Re: [Qemu-ppc] [for-2.7 PATCH v3 06/15] cpu: Abstract CPU core type

[Eduardo Habkost]

On Thu, Jun 02, 2016 at 01:38:58PM +1000, David Gibson wrote:
> On Thu, May 12, 2016 at 09:18:16AM +0530, Bharata B Rao wrote:
> > Add an abstract CPU core type that could be used by machines that want
> > to define and hotplug CPUs in core granularity.
> > 
> > Signed-off-by: Bharata B Rao <address@hidden>
> > Signed-off-by: Igor Mammedov <address@hidden>
> >                [Integer core property]
> > Reviewed-by: David Gibson <address@hidden>
> 
> Igor, Eduardo,
> 
> Do you think we're comfortable enough with this abstract core concept
> to merge it now?  If so which tree should it go through?

TBH, I haven't reviewed the concept carefully. I hoped that
people that spent more time thinking about long-term plans
(especially Andreas) would help move the discussion forward, but
Andreas is moving away from QOM CPU.

I need to review the previous discussions more carefully, but the
concept looks simple enough to me, and I don't think we should
hold spapr work because we want a Grand Plan for generic CPU
abstractions to be finished first. If David, Igor, and the people
working on spapr are happy with it, I trust their judgement.

I just wish the interface was better documented, especially the
meaning of the "core" and "threads" properties. I would prefer to
have "core-id" as the property name instead of "core" (most of
the error messages related to it (in patch 08/15) say "core id").


> 
> > ---
> >  hw/cpu/Makefile.objs  |  1 +
> >  hw/cpu/core.c         | 88 
> > +++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/hw/cpu/core.h | 31 ++++++++++++++++++
> >  3 files changed, 120 insertions(+)
> >  create mode 100644 hw/cpu/core.c
> >  create mode 100644 include/hw/cpu/core.h
> > 
> > diff --git a/hw/cpu/Makefile.objs b/hw/cpu/Makefile.objs
> > index 0954a18..942a4bb 100644
> > --- a/hw/cpu/Makefile.objs
> > +++ b/hw/cpu/Makefile.objs
> > @@ -2,4 +2,5 @@ obj-$(CONFIG_ARM11MPCORE) += arm11mpcore.o
> >  obj-$(CONFIG_REALVIEW) += realview_mpcore.o
> >  obj-$(CONFIG_A9MPCORE) += a9mpcore.o
> >  obj-$(CONFIG_A15MPCORE) += a15mpcore.o
> > +obj-y += core.o
> >  
> > diff --git a/hw/cpu/core.c b/hw/cpu/core.c
> > new file mode 100644
> > index 0000000..fa5bc82
> > --- /dev/null
> > +++ b/hw/cpu/core.c
> > @@ -0,0 +1,88 @@
> > +/*
> > + * CPU core abstract device
> > + *
> > + * Copyright (C) 2016 Bharata B Rao <address@hidden>
> > + *
> > + * 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 "qapi/visitor.h"
> > +#include "qapi/error.h"
> > +#include "sysemu/cpus.h"
> > +
> > +static void core_prop_get_core(Object *obj, Visitor *v, const char *name,
> > +                               void *opaque, Error **errp)
> > +{
> > +    CPUCore *core = CPU_CORE(obj);
> > +    int64_t value = core->core;
> > +
> > +    visit_type_int(v, name, &value, errp);
> > +}
> > +
> > +static void core_prop_set_core(Object *obj, Visitor *v, const char *name,
> > +                               void *opaque, Error **errp)
> > +{
> > +    CPUCore *core = 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;
> > +    }
> > +
> > +    core->core = value;
> > +}
> > +
> > +static void core_prop_get_threads(Object *obj, Visitor *v, const char 
> > *name,
> > +                                  void *opaque, Error **errp)
> > +{
> > +    CPUCore *core = CPU_CORE(obj);
> > +    int64_t value = core->threads;
> > +
> > +    visit_type_int(v, name, &value, errp);
> > +}
> > +
> > +static void core_prop_set_threads(Object *obj, Visitor *v, const char 
> > *name,
> > +                                  void *opaque, Error **errp)
> > +{
> > +    CPUCore *core = 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;
> > +    }
> > +
> > +    core->threads = value;
> > +}
> > +
> > +static void cpu_core_instance_init(Object *obj)
> > +{
> > +    CPUCore *core = CPU_CORE(obj);
> > +
> > +    object_property_add(obj, "core", "int", core_prop_get_core,
> > +                        core_prop_set_core, NULL, NULL, NULL);
> > +    object_property_add(obj, "threads", "int", core_prop_get_threads,
> > +                        core_prop_set_threads, NULL, NULL, NULL);
> > +    core->threads = smp_threads;
> > +}
> > +
> > +static const TypeInfo cpu_core_type_info = {
> > +    .name = TYPE_CPU_CORE,
> > +    .parent = TYPE_DEVICE,
> > +    .abstract = true,
> > +    .instance_size = sizeof(CPUCore),
> > +    .instance_init = cpu_core_instance_init,
> > +};
> > +
> > +static void cpu_core_register_types(void)
> > +{
> > +    type_register_static(&cpu_core_type_info);
> > +}
> > +
> > +type_init(cpu_core_register_types)
> > diff --git a/include/hw/cpu/core.h b/include/hw/cpu/core.h
> > new file mode 100644
> > index 0000000..a2a5a04
> > --- /dev/null
> > +++ b/include/hw/cpu/core.h
> > @@ -0,0 +1,31 @@
> > +/*
> > + * CPU core abstract device
> > + *
> > + * Copyright (C) 2016 Bharata B Rao <address@hidden>
> > + *
> > + * 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_CPU_CORE_H
> > +#define HW_CPU_CORE_H
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/qdev.h"
> > +
> > +#define TYPE_CPU_CORE "cpu-core"
> > +
> > +#define CPU_CORE(obj) \
> > +    OBJECT_CHECK(CPUCore, (obj), TYPE_CPU_CORE)
> > +
> > +typedef struct CPUCore {
> > +    /*< private >*/
> > +    DeviceState parent_obj;
> > +
> > +    /*< public >*/
> > +    int core;
> > +    int threads;
> > +} CPUCore;
> > +
> > +#define CPU_CORE_PROP_CORE "core"
> > +
> > +#endif
> 
> -- 
> David Gibson                  | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au        | minimalist, thank you.  NOT _the_ 
> _other_
>                               | _way_ _around_!
> http://www.ozlabs.org/~dgibson



-- 
Eduardo