hw/loongarch/virt: Implement cpu unplug interface

Implement cpu unplug interfaces including virt_cpu_unplug_request()
and virt_cpu_unplug().

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

hw/loongarch/virt.c

@@ -816,6 +816,19 @@ static int virt_get_arch_id_from_topo(MachineState *ms, LoongArchCPUTopo *topo)
     return arch_id;
 }
 
+/* Find cpu slot in machine->possible_cpus by arch_id */
+static CPUArchId *virt_find_cpu_slot(MachineState *ms, int arch_id)
+{
+    int n;
+    for (n = 0; n < ms->possible_cpus->len; n++) {
+        if (ms->possible_cpus->cpus[n].arch_id == arch_id) {
+            return &ms->possible_cpus->cpus[n];
+        }
+    }
+
+    return NULL;
+}
+
 static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
                               DeviceState *dev, Error **errp)
 {
@@ -824,11 +837,56 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
 static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
                                     DeviceState *dev, Error **errp)
 {
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
+    Error *err = NULL;
+    LoongArchCPU *cpu = LOONGARCH_CPU(dev);
+    CPUState *cs = CPU(dev);
+
+    if (cs->cpu_index == 0) {
+        error_setg(&err, "hot-unplug of boot cpu(id%d=%d:%d:%d) not supported",
+                   cs->cpu_index, cpu->socket_id,
+                   cpu->core_id, cpu->thread_id);
+        error_propagate(errp, err);
+        return;
+    }
+
+    hotplug_handler_unplug_request(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
+    if (err) {
+        error_propagate(errp, err);
+    }
 }
 
 static void virt_cpu_unplug(HotplugHandler *hotplug_dev,
                             DeviceState *dev, Error **errp)
 {
+    CPUArchId *cpu_slot;
+    Error *err = NULL;
+    LoongArchCPU *cpu = LOONGARCH_CPU(dev);
+    LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
+
+    /* Notify ipi and extioi irqchip to remove interrupt routing to CPU */
+    hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->ipi), dev, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->extioi), dev, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    /* Notify acpi ged CPU removed */
+    hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
+    cpu_slot->cpu = NULL;
+    return;
 }
 
 static void virt_cpu_plug(HotplugHandler *hotplug_dev,