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

[liu ping fan]

On Wed, Jul 11, 2012 at 8:27 PM, Igor Mammedov <address@hidden> wrote:
> On 07/11/2012 09:35 AM, liu ping fan wrote:
>>
>> On Tue, Jul 10, 2012 at 9:35 PM, Igor Mammedov <address@hidden>
>> 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 <address@hidden>
>>>>>>> ---
>>>>>>>     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.
>
Just wonder whether it is acceptable to call apic_reset directly , or
before that, we must make CPU a child of DeviceState, then using
qdev_reset_all()

pingfan
>
>>
>> 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
>
>