Re: [Qemu-devel] [PATCH 06/10] spapr: add hotplug interrupt machine options

[David Gibson]

On Mon, Oct 24, 2016 at 11:47:32PM -0500, Michael Roth wrote:
> This adds machine options of the form:
> 
>   -machine pseries,modern-hotplug-events=true
>   -machine pseries,modern-hotplug-events=false
> 
> If false, QEMU will force the use of "legacy" style hotplug events,
> which are surfaced through EPOW events instead of a dedicated
> hot plug event source, and lack certain features necessary, mainly,
> for memory unplug support.
> 
> If true, QEMU will enable support for "modern" dedicated hot plug
> event source. Note that we will still default to "legacy" style unless
> the guest advertises support for the "modern" hotplug events via
> ibm,client-architecture-support hcall during early boot.
> 
> For pseries-2.7 and earlier we default to false, for newer machine
> types we default to true.
> 
> Signed-off-by: Michael Roth <address@hidden>

I think this either needs to go after the next patch, or be merged
with it.

As it stands, after this patch, you're advertising availability of the
new mechanism without having actually implemented it.

> ---
>  hw/ppc/spapr.c              | 33 +++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h      |  1 +
>  include/hw/ppc/spapr_ovec.h |  1 +
>  3 files changed, 35 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 828072a..a3ea140 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1789,6 +1789,11 @@ static void ppc_spapr_init(MachineState *machine)
>  
>      spapr_ovec_set(spapr->ov5, OV5_FORM1_AFFINITY);
>  
> +    /* advertise support for dedicated HP event source to guests */
> +    if (spapr->use_hotplug_event_source) {
> +        spapr_ovec_set(spapr->ov5, OV5_HP_EVT);
> +    }
> +
>      /* init CPUs */
>      if (machine->cpu_model == NULL) {
>          machine->cpu_model = kvm_enabled() ? "host" : smc->tcg_default_cpu;
> @@ -2138,16 +2143,41 @@ static void spapr_set_kvm_type(Object *obj, const 
> char *value, Error **errp)
>      spapr->kvm_type = g_strdup(value);
>  }
>  
> +static bool spapr_get_modern_hotplug_events(Object *obj, Error **errp)
> +{
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> +    return spapr->use_hotplug_event_source;
> +}
> +
> +static void spapr_set_modern_hotplug_events(Object *obj, bool value,
> +                                            Error **errp)
> +{
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> +
> +    spapr->use_hotplug_event_source = value;
> +}
> +
>  static void spapr_machine_initfn(Object *obj)
>  {
>      sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
>  
>      spapr->htab_fd = -1;
> +    spapr->use_hotplug_event_source = true;
>      object_property_add_str(obj, "kvm-type",
>                              spapr_get_kvm_type, spapr_set_kvm_type, NULL);
>      object_property_set_description(obj, "kvm-type",
>                                      "Specifies the KVM virtualization mode 
> (HV, PR)",
>                                      NULL);
> +    object_property_add_bool(obj, "modern-hotplug-events",
> +                            spapr_get_modern_hotplug_events,
> +                            spapr_set_modern_hotplug_events,
> +                            NULL);
> +    object_property_set_description(obj, "modern-hotplug-events",
> +                                    "Use dedicated hotplug event mechanism 
> in"
> +                                    " place of standard EPOW events when 
> possible"
> +                                    " (required for memory hot-unplug 
> support)",
> +                                    NULL);
>  }
>  
>  static void spapr_machine_finalizefn(Object *obj)
> @@ -2594,7 +2624,10 @@ static void phb_placement_2_7(sPAPRMachineState 
> *spapr, uint32_t index,
>  
>  static void spapr_machine_2_7_instance_options(MachineState *machine)
>  {
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
> +
>      spapr_machine_2_8_instance_options(machine);
> +    spapr->use_hotplug_event_source = false;
>  }
>  
>  static void spapr_machine_2_7_class_options(MachineClass *mc)
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index b6f9f1b..851f536 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -80,6 +80,7 @@ struct sPAPRMachineState {
>      uint32_t check_exception_irq;
>      Notifier epow_notifier;
>      QTAILQ_HEAD(, sPAPREventLogEntry) pending_events;
> +    bool use_hotplug_event_source;
>  
>      /* Migration state */
>      int htab_save_index;
> diff --git a/include/hw/ppc/spapr_ovec.h b/include/hw/ppc/spapr_ovec.h
> index 47fa04c..92167c6 100644
> --- a/include/hw/ppc/spapr_ovec.h
> +++ b/include/hw/ppc/spapr_ovec.h
> @@ -45,6 +45,7 @@ typedef struct sPAPROptionVector sPAPROptionVector;
>  /* option vector 5 */
>  #define OV5_DRCONF_MEMORY       OV_BIT(2, 2)
>  #define OV5_FORM1_AFFINITY      OV_BIT(5, 0)
> +#define OV5_HP_EVT              OV_BIT(6, 5)
>  
>  /* interfaces */
>  sPAPROptionVector *spapr_ovec_new(void);

-- 
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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