Re: [Qemu-devel] [RFC PATCH v0 2/6] spapr: CPU core device

[Thomas Huth <thuth@redhat.com>]

On 25.02.2016 17:22, Bharata B Rao wrote:
> Add sPAPR specific CPU core device that is based on generic CPU core device.
> Creating this core device will result in creation of all the CPU thread
> devices that are part of this core.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> ---
...
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> new file mode 100644
> index 0000000..c44eb61
> --- /dev/null
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -0,0 +1,210 @@
> +/*
> + * sPAPR CPU core device, acts as container of CPU thread devices.
> + *
> + * Copyright (C) 2016 Bharata B Rao <bharata@linux.vnet.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +#include "hw/cpu/core.h"
> +#include "hw/ppc/spapr_cpu_core.h"
> +#include "hw/ppc/spapr.h"
> +#include "hw/boards.h"
> +#include "qemu/error-report.h"
> +#include "qapi/visitor.h"
> +#include <sysemu/cpus.h>
> +
> +static int spapr_cpu_core_realize_child(Object *child, void *opaque)
> +{
> +    Error **errp = opaque;
> +
> +    object_property_set_bool(child, true, "realized", errp);
> +    if (*errp) {
> +        return 1;
> +    }
> +    return 0;
> +}
> +
> +static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +    Error *local_err = NULL;
> +
> +    if (!core->nr_threads) {
> +        error_setg(errp, "nr_threads property can't be 0");
> +        return;
> +    }
> +
> +    if (!core->cpu_model) {
> +        error_setg(errp, "cpu_model property isn't set");
> +        return;
> +    }
> +
> +    /*
> +     * TODO: If slot isn't specified, plug this core into
> +     * an existing empty slot.
> +     */
> +    if (!core->slot) {
> +        error_setg(errp, "slot property isn't set");
> +        return;
> +    }
> +
> +    object_property_set_link(OBJECT(spapr), OBJECT(core), core->slot,
> +                             &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
> +    object_child_foreach(OBJECT(dev), spapr_cpu_core_realize_child, errp);
> +}
> +
> +/*
> + * This creates the CPU threads for a given @core.
> + *
> + * In order to create the threads, we need two inputs - number of
> + * threads and the cpu_model. These are set as core object's properties.
> + * When both of them become available/set, this routine will be called from
> + * either property's set handler to create the threads.
> + *
> + * TODO: Dependence of threads creation on two properties is resulting
> + * in this not-so-clean way of creating threads from either of the
> + * property setters based on the order in which they get set. Check if
> + * this can be handled in a better manner.
> + */
> +static void spapr_cpu_core_create_threads(sPAPRCPUCore *core, Error **errp)
> +{
> +    int i;
> +
> +    for (i = 0; i < core->nr_threads; i++) {
> +        char id[32];
> +        char type[32];
> +
> +        snprintf(type, sizeof(type), "%s-%s", core->cpu_model,
> +                 TYPE_POWERPC_CPU);
> +        object_initialize(&core->threads[i], sizeof(core->threads[i]), type);
> +
> +        snprintf(id, sizeof(id), "thread[%d]", i);
> +        object_property_add_child(OBJECT(core), id, OBJECT(&core->threads[i]),
> +                                  errp);

Need to check errp here to see whether something went wrong?

> +    }
> +}
> +
> +static char *spapr_cpu_core_prop_get_slot(Object *obj, Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +
> +    return core->slot;
> +}
> +
> +static void spapr_cpu_core_prop_set_slot(Object *obj, const char *val,
> +                                              Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +
> +    core->slot = g_strdup(val);
> +}
> +
> +static char *spapr_cpu_core_prop_get_cpu_model(Object *obj, Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +
> +    return core->cpu_model;
> +}
> +
> +static void spapr_cpu_core_prop_set_cpu_model(Object *obj, const char *val,
> +                                              Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +    MachineState *machine = MACHINE(qdev_get_machine());
> +
> +    /*
> +     * cpu_model can't be different from what is specified with -cpu
> +     */
> +    if (strcmp(val, machine->cpu_model)) {
> +       error_setg(errp, "cpu_model should be %s", machine->cpu_model);

