Re: [Qemu-devel] [RFC PATCH v2 12/23] spapr: CPU hotplug support

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

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On Mon, Mar 23, 2015 at 07:05:53PM +0530, Bharata B Rao wrote:
> Support CPU hotplug via device-add command. 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 <bharata@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c        | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/ppc/spapr_events.c |  8 +++---
>  hw/ppc/spapr_rtas.c   | 11 ++++++++
>  3 files changed, 91 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index f52d38f..b48994b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -33,6 +33,7 @@
>  #include "sysemu/block-backend.h"
>  #include "sysemu/cpus.h"
>  #include "sysemu/kvm.h"
> +#include "sysemu/device_tree.h"
>  #include "kvm_ppc.h"
>  #include "mmu-hash64.h"
>  #include "qom/cpu.h"
> @@ -660,6 +661,10 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset)
>      QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
>      unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
>      uint32_t cpus_per_socket = sockets ? (smp_cpus / sockets) : 1;
> +    sPAPRDRConnector *drc =
> +        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
> +    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    int drc_index = drck->get_index(drc);
>  
>      _FDT((fdt_setprop_cell(fdt, offset, "reg", index)));
>      _FDT((fdt_setprop_string(fdt, offset, "device_type", "cpu")));
> @@ -728,6 +733,8 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset)
>  
>      _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id",
>                              cs->cpu_index / cpus_per_socket)));
> +    _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index)));
> +

What effect will this have when running with DR disabled?

>      _FDT(spapr_fixup_cpu_numa_smt_dt(fdt, offset, cs, spapr));
>  }
> @@ -1840,6 +1847,70 @@ static void spapr_nmi(NMIState *n, int cpu_index, Error **errp)
>      }
>  }
>  
> +static void spapr_cpu_hotplug_add(DeviceState *dev, CPUState *cs, Error **errp)
> +{
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    DeviceClass *dc = DEVICE_GET_CLASS(cs);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    sPAPRDRConnector *drc =
> +        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> +    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    void *fdt;
> +    int offset, i, fdt_size;
> +    char *nodename;
> +
> +    fdt = create_device_tree(&fdt_size);
> +    nodename = g_strdup_printf("%s@%x", dc->fw_name, id);
> +    offset = fdt_add_subnode(fdt, 0, nodename);
> +
> +    /* Set NUMA node for the added CPU core */
> +    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_populate_cpu_dt(cs, fdt, offset);
> +    g_free(nodename);
> +
> +    drck->attach(drc, dev, fdt, offset, !dev->hotplugged, errp);
> +    if (*errp) {
> +        g_free(fdt);
> +    }
> +}
> +
> +static void spapr_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> +                            Error **errp)
> +{
> +    CPUState *cs = CPU(dev);
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    sPAPRDRConnector *drc =
> +        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> +    int smt = kvmppc_smt_threads();
> +    Error *local_err = NULL;
> +
> +    /*
> +     * SMT threads return from here, only main thread (core) will
> +     * continue and signal hotplug event to the guest.
> +     */
> +    if ((id % smt) != 0) {
> +        return;
> +    }
> +
> +    g_assert(drc);
> +
> +    spapr_cpu_hotplug_add(dev, cs, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +    spapr_hotplug_req_add_event(drc);
> +
> +    return;
> +}
> +
>  static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
> @@ -1848,6 +1919,10 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>          PowerPCCPU *cpu = POWERPC_CPU(cs);
>  
>          spapr_cpu_init(cpu);
> +        spapr_cpu_reset(cpu);
> +        if (dev->hotplugged && spapr->dr_cpu_enabled) {
> +            spapr_cpu_plug(hotplug_dev, dev, errp);
> +        }
>      }
>  }
>  
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index be82815..4ae818a 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -421,14 +421,16 @@ static void spapr_hotplug_req_event(sPAPRDRConnector *drc, uint8_t hp_action)
>      hp->hdr.section_length = cpu_to_be16(sizeof(*hp));
>      hp->hdr.section_version = 1; /* includes extended modifier */
>      hp->hotplug_action = hp_action;
> -
> +    hp->drc.index = cpu_to_be32(drck->get_index(drc));
> +    hp->hotplug_identifier = RTAS_LOG_V6_HP_ID_DRC_INDEX;
>  
>      switch (drc_type) {
>      case SPAPR_DR_CONNECTOR_TYPE_PCI:
> -        hp->drc.index = cpu_to_be32(drck->get_index(drc));
> -        hp->hotplug_identifier = RTAS_LOG_V6_HP_ID_DRC_INDEX;
>          hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_PCI;
>          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 57ec97a..48aeb86 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -121,6 +121,16 @@ static void rtas_query_cpu_stopped_state(PowerPCCPU *cpu_,
>      rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>  }
>  
> +static void spapr_cpu_set_endianness(PowerPCCPU *cpu)
> +{
> +    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(fcpu);

In some ways it might be nicer to store the global endian mode in
sPAPRMachineState, updating it on H_SET_MODE, rather than copying the
first cpu, although I guess that works.

> +    if (!(*pcc->interrupts_big_endian)(fcpu)) {
> +        cpu->env.spr[SPR_LPCR] |= LPCR_ILE;
> +    }
> +}
> +
>  static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
>                             uint32_t token, uint32_t nargs,
>                             target_ulong args,
> @@ -157,6 +167,7 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
>          env->nip = start;
>          env->gpr[3] = r3;
>          cs->halted = 0;
> +        spapr_cpu_set_endianness(cpu);
>  
>          qemu_cpu_kick(cs);
>  

-- 
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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