On Fri, Sep 22, 2017 at 02:42:07PM +0200, Cédric Le Goater wrote: > On 09/22/2017 01:00 PM, David Gibson wrote: > > On Tue, Sep 19, 2017 at 03:15:44PM +0200, Cédric Le Goater wrote: > >> On 09/19/2017 04:27 AM, David Gibson wrote: > >>> On Mon, Sep 11, 2017 at 07:12:15PM +0200, Cédric Le Goater wrote: > >>>> Start with a couple of attributes for the XIVE sPAPR controller > >>>> model. The number of provisionned IRQ is necessary to size the > >>>> different internal XIVE tables, the number of CPUs is also. > >>>> > >>>> Signed-off-by: Cédric Le Goater <c...@kaod.org> > >>> > >>> [snip] > >>> > >>>> +static void spapr_xive_realize(DeviceState *dev, Error **errp) > >>>> +{ > >>>> + sPAPRXive *xive = SPAPR_XIVE(dev); > >>>> + > >>>> + if (!xive->nr_targets) { > >>>> + error_setg(errp, "Number of interrupt targets needs to be > >>>> greater 0"); > >>>> + return; > >>>> + } > >>>> + /* We need to be able to allocate at least the IPIs */ > >>>> + if (!xive->nr_irqs || xive->nr_irqs < xive->nr_targets) { > >>>> + error_setg(errp, "Number of interrupts too small"); > >>>> + return; > >>>> + } > >>>> +} > >>>> + > >>>> +static Property spapr_xive_properties[] = { > >>>> + DEFINE_PROP_UINT32("nr-irqs", sPAPRXive, nr_irqs, 0), > >>>> + DEFINE_PROP_UINT32("nr-targets", sPAPRXive, nr_targets, 0), > >>> > >>> I'm a bit uneasy about the number of targets having to be set in > >>> advance: this can make life awkward when CPUs are hotplugged. I know > >>> there's something similar in xics, but it has caused some hassles, and > >>> we're starting to move away from it. > >>> > >>> Do you really need this? > >>> > >> > >> Some of the internal table size depend on the number of cpus > >> defined for the machine. > > > > Which ones? My impression was that there needed to be at least #cpus > > * #priority-levels EQs, but there could be more than that, > > euh no, not in spapr mode at least. There are 8 queues per cpu.
Ok. > > so it was no longer as tightly bound to the number if "interrupt servers"> > > as xics. > > ah. I think I see what you mean, that we could allocate them on the > fly when needed by some hcalls ? Not at hcall time, no, but at cpu hot(un)plug time I was wondering if we could (de)allocate them then. > The other place where I use the nr_targets is to provision the > IRQ numbers for the IPIs but that could probably be done in some > other way, specially it there is a IRQ allocator at the machine > level. Hm, ok. > > C. > >> When the sPAPRXive object is instantiated, > >> we use xics_max_server_number() to get the max number of cpus > >> provisioned. > >> > >> C. > >> > > > -- 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
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