s/should/must/

> +       return;
> +    }
> +
> +    core->cpu_model = g_strdup(val);
> +    if (core->nr_threads && core->cpu_model) {
> +        spapr_cpu_core_create_threads(core, errp);
> +    }
> +}
> +
> +static void spapr_cpu_core_prop_get_nr_threads(Object *obj, Visitor *v,
> +                                               const char *name, void *opaque,
> +                                               Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +    int64_t value = core->nr_threads;
> +
> +    visit_type_int(v, name, &value, errp);
> +}
> +
> +static void spapr_cpu_core_prop_set_nr_threads(Object *obj, Visitor *v,
> +                                               const char *name, void *opaque,
> +                                               Error **errp)
> +{
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(obj);
> +    Error *local_err = NULL;
> +    int64_t value;
> +
> +    visit_type_int(v, name, &value, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
> +    /* Allow only homogeneous configuration */
> +    if (value != smp_threads) {
> +        error_setg(errp, "nr_threads should be %d", smp_threads);

s/should/must/

> +        return;
> +    }
> +
> +    core->nr_threads = value;
> +    core->threads = g_malloc0(core->nr_threads * sizeof(PowerPCCPU));

I think it's preferable to use g_new0 for such allocations instead.

Also, should this memory maybe be freed during instance_finalize again,
so that there is no memory leak here in case the cores are deleted again
one day?

> +    if (core->nr_threads && core->cpu_model) {
> +        spapr_cpu_core_create_threads(core, errp);
> +    }
> +}
> +
> +static void spapr_cpu_core_instance_init(Object *obj)
> +{
> +    object_property_add(obj, "nr_threads", "int",
> +                        spapr_cpu_core_prop_get_nr_threads,
> +                        spapr_cpu_core_prop_set_nr_threads,
> +                        NULL, NULL, NULL);
> +    object_property_add_str(obj, "cpu_model",
> +                            spapr_cpu_core_prop_get_cpu_model,
> +                            spapr_cpu_core_prop_set_cpu_model,
> +                            NULL);
> +    object_property_add_str(obj, "slot",
> +                            spapr_cpu_core_prop_get_slot,
> +                            spapr_cpu_core_prop_set_slot,
> +                            NULL);
> +}
> +
> +static void spapr_cpu_core_class_init(ObjectClass *oc, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +
> +    dc->realize = spapr_cpu_core_realize;
> +}
> +
> +static const TypeInfo spapr_cpu_core_type_info = {
> +    .name = TYPE_SPAPR_CPU_CORE,
> +    .parent = TYPE_CPU_CORE,
> +    .instance_init = spapr_cpu_core_instance_init,
> +    .instance_size = sizeof(sPAPRCPUCore),
> +    .class_init = spapr_cpu_core_class_init,
> +};
> +
> +static void spapr_cpu_core_register_types(void)
> +{
> +    type_register_static(&spapr_cpu_core_type_info);
> +}
> +
> +type_init(spapr_cpu_core_register_types)
> diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
> new file mode 100644
> index 0000000..ed9bc7f
> --- /dev/null
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -0,0 +1,32 @@
> +/*
> + * sPAPR CPU core device.
> + *
> + * Copyright (C) 2016 Bharata B Rao <bharata@linux.vnet.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +#ifndef HW_SPAPR_CPU_CORE_H
> +#define HW_SPAPR_CPU_CORE_H
> +
> +#include "hw/qdev.h"
> +#include "hw/cpu/core.h"
> +
> +#define TYPE_SPAPR_CPU_CORE "spapr-cpu-core"
> +#define SPAPR_CPU_CORE(obj) \
> +    OBJECT_CHECK(sPAPRCPUCore, (obj), TYPE_SPAPR_CPU_CORE)
> +
> +typedef struct sPAPRCPUCore {
> +    /*< private >*/
> +    DeviceState parent_obj;
> +
> +    /*< public >*/
> +    int nr_threads;
> +    char *cpu_model;
> +    char *slot;

<bikeshedpainting>
I'd maybe call that "slot_name" instead ... if you only call it "slot",
I'd rather think of an integer value than a string here.
</bikeshedpainting>

> +    PowerPCCPU *threads;
> +} sPAPRCPUCore;
> +
> +#define SPAPR_CPU_CORE_SLOT_PROP "slot"
> +
> +#endif
> 

 Thomas