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

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 22 Jun 2016 08:00:28 +0530
Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:

> 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.
You can use -global without that work but so far it looks like it will
make into 2.7.

CCed Eduardo so he could say it for sure as it goes via his tree.

> 
> Regards,
> Bharata.
> 
>