memory: Open code FlatView rendering

We are going to share FlatView's between AddressSpace's and per-AS
memory listeners won't suit the purpose anymore so open code
the dispatch tree rendering.

Since there is a good chance that dispatch_listener was the only
listener, this avoids address_space_update_topology_pass() if there is
no registered listeners; this should improve starting time.

This should cause no behavioural change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20170921085110.25598-3-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/memory.c b/memory.c
index 51f54ab..3241e44 100644
--- a/memory.c
+++ b/memory.c
@@ -884,14 +884,24 @@ static void address_space_update_topology_pass(AddressSpace *as,
     }
 }
 
-
 static void address_space_update_topology(AddressSpace *as)
 {
     FlatView *old_view = address_space_get_flatview(as);
     FlatView *new_view = generate_memory_topology(as->root);
+    int i;
 
-    address_space_update_topology_pass(as, old_view, new_view, false);
-    address_space_update_topology_pass(as, old_view, new_view, true);
+    mem_begin(as);
+    for (i = 0; i < new_view->nr; i++) {
+        MemoryRegionSection mrs =
+            section_from_flat_range(&new_view->ranges[i], as);
+        mem_add(as, &mrs);
+    }
+    mem_commit(as);
+
+    if (!QTAILQ_EMPTY(&as->listeners)) {
+        address_space_update_topology_pass(as, old_view, new_view, false);
+        address_space_update_topology_pass(as, old_view, new_view, true);
+    }
 
     /* Writes are protected by the BQL.  */
     atomic_rcu_set(&as->current_map, new_view);
@@ -2626,7 +2636,7 @@ void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name)
     QTAILQ_INIT(&as->listeners);
     QTAILQ_INSERT_TAIL(&address_spaces, as, address_spaces_link);
     as->name = g_strdup(name ? name : "anonymous");
-    address_space_init_dispatch(as);
+    as->dispatch = NULL;
     memory_region_update_pending |= root->enabled;
     memory_region_transaction_commit();
 }
@@ -2677,7 +2687,6 @@ void address_space_destroy(AddressSpace *as)
     as->root = NULL;
     memory_region_transaction_commit();
     QTAILQ_REMOVE(&address_spaces, as, address_spaces_link);
-    address_space_unregister(as);
 
     /* At this point, as->dispatch and as->current_map are dummy
      * entries that the guest should never use.  Wait for the old