Re: [Qemu-devel] [PATCH 3/5] target-i386: call x86_cpu_realize() after APIC is initialized.

[Igor Mammedov <imammedo@redhat.com>]

On 07/11/2012 09:35 AM, liu ping fan wrote:
> On Tue, Jul 10, 2012 at 9:35 PM, Igor Mammedov <imammedo@redhat.com> wrote:
>> On 07/09/2012 02:57 PM, Andreas Färber wrote:
>>>
>>> Am 09.07.2012 12:59, schrieb igor:
>>>>
>>>> On 06/20/2012 03:35 PM, Andreas Färber wrote:
>>>>>
>>>>> Am 20.06.2012 14:59, schrieb Igor Mammedov:
>>>>>>
>>>>>> It's not correct to make CPU runnable (i.e. calling x86_cpu_realize())
>>>>>> when not all properties are set (APIC in this case).
>>>>>>
>>>>>> Fix it by calling x86_cpu_realize() at board level after APIC is
>>>>>> initialized, right before cpu_reset().
>>>>>>
>>>>>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
>>>>>> ---
>>>>>>     hw/pc.c              |    1 +
>>>>>>     target-i386/helper.c |    2 --
>>>>>>     2 files changed, 1 insertion(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/pc.c b/hw/pc.c
>>>>>> index 8368701..8a662cf 100644
>>>>>> --- a/hw/pc.c
>>>>>> +++ b/hw/pc.c
>>>>>> @@ -948,6 +948,7 @@ static X86CPU *pc_new_cpu(const char *cpu_model)
>>>>>>             env->apic_state = apic_init(env, env->cpuid_apic_id);
>>>>>>         }
>>>>>>         qemu_register_reset(pc_cpu_reset, cpu);
>>>>>> +    x86_cpu_realize(OBJECT(cpu), NULL);
>>>>>>         pc_cpu_reset(cpu);
>>>>>>         return cpu;
>>>>>>     }
>>>>>> diff --git a/target-i386/helper.c b/target-i386/helper.c
>>>>>> index c52ec13..b38ea7f 100644
>>>>>> --- a/target-i386/helper.c
>>>>>> +++ b/target-i386/helper.c
>>>>>> @@ -1161,8 +1161,6 @@ X86CPU *cpu_x86_init(const char *cpu_model)
>>>>>>             return NULL;
>>>>>>         }
>>>>>>
>>>>>> -    x86_cpu_realize(OBJECT(cpu), NULL);
>>>>>> -
>>>>>>         return cpu;
>>>>>>     }
>>>>>>
>>>>>
>>>>> This will require changes in linux-user and possibly bsd-user. Having a
>>>>> cpu_realize() would probably help with avoiding #ifdef'ery.
>>>>> Unfortunately deriving CPUState from DeviceState proves a bit difficult
>>>>> in the meantime (it worked at one point, now there's lots of circular
>>>>> header dependencies), and realize support for Object got stopped.
>>>>>
>>>> As alternative to keep, I could leave x86_cpu_realize() in
>>>> cpu_x86_init() and keep pc_cpu_reset() in pc_new_cpu(). That will result
>>>> in calling cpu_reset() 3 instead of 2 times.
>>>> Later when apic_init is moved inside cpu.c, a pc_cpu_reset() in
>>>> pc_new_cpu() would be unnecessary and could be cleaned up then.
>>>
>>>
>>> Let me explain in more detail what I was thinking about: cpu_init() and
>>> cpu_x86_init() today return an initialized/realized object. I don't want
>>> bugs to creep into the user emulators because someone is not aware that
>>> x86 is semantically differing from all other targets.
>>>
>>> What I did for a qemu-rl78 machine is to inline cpu_rl78_init() so that
>>> I could put code in between, i.e., for x86: object_new(), APIC/BSP
>>> stuff, x86_cpu_realize(). That way any addition to the realize function
>>> will still affect the user emulators.
>>> The downside is that when we add x86 CPU subclasses we'd have to
>>> remember to update two places. The solution to that would be to split
>>> out a x86_cpu_new() function used from cpu_x86_init() and wherever you
>>> need it for the PC machine. Then the code is still maintainable in one
>>> central place and you get to do your APIC cleanups, and we don't depend
>>> on a central realize implementation or device parent, what do you think?
>>
>>
>> If you mean x86_cpu_new() == pc_new_cpu() that calls cpu_x86_init(),
>> then I'd like get rid of pc_new_cpu() completely, eventually replacing it by
>> cpu_x86_init() in hw/pc.c:pc_cpus_init(), something like this:
>>
>> -static X86CPU *pc_new_cpu(const char *cpu_model)
>> -{
>> -    X86CPU *cpu;
>> -    CPUX86State *env;
>> -
>> -    cpu = cpu_x86_init(cpu_model);
>> -    if (cpu == NULL) {
>> -        fprintf(stderr, "Unable to find x86 CPU definition\n");
>> -        exit(1);
>> -    }
>> -    env = &cpu->env;
>> -    if ((env->cpuid_features & CPUID_APIC) || smp_cpus > 1) {
>> -        env->apic_state = apic_init(env, env->cpuid_apic_id);
>> -    }
>> -    cpu_reset(CPU(cpu));
>> -    return cpu;
>> -}
>> -
>>   void pc_cpus_init(const char *cpu_model)
>>   {
>>       int i;
>> @@ -950,7 +932,7 @@ void pc_cpus_init(const char *cpu_model)
>>       }
>>
>>       for(i = 0; i < smp_cpus; i++) {
>> -        pc_new_cpu(cpu_model);
>> +        cpu_x86_init(cpu_model);
>>       }
>>   }
>>
>> goal I'm aiming at is to have a working cpu object that could be created
>> using qdev_device_add without any adhoc calls. So in the end cpu_x86_init()
>> should become object_new(x86_cpu), [set props], realize() and nothing else.
>
> Could we think apic's "creation + realize" as part of
> x86_cpu_realize(), but not [set props]?
> For the concept of building sub log unit inside chip.

Yes, sure.
Please look at https://github.com/imammedo/qemu/tree/x86_qom_apic
it lacks apic_reset() from cpu_reset() but it is easy to add.

>
> Regards,
> pingfan
>> And maybe in some far future removing cpu_init -> cpu_x86_init() completely.
>> That would give us a single implementation of CPU one place (cpu.c)
>> --
>> -----
>> Regards,
>>   Igor
>>
>>
>>

-- 
-----
  Igor