hw/loongarch/virt: Implement cpu plug interface

Implement cpu plug interface, and cold-plug cpu uses plug interface
when cpu object is created.

Co-developed-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>

hw/loongarch/virt.c

@@ -647,15 +647,13 @@ static void fw_cfg_add_memory(MachineState *ms)
 
 static void virt_init(MachineState *machine)
 {
-    LoongArchCPU *lacpu;
     const char *cpu_model = machine->cpu_type;
     MemoryRegion *address_space_mem = get_system_memory();
     LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(machine);
     int i;
     hwaddr base, size, ram_size = machine->ram_size;
-    const CPUArchIdList *possible_cpus;
     MachineClass *mc = MACHINE_GET_CLASS(machine);
-    CPUState *cpu;
+    Object *cpuobj;
 
     if (!cpu_model) {
         cpu_model = LOONGARCH_CPU_TYPE_NAME("la464");
@@ -671,14 +669,15 @@ static void virt_init(MachineState *machine)
     memory_region_add_subregion(&lvms->system_iocsr, 0, &lvms->iocsr_mem);
 
     /* Init CPUs */
-    possible_cpus = mc->possible_cpu_arch_ids(machine);
-    for (i = 0; i < possible_cpus->len; i++) {
-        cpu = cpu_create(machine->cpu_type);
-        cpu->cpu_index = i;
-        machine->possible_cpus->cpus[i].cpu = cpu;
-        lacpu = LOONGARCH_CPU(cpu);
-        lacpu->phy_id = machine->possible_cpus->cpus[i].arch_id;
-        lacpu->env.address_space_iocsr = &lvms->as_iocsr;
+    mc->possible_cpu_arch_ids(machine);
+    for (i = 0; i < machine->smp.cpus; i++) {
+        cpuobj = object_new(machine->cpu_type);
+        if (cpuobj == NULL) {
+            error_report("Fail to create object with type %s ",
+                         machine->cpu_type);
+            exit(EXIT_FAILURE);
+        }
+        qdev_realize_and_unref(DEVICE(cpuobj), NULL, &error_fatal);
     }
     fw_cfg_add_memory(machine);
 
@@ -829,9 +828,52 @@ static CPUArchId *virt_find_cpu_slot(MachineState *ms, int arch_id)
     return NULL;
 }
 
+/* Find cpu slot for cold-plut CPU object where cpu is NULL */
+static CPUArchId *virt_find_empty_cpu_slot(MachineState *ms)
+{
+    int n;
+    for (n = 0; n < ms->possible_cpus->len; n++) {
+        if (ms->possible_cpus->cpus[n].cpu == NULL) {
+            return &ms->possible_cpus->cpus[n];
+        }
+    }
+
+    return NULL;
+}
+
 static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
                               DeviceState *dev, Error **errp)
 {
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
+    MachineState *ms = MACHINE(OBJECT(hotplug_dev));
+    LoongArchCPU *cpu = LOONGARCH_CPU(dev);
+    CPUState *cs = CPU(dev);
+    CPUArchId *cpu_slot;
+    Error *err = NULL;
+    LoongArchCPUTopo topo;
+
+    if (lvms->acpi_ged) {
+        error_setg(&err, "CPU hotplug not supported");
+        goto out;
+    } else {
+        /* For cold-add cpu, find empty cpu slot */
+        cpu_slot = virt_find_empty_cpu_slot(ms);
+        topo.socket_id = cpu_slot->props.socket_id;
+        topo.core_id = cpu_slot->props.core_id;
+        topo.thread_id = cpu_slot->props.thread_id;
+        object_property_set_int(OBJECT(dev), "socket-id", topo.socket_id, NULL);
+        object_property_set_int(OBJECT(dev), "core-id", topo.core_id, NULL);
+        object_property_set_int(OBJECT(dev), "thread-id", topo.thread_id, NULL);
+    }
+
+    cpu->env.address_space_iocsr = &lvms->as_iocsr;
+    cpu->phy_id = cpu_slot->arch_id;
+    cs->cpu_index = cpu_slot - ms->possible_cpus->cpus;
+    numa_cpu_pre_plug(cpu_slot, dev, &err);
+out:
+    if (err) {
+        error_propagate(errp, err);
+    }
 }
 
 static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
@@ -892,6 +934,30 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev,
 static void virt_cpu_plug(HotplugHandler *hotplug_dev,
                           DeviceState *dev, Error **errp)
 {
+    CPUArchId *cpu_slot;
+    LoongArchCPU *cpu = LOONGARCH_CPU(dev);
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
+    Error *err = NULL;
+
+    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
+    cpu_slot->cpu = CPU(dev);
+    if (lvms->ipi) {
+        hotplug_handler_plug(HOTPLUG_HANDLER(lvms->ipi), dev, &err);
+        if (err) {
+            error_propagate(errp, err);
+            return;
+        }
+    }
+
+    if (lvms->extioi) {
+        hotplug_handler_plug(HOTPLUG_HANDLER(lvms->extioi), dev, &err);
+        if (err) {
+            error_propagate(errp, err);
+            return;
+        }
+    }
+
+    return;
 }
 
 static bool memhp_type_supported(DeviceState *dev)

target/loongarch/cpu.c

@@ -932,6 +932,7 @@ static void loongarch_cpu_class_init(ObjectClass *c, void *data)
 #ifdef CONFIG_TCG
     cc->tcg_ops = &loongarch_tcg_ops;
 #endif
+    dc->user_creatable = true;
 }
 
 static const gchar *loongarch32_gdb_arch_name(CPUState *cs)