spapr: CPU hot unplug support

Remove the CPU core device by removing the underlying CPU thread devices. Hot removal of CPU for sPAPR guests is achieved by sending the hot unplug notification to the guest. Release the vCPU object after CPU hot unplug so that vCPU fd can be parked and reused. Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
geofft · Jun 17, 2016 · 6f4b5c3 · 6f4b5c3
1 parent af81cf3
commit 6f4b5c3
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Showing 3 changed files with 69 additions and 0 deletions.
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
@@ -2313,8 +2313,16 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
 static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
                                       DeviceState *dev, Error **errp)
 {
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
+
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         error_setg(errp, "Memory hot unplug not supported by sPAPR");
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
+        if (!smc->dr_cpu_enabled) {
+            error_setg(errp, "CPU hot unplug not supported on this machine");
+            return;
+        }
+        spapr_core_unplug(hotplug_dev, dev, errp);
     }
 }
 

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
@@ -38,6 +38,14 @@ static void spapr_cpu_reset(void *opaque)
                                 &error_fatal);
 }
 
+static void spapr_cpu_destroy(PowerPCCPU *cpu)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+
+    xics_cpu_destroy(spapr->icp, cpu);
+    qemu_unregister_reset(spapr_cpu_reset, cpu);
+}
+
 void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
 {
     CPUPPCState *env = &cpu->env;
@@ -88,6 +96,57 @@ char *spapr_get_cpu_core_type(const char *model)
     return core_type;
 }
 
+static void spapr_core_release(DeviceState *dev, void *opaque)
+{
+    sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
+    const char *typename = object_class_get_name(sc->cpu_class);
+    size_t size = object_type_get_instance_size(typename);
+    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
+    CPUCore *cc = CPU_CORE(dev);
+    int smt = kvmppc_smt_threads();
+    int i;
+
+    for (i = 0; i < cc->nr_threads; i++) {
+        void *obj = sc->threads + i * size;
+        DeviceState *dev = DEVICE(obj);
+        CPUState *cs = CPU(dev);
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+        spapr_cpu_destroy(cpu);
+        cpu_remove_sync(cs);
+        object_unparent(obj);
+    }
+
+    spapr->cores[cc->core_id / smt] = NULL;
+
+    g_free(core->threads);
+    object_unparent(OBJECT(dev));
+}
+
+void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                       Error **errp)
+{
+    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
+    PowerPCCPU *cpu = POWERPC_CPU(core->threads);
+    int id = ppc_get_vcpu_dt_id(cpu);
+    sPAPRDRConnector *drc =
+        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
+    sPAPRDRConnectorClass *drck;
+    Error *local_err = NULL;
+
+    g_assert(drc);
+
+    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
+    drck->detach(drc, dev, spapr_core_release, NULL, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    spapr_hotplug_req_remove_by_index(drc);
+}
+
 void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                      Error **errp)
 {

diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
@@ -31,4 +31,6 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
 char *spapr_get_cpu_core_type(const char *model);
 void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                      Error **errp);
+void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                       Error **errp);
 #endif