Re: [RFC PATCH 04/10] ppc/pnv: specialise init for powernv8/9/10 machines

["Cédric Le Goater" <clg@kaod.org>]

On 5/28/24 09:10, Harsh Prateek Bora wrote:
> Hi Nick,
> 
> On 5/26/24 17:56, Nicholas Piggin wrote:
>> This will allow different settings and checks for different
>> machine types with later changes.
>>
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>>   hw/ppc/pnv.c | 35 ++++++++++++++++++++++++++++++-----
>>   1 file changed, 30 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
>> index 6e3a5ccdec..a706de2e36 100644
>> --- a/hw/ppc/pnv.c
>> +++ b/hw/ppc/pnv.c
>> @@ -976,11 +976,6 @@ static void pnv_init(MachineState *machine)
>>       pnv->num_chips =
>>           machine->smp.max_cpus / (machine->smp.cores * machine->smp.threads);
>> -    if (machine->smp.threads > 8) {
>> -        error_report("Cannot support more than 8 threads/core "
>> -                     "on a powernv machine");
>> -        exit(1);
>> -    }
>>       if (!is_power_of_2(machine->smp.threads)) {
>>           error_report("Cannot support %d threads/core on a powernv"
>>                        "machine because it must be a power of 2",
>> @@ -1076,6 +1071,33 @@ static void pnv_init(MachineState *machine)
>>       }
>>   }
>> +static void pnv_power8_init(MachineState *machine)
>> +{
>> +    if (machine->smp.threads > 8) {
>> +        error_report("Cannot support more than 8 threads/core "
>> +                     "on a powernv POWER8 machine");
> 
> We could use mc->desc for machine name above, so that ..
> 
>> +        exit(1);
>> +    }
> 
> with this patch, we can reuse p8 init for both p9 and p10 (and not just reuse p9 for p10 with hard coded string?).

Good idea. You could add a 'max_smt' attribute to PnvMachineClass to limit
POWER8 to one.


Thanks,

C.


> 
> With that,
> Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> 
>> +
>> +    pnv_init(machine);
>> +}
>> +
>> +static void pnv_power9_init(MachineState *machine)
>> +{
>> +    if (machine->smp.threads > 8) {
>> +        error_report("Cannot support more than 8 threads/core "
>> +                     "on a powernv9/10 machine");
>> +        exit(1);
>> +    }
>> +
>> +    pnv_init(machine);
>> +}
>> +
>> +static void pnv_power10_init(MachineState *machine)
>> +{
>> +    pnv_power9_init(machine);
>> +}
>> +
>>   /*
>>    *    0:21  Reserved - Read as zeros
>>    *   22:24  Chip ID
>> @@ -2423,6 +2445,7 @@ static void pnv_machine_power8_class_init(ObjectClass *oc, void *data)
>>       };
>>       mc->desc = "IBM PowerNV (Non-Virtualized) POWER8";
>> +    mc->init = pnv_power8_init;
>>       mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power8_v2.0");
>>       compat_props_add(mc->compat_props, phb_compat, G_N_ELEMENTS(phb_compat));
>> @@ -2449,6 +2472,7 @@ static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
>>       };
>>       mc->desc = "IBM PowerNV (Non-Virtualized) POWER9";
>> +    mc->init = pnv_power9_init;
>>       mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power9_v2.2");
>>       compat_props_add(mc->compat_props, phb_compat, G_N_ELEMENTS(phb_compat));
>> @@ -2473,6 +2497,7 @@ static void pnv_machine_p10_common_class_init(ObjectClass *oc, void *data)
>>           { TYPE_PNV_PHB_ROOT_PORT, "version", "5" },
>>       };
>> +    mc->init = pnv_power10_init;
>>       mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power10_v2.0");
>>       compat_props_add(mc->compat_props, phb_compat, G_N_ELEMENTS(phb_compat));