From: Laurent Vivier <lvivier@redhat.com>

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>
Message-Id: <20201015210318.117386-1-lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 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 1069d0197b..1add53547e 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));
+        }
+    }
+
     rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
 }
 
-- 
2.26.2