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.

Backports commit 1b04a1580917d9e41fd37ca62cbff9b4bf061e96 from qemu

qemu/exec.c

@@ -1080,9 +1080,8 @@ static void register_multipage(struct uc_struct *uc,
     phys_page_set(uc, d, start_addr >> TARGET_PAGE_BITS, num_pages, section_index);
 }
 
-static void mem_add(MemoryListener *listener, MemoryRegionSection *section)
+void mem_add(AddressSpace *as, MemoryRegionSection *section)
 {
-    AddressSpace *as = container_of(listener, AddressSpace, dispatch_listener);
     AddressSpaceDispatch *d = as->next_dispatch;
     MemoryRegionSection now = *section, remain = *section;
     Int128 page_size = int128_make64(TARGET_PAGE_SIZE);
@@ -1845,9 +1844,8 @@ void phys_mem_clean(AddressSpace *as)
     g_free(d->map.sections);
 }
 
-static void mem_begin(MemoryListener *listener)
+void mem_begin(AddressSpace *as)
 {
-    AddressSpace *as = container_of(listener, AddressSpace, dispatch_listener);
     AddressSpaceDispatch *d = g_new0(AddressSpaceDispatch, 1);
     uint16_t n;
     PhysPageEntry ppe = { 1, PHYS_MAP_NODE_NIL };
@@ -1867,9 +1865,8 @@ static void mem_begin(MemoryListener *listener)
     as->next_dispatch = d;
 }
 
-static void mem_commit(MemoryListener *listener)
+void mem_commit(AddressSpace *as)
 {
-    AddressSpace *as = container_of(listener, AddressSpace, dispatch_listener);
     AddressSpaceDispatch *cur = as->dispatch;
     AddressSpaceDispatch *next = as->next_dispatch;
 
@@ -1903,31 +1900,10 @@ static void tcg_commit(MemoryListener *listener)
     tlb_flush(cpuas->cpu);
 }
 
-void address_space_init_dispatch(AddressSpace *as)
-{
-    MemoryListener ml = { 0 };
-
-    ml.begin = mem_begin;
-    ml.commit = mem_commit;
-    ml.region_add = mem_add;
-    ml.region_nop = mem_add;
-    ml.priority = 0;
-
-    as->dispatch = NULL;
-    as->dispatch_listener = ml;
-    memory_listener_register(as->uc, &as->dispatch_listener, as);
-}
-
-void address_space_unregister(AddressSpace *as)
-{
-    memory_listener_unregister(as->uc, &as->dispatch_listener);
-}
-
 void address_space_destroy_dispatch(AddressSpace *as)
 {
     AddressSpaceDispatch *d = as->dispatch;
 
-    memory_listener_unregister(as->uc, &as->dispatch_listener);
     g_free(d->map.nodes);
     g_free(d);
 

qemu/include/exec/memory-internal.h

@@ -22,7 +22,6 @@
 #ifndef CONFIG_USER_ONLY
 typedef struct AddressSpaceDispatch AddressSpaceDispatch;
 
-void address_space_init_dispatch(AddressSpace *as);
 void address_space_destroy_dispatch(AddressSpace *as);
 
 extern const MemoryRegionOps unassigned_mem_ops;
@@ -30,7 +29,9 @@ extern const MemoryRegionOps unassigned_mem_ops;
 bool memory_region_access_valid(MemoryRegion *mr, hwaddr addr,
                                 unsigned size, bool is_write);
 
-void address_space_unregister(AddressSpace *as);
+void mem_add(AddressSpace *as, MemoryRegionSection *section);
+void mem_begin(AddressSpace *as);
+void mem_commit(AddressSpace *as);
 
 #endif
 #endif

qemu/include/exec/memory.h

@@ -236,7 +236,6 @@ struct AddressSpace {
     struct FlatView *current_map;
     struct AddressSpaceDispatch *dispatch;
     struct AddressSpaceDispatch *next_dispatch;
-    MemoryListener dispatch_listener;
     struct uc_struct* uc;
 
     QTAILQ_HEAD(memory_listeners_as, MemoryListener) listeners;

qemu/memory.c

@@ -757,9 +757,20 @@ 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);
+    mem_begin(as);
-    address_space_update_topology_pass(as, old_view, new_view, true);
+    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);
+    }
 
     flatview_unref(as->current_map);
     as->current_map = new_view;
@@ -1798,7 +1809,7 @@ void address_space_init(struct uc_struct *uc, AddressSpace *as, MemoryRegion *ro
     QTAILQ_INIT(&as->listeners);
     QTAILQ_INSERT_TAIL(&uc->address_spaces, as, address_spaces_link);
     as->name = g_strdup(name ? name : "anonymous");
-    address_space_init_dispatch(as);
+    as->dispatch = NULL;
     uc->memory_region_update_pending |= root->enabled;
     memory_region_transaction_commit(uc);
 }
@@ -1856,7 +1867,6 @@ void address_space_destroy(AddressSpace *as)
     as->root = NULL;
     memory_region_transaction_commit(as->uc);
     QTAILQ_REMOVE(&as->uc->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