Re: [Qemu-devel] [PATCH 07/16] cpu: introduce get_arch_id() method and override it for target-i386

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 22 Apr 2013 18:33:48 +0200
Andreas Färber <afaerber@suse.de> wrote:

> Am 16.04.2013 00:12, schrieb Igor Mammedov:
> > get_arch_id() adds possibility for generic code to get guest visible
> > CPU ID without accessing CPUArchState. If target doesn't override it,
> > it will return cpu_index.
> > 
> > Override it on target-i386 to return APIC ID.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >  * 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(+)
> 
> Eduardo and me had discussed on IRC that apparently the only reason we
> need this generalized "arch_id" is that acpi_piix4 is shared between x86
> and mips. Did you investigate whether we can just access the x86 apic-id
> property instead for x86 and leave mips as-is without hotplug support?
Yep, one possible way is to used so unloved ifdefs in piix4.c and inclusion
of cpu.h in it, which is not nice as well.

BTW:
 * if ACPI will be someday used for on ARM then using cpu_arch_id() when
   building ACPI tables is also justified.
 * it could reused in s360 hotplug patches as well, if you looked at my
   review comment on its CPU hot-plug patch.


> Andreas
> 
> > 
> > diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> > index 6ce6f10..428aaf0 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 819986e..a13ddda 100644
> > --- a/qom/cpu.c
> > +++ b/qom/cpu.c
> > @@ -76,6 +76,11 @@ 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);
> > @@ -83,6 +88,7 @@ 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 e2302d8..a415fa3 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 = {
> > 
> 
>