Re: [PATCH 2/7] spapr, xive: Turn "nr-ends" property into "nr-servers" property

[Greg Kurz <groug@kaod.org>]

On Thu, 3 Oct 2019 14:21:59 +0200
Cédric Le Goater <clg@kaod.org> wrote:

> On 03/10/2019 14:01, Greg Kurz wrote:
> > The sPAPR XIVE object has an nr_ends field which happens to be a
> > multiple of spapr_max_server_number(). It is currently set with
> > the help of "nr-ends" property. This is a bit unfortunate since
> > it exposes to the sPAPR irq frontend what should remain an
> > implemantation detail within the XIVE backend.
> 
> implementation
> 

oops

> > It will be possible soon to inform the XIVE KVM device about the
> > range of VCPU ids that may be used in the VM, as returned by the
> > spapr_max_server_number() function. This will allow the device
> > to substantially reduce the consumption of scarce resources
> > in the XIVE HW.
> > 
> > For both reasons, replace the "nr-ends" property with an "nr-servers"
> > one. The existing nr_ends field must be kept though since it tells how
> > many ENDs are migrated, it is derived from "nr-servers" at realize time
> > for simplicity. Convert spapr_dt_xive() to use it as well.
> 
> Looks good. one question below.
> 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> >  hw/intc/spapr_xive.c        |   21 ++++++++++++++++-----
> >  hw/ppc/spapr_irq.c          |    2 +-
> >  include/hw/ppc/spapr_xive.h |    1 +
> >  3 files changed, 18 insertions(+), 6 deletions(-)
> > 
> > diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
> > index 04879abf2e7a..62888ddc68db 100644
> > --- a/hw/intc/spapr_xive.c
> > +++ b/hw/intc/spapr_xive.c
> > @@ -99,6 +99,15 @@ int spapr_xive_end_to_target(uint8_t end_blk, uint32_t end_idx,
> >      return 0;
> >  }
> >  
> > +static uint32_t spapr_xive_vcpu_id_to_end_idx(uint32_t vcpu_id)
> 
> 
> may be use a simpler macro :
> 
> #define spapr_xive_cpu_end_idx(vcpu, prio) (((vcpu) << 3) + prio) 
> 

Will do but I'll keep the comment.

> > +{
> > +    /*
> > +     * 8 XIVE END structures per CPU. One for each available
> > +     * priority
> > +     */
> > +    return vcpu_id << 3;
> > +}
> > +
> >  static void spapr_xive_cpu_to_end(PowerPCCPU *cpu, uint8_t prio,
> >                                    uint8_t *out_end_blk, uint32_t *out_end_idx)
> >  {
> > @@ -109,7 +118,7 @@ static void spapr_xive_cpu_to_end(PowerPCCPU *cpu, uint8_t prio,
> >      }
> >  
> >      if (out_end_idx) {
> > -        *out_end_idx = (cpu->vcpu_id << 3) + prio;
> > +        *out_end_idx = spapr_xive_vcpu_id_to_end_idx(cpu->vcpu_id) + prio;
> >      }
> >  }
> >  
> > @@ -283,11 +292,13 @@ static void spapr_xive_realize(DeviceState *dev, Error **errp)
> >          return;
> >      }
> >  
> > -    if (!xive->nr_ends) {
> > -        error_setg(errp, "Number of interrupt needs to be greater 0");
> > +    if (!xive->nr_servers) {
> > +        error_setg(errp, "Number of interrupt servers must be greater than 0");
> >          return;
> >      }
> >  
> > +    xive->nr_ends = spapr_xive_vcpu_id_to_end_idx(xive->nr_servers);
> > +
> >      /*
> >       * Initialize the internal sources, for IPIs and virtual devices.
> >       */
> > @@ -489,7 +500,7 @@ static const VMStateDescription vmstate_spapr_xive = {
> >  
> >  static Property spapr_xive_properties[] = {
> >      DEFINE_PROP_UINT32("nr-irqs", SpaprXive, nr_irqs, 0),
> > -    DEFINE_PROP_UINT32("nr-ends", SpaprXive, nr_ends, 0),
> > +    DEFINE_PROP_UINT32("nr-servers", SpaprXive, nr_servers, 0),
> >      DEFINE_PROP_UINT64("vc-base", SpaprXive, vc_base, SPAPR_XIVE_VC_BASE),
> >      DEFINE_PROP_UINT64("tm-base", SpaprXive, tm_base, SPAPR_XIVE_TM_BASE),
> >      DEFINE_PROP_END_OF_LIST(),
> > @@ -1550,7 +1561,7 @@ void spapr_dt_xive(SpaprMachineState *spapr, uint32_t nr_servers, void *fdt,
> 
> we should remove the 'uint32_t nr_servers' parameter from spapr_dt_xive() 
> then ?
> 

Yes but this would also affect XICS since this function is a backend
method. It is hence done in the next patch.

> >      /* Interrupt number ranges for the IPIs */
> >      uint32_t lisn_ranges[] = {
> >          cpu_to_be32(0),
> > -        cpu_to_be32(nr_servers),
> > +        cpu_to_be32(xive->nr_servers),
> >      };
> >      /*
> >       * EQ size - the sizes of pages supported by the system 4K, 64K,
> > diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
> > index 457eabe24cda..025fd00143a2 100644
> > --- a/hw/ppc/spapr_irq.c
> > +++ b/hw/ppc/spapr_irq.c
> > @@ -591,7 +591,7 @@ void spapr_irq_init(SpaprMachineState *spapr, Error **errp)
> >           * 8 XIVE END structures per CPU. One for each available
> >           * priority
> >           */
> > -        qdev_prop_set_uint32(dev, "nr-ends", nr_servers << 3);
> > +        qdev_prop_set_uint32(dev, "nr-servers", nr_servers);
> >          qdev_init_nofail(dev);
> >  
> >          spapr->xive = SPAPR_XIVE(dev);
> > diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
> > index 0df20a6590a5..4a4a6fc6be7f 100644
> > --- a/include/hw/ppc/spapr_xive.h
> > +++ b/include/hw/ppc/spapr_xive.h
> > @@ -22,6 +22,7 @@ typedef struct SpaprXive {
> >      /* Internal interrupt source for IPIs and virtual devices */
> >      XiveSource    source;
> >      hwaddr        vc_base;
> > +    uint32_t      nr_servers;
> >  
> >      /* END ESB MMIOs */
> >      XiveENDSource end_source;
> > 
>