Re: [Qemu-devel] [RFC 08/13] pc: add writeonly 'cpu' property to PCMachine

[Igor Mammedov]

On Wed, 18 Jan 2017 16:27:21 -0200
Eduardo Habkost <address@hidden> wrote:

> On Wed, Jan 18, 2017 at 06:13:24PM +0100, Igor Mammedov wrote:
> > it will allow generic numa code to set cpu to numa node mapping
> > in target independent manner in the next patch.
> > 
> > Signed-off-by: Igor Mammedov <address@hidden>  
> 
> This looks like a creative way to abuse the QOM property system.
> What's the problem with using a simple C function like:
>   void (*set_cpu_affinity)(MachineState *m, CpuInstanceProperties *props, 
> Error **errp)
Agreed, it should simplify parsing code as well.

> ?
> 
> 
> > ---
> >  hw/i386/pc.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 56 insertions(+)
> > 
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index f8ea635..1d33a5e 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -2201,6 +2201,56 @@ static void pc_machine_set_pit(Object *obj, bool 
> > value, Error **errp)
> >      pcms->pit = value;
> >  }
> >  
> > +static void pc_machine_set_cpu(Object *obj, Visitor *v, const char *name,
> > +                               void *opaque, Error **errp)
> > +{
> > +    uint32_t apic_id;
> > +    X86CPUTopoInfo topo;
> > +    CPUArchId *cpu_slot;
> > +    Error *local_err = NULL;
> > +    CpuInstanceProperties *cpu_props = NULL;
> > +    PCMachineState *pcms = PC_MACHINE(obj);
> > +    MachineClass *mc = MACHINE_GET_CLASS(obj);
> > +
> > +    visit_type_CpuInstanceProperties(v, name, &cpu_props, &local_err);
> > +    if (local_err) {
> > +        goto out;
> > +    }
> > +
> > +    if (!cpu_props->has_node_id) {
> > +        error_setg(&local_err, "node-id property is not specified");
> > +        goto out;
> > +    }
> > +
> > +    /*
> > +     * make sure that possible_cpus is initialized
> > +     * as property setter might be called before machine init is called
> > +     */
> > +    mc->possible_cpu_arch_ids(MACHINE(obj));
> > +
> > +    topo.pkg_id = cpu_props->socket_id;
> > +    topo.core_id = cpu_props->core_id;
> > +    topo.smt_id = cpu_props->thread_id;
> > +    apic_id = apicid_from_topo_ids(smp_cores, smp_threads, &topo);
> > +    cpu_slot = pc_find_cpu_slot(pcms, apic_id, NULL);
> > +    if (!cpu_slot) {
> > +        error_setg(&local_err, "unable to find CPU");
> > +        goto out;
> > +    }
> > +
> > +    if (cpu_slot->props.has_node_id) {
> > +        error_setg(&local_err, "CPU has already been assigned to node: 
> > %"PRId64,
> > +                   cpu_slot->props.node_id);
> > +        goto out;
> > +    }
> > +    cpu_slot->props.has_node_id = true;
> > +    cpu_slot->props.node_id = cpu_props->node_id;
> > +
> > + out:
> > +    error_propagate(errp, local_err);
> > +    qapi_free_CpuInstanceProperties(cpu_props);
> > +}
> > +
> >  static void pc_machine_initfn(Object *obj)
> >  {
> >      PCMachineState *pcms = PC_MACHINE(obj);
> > @@ -2395,6 +2445,12 @@ static void pc_machine_class_init(ObjectClass *oc, 
> > void *data)
> >  
> >      object_class_property_add_bool(oc, PC_MACHINE_PIT,
> >          pc_machine_get_pit, pc_machine_set_pit, &error_abort);
> > +
> > +    object_class_property_add(oc, "cpu", "CpuInstanceProperties",
> > +        NULL, pc_machine_set_cpu,
> > +        NULL, NULL, &error_abort);
> > +    object_class_property_set_description(oc, "cpu",
> > +        "Possible cpu placement", &error_abort);
> >  }
> >  
> >  static const TypeInfo pc_machine_info = {
> > -- 
> > 2.7.4
> >   
>