[RFC 15/41] hw/cpu/core: Allow to configure plugged threads for cpu-core

[Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx>]

From: Zhao Liu <zhao1.liu@xxxxxxxxx>

When the core abstraction is applied for the architecture support CPU
hotplug, the plugged CPUs and unplugged CPUs are distributed among the
cores created in the topology tree.

Add plugged_threads field to help cpu-core decide to how many CPUs to
create.

Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
---
 hw/cpu/core.c                   | 33 +++++++++++++++++++++++++++++++++
 hw/ppc/pnv_core.c               |  6 +++++-
 hw/ppc/spapr_cpu_core.c         |  6 +++++-
 include/hw/cpu/core.h           |  9 +++++++++
 include/hw/ppc/pnv_core.h       |  2 ++
 include/hw/ppc/spapr_cpu_core.h |  2 ++
 6 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/hw/cpu/core.c b/hw/cpu/core.c
index 7e274d6aebb7..15546b5b2339 100644
--- a/hw/cpu/core.c
+++ b/hw/cpu/core.c
@@ -36,6 +36,20 @@ static void core_prop_set_nr_threads(Object *obj, Visitor 
*v, const char *name,
     core->nr_threads = value;
 }
 
+static void core_prop_set_plugged_threads(Object *obj, Visitor *v,
+                                          const char *name, void *opaque,
+                                          Error **errp)
+{
+    CPUCore *core = CPU_CORE(obj);
+    int64_t value;
+
+    if (!visit_type_int(v, name, &value, errp)) {
+        return;
+    }
+
+    core->plugged_threads = value;
+}
+
 static void cpu_core_instance_init(Object *obj)
 {
     CPUCore *core = CPU_CORE(obj);
@@ -48,6 +62,22 @@ static void cpu_core_instance_init(Object *obj)
     if (current_machine) {
         core->nr_threads = current_machine->smp.threads;
     }
+
+    core->plugged_threads = -1;
+}
+
+static void cpu_core_realize(DeviceState *dev, Error **errp)
+{
+    CPUCore *core = CPU_CORE(dev);
+
+    if (core->plugged_threads > core->nr_threads) {
+        error_setg(errp, "Plugged threads (plugged-threads: %d) must "
+                   "not be more than max threads (nr-threads: %d)",
+                   core->plugged_threads, core->nr_threads);
+        return;
+    } else if (core->plugged_threads == -1) {
+        core->plugged_threads = core->nr_threads;
+    }
 }
 
 static void cpu_core_class_init(ObjectClass *oc, void *data)
@@ -57,6 +87,9 @@ static void cpu_core_class_init(ObjectClass *oc, void *data)
     set_bit(DEVICE_CATEGORY_CPU, dc->categories);
     object_class_property_add(oc, "nr-threads", "int", 
core_prop_get_nr_threads,
                               core_prop_set_nr_threads, NULL, NULL);
+    object_class_property_add(oc, "plugged-threads", "int", NULL,
+                              core_prop_set_plugged_threads, NULL, NULL);
+    dc->realize = cpu_core_realize;
 }
 
 static const TypeInfo cpu_core_type_info = {
diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
index a90d1ec92bd8..8b75739697d1 100644
--- a/hw/ppc/pnv_core.c
+++ b/hw/ppc/pnv_core.c
@@ -276,6 +276,8 @@ static void pnv_core_realize(DeviceState *dev, Error **errp)
 
     assert(pc->chip);
 
+    pcc->parent_realize(dev, errp);
+
     pc->threads = g_new(PowerPCCPU *, cc->nr_threads);
     for (i = 0; i < cc->nr_threads; i++) {
         PowerPCCPU *cpu;
@@ -376,11 +378,13 @@ static void pnv_core_power10_class_init(ObjectClass *oc, 
void *data)
 static void pnv_core_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
+    PnvCoreClass *pcc = PNV_CORE_CLASS(oc);
 
-    dc->realize = pnv_core_realize;
     dc->unrealize = pnv_core_unrealize;
     device_class_set_props(dc, pnv_core_properties);
     dc->user_creatable = false;
+    device_class_set_parent_realize(dc, pnv_core_realize,
+                                    &pcc->parent_realize);
 }
 
 #define DEFINE_PNV_CORE_TYPE(family, cpu_model) \
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 7c2ea1424747..5533a386f350 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -331,6 +331,7 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error 
**errp)
         (SpaprMachineState *) object_dynamic_cast(qdev_get_machine(),
                                                   TYPE_SPAPR_MACHINE);
     SpaprCpuCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
+    SpaprCpuCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(sc);
     CPUCore *cc = CPU_CORE(OBJECT(dev));
     int i;
 
@@ -339,6 +340,8 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error 
**errp)
         return;
     }
 
+    scc->parent_realize(dev, errp);
+
     qemu_register_reset(spapr_cpu_core_reset_handler, sc);
     sc->threads = g_new0(PowerPCCPU *, cc->nr_threads);
     for (i = 0; i < cc->nr_threads; i++) {
@@ -363,11 +366,12 @@ static void spapr_cpu_core_class_init(ObjectClass *oc, 
void *data)
     DeviceClass *dc = DEVICE_CLASS(oc);
     SpaprCpuCoreClass *scc = SPAPR_CPU_CORE_CLASS(oc);
 
-    dc->realize = spapr_cpu_core_realize;
     dc->unrealize = spapr_cpu_core_unrealize;
     dc->reset = spapr_cpu_core_reset;
     device_class_set_props(dc, spapr_cpu_core_properties);
     scc->cpu_type = data;
+    device_class_set_parent_realize(dc, spapr_cpu_core_realize,
+                                    &scc->parent_realize);
 }
 
 #define DEFINE_SPAPR_CPU_CORE_TYPE(cpu_model) \
diff --git a/include/hw/cpu/core.h b/include/hw/cpu/core.h
index 17f117bd5225..87d50151ab01 100644
--- a/include/hw/cpu/core.h
+++ b/include/hw/cpu/core.h
@@ -21,7 +21,16 @@ struct CPUCore {
     DeviceState parent_obj;
 
     /*< public >*/
+    int core_id;
+
+    /* Maximum number of threads contained in this core. */
     int nr_threads;
+
+    /*
+     * How many threads should be plugged in this core via
+     * "-device"/"device_add"?
+     */
+    int plugged_threads;
 };
 
 #endif
diff --git a/include/hw/ppc/pnv_core.h b/include/hw/ppc/pnv_core.h
index 56c3f6b51f2f..3b9edf69f9fb 100644
--- a/include/hw/ppc/pnv_core.h
+++ b/include/hw/ppc/pnv_core.h
@@ -49,6 +49,8 @@ struct PnvCoreClass {
     /*< public >*/
     const MemoryRegionOps *xscom_ops;
     uint64_t xscom_size;
+
+    DeviceRealize parent_realize;
 };
 
 #define PNV_CORE_TYPE_SUFFIX "-" TYPE_PNV_CORE
diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
index db3e515051ca..dabdbd4bcbc9 100644
--- a/include/hw/ppc/spapr_cpu_core.h
+++ b/include/hw/ppc/spapr_cpu_core.h
@@ -37,6 +37,8 @@ struct SpaprCpuCoreClass {
 
     /*< public >*/
     const char *cpu_type;
+
+    DeviceRealize parent_realize;
 };
 
 const char *spapr_get_cpu_core_type(const char *cpu_type);
-- 
2.34.1