memory: Move AddressSpaceDispatch from AddressSpace to FlatView

As we are going to share FlatView's between AddressSpace's,
and AddressSpaceDispatch is a structure to perform quick lookup
in FlatView, this moves ASD to FlatView.

After previosly open coded ASD rendering, we can also remove
as->next_dispatch as the new FlatView pointer is stored
on a stack and set to an AS atomically.

flatview_destroy() is executed under RCU instead of
address_space_dispatch_free() now.

This makes mem_begin/mem_commit to work with ASD and mem_add with FV
as later on mem_add will be taking FV as an argument anyway.

This should cause no behavioural change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20170921085110.25598-5-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 24 insertions, 7 deletions

diff --git a/memory.c b/memory.c
index eec668e..962e9b9 100644
--- a/memory.c
+++ b/memory.c
@@ -229,6 +229,7 @@ struct FlatView {
     FlatRange *ranges;
     unsigned nr;
     unsigned nr_allocated;
+    struct AddressSpaceDispatch *dispatch;
 };
 
 typedef struct AddressSpaceOps AddressSpaceOps;
@@ -289,6 +290,9 @@ static void flatview_destroy(FlatView *view)
 {
     int i;
 
+    if (view->dispatch) {
+        address_space_dispatch_free(view->dispatch);
+    }
     for (i = 0; i < view->nr; i++) {
         memory_region_unref(view->ranges[i].mr);
     }
@@ -304,10 +308,25 @@ static bool flatview_ref(FlatView *view)
 static void flatview_unref(FlatView *view)
 {
     if (atomic_fetch_dec(&view->ref) == 1) {
-        flatview_destroy(view);
+        call_rcu(view, flatview_destroy, rcu);
     }
 }
 
+static FlatView *address_space_to_flatview(AddressSpace *as)
+{
+    return atomic_rcu_read(&as->current_map);
+}
+
+AddressSpaceDispatch *flatview_to_dispatch(FlatView *fv)
+{
+    return fv->dispatch;
+}
+
+AddressSpaceDispatch *address_space_to_dispatch(AddressSpace *as)
+{
+    return flatview_to_dispatch(address_space_to_flatview(as));
+}
+
 static bool can_merge(FlatRange *r1, FlatRange *r2)
 {
     return int128_eq(addrrange_end(r1->addr), r2->addr.start)
@@ -891,13 +910,13 @@ static void address_space_update_topology(AddressSpace *as)
     FlatView *new_view = generate_memory_topology(as->root);
     int i;
 
-    mem_begin(as);
+    new_view->dispatch = 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_add(as, new_view, &mrs);
     }
-    mem_commit(as);
+    mem_commit(new_view->dispatch);
 
     if (!QTAILQ_EMPTY(&as->listeners)) {
         address_space_update_topology_