Re: [Qemu-devel] [PATCH v3 7/7] spapr: consolidate the logic of core cpu_dt_id

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Jul 06, 2016 at 02:14:59PM +0200, Greg Kurz wrote:
> POWER5 and newer cpus from IBM have a specific numbering scheme for
> DT ids. This is currently open coded in several places.
> 
> This patch consolidates the logic in helpers.
> 
> Suggested-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> Signed-off-by: Greg Kurz <groug@kaod.org>

This seems backwards to me.  I think we should be constructing the
vcpu ids from the core id, not the other way around.  Doing things
that way will take a bit longer, but this seems like execessive work
as an interim cleanup until it's obsoleted by core based numbering.

> ---
>  hw/ppc/spapr.c                  |   11 ++++-------
>  hw/ppc/spapr_cpu_core.c         |   26 +++++++++++++++++++-------
>  include/hw/ppc/spapr_cpu_core.h |    9 +++++++++
>  3 files changed, 32 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index baefc7bd279c..89e61b976c60 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -199,7 +199,6 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr)
>      int ret = 0, offset, cpus_offset;
>      CPUState *cs;
>      char cpu_model[32];
> -    int smt = kvmppc_smt_threads();
>      uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
>  
>      CPU_FOREACH(cs) {
> @@ -207,7 +206,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr)
>          DeviceClass *dc = DEVICE_GET_CLASS(cs);
>          int index = ppc_get_vcpu_dt_id(cpu);
>  
> -        if ((index % smt) != 0) {
> +        if (!spapr_core_dt_id_is_valid(index)) {
>              continue;
>          }
>  
> @@ -735,7 +734,6 @@ static void spapr_populate_cpus_dt_node(void *fdt, sPAPRMachineState *spapr)
>      CPUState *cs;
>      int cpus_offset;
>      char *nodename;
> -    int smt = kvmppc_smt_threads();
>  
>      cpus_offset = fdt_add_subnode(fdt, 0, "cpus");
>      _FDT(cpus_offset);
> @@ -753,7 +751,7 @@ static void spapr_populate_cpus_dt_node(void *fdt, sPAPRMachineState *spapr)
>          DeviceClass *dc = DEVICE_GET_CLASS(cs);
>          int offset;
>  
> -        if ((index % smt) != 0) {
> +        if (!spapr_core_dt_id_is_valid(index)) {
>              continue;
>          }
>  
> @@ -1822,7 +1820,7 @@ static void ppc_spapr_init(MachineState *machine)
>  
>          spapr->cores = g_new0(Object *, spapr_max_cores);
>          for (i = 0; i < spapr_max_cores; i++) {
> -            int core_dt_id = i * smt;
> +            int core_dt_id = spapr_core_index_to_dt_id(i);
>              sPAPRDRConnector *drc =
>                  spapr_dr_connector_new(OBJECT(spapr),
>                                         SPAPR_DR_CONNECTOR_TYPE_CPU, core_dt_id);
> @@ -2386,7 +2384,6 @@ static HotpluggableCPUList *spapr_query_hotpluggable_cpus(MachineState *machine)
>      HotpluggableCPUList *head = NULL;
>      sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
>      int spapr_max_cores = max_cpus / smp_threads;
> -    int smt = kvmppc_smt_threads();
>  
>      for (i = 0; i < spapr_max_cores; i++) {
>          HotpluggableCPUList *list_item = g_new0(typeof(*list_item), 1);
> @@ -2396,7 +2393,7 @@ static HotpluggableCPUList *spapr_query_hotpluggable_cpus(MachineState *machine)
>          cpu_item->type = spapr_get_cpu_core_type(machine->cpu_model);
>          cpu_item->vcpus_count = smp_threads;
>          cpu_props->has_core_id = true;
> -        cpu_props->core_id = i * smt;
> +        cpu_props->core_id = spapr_core_index_to_dt_id(i);
>          /* TODO: add 'has_node/node' here to describe
>             to which node core belongs */
>  
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index e3a3024baf32..b104778350df 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -103,7 +103,6 @@ static void spapr_core_release(DeviceState *dev, void *opaque)
>      size_t size = object_type_get_instance_size(typename);
>      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>      CPUCore *cc = CPU_CORE(dev);
> -    int smt = kvmppc_smt_threads();
>      int i;
>  
>      for (i = 0; i < cc->nr_threads; i++) {
> @@ -117,7 +116,7 @@ static void spapr_core_release(DeviceState *dev, void *opaque)
>          object_unparent(obj);
>      }
>  
> -    spapr->cores[cc->core_id / smt] = NULL;
> +    spapr->cores[spapr_dt_id_to_core_index(cc->core_id)] = NULL;
>  
>      g_free(sc->threads);
>      object_unparent(OBJECT(dev));
> @@ -160,10 +159,9 @@ void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      void *fdt = NULL;
>      int fdt_offset = 0;
>      int index;
> -    int smt = kvmppc_smt_threads();
>  
>      drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
> -    index = cc->core_id / smt;
> +    index = spapr_dt_id_to_core_index(cc->core_id);
>      spapr->cores[index] = OBJECT(dev);
>  
>      if (!smc->dr_cpu_enabled) {
> @@ -217,7 +215,6 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
>      int spapr_max_cores = max_cpus / smp_threads;
>      int index;
> -    int smt = kvmppc_smt_threads();
>      Error *local_err = NULL;
>      CPUCore *cc = CPU_CORE(dev);
>      char *base_core_type = spapr_get_cpu_core_type(machine->cpu_model);
> @@ -238,12 +235,12 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>          goto out;
>      }
>  
> -    if (cc->core_id % smt) {
> +    if (!spapr_core_dt_id_is_valid(cc->core_id)) {
>          error_setg(&local_err, "invalid core id %d\n", cc->core_id);
>          goto out;
>      }
>  
> -    index = cc->core_id / smt;
> +    index = spapr_dt_id_to_core_index(cc->core_id);
>      if (index < 0 || index >= spapr_max_cores) {
>          error_setg(&local_err, "core id %d out of range", cc->core_id);
>          goto out;
> @@ -331,6 +328,21 @@ static void spapr_cpu_core_class_init(ObjectClass *oc, void *data)
>      dc->realize = spapr_cpu_core_realize;
>  }
>  
> +unsigned spapr_core_index_to_dt_id(unsigned index)
> +{
> +    return index * kvmppc_smt_threads();
> +}
> +
> +unsigned spapr_dt_id_to_core_index(unsigned dt_id)
> +{
> +    return dt_id / kvmppc_smt_threads();
> +}
> +
> +unsigned spapr_dt_id_to_thread_index(unsigned dt_id)
> +{
> +    return dt_id % kvmppc_smt_threads();
> +}
> +
>  /*
>   * instance_init routines from different flavours of sPAPR CPU cores.
>   */
> diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
> index 1c9b3195cce9..be7be91308ce 100644
> --- a/include/hw/ppc/spapr_cpu_core.h
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -33,4 +33,13 @@ void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>                       Error **errp);
>  void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
>                         Error **errp);
> +
> +unsigned spapr_core_index_to_dt_id(unsigned index);
> +unsigned spapr_dt_id_to_core_index(unsigned dt_id);
> +unsigned spapr_dt_id_to_thread_index(unsigned dt_id);
> +
> +static inline bool spapr_core_dt_id_is_valid(unsigned dt_id)
> +{
> +    return spapr_dt_id_to_thread_index(dt_id) == 0;
> +}
>  #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

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