Re: [RFC v3 9/9] i386: split cpu accelerators from cpu.c

[Eduardo Habkost <ehabkost@redhat.com>]

On Thu, Nov 19, 2020 at 09:53:09AM +0100, Claudio Fontana wrote:
> Hi,
> 
> On 11/18/20 7:28 PM, Eduardo Habkost wrote:
> > On Wed, Nov 18, 2020 at 11:29:36AM +0100, Claudio Fontana wrote:
> >> split cpu.c into:
> >>
> >> cpu.c            cpuid and common x86 cpu functionality
> >> host-cpu.c       host x86 cpu functions and "host" cpu type
> >> kvm/cpu.c        KVM x86 cpu type
> >> hvf/cpu.c        HVF x86 cpu type
> >> tcg/cpu.c        TCG x86 cpu type
> >>
> >> The accel interface of the X86CPUClass is set at MODULE_INIT_ACCEL_CPU
> >> time, when the accelerator is known.
> >>
> >> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> >> ---
> > [...]
> >> +/**
> >> + * X86CPUAccel:
> >> + * @name: string name of the X86 CPU Accelerator
> >> + *
> >> + * @common_class_init: initializer for the common cpu
> > 
> > So this will be called for every single CPU class.
> 
> Not really, it's called for every TYPE_X86_CPU cpu class (if an accel interface is registered).

This means every single non-abstract CPU class in
qemu-system-x86_64, correct?

> 
> This function extends the existing x86_cpu_common_class_init (target/i386/cpu.c),
> where some methods of the base class CPUClass are set.
> 
> > 
> >> + * @instance_init: cpu instance initialization
> >> + * @realizefn: realize function, called first in x86 cpu realize
> >> + *
> >> + * X86 CPU accelerator-specific CPU initializations
> >> + */
> >> +
> >> +struct X86CPUAccel {
> >> +    const char *name;
> >> +
> >> +    void (*common_class_init)(X86CPUClass *xcc);
> >> +    void (*instance_init)(X86CPU *cpu);
> >> +    void (*realizefn)(X86CPU *cpu, Error **errp);
> >>  };
> >>  
> >> +void x86_cpu_accel_init(const X86CPUAccel *accel);
> > [...]
> >> +static void x86_cpu_accel_init_aux(ObjectClass *klass, void *opaque)
> >> +{
> >> +    X86CPUClass *xcc = X86_CPU_CLASS(klass);
> >> +    const X86CPUAccel **accel = opaque;
> >> +
> >> +    xcc->accel = *accel;
> >> +    xcc->accel->common_class_init(xcc);
> >> +}
> >> +
> >> +void x86_cpu_accel_init(const X86CPUAccel *accel)
> >> +{
> >> +    object_class_foreach(x86_cpu_accel_init_aux, TYPE_X86_CPU, false, &accel);
> >> +}
> > 
> > This matches the documented behavior.
> > 
> > [...]
> >> +void host_cpu_class_init(X86CPUClass *xcc)
> >> +{
> >> +    xcc->host_cpuid_required = true;
> >> +    xcc->ordering = 8;
> >> +    xcc->model_description =
> >> +        g_strdup_printf("%s processor with all supported host features ",
> >> +                        xcc->accel->name);
> >> +}
> > [...]
> >> +static void hvf_cpu_common_class_init(X86CPUClass *xcc)
> >> +{
> >> +    host_cpu_class_init(xcc);
> > 
> > Why are you calling host_cpu_class_init() for all CPU types?
> 
> I am not..

I don't get it.  You are calling host_cpu_class_init() for every
single non-abstract TYPE_X86_CPU subclass (which includes all CPU
models in qemu-system-x86_64), and I don't understand why, or if
this is really intentional.

> 
> > 
> >> +}
> > [...]
> >> +static void kvm_cpu_common_class_init(X86CPUClass *xcc)
> >> +{
> >> +    host_cpu_class_init(xcc);
> >> +}
> > 
> > Same question as above.
> > 
> 
> Ciao,
> 
> Claudio
> 

-- 
Eduardo