@event access is read-only.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/exec/memory.h | 2 +-
 system/memory.c       | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 1be58f694c..2bf5e23b6a 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1852,7 +1852,7 @@ void memory_region_notify_iommu(IOMMUMemoryRegion *iommu_mr,
  *         range.
  */
 void memory_region_notify_iommu_one(IOMMUNotifier *notifier,
-                                    IOMMUTLBEvent *event);
+                                    const IOMMUTLBEvent *event);
 
 /**
  * memory_region_unmap_iommu_notifier_range: notify a unmap for an IOMMU
diff --git a/system/memory.c b/system/memory.c
index 74cd73ebc7..f3a37c97c1 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -2006,9 +2006,9 @@ void memory_region_unregister_iommu_notifier(MemoryRegion *mr,
 }
 
 void memory_region_notify_iommu_one(IOMMUNotifier *notifier,
-                                    IOMMUTLBEvent *event)
+                                    const IOMMUTLBEvent *event)
 {
-    IOMMUTLBEntry *entry = &event->entry;
+    const IOMMUTLBEntry *entry = &event->entry;
     hwaddr entry_end = entry->iova + entry->addr_mask;
     IOMMUTLBEntry tmp = *entry;
 
-- 
2.41.0