Re: [PATCH 04/10] spapr: add spapr_machine_using_legacy_numa() helper

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

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On Fri, Aug 14, 2020 at 05:54:18PM -0300, Daniel Henrique Barboza wrote:
> The changes to come to NUMA support are all guest visible. In
> theory we could just create a new 5_1 class option flag to
> avoid the changes to cascade to 5.1 and under. The reality is that
> these changes are only relevant if the machine has more than one
> NUMA node. There is no need to change guest behavior that has
> been around for years needlesly.
> 
> This new helper will be used by the next patches to determine
> whether we should retain the (soon to be) legacy NUMA behavior
> in the pSeries machine. The new behavior will only be exposed
> if::
> 
> - machine is pseries-5.2 and newer;
> - more than one NUMA node is declared in NUMA state.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Seems reasonable.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/ppc/spapr.c         | 12 ++++++++++++
>  include/hw/ppc/spapr.h |  2 ++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 22e78cfc84..073a59c47d 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -308,6 +308,15 @@ static hwaddr spapr_node0_size(MachineState *machine)
>      return machine->ram_size;
>  }
>  
> +bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr)
> +{
> +    MachineState *machine = MACHINE(spapr);
> +    SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
> +
> +    return smc->pre_5_2_numa_associativity ||
> +           machine->numa_state->num_nodes <= 1;
> +}
> +
>  static void add_str(GString *s, const gchar *s1)
>  {
>      g_string_append_len(s, s1, strlen(s1) + 1);
> @@ -4602,8 +4611,11 @@ DEFINE_SPAPR_MACHINE(5_2, "5.2", true);
>   */
>  static void spapr_machine_5_1_class_options(MachineClass *mc)
>  {
> +    SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> +
>      spapr_machine_5_2_class_options(mc);
>      compat_props_add(mc->compat_props, hw_compat_5_1, hw_compat_5_1_len);
> +    smc->pre_5_2_numa_associativity = true;
>  }
>  
>  DEFINE_SPAPR_MACHINE(5_1, "5.1", false);
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 739a6a4942..d9f1afa8b2 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -130,6 +130,7 @@ struct SpaprMachineClass {
>      bool smp_threads_vsmt; /* set VSMT to smp_threads by default */
>      hwaddr rma_limit;          /* clamp the RMA to this size */
>      bool pre_5_1_assoc_refpoints;
> +    bool pre_5_2_numa_associativity;
>  
>      void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
>                            uint64_t *buid, hwaddr *pio, 
> @@ -847,6 +848,7 @@ int spapr_max_server_number(SpaprMachineState *spapr);
>  void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
>                        uint64_t pte0, uint64_t pte1);
>  void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered);
> +bool spapr_machine_using_legacy_numa(SpaprMachineState *spapr);
>  
>  /* DRC callbacks. */
>  void spapr_core_release(DeviceState *dev);

-- 
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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