Re: [PATCH v5 4/7] ppc/pnv: Add a PnvChip pointer to PnvCore

[Cédric Le Goater]

On 24/10/2019 04:38, David Gibson wrote:
> On Tue, Oct 22, 2019 at 06:38:09PM +0200, Cédric Le Goater wrote:
>> We will use it to reset the interrupt presenter from the CPU reset
>> handler.
>>
>> Signed-off-by: Cédric Le Goater <address@hidden>
>> Reviewed-by: Greg Kurz <address@hidden>
>> ---
>>  include/hw/ppc/pnv_core.h | 3 +++
>>  hw/ppc/pnv_core.c         | 3 ++-
>>  2 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/ppc/pnv_core.h b/include/hw/ppc/pnv_core.h
>> index bfbd2ec42aa6..55eee95104da 100644
>> --- a/include/hw/ppc/pnv_core.h
>> +++ b/include/hw/ppc/pnv_core.h
>> @@ -31,6 +31,8 @@
>>  #define PNV_CORE_GET_CLASS(obj) \
>>       OBJECT_GET_CLASS(PnvCoreClass, (obj), TYPE_PNV_CORE)
>>  
>> +typedef struct PnvChip PnvChip;
>> +
>>  typedef struct PnvCore {
>>      /*< private >*/
>>      CPUCore parent_obj;
>> @@ -38,6 +40,7 @@ typedef struct PnvCore {
>>      /*< public >*/
>>      PowerPCCPU **threads;
>>      uint32_t pir;
>> +    PnvChip *chip;
> 
> I don't love having this as a redundant encoding of the information
> already in the property, since it raises the possibility of confusing
> bugs if they ever got out of sync.

Indeed.

> It's not a huge deal, but it would be nice to at least to at least
> consider either a) grabbing the property everywhere you need it (if
> there aren't too many places) 

We need the chip at core creation and core reset to call the 
interrupt chip handlers. These are not hot path but the pointer
seemed practical.

> or b) customizing the property
> definition so it's written directly into that field.

OK. That is better than just a link.

C. 

> 
>>  
>>      MemoryRegion xscom_regs;
>>  } PnvCore;
>> diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
>> index 9f981a4940e6..cc17bbfed829 100644
>> --- a/hw/ppc/pnv_core.c
>> +++ b/hw/ppc/pnv_core.c
>> @@ -222,6 +222,7 @@ static void pnv_core_realize(DeviceState *dev, Error 
>> **errp)
>>                                  "required link 'chip' not found: ");
>>          return;
>>      }
>> +    pc->chip = PNV_CHIP(chip);
>>  
>>      pc->threads = g_new(PowerPCCPU *, cc->nr_threads);
>>      for (i = 0; i < cc->nr_threads; i++) {
>> @@ -243,7 +244,7 @@ static void pnv_core_realize(DeviceState *dev, Error 
>> **errp)
>>      }
>>  
>>      for (j = 0; j < cc->nr_threads; j++) {
>> -        pnv_realize_vcpu(pc->threads[j], PNV_CHIP(chip), &local_err);
>> +        pnv_realize_vcpu(pc->threads[j], pc->chip, &local_err);
>>          if (local_err) {
>>              goto err;
>>          }
>