memory: Add iommu map/unmap notifiers

This patch adds a NotifierList to MemoryRegions which represent IOMMUs
allowing other parts of the code to register interest in mappings or
unmappings from the IOMMU.  All IOMMU implementations will need to call
memory_region_notify_iommu() to inform those waiting on the notifier list,
whenever an IOMMU mapping is made or removed.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/memory.c b/memory.c
index 7eb8d46..2a94d7d 100644
--- a/memory.c
+++ b/memory.c
@@ -1072,6 +1072,7 @@
     memory_region_init(mr, name, size);
     mr->iommu_ops = ops,
     mr->terminates = true;  /* then re-forwards */
+    notifier_list_init(&mr->iommu_notify);
 }
 
 void memory_region_init_reservation(MemoryRegion *mr,
@@ -1124,6 +1125,23 @@
     return mr->iommu_ops;
 }
 
+void memory_region_register_iommu_notifier(MemoryRegion *mr, Notifier *n)
+{
+    notifier_list_add(&mr->iommu_notify, n);
+}
+
+void memory_region_unregister_iommu_notifier(Notifier *n)
+{
+    notifier_remove(n);
+}
+
+void memory_region_notify_iommu(MemoryRegion *mr,
+                                IOMMUTLBEntry entry)
+{
+    assert(memory_region_is_iommu(mr));
+    notifier_list_notify(&mr->iommu_notify, &entry);
+}
+
 void memory_region_set_log(MemoryRegion *mr, bool log, unsigned client)
 {
     uint8_t mask = 1 << client;