Re: [Qemu-devel] [RFC PATCH v0 4/6] spapr: CPU hotplug support

[David Gibson]

On Thu, Feb 25, 2016 at 09:52:40PM +0530, Bharata B Rao wrote:
> Set up device tree entries for the hotplugged CPU core and use the
> exising EPOW event infrastructure to send CPU hotplug notification to
> the guest.
> 
> Signed-off-by: Bharata B Rao <address@hidden>
> ---
>  hw/ppc/spapr.c         | 136 
> ++++++++++++++++++++++++++++++++++++++++++++++++-
>  hw/ppc/spapr_events.c  |   3 ++
>  hw/ppc/spapr_rtas.c    |  24 +++++++++
>  include/hw/ppc/spapr.h |   1 +
>  4 files changed, 163 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 1f0d232..780cd00 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -603,6 +603,18 @@ static void spapr_populate_cpu_dt(CPUState *cs, void 
> *fdt, int offset,
>      size_t page_sizes_prop_size;
>      uint32_t vcpus_per_socket = smp_threads * smp_cores;
>      uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
> +    sPAPRDRConnector *drc;
> +    sPAPRDRConnectorClass *drck;
> +    int drc_index;
> +
> +    if (smc->dr_cpu_enabled) {
> +        drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
> +        g_assert(drc);
> +        drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +        drc_index = drck->get_index(drc);
> +        _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index)));
> +    }
>  
>      /* Note: we keep CI large pages off for now because a 64K capable guest
>       * provisioned with large pages might otherwise try to map a qemu
> @@ -987,6 +999,16 @@ static void spapr_finalize_fdt(sPAPRMachineState *spapr,
>          _FDT(spapr_drc_populate_dt(fdt, 0, NULL, 
> SPAPR_DR_CONNECTOR_TYPE_LMB));
>      }
>  
> +    if (smc->dr_cpu_enabled) {
> +        int offset = fdt_path_offset(fdt, "/cpus");
> +        ret = spapr_drc_populate_dt(fdt, offset, NULL,
> +                                    SPAPR_DR_CONNECTOR_TYPE_CPU);
> +        if (ret < 0) {
> +            fprintf(stderr, "Couldn't set up CPU DR device tree 
> properties\n");
> +            exit(1);
> +        }
> +    }
> +
>      _FDT((fdt_pack(fdt)));
>  
>      if (fdt_totalsize(fdt) > FDT_MAX_SIZE) {
> @@ -1759,6 +1781,7 @@ static void ppc_spapr_init(MachineState *machine)
>      char *filename;
>      int spapr_cores = smp_cpus / smp_threads;
>      int spapr_max_cores = max_cpus / smp_threads;
> +    int smt = kvmppc_smt_threads();
>  
>      msi_supported = true;
>  
> @@ -1813,6 +1836,15 @@ static void ppc_spapr_init(MachineState *machine)
>          spapr_validate_node_memory(machine, &error_fatal);
>      }
>  
> +    if (smc->dr_cpu_enabled) {
> +        for (i = 0; i < spapr_max_cores; i++) {
> +            sPAPRDRConnector *drc =
> +                spapr_dr_connector_new(OBJECT(spapr),
> +                                       SPAPR_DR_CONNECTOR_TYPE_CPU, i * smt);
> +            qemu_register_reset(spapr_drc_reset, drc);
> +        }
> +    }
> +
>      /* init CPUs */
>      if (machine->cpu_model == NULL) {
>          machine->cpu_model = kvm_enabled() ? "host" : "POWER7";
> @@ -2247,6 +2279,88 @@ out:
>      error_propagate(errp, local_err);
>  }
>  
> +static void *spapr_populate_hotplug_cpu_dt(DeviceState *dev, CPUState *cs,
> +                                           int *fdt_offset,
> +                                           sPAPRMachineState *spapr)
> +{
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    DeviceClass *dc = DEVICE_GET_CLASS(cs);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    void *fdt;
> +    int offset, fdt_size;
> +    char *nodename;
> +
> +    fdt = create_device_tree(&fdt_size);
> +    nodename = g_strdup_printf("address@hidden", dc->fw_name, id);
> +    offset = fdt_add_subnode(fdt, 0, nodename);
> +
> +    spapr_populate_cpu_dt(cs, fdt, offset, spapr);
> +    g_free(nodename);
> +
> +    *fdt_offset = offset;
> +    return fdt;
> +}
> +
> +static void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> +                            Error **errp)
> +{
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
> +    sPAPRMachineState *ms = SPAPR_MACHINE(qdev_get_machine());
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> +    PowerPCCPU *cpu = &core->threads[0];
> +    CPUState *cs = CPU(cpu);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    sPAPRDRConnector *drc =
> +        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> +    sPAPRDRConnectorClass *drck;
> +    Error *local_err = NULL;
> +    void *fdt = NULL;
> +    int fdt_offset = 0;
> +
> +    if (!smc->dr_cpu_enabled) {
> +        /*
> +         * This is a cold plugged CPU core but the machine doesn't support
> +         * DR. So skip the hotplug path ensuring that the core is brought
> +         * up online with out an associated DR connector.
> +         */
> +        return;
> +    }
> +
> +    g_assert(drc);
> +
> +    /*
> +     * Setup CPU DT entries only for hotplugged CPUs. For boot time or
> +     * coldplugged CPUs DT entries are setup in spapr_finalize_fdt().
> +     */
> +    if (dev->hotplugged) {
> +        fdt = spapr_populate_hotplug_cpu_dt(dev, cs, &fdt_offset, ms);
> +        dev->hotplugged = true;
> +    }
> +
> +    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, &local_err);
> +    if (local_err) {
> +        g_free(fdt);
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
> +    if (dev->hotplugged) {
> +        /*
> +         * Send hotplug notification interrupt to the guest only in case
> +         * of hotplugged CPUs.
> +         */
> +        spapr_hotplug_req_add_by_index(drc);
> +    } else {
> +        /*
> +         * Set the right DRC states for cold plugged CPU.
> +         */
> +        drck->set_allocation_state(drc, SPAPR_DR_ALLOCATION_STATE_USABLE);
> +        drck->set_isolation_state(drc, SPAPR_DR_ISOLATION_STATE_UNISOLATED);
> +    }
> +    return;
> +}
> +
>  static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
> @@ -2291,8 +2405,25 @@ static void spapr_machine_device_plug(HotplugHandler 
> *hotplug_dev,
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
>          CPUState *cs = CPU(dev);
>          PowerPCCPU *cpu = POWERPC_CPU(cs);
> +        int i;
> +
> +        if (!smc->dr_cpu_enabled && dev->hotplugged) {
> +            error_setg(errp, "CPU hotplug not supported for this machine");
> +            return;
> +        }
> +
> +        /* Set NUMA node for the added CPUs  */
> +        for (i = 0; i < nb_numa_nodes; i++) {
> +            if (test_bit(cs->cpu_index, numa_info[i].node_cpu)) {
> +                cs->numa_node = i;
> +                break;
> +            }
> +        }
>  
>          spapr_cpu_init(ms, cpu, errp);
> +        spapr_cpu_reset(cpu);

