "hw/core/cpu-slot.h"
 #include "hw/core/cpu-topo.h"
 #include "hw/qdev-properties.h"
+#include "monitor/user-child.h"
 #include "qapi/error.h"
 
 const char *cpu_topo_level_to_string(CPUTopoLevel level)
@@ -272,10 +274,38 @@ static void cpu_topo_unrealize(DeviceState *dev)
     }
 }
 
+/*
+ * Prefer to insert topology device into topology tree where the CPU
+ * slot is the root.
+ */
+static Object *cpu_topo_get_parent(UserChild *uc, Error **errp)
+{
+    return cpu_slot_get_free_parent(CPU_TOPO(uc), errp);
+}
+
+static char *cpu_topo_get_child_name(UserChild *uc, Object *parent)
+{
+    return cpu_slot_name_future_child(CPU_TOPO(uc));
+}
+
+/* Only check type. Other topology details with be checked at realize(). */
+static bool cpu_topo_check_user_parent(UserChild *uc, Object *parent)
+{
+    CPUTopoState *topo;
+
+    topo = (CPUTopoState *)object_dynamic_cast(parent, TYPE_CPU_TOPO);
+    if (!topo) {
+        return false;
+    }
+
+    return true;
+}
+
 static void cpu_topo_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
     CPUTopoClass *tc = CPU_TOPO_CLASS(oc);
+    UserChildClass *ucc = USER_CHILD_CLASS(oc);
 
     /* All topology devices belong to CPU property. */
     set_bit(DEVICE_CATEGORY_CPU, dc->categories);
@@ -290,6 +320,10 @@ static void cpu_topo_class_init(ObjectClass *oc, void 
*data)
     dc->hotpluggable = false;
 
     tc->level = CPU_TOPO_UNKNOWN;
+
+    ucc->get_parent = cpu_topo_get_parent;
+    ucc->get_child_name = cpu_topo_get_child_name;
+    ucc->check_parent = cpu_topo_check_user_parent;
 }
 
 static void cpu_topo_instance_init(Object *obj)
@@ -310,6 +344,10 @@ static const TypeInfo cpu_topo_type_info = {
     .class_init = cpu_topo_class_init,
     .instance_size = sizeof(CPUTopoState),
     .instance_init = cpu_topo_instance_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CHILD },
+        { }
+    }
 };
 
 static void cpu_topo_register_types(void)
diff --git a/include/hw/core/cpu-slot.h b/include/hw/core/cpu-slot.h
index 9e1c6d6b7ff2..1a63f55f52c3 100644
--- a/include/hw/core/cpu-slot.h
+++ b/include/hw/core/cpu-slot.h
@@ -102,4 +102,7 @@ void machine_plug_cpu_slot(MachineState *ms);
 void machine_create_smp_topo_tree(MachineState *ms, Error **errp);
 bool machine_validate_cpu_topology(MachineState *ms, Error **errp);
 
+Object *cpu_slot_get_free_parent(CPUTopoState *child, Error **errp);
+char *cpu_slot_name_future_child(CPUTopoState *child);
+
 #endif /* CPU_SLOT_H */
diff --git a/include/hw/core/cpu-topo.h b/include/hw/core/cpu-topo.h
index d27da0335c42..6cef26cce0b7 100644
--- a/include/hw/core/cpu-topo.h
+++ b/include/hw/core/cpu-topo.h
@@ -48,6 +48,8 @@ OBJECT_DECLARE_TYPE(CPUTopoState, CPUTopoClass, CPU_TOPO)
  *     new child (including direct child and non-direct child) is added.
  * @check_topo_child: Method to check the support for new child (including
  *     direct child and non-direct child) to be added.
+ * @search_parent_pre_plug: Method to search proper topology parent of @child
+ *     from @root.
  */
 struct CPUTopoClass {
     /*< private >*/
@@ -59,6 +61,8 @@ struct CPUTopoClass {
                              bool is_realize);
     void (*check_topo_child)(CPUTopoState *parent, CPUTopoState *child,
                              Error **errp);
+    Object *(*search_parent_pre_plug)(CPUTopoState *child, CPUTopoState *root,
+                                      Error **errp);
 };
 
 /**
-- 
2.34.1