hw/ppc: clear pending_events on machine reset

The sPAPR machine isn't clearing up the pending events QTAILQ on
machine reboot. This allows for unprocessed hotplug/epow events
to persist in the queue after reset and, when reasserting the IRQs in
check_exception later on, these will be being processed by the OS.

This patch implements a new function called 'spapr_clear_pending_events'
that clears up the pending_events QTAILQ. This helper is then called
inside ppc_spapr_reset to clear up the events queue, preventing
old/deprecated events from persisting after a reset.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -1392,6 +1392,7 @@ static void ppc_spapr_reset(void)
     }
 
     qemu_devices_reset();
+    spapr_clear_pending_events(spapr);
 
     /*
      * We place the device tree and RTAS just below either the top of the RMA,

hw/ppc/spapr_events.c

@@ -700,6 +700,17 @@ static void event_scan(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
 }
 
+void spapr_clear_pending_events(sPAPRMachineState *spapr)
+{
+    sPAPREventLogEntry *entry = NULL;
+
+    QTAILQ_FOREACH(entry, &spapr->pending_events, next) {
+        QTAILQ_REMOVE(&spapr->pending_events, entry, next);
+        g_free(entry->extended_log);
+        g_free(entry);
+    }
+}
+
 void spapr_events_init(sPAPRMachineState *spapr)
 {
     QTAILQ_INIT(&spapr->pending_events);

include/hw/ppc/spapr.h

@@ -662,6 +662,7 @@ void spapr_cpu_parse_features(sPAPRMachineState *spapr);
 int spapr_hpt_shift_for_ramsize(uint64_t ramsize);
 void spapr_reallocate_hpt(sPAPRMachineState *spapr, int shift,
                           Error **errp);
+void spapr_clear_pending_events(sPAPRMachineState *spapr);
 
 /* CPU and LMB DRC release callbacks. */
 void spapr_core_release(DeviceState *dev);