---
Changes v2->v3:
* allow CPU objects to be indirect children of the cluster;
this is useful for ARMv7M, where the CPU object is a child
of the armv7m container and the board code that sets up
the cluster object only has the armv7m container object:
this is done by using object_child_foreach_recursive()
rather than an open-coded child iteration
* add an assertion that the cluster has at least one CPU,
which catches the easiest-to-make errors when creating
and populating the cluster
---
include/hw/cpu/cluster.h | 24 +++++++++++++++++++++
include/qom/cpu.h | 7 ++++++
hw/cpu/cluster.c | 46 ++++++++++++++++++++++++++++++++++++++++
qom/cpu.c | 1 +
4 files changed, 78 insertions(+)
diff --git a/include/hw/cpu/cluster.h b/include/hw/cpu/cluster.h
index 73818232437..549c2d31d43 100644
--- a/include/hw/cpu/cluster.h
+++ b/include/hw/cpu/cluster.h
@@ -34,12 +34,36 @@
* 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.
+ *
+ * A cluster is created by creating an object of TYPE_CPU_CLUSTER, and then
+ * adding the CPUs to it as QOM child objects (e.g. using the
+ * object_initialize_child() or object_property_add_child() functions).
+ * The CPUs may be either direct children of the cluster object, or indirect
+ * children (e.g. children of children of the cluster object).
+ *
+ * All CPUs must be added as children before the cluster is realized.
+ * (Regrettably QOM provides no way to prevent adding children to a realized
+ * object and no way for the parent to be notified when a new child is added
+ * to it, so this restriction is not checked for, but the system will not
+ * behave correctly if it is not adhered to. The cluster will assert that
+ * it contains at least one CPU, which should catch most inadvertent
+ * violations of this constraint.)
+ *
+ * A CPU which is not put into any cluster will be considered implicitly
+ * to be in a cluster with all the other "loose" CPUs, so all CPUs that are
+ * not assigned to clusters must be identical.
*/
#define TYPE_CPU_CLUSTER "cpu-cluster"
#define CPU_CLUSTER(obj) \
OBJECT_CHECK(CPUClusterState, (obj), TYPE_CPU_CLUSTER)
+/*
+ * This limit is imposed by TCG, which puts the cluster ID into an
+ * 8 bit field (and uses all-1s for the default "not in any cluster").
+ */
+#define MAX_CLUSTERS 255
+
/**
* CPUClusterState:
* @cluster_id: The cluster ID. This value is for internal use only and should
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 16bbed1ae09..4c2feb9c17b 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -280,6 +280,11 @@ struct qemu_work_item;
/**
* CPUState:
* @cpu_index: CPU index (informative).
+ * @cluster_index: Identifies which cluster this CPU is in.
+ * For boards which don't define clusters or for "loose" CPUs not assigned
+ * to a cluster this will be UNASSIGNED_CLUSTER_INDEX; otherwise it will
+ * be the same as the cluster-id property of the CPU object's
TYPE_CPU_CLUSTER
+ * QOM parent.
* @nr_cores: Number of cores within this CPU package.
* @nr_threads: Number of threads within this CPU.
* @running: #true if CPU is currently running (lockless).
@@ -405,6 +410,7 @@ struct CPUState {
/* TODO Move common fields from CPUArchState here. */
int cpu_index;
+ int cluster_index;
uint32_t halted;
uint32_t can_do_io;
int32_t exception_index;
@@ -1111,5 +1117,6 @@ extern const struct VMStateDescription vmstate_cpu_common;
#endif /* NEED_CPU_H */
#define UNASSIGNED_CPU_INDEX -1
+#define UNASSIGNED_CLUSTER_INDEX -1
#endif
diff --git a/hw/cpu/cluster.c b/hw/cpu/cluster.c
index 9d50a235d5c..25f90702b16 100644
--- a/hw/cpu/cluster.c
+++ b/hw/cpu/cluster.c
@@ -20,19 +20,65 @@
#include "qemu/osdep.h"
#include "hw/cpu/cluster.h"
+#include "qom/cpu.h"
#include "qapi/error.h"
#include "qemu/module.h"
+#include "qemu/cutils.h"
static Property cpu_cluster_properties[] = {
DEFINE_PROP_UINT32("cluster-id", CPUClusterState, cluster_id, 0),
DEFINE_PROP_END_OF_LIST()
};
+typedef struct CallbackData {
+ CPUClusterState *cluster;
+ int cpu_count;
+} CallbackData;
+
+static int add_cpu_to_cluster(Object *obj, void *opaque)
+{
+ CallbackData *cbdata = opaque;
+ CPUState *cpu = (CPUState *)object_dynamic_cast(obj, TYPE_CPU);
+
+ if (cpu) {
+ cpu->cluster_index = cbdata->cluster->cluster_id;
+ cbdata->cpu_count++;
+ }
+ return 0;
+}
+
+static void cpu_cluster_realize(DeviceState *dev, Error **errp)
+{
+ /* Iterate through all our CPU children and set their cluster_index */
+ CPUClusterState *cluster = CPU_CLUSTER(dev);
+ Object *cluster_obj = OBJECT(dev);
+ CallbackData cbdata = {
+ .cluster = cluster,
+ .cpu_count = 0,
+ };
+
+ if (cluster->cluster_id >= MAX_CLUSTERS) {
+ error_setg(errp, "cluster-id must be less than %d", MAX_CLUSTERS);
+ return;
+ }
+
+ object_child_foreach_recursive(cluster_obj, add_cpu_to_cluster, &cbdata);
+
+ /*
+ * A cluster with no CPUs is a bug in the board/SoC code that created it;
+ * if you hit this during development of new code, check that you have
+ * created the CPUs and parented them into the cluster object before
+ * realizing the cluster object.
+ */
+ assert(cbdata.cpu_count > 0);
+}
+
static void cpu_cluster_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->props = cpu_cluster_properties;
+ dc->realize = cpu_cluster_realize;
}
static const TypeInfo cpu_cluster_type_info = {
diff --git a/qom/cpu.c b/qom/cpu.c
index 5442a7323be..f5579b1cd50 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -364,6 +364,7 @@ static void cpu_common_initfn(Object *obj)
CPUClass *cc = CPU_GET_CLASS(obj);
cpu->cpu_index = UNASSIGNED_CPU_INDEX;
+ cpu->cluster_index = UNASSIGNED_CLUSTER_INDEX;
cpu->gdb_num_regs = cpu->gdb_num_g_regs = cc->gdb_num_core_regs;
/* *-user doesn't have configurable SMP topology */
/* the default value is changed by qemu_init_vcpu() for softmmu */