Re: [PATCH v4 5/8] mips/cps: Use start-powered-off CPUState property

[Philippe Mathieu-Daudé]

On 8/18/20 9:26 AM, Philippe Mathieu-Daudé wrote:
> On 8/18/20 5:33 AM, Thiago Jung Bauermann wrote:
>> Instead of setting CPUState::halted to 1 in main_cpu_reset(), use the
>> start-powered-off property which makes cpu_common_reset() initialize it
>> to 1 in common code.
>>
>> Also change creation of CPU object from cpu_create() to object_new() and
>> qdev_realize() because cpu_create() realizes the CPU and it's not possible to
>> set a property after the object is realized.
>>
>> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
>> ---
>>  hw/mips/cps.c | 16 ++++++++++++----
>>  1 file changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/mips/cps.c b/hw/mips/cps.c
>> index 615e1a1ad2..be85357dc0 100644
>> --- a/hw/mips/cps.c
>> +++ b/hw/mips/cps.c
>> @@ -52,9 +52,6 @@ static void main_cpu_reset(void *opaque)
>>      CPUState *cs = CPU(cpu);
>>  
>>      cpu_reset(cs);
>> -
>> -    /* All VPs are halted on reset. Leave powering up to CPC. */
>> -    cs->halted = 1;
>>  }
>>  
>>  static bool cpu_mips_itu_supported(CPUMIPSState *env)
>> @@ -76,7 +73,9 @@ static void mips_cps_realize(DeviceState *dev, Error 
>> **errp)
>>      bool saar_present = false;
>>  
>>      for (i = 0; i < s->num_vp; i++) {
>> -        cpu = MIPS_CPU(cpu_create(s->cpu_type));
>> +        Error *err = NULL;
>> +
>> +        cpu = MIPS_CPU(object_new(s->cpu_type));
>>  
>>          /* Init internal devices */
>>          cpu_mips_irq_init_cpu(cpu);
>> @@ -89,7 +88,16 @@ static void mips_cps_realize(DeviceState *dev, Error 
>> **errp)
>>              env->itc_tag = mips_itu_get_tag_region(&s->itu);
>>              env->itu = &s->itu;
>>          }
>> +        /* All VPs are halted on reset. Leave powering up to CPC. */
>> +        object_property_set_bool(OBJECT(cpu), "start-powered-off", true,
>> +                                 &error_abort);
>>          qemu_register_reset(main_cpu_reset, cpu);
>> +
>> +        if (!qdev_realize(DEVICE(cpu), NULL, &err)) {
>> +            error_report_err(err);
>> +            object_unref(OBJECT(cpu));
>> +            exit(EXIT_FAILURE);
>> +        }
> 
> Here errp is available, so we can propagate the error to the caller:
> 
>            if (!qdev_realize(DEVICE(cpu), NULL, errp)) {

Igor corrected me in the previous patch, to avoid leaking the
reference this snippet misses:

                 object_unref(OBJECT(cpu));

>                return;
>            }
> 
> For example in hw/mips/boston.c:
> 
>     object_initialize_child(OBJECT(machine), "cps", &s->cps, TYPE_MIPS_CPS);
>     object_property_set_str(OBJECT(&s->cps), "cpu-type", machine->cpu_type,
>                             &error_fatal);
>     object_property_set_int(OBJECT(&s->cps), "num-vp", machine->smp.cpus,
>                             &error_fatal);
>     sysbus_realize(SYS_BUS_DEVICE(&s->cps), &error_fatal);
> 
> This will be propagated here ---------------^^^^^^^^^^^^^
> 
>>      }
>>  
>>      cpu = MIPS_CPU(first_cpu);
>>