It looks to me like all of this setup should be either in the last
patch, or in this one, not split between them.

> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
> +        spapr_core_plug(hotplug_dev, dev, errp);
>      }
>  }
>  
> @@ -2308,7 +2439,8 @@ static HotplugHandler 
> *spapr_get_hotpug_handler(MachineState *machine,
>                                               DeviceState *dev)
>  {
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
> -        object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> +        object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
> +        object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
>          return HOTPLUG_HANDLER(machine);
>      }
>      return NULL;
> @@ -2352,6 +2484,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>      mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
>  
>      smc->dr_lmb_enabled = true;
> +    smc->dr_cpu_enabled = true;
>      fwc->get_dev_path = spapr_get_fw_dev_path;
>      nc->nmi_monitor_handler = spapr_nmi;
>  }
> @@ -2431,6 +2564,7 @@ static void 
> spapr_machine_2_5_class_options(MachineClass *mc)
>  
>      spapr_machine_2_6_class_options(mc);
>      smc->use_ohci_by_default = true;
> +    smc->dr_cpu_enabled = false;
>      SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_5);
>  }
>  
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index f5eac4b..e50bb16 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -437,6 +437,9 @@ static void spapr_hotplug_req_event(uint8_t hp_id, 
> uint8_t hp_action,
>      case SPAPR_DR_CONNECTOR_TYPE_LMB:
>          hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_MEMORY;
>          break;
> +    case SPAPR_DR_CONNECTOR_TYPE_CPU:
> +        hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_CPU;
> +        break;
>      default:
>          /* we shouldn't be signaling hotplug events for resources
>           * that don't support them
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index b7c5ebd..cc0369e 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -34,6 +34,7 @@
>  
>  #include "hw/ppc/spapr.h"
>  #include "hw/ppc/spapr_vio.h"
> +#include "hw/ppc/ppc.h"
>  #include "qapi-event.h"
>  #include "hw/boards.h"
>  
> @@ -161,6 +162,27 @@ static void rtas_query_cpu_stopped_state(PowerPCCPU 
> *cpu_,
>      rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>  }
>  
> +/*
> + * Set the timebase offset of the CPU to that of first CPU.
> + * This helps hotplugged CPU to have the correct timebase offset.
> + */
> +static void spapr_cpu_update_tb_offset(PowerPCCPU *cpu)
> +{
> +    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> +
> +    cpu->env.tb_env->tb_offset = fcpu->env.tb_env->tb_offset;
> +}
> +
> +static void spapr_cpu_set_endianness(PowerPCCPU *cpu)
> +{
> +    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(fcpu);
> +
> +    if (!pcc->interrupts_big_endian(fcpu)) {
> +        cpu->env.spr[SPR_LPCR] |= LPCR_ILE;
> +    }
> +}
> +

Any particular reason for doing these things at rtas_start_cpu() time,
but other initialization at plug time?  Could you consolidate it to
one place or the other?

>  static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPRMachineState *spapr,
>                             uint32_t token, uint32_t nargs,
>                             target_ulong args,
> @@ -197,6 +219,8 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, 
> sPAPRMachineState *spapr,
>          env->nip = start;
>          env->gpr[3] = r3;
>          cs->halted = 0;
> +        spapr_cpu_set_endianness(cpu);
> +        spapr_cpu_update_tb_offset(cpu);
>  
>          qemu_cpu_kick(cs);
>  
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 20b3417..eb4ccd1 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -36,6 +36,7 @@ struct sPAPRMachineClass {
>  
>      /*< public >*/
>      bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs */
> +    bool dr_cpu_enabled;       /* enable dynamic-reconfig/hotplug of CPUs */
>      bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
>  };
>  

-- 
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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