Re: [Qemu-devel] [RFC PATCH v1 07/13] spapr: Start all the threads of CPU core when core is hotplugged

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

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On Thu, Jan 08, 2015 at 11:40:14AM +0530, Bharata B Rao wrote:
> PowerPC kernel adds or removes CPUs in core granularity and hence
> onlines/offlines all the SMT threads of a core during hot plug/unplug.
> Support this notion by starting all SMT threads of a core when a core
> is hotplugged.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index a293a59..4347471 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1376,6 +1376,8 @@ static void spapr_drc_reset(void *opaque)
>      }
>  }
>  
> +static const char *current_cpu_model;

More new global variables?  Please don't.

>  /* pSeries LPAR / sPAPR hardware init */
>  static void ppc_spapr_init(MachineState *machine)
>  {
> @@ -1473,6 +1475,8 @@ static void ppc_spapr_init(MachineState *machine)
>          }
>      }
>  
> +    current_cpu_model = cpu_model;
> +
>      /* allocate RAM */
>      spapr->ram_limit = ram_size;
>      spapr->maxram_limit = machine->maxram_size;
> @@ -1912,10 +1916,31 @@ static void spapr_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      PowerPCCPU *cpu = POWERPC_CPU(cs);
>      sPAPRDRConnector *drc =
>          spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cpu->cpu_dt_id);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    int smt = kvmppc_smt_threads();
> +    int i;
> +
> +    /*
> +     * SMT threads return from here, only main thread (core) will
> +     * continue, create threads and signal hotplug event to the guest.
> +     */
> +    if ((id % smt) != 0) {
> +        return;
> +    }
>  
>      /* TODO: Check if DR is enabled ? */
>      g_assert(drc);
>  
> +    /* Start rest of the SMT threads of the hot plugged core */
> +    for (i = 1; i < smp_threads; i++) {
> +        cpu = cpu_ppc_init(current_cpu_model);
> +        if (cpu == NULL) {
> +            fprintf(stderr, "Unable to find PowerPC CPU definition\n");
> +            exit(1);
> +        }
> +        spapr_cpu_reset(cpu);
> +    }
> +
>      spapr_cpu_reset(POWERPC_CPU(CPU(dev)));
>      spapr_cpu_hotplug_add(dev, cs);
>      spapr_hotplug_req_add_event(drc);

-- 
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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