Re: [Qemu-devel] [PATCH 2/3] spapr: compute default value of "hpt-max-page-size" later

[David Gibson]

On Fri, Jun 29, 2018 at 04:08:22PM -0300, Eduardo Habkost wrote:
> On Thu, Jun 28, 2018 at 12:15:14PM +0200, Greg Kurz wrote:
> [...]
> > @@ -2527,6 +2527,18 @@ static void spapr_machine_init(MachineState *machine)
> >      QLIST_INIT(&spapr->phbs);
> >      QTAILQ_INIT(&spapr->pending_dimm_unplugs);
> >  
> > +    /* This is for pseries-2.12 and older machine types */
> > +    if (!smc->default_caps.caps[SPAPR_CAP_HPT_MAXPAGESIZE]) {
> > +        uint8_t mps;
> > +
> > +        if (kvmppc_hpt_needs_host_contiguous_pages()) {
> > +            mps = ctz64(qemu_getrampagesize());
> > +        } else {
> > +            mps = 34; /* allow everything up to 16GiB, i.e. everything */
> > +        }
> > +        smc->default_caps.caps[SPAPR_CAP_HPT_MAXPAGESIZE] = mps;
> 
> Initializing class fields on instance init functions is a sign
> that the information doesn't belong to the class struct.  Can't
> this be handled at default_caps_with_cpu()?

Yeah, doing it inside default_caps_with_cpu() probably makes more
sense.

> > +    }
> > +
> >      /* Determine capabilities to run with */
> >      spapr_caps_init(spapr);
> >  
> > @@ -4103,17 +4115,16 @@ static void 
> > spapr_machine_2_12_instance_options(MachineState *machine)
> >  static void spapr_machine_2_12_class_options(MachineClass *mc)
> >  {
> >      sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> > -    uint8_t mps;
> >  
> >      spapr_machine_3_0_class_options(mc);
> >      SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_12);
> >  
> > -    if (kvmppc_hpt_needs_host_contiguous_pages()) {
> > -        mps = ctz64(qemu_getrampagesize());
> > -    } else {
> > -        mps = 34; /* allow everything up to 16GiB, i.e. everything */
> > -    }
> > -    smc->default_caps.caps[SPAPR_CAP_HPT_MAXPAGESIZE] = mps;
> > +    /* We depend on kvm_enabled() to choose a default value for the
> > +     * hpt-max-page-size capability. Of course we can't do it here
> > +     * because this is too early and the HW accelerator isn't initialzed
> > +     * yet. Postpone this to spapr_machine_init().
> > +     */
> > +    smc->default_caps.caps[SPAPR_CAP_HPT_MAXPAGESIZE] = 0;
> >  }
> >  
> >  DEFINE_SPAPR_MACHINE(2_12, "2.12", false);
> > 
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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