hw/loongarch/virt: Enable cpu hotplug feature on virt machine

On virt machine, enable CPU hotplug feature has_hotpluggable_cpus. For
hot-added CPUs, there is socket-id/core-id/thread-id property set,
arch_id can be caculated from these properties. So that cpu slot can be
searched from its arch_id.

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

hw/loongarch/virt.c

@@ -861,10 +861,42 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
     CPUArchId *cpu_slot;
     Error *err = NULL;
     LoongArchCPUTopo topo;
+    int arch_id;
 
     if (lvms->acpi_ged) {
-        error_setg(&err, "CPU hotplug not supported");
-        goto out;
+        if ((cpu->thread_id < 0) || (cpu->thread_id >= ms->smp.threads)) {
+            error_setg(&err,
+                       "Invalid thread-id %u specified, must be in range 1:%u",
+                       cpu->thread_id, ms->smp.threads - 1);
+            goto out;
+        }
+
+        if ((cpu->core_id < 0) || (cpu->core_id >= ms->smp.cores)) {
+            error_setg(&err,
+                       "Invalid core-id %u specified, must be in range 1:%u",
+                       cpu->core_id, ms->smp.cores - 1);
+            goto out;
+        }
+
+        if ((cpu->socket_id < 0) || (cpu->socket_id >= ms->smp.sockets)) {
+            error_setg(&err,
+                       "Invalid socket-id %u specified, must be in range 1:%u",
+                       cpu->socket_id, ms->smp.sockets - 1);
+            goto out;
+        }
+
+        topo.socket_id = cpu->socket_id;
+        topo.core_id = cpu->core_id;
+        topo.thread_id = cpu->thread_id;
+        arch_id =  virt_get_arch_id_from_topo(ms, &topo);
+        cpu_slot = virt_find_cpu_slot(ms, arch_id);
+        if (CPU(cpu_slot->cpu)) {
+            error_setg(&err,
+                       "cpu(id%d=%d:%d:%d) with arch-id %" PRIu64 " exists",
+                       cs->cpu_index, cpu->socket_id, cpu->core_id,
+                       cpu->thread_id, cpu_slot->arch_id);
+            goto out;
+        }
     } else {
         /* For cold-add cpu, find empty cpu slot */
         cpu_slot = virt_find_empty_cpu_slot(ms);
@@ -967,6 +999,13 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
         }
     }
 
+    if (lvms->acpi_ged) {
+        hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
+        if (err) {
+            error_propagate(errp, err);
+        }
+    }
+
     return;
 }
 
@@ -1149,6 +1188,7 @@ static void virt_class_init(ObjectClass *oc, void *data)
     mc->numa_mem_supported = true;
     mc->auto_enable_numa_with_memhp = true;
     mc->auto_enable_numa_with_memdev = true;
+    mc->has_hotpluggable_cpus = true;
     mc->get_hotplug_handler = virt_get_hotplug_handler;
     mc->default_nic = "virtio-net-pci";
     hc->plug = virt_device_plug_cb;