Re: [Qemu-devel] [PATCH v2 6/7] spapr: use ppc_set_vcpu_dt_id() in CPU hotplug code

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Sat, Jul 02, 2016 at 12:42:04AM +0200, Greg Kurz wrote:
> Starting with version 2.7, pseries machine now support hotplug of
> cpu cores. The implementation requires to open code cpu creation
> and thus does not call ppc_cpu_init().
> 
> This patch does all the plumbing to allow pseries machine types
> with version >= 2.7 to generate cpu DT ids out of the indexes
> of the cores and threads in their respective arrays.
> 
> Suggested-by: Igor Mammedov <imammedo@redhat.com>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  hw/ppc/ppc.c            |    2 +-
>  hw/ppc/spapr_cpu_core.c |   11 +++++++++--
>  include/hw/ppc/ppc.h    |    1 +
>  3 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index dbc8ac7b3a9b..12de255fb211 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -1352,7 +1352,7 @@ PowerPCCPU *ppc_get_vcpu_by_dt_id(int cpu_dt_id)
>      return NULL;
>  }
> 
> -static void ppc_set_vcpu_dt_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
> +void ppc_set_vcpu_dt_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
>  {
>      ;
>  }
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 70b6b0b5ee17..475c8063f086 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -259,13 +259,20 @@ out:
>      error_propagate(errp, local_err);
>  }
> 
> -static void spapr_cpu_core_realize_child(Object *child, Error **errp)
> +static void spapr_cpu_core_realize_child(Object *child, int cpu_index,
> +                                         Error **errp)
>  {
>      Error *local_err = NULL;
>      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>      CPUState *cs = CPU(child);
>      PowerPCCPU *cpu = POWERPC_CPU(cs);
> 
> +    ppc_set_vcpu_dt_id(cpu, cpu_index, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
>      object_property_set_bool(child, true, "realized", &local_err);
>      if (local_err) {
>          error_propagate(errp, local_err);
> @@ -306,7 +313,7 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
>      for (j = 0; j < cc->nr_threads; j++) {
>          obj = sc->threads + j * size;
> 
> -        spapr_cpu_core_realize_child(obj, &local_err);
> +        spapr_cpu_core_realize_child(obj, cc->core_id + j, &local_err);

cc->core_id is essentially the cpu_dt_id. For boot time cores, we set this
(via core-id prop) explicitly. For hotplugged cores, we expect user to
set this mandatorily on -device/device_add. The value that the
user is expected to provide as core-id is in fact supplied by us via
query-hotpluggable-cpus. So there are two places (ppc_spapr_init &
spapr_query_hotpluggable_cpus) where we generate the cpu_dt_id by
open coding as (core_index * smt). Can we have consolidate this logic
into some well defined routine like ppc_core_index_to_dt_id() ?

Regards,
Bharata.