Re: [Qemu-devel] [RFC PATCH v0 1/1] spapr: Support setting of compat CPU type for CPU cores

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

On Tue, Jun 21, 2016 at 09:09:57AM +0200, Igor Mammedov wrote:
> On Sat, 18 Jun 2016 14:04:06 +0530
> Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:
> 
> > Compat CPU type is typically specified on -cpu cmdline option like:
> > -cpu host,compat=power7 or -cpu POWER8E,compat=power7 etc.
> > With the introduction of sPAPR CPU core devices, we need to support
> > the same for core devices too.
> > 
> > Support the specification of CPU compat type on device_add command for
> > sPAPRCPUCore devices like:
> > (qemu) device_add
> > POWER8E-spapr-cpu-core,id=core3,compat=power7,core-id=24
> > 
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > ---
> > Applies on ppc-for-2.7 branch of David Gibson's tree.
> > 
> >  hw/ppc/spapr.c                  |  8 +++++
> >  hw/ppc/spapr_cpu_core.c         | 73
> > +++++++++++++++++++++++++++++++++++++++++
> > include/hw/ppc/spapr_cpu_core.h |  2 ++ 3 files changed, 83
> > insertions(+)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 778fa25..2049d7d 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1807,6 +1807,7 @@ static void ppc_spapr_init(MachineState
> > *machine) if (i < spapr_cores) {
> >                  char *type =
> > spapr_get_cpu_core_type(machine->cpu_model); Object *core;
> > +                char *compat;
> >  
> >                  if (!object_class_by_name(type)) {
> >                      error_report("Unable to find sPAPR CPU Core
> > definition"); @@ -1818,6 +1819,13 @@ static void
> > ppc_spapr_init(MachineState *machine) &error_fatal);
> >                  object_property_set_int(core, core_dt_id,
> > CPU_CORE_PROP_CORE_ID, &error_fatal);
> > +                compat =
> > spapr_get_cpu_compat_type(machine->cpu_model);
> > +                if (compat) {
> > +                    object_property_set_str(core, compat, "compat",
> > +                                            &error_fatal);
> > +                    g_free(compat);
> > +                }
> > +
> >                  object_property_set_bool(core, true, "realized",
> > &error_fatal); }
> >          }
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 3a5da09..9eb63cc 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -96,6 +96,24 @@ char *spapr_get_cpu_core_type(const char *model)
> >      return core_type;
> >  }
> >  
> > +/*
> > + * Returns the CPU compat type specified in -cpu @model.
> > + */
> > +char *spapr_get_cpu_compat_type(const char *model)
> CPUClass already has such parser and hook to override it in case of
> target does legacy parsing, see CPUClass->parse_features.
> Maybe extending generic core in similar way and reusing generic parser
> will do the job.

In fact, I am already using CPUClass->parse_features() to set the
feature properties (which right now is only compat= for us) for core device.

What I need in the above routine spapr_get_cpu_compat_type() is to
extract "compat=", so that I can verify that the compat type specified
with -device matches with what was specified with -cpu.

> 
> However we are in progress [1] of converting legacy
>  -cpu cpuname,feat1=x,feat2=y,...
> into a set of global properties
>  -global cputype.feat1=x ...
> 
> it would be better if you wouldn't start using -cpu for features
> but use directly -global mechanism,
> for that you need only have a corresponding property in spapr_core type.

Will this work be part of 2.7 ? If not, we will have to use -cpu to extract
the compat type since powerpc core hotplug is already upstream.

Regards,
Bharata.