To save some state when the guest is migrated, we capture the IRQ
bitmap after all devices have been reseted and store it as a reference
for the machine.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 hw/ppc/spapr.c         | 5 ++++-
 include/hw/ppc/spapr.h | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 70f6a96ec909..d4d0a36cc5bf 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1437,6 +1437,9 @@ static void ppc_spapr_reset(void)
     qemu_devices_reset();
     spapr_clear_pending_events(spapr);
 
+    spapr->irq_map_ref = bitmap_new(spapr->nr_irqs);
+    bitmap_copy(spapr->irq_map_ref, spapr->irq_map, spapr->nr_irqs);
+
     /*
      * We place the device tree and RTAS just below either the top of the RMA,
      * or just below 2GB, whichever is lowere, so that it can be
@@ -1706,7 +1709,7 @@ static bool spapr_irq_map_needed(void *opaque)
         return false;
     }
 
-    return true;
+    return !bitmap_equal(spapr->irq_map, spapr->irq_map_ref, spapr->nr_irqs);
 }
 
 static const VMStateDescription vmstate_spapr_irq_map = {
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 71faeff17a40..090eda962ccb 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -82,6 +82,7 @@ struct sPAPRMachineState {
     struct sPAPRNVRAM *nvram;
     int32_t nr_irqs;
     unsigned long *irq_map;
+    unsigned long *irq_map_ref;
     ICSState *ics;
     sPAPRRTCState rtc;
 
-- 
2.13.6