Re: [PATCH for-5.0 v5 14/23] ppc/spapr: Implement the XiveFabric interface

[Greg Kurz <groug@kaod.org>]

On Thu, 21 Nov 2019 07:56:32 +0100
Cédric Le Goater <clg@kaod.org> wrote:

> On 20/11/2019 18:53, Greg Kurz wrote:
> > On Fri, 15 Nov 2019 17:24:27 +0100
> > Cédric Le Goater <clg@kaod.org> wrote:
> > 
> >> The CAM line matching sequence in the pseries machine does not change
> >> much apart from the use of the new QOM interfaces. There is an extra
> >> indirection because of the sPAPR IRQ backend of the machine. Only the
> >> XIVE backend implements the new 'match_nvt' handler.
> >>
> > 
> > The changelog needs an update since you dropped the indirection you had
> > in v4.
> 
> Indeed.
> 
> > 
> >> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> >> ---
> >>  hw/ppc/spapr.c | 36 ++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 36 insertions(+)
> >>
> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> >> index 94f9d27096af..a8f5850f65bb 100644
> >> --- a/hw/ppc/spapr.c
> >> +++ b/hw/ppc/spapr.c
> >> @@ -4270,6 +4270,39 @@ static void spapr_pic_print_info(InterruptStatsProvider *obj,
> >>                     kvm_irqchip_in_kernel() ? "in-kernel" : "emulated");
> >>  }
> >>  
> >> +static int spapr_xive_match_nvt(XiveFabric *xfb, uint8_t format,
> >> +                                uint8_t nvt_blk, uint32_t nvt_idx,
> >> +                                bool cam_ignore, uint8_t priority,
> >> +                                uint32_t logic_serv, XiveTCTXMatch *match)
> >> +{
> >> +    SpaprMachineState *spapr = SPAPR_MACHINE(xfb);
> >> +    XivePresenter *xptr = XIVE_PRESENTER(spapr->xive);
> >> +    XivePresenterClass *xpc = XIVE_PRESENTER_GET_CLASS(xptr);
> >> +    int count;
> >> +
> > 
> > As suggested by David, you should probably assert() that XIVE is in use
> > for extra paran^Wsafety.
> 
> I don't see the need. The stack call is clear enough IMO. It can only be 
> reached from the XiveRouter.
> 

Hmm... the assert() proposal isn't about this getting called by some
other code, it is about ensuring XIVE is the active IC in case the
machine was started with ic-mode=dual. But if you're confident enough
it can never ever happen, no matter any subsequent change may done to
the code, then don't add it :)

> Thanks,
> 
> C. 
> 
> > With these fixed,
> > 
> > Reviewed-by: Greg Kurz <groug@kaod.org>
> > 
> >> +    count = xpc->match_nvt(xptr, format, nvt_blk, nvt_idx, cam_ignore,
> >> +                           priority, logic_serv, match);
> >> +    if (count < 0) {
> >> +        return count;
> >> +    }
> >> +
> >> +    /*
> >> +     * When we implement the save and restore of the thread interrupt
> >> +     * contexts in the enter/exit CPU handlers of the machine and the
> >> +     * escalations in QEMU, we should be able to handle non dispatched
> >> +     * vCPUs.
> >> +     *
> >> +     * Until this is done, the sPAPR machine should find at least one
> >> +     * matching context always.
> >> +     */
> >> +    if (count == 0) {
> >> +        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: NVT %x/%x is not dispatched\n",
> >> +                      nvt_blk, nvt_idx);
> >> +    }
> >> +
> >> +    return count;
> >> +}
> >> +
> >>  int spapr_get_vcpu_id(PowerPCCPU *cpu)
> >>  {
> >>      return cpu->vcpu_id;
> >> @@ -4366,6 +4399,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
> >>      PPCVirtualHypervisorClass *vhc = PPC_VIRTUAL_HYPERVISOR_CLASS(oc);
> >>      XICSFabricClass *xic = XICS_FABRIC_CLASS(oc);
> >>      InterruptStatsProviderClass *ispc = INTERRUPT_STATS_PROVIDER_CLASS(oc);
> >> +    XiveFabricClass *xfc = XIVE_FABRIC_CLASS(oc);
> >>  
> >>      mc->desc = "pSeries Logical Partition (PAPR compliant)";
> >>      mc->ignore_boot_device_suffixes = true;
> >> @@ -4442,6 +4476,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
> >>      smc->linux_pci_probe = true;
> >>      smc->smp_threads_vsmt = true;
> >>      smc->nr_xirqs = SPAPR_NR_XIRQS;
> >> +    xfc->match_nvt = spapr_xive_match_nvt;
> >>  }
> >>  
> >>  static const TypeInfo spapr_machine_info = {
> >> @@ -4460,6 +4495,7 @@ static const TypeInfo spapr_machine_info = {
> >>          { TYPE_PPC_VIRTUAL_HYPERVISOR },
> >>          { TYPE_XICS_FABRIC },
> >>          { TYPE_INTERRUPT_STATS_PROVIDER },
> >> +        { TYPE_XIVE_FABRIC },
> >>          { }
> >>      },
> >>  };
> > 
>