Re: [Qemu-devel] [PATCH v4 03/17] spapr_rtas: add get/set-power-level RTAS interfaces

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Quoting David Gibson (2015-01-26 23:24:11)
> On Sun, Jan 25, 2015 at 11:21:26PM -0600, Michael Roth wrote:
> > Quoting David Gibson (2015-01-16 00:21:55)
> > > On Tue, Dec 23, 2014 at 06:30:17AM -0600, Michael Roth wrote:
> > > > From: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> > > > 
> > > > Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> > > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> > > > ---
> > > >  hw/ppc/spapr_rtas.c | 25 +++++++++++++++++++++++++
> > > >  1 file changed, 25 insertions(+)
> > > > 
> > > > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> > > > index 2ec2a8e..a2fb533 100644
> > > > --- a/hw/ppc/spapr_rtas.c
> > > > +++ b/hw/ppc/spapr_rtas.c
> > > > @@ -290,6 +290,27 @@ static void rtas_ibm_os_term(PowerPCCPU *cpu,
> > > >      rtas_st(rets, 0, ret);
> > > >  }
> > > >  
> > > > +static void rtas_set_power_level(PowerPCCPU *cpu, sPAPREnvironment *spapr,
> > > > +                                 uint32_t token, uint32_t nargs,
> > > > +                                 target_ulong args, uint32_t nret,
> > > > +                                 target_ulong rets)
> > > > +{
> > > > +    /* we currently only use a single, "live insert" powerdomain for
> > > > +     * hotplugged/dlpar'd resources, so the power is always live/full (100)
> > > > +     */
> > > 
> > > Even so, you should at least validate the number of args and rets, and
> > > preferably check that the user isn't attempt to set something for some
> > > other, non-existent power domain.
> > > 
> > > > +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> > > > +    rtas_st(rets, 1, 100);
> > > > +}
> > > > +
> > > > +static void rtas_get_power_level(PowerPCCPU *cpu, sPAPREnvironment *spapr,
> > > > +                                  uint32_t token, uint32_t nargs,
> > > > +                                  target_ulong args, uint32_t nret,
> > > > +                                  target_ulong rets)
> > > > +{
> > > > +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> > > > +    rtas_st(rets, 1, 100);
> > > > +}
> > > > +
> > > >  static struct rtas_call {
> > > >      const char *name;
> > > >      spapr_rtas_fn fn;
> > > > @@ -419,6 +440,10 @@ static void core_rtas_register_types(void)
> > > >                          rtas_ibm_set_system_parameter);
> > > >      spapr_rtas_register(RTAS_IBM_OS_TERM, "ibm,os-term",
> > > >                          rtas_ibm_os_term);
> > > > +    spapr_rtas_register(RTAS_SET_POWER_LEVEL, "set-power-level",
> > > > +                        rtas_set_power_level);
> > > > +    spapr_rtas_register(RTAS_GET_POWER_LEVEL, "get-power-level",
> > > > +                        rtas_get_power_level);
> > > >  }
> > > >  
> > > >  type_init(core_rtas_register_types)
> > > 
> > > This code should probably go in spapr_drc.c.  The idea that spapr_rtas
> > > was just the RTAS dispatch code, and RTAS functions that had no other
> > > home.  Generally RTAS functions should live with the devices they're
> > > connected to.
> > 
> > In this particular case the calls act on a "power domain" which isn't
> > actually modeled in QEMU (we just assume a single "live-insertion" domain
> > which just magically does everything we want), so I think it makes
> > sense to leave these here.
> 
> Yeah, fair enough.

Hmm, looking at it again, set-indicator and get-sensor-state aren't actually
specific to DR, but might be extended to handle a number of other types of
sensors in the future ("Reset Component", "Error Log", and "Global Interrupt
Queue Control" may be interesting in this regard).

So it looks like only configure-connector is specifically for DR. Still
planning on moving it to spapr_drc_rtas.c, unless you'd prefer not to
at this point (it'll be lonely for the foreseable future).

> 
> > But for the others it does make sense to tie them with spapr_drc.c, or
> > maybe spapr_drc_rtas.c to maintain the encapsulation of DRC state behind
> > well-defined accessors.
> 
> Ok.
> 
> -- 
> 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