Re: [PATCH] ppc/spapr: re-assert IRQs during event-scan if there are pending

[Greg Kurz]

On Thu, 15 Oct 2020 23:03:18 +0200
Laurent Vivier <lvivier@redhat.com> wrote:

> If we hotplug a CPU during the first second of the kernel boot,
> the IRQ can be sent to the kernel while the RTAS event handler
> is not installed. The event is queued, but the kernel doesn't
> collect it and ignores the new CPU.
> 
> As the code relies on edge-triggered IRQ, we can re-assert it
> during the event-scan RTAS call if there are still pending
> events (as it is already done in check-exception).
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---

Any BugId to share ?

>  hw/ppc/spapr_events.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index 1069d0197b4f..1add53547ec3 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -1000,10 +1000,22 @@ static void event_scan(PowerPCCPU *cpu, 
> SpaprMachineState *spapr,
>                         target_ulong args,
>                         uint32_t nret, target_ulong rets)
>  {
> +    int i;
>      if (nargs != 4 || nret != 1) {
>          rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>          return;
>      }
> +
> +    for (i = 0; i < EVENT_CLASS_MAX; i++) {
> +        if (rtas_event_log_contains(EVENT_CLASS_MASK(i))) {
> +            const SpaprEventSource *source =
> +                spapr_event_sources_get_source(spapr->event_sources, i);
> +
> +            g_assert(source->enabled);
> +            qemu_irq_pulse(spapr_qirq(spapr, source->irq));
> +        }
> +    }
> +

This looks good but any reason for not putting this in a function called by
both event_scan() and check_exception() ?

Anyway, this can be done as a follow-up:

Reviewed-by: Greg Kurz <groug@kaod.org>

>      rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
>  }
>