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Re: [Qemu-devel] [PATCH 08/19] cpu: introduce get_arch_id() method and o


From: Eduardo Habkost
Subject: Re: [Qemu-devel] [PATCH 08/19] cpu: introduce get_arch_id() method and override it for target-i386
Date: Fri, 12 Apr 2013 10:47:39 -0300
User-agent: Mutt/1.5.21 (2010-09-15)

On Fri, Apr 12, 2013 at 12:31:22PM +0200, Igor Mammedov wrote:
> On Thu, 11 Apr 2013 16:04:26 -0300
> Eduardo Habkost <address@hidden> wrote:
> 
> > On Thu, Apr 11, 2013 at 04:51:47PM +0200, Igor Mammedov wrote:
> > > get_arch_id() adds possibility for generic code to get guest visible
> > > CPI id without accessing CPUArchState. If target doesn't override it,
> > > it will return cpu_index.
> > > 
> > > Override it on target-i386 to return APIC ID.
> > 
> > The code implementing the method looks OK, so:
> > 
> > Reviewed-by: Eduardo Habkost <address@hidden>
> > 
> > But I still need to understand better why exactly i386 needs to use it
> > and make the externally-visible hotplug interface based on APIC IDs if
> > all other architectures are going to be happy using CPU indexes to do
> > the same thing.
> get_arch_id() was prompted by 10/19 which is used not only by target-i386.
> so it was introduced to make acpi_piix4 CPU hotplug more generic. And proved
> to useful in a number of other places.

OK, so get_arch_id() is useful for other code too, not just for the
external cpu-add interface. It makes lots of sense to use it on
acpi_piix4, yes.

(My question about making the cpu-add interface based on arch IDs
instead of arch-independent CPU indexes is being discussed under patch
18/19).

> 
> > 
> > > 
> > > Signed-off-by: Igor Mammedov <address@hidden>
> > > ---
> > >  * it will be used later by new cpu_exists() generic function and
> > >    acpi_piix.
> > >  * s/cpu_firmware_id/cpu_arch_id/
> > > ---
> > >  include/qom/cpu.h |  2 ++
> > >  qom/cpu.c         |  6 ++++++
> > >  target-i386/cpu.c | 10 ++++++++++
> > >  3 files changed, 18 insertions(+)
> > > 
> > > diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> > > index 3664a1b..b376416 100644
> > > --- a/include/qom/cpu.h
> > > +++ b/include/qom/cpu.h
> > > @@ -45,6 +45,7 @@ typedef struct CPUState CPUState;
> > >   * instantiatable CPU type.
> > >   * @reset: Callback to reset the #CPUState to its initial state.
> > >   * @do_interrupt: Callback for interrupt handling.
> > > + * @get_arch_id: Callback for getting architecture depended CPU ID
> > >   * @vmsd: State description for migration.
> > >   *
> > >   * Represents a CPU family or model.
> > > @@ -58,6 +59,7 @@ typedef struct CPUClass {
> > >  
> > >      void (*reset)(CPUState *cpu);
> > >      void (*do_interrupt)(CPUState *cpu);
> > > +    int64_t (*get_arch_id)(CPUState *cpu);
> > >  
> > >      const struct VMStateDescription *vmsd;
> > >  } CPUClass;
> > > diff --git a/qom/cpu.c b/qom/cpu.c
> > > index fe85960..90cbd77 100644
> > > --- a/qom/cpu.c
> > > +++ b/qom/cpu.c
> > > @@ -77,6 +77,11 @@ static void cpu_common_realizefn(DeviceState *dev, 
> > > Error **errp)
> > >      }
> > >  }
> > >  
> > > +static int64_t cpu_common_get_arch_id(CPUState *cpu)
> > > +{
> > > +    return cpu->cpu_index;
> > > +}
> > > +
> > >  static void cpu_class_init(ObjectClass *klass, void *data)
> > >  {
> > >      DeviceClass *dc = DEVICE_CLASS(klass);
> > > @@ -84,6 +89,7 @@ static void cpu_class_init(ObjectClass *klass, void 
> > > *data)
> > >  
> > >      k->class_by_name = cpu_common_class_by_name;
> > >      k->reset = cpu_common_reset;
> > > +    k->get_arch_id = cpu_common_get_arch_id;
> > >      dc->realize = cpu_common_realizefn;
> > >      dc->no_user = 1;
> > >  }
> > > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > > index c28436c..9cca031 100644
> > > --- a/target-i386/cpu.c
> > > +++ b/target-i386/cpu.c
> > > @@ -2272,6 +2272,14 @@ static void x86_cpu_initfn(Object *obj)
> > >      }
> > >  }
> > >  
> > > +static int64_t x86_cpu_get_arch_id(CPUState *cpu)
> > > +{
> > > +    X86CPU *x86cpu = X86_CPU(cpu);
> > > +    CPUX86State *env = &x86cpu->env;
> > > +
> > > +    return env->cpuid_apic_id;
> > > +}
> > > +
> > >  static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
> > >  {
> > >      X86CPUClass *xcc = X86_CPU_CLASS(oc);
> > > @@ -2286,6 +2294,8 @@ static void x86_cpu_common_class_init(ObjectClass 
> > > *oc, void *data)
> > >  
> > >      cc->do_interrupt = x86_cpu_do_interrupt;
> > >      cpu_class_set_vmsd(cc, &vmstate_x86_cpu);
> > > +
> > > +    cc->get_arch_id = x86_cpu_get_arch_id;
> > >  }
> > >  
> > >  static const TypeInfo x86_cpu_type_info = {
> > > -- 
> > > 1.8.2
> > > 
> > 
> > -- 
> > Eduardo
> 
> 
> -- 
> Regards,
>   Igor

-- 
Eduardo



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