hw/cpu: introduce CPU clusters

This commit adds the cpu-cluster type. It aims at gathering CPUs from
the same cluster in a machine.

For now it only has a `cluster-id` property.

Documentation in cluster.h written with the help of Peter Maydell.

Signed-off-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20181207090135.7651-2-luc.michel@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

MAINTAINERS

@@ -1195,7 +1195,9 @@ M: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
 S: Supported
 F: hw/core/machine.c
 F: hw/core/null-machine.c
+F: hw/cpu/cluster.c
 F: include/hw/boards.h
+F: include/hw/cpu/cluster.h
 T: git https://github.com/ehabkost/qemu.git machine-next
 
 Xtensa Machines

hw/cpu/Makefile.objs

@@ -2,4 +2,4 @@ obj-$(CONFIG_ARM11MPCORE) += arm11mpcore.o
 obj-$(CONFIG_REALVIEW) += realview_mpcore.o
 obj-$(CONFIG_A9MPCORE) += a9mpcore.o
 obj-$(CONFIG_A15MPCORE) += a15mpcore.o
-common-obj-y += core.o
+common-obj-y += core.o cluster.o

hw/cpu/cluster.c

@@ -0,0 +1,50 @@
+/*
+ * QEMU CPU cluster
+ *
+ * Copyright (c) 2018 GreenSocs SAS
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see
+ * <http://www.gnu.org/licenses/gpl-2.0.html>
+ */
+
+#include "qemu/osdep.h"
+#include "hw/cpu/cluster.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+
+static Property cpu_cluster_properties[] = {
+    DEFINE_PROP_UINT32("cluster-id", CPUClusterState, cluster_id, 0),
+    DEFINE_PROP_END_OF_LIST()
+};
+
+static void cpu_cluster_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = cpu_cluster_properties;
+}
+
+static const TypeInfo cpu_cluster_type_info = {
+    .name = TYPE_CPU_CLUSTER,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(CPUClusterState),
+    .class_init = cpu_cluster_class_init,
+};
+
+static void cpu_cluster_register_types(void)
+{
+    type_register_static(&cpu_cluster_type_info);
+}
+
+type_init(cpu_cluster_register_types)

include/hw/cpu/cluster.h

@@ -0,0 +1,58 @@
+/*
+ * QEMU CPU cluster
+ *
+ * Copyright (c) 2018 GreenSocs SAS
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see
+ * <http://www.gnu.org/licenses/gpl-2.0.html>
+ */
+#ifndef HW_CPU_CLUSTER_H
+#define HW_CPU_CLUSTER_H
+
+#include "qemu/osdep.h"
+#include "hw/qdev.h"
+
+/*
+ * CPU Cluster type
+ *
+ * A cluster is a group of CPUs which are all identical and have the same view
+ * of the rest of the system. It is mainly an internal QEMU representation and
+ * does not necessarily match with the notion of clusters on the real hardware.
+ *
+ * If CPUs are not identical (for example, Cortex-A53 and Cortex-A57 CPUs in an
+ * Arm big.LITTLE system) they should be in different clusters. If the CPUs do
+ * not have the same view of memory (for example the main CPU and a management
+ * controller processor) they should be in different clusters.
+ */
+
+#define TYPE_CPU_CLUSTER "cpu-cluster"
+#define CPU_CLUSTER(obj) \
+    OBJECT_CHECK(CPUClusterState, (obj), TYPE_CPU_CLUSTER)
+
+/**
+ * CPUClusterState:
+ * @cluster_id: The cluster ID. This value is for internal use only and should
+ *   not be exposed directly to the user or to the guest.
+ *
+ * State of a CPU cluster.
+ */
+typedef struct CPUClusterState {
+    /*< private >*/
+    DeviceState parent_obj;
+
+    /*< public >*/
+    uint32_t cluster_id;
+} CPUClusterState;
+
+#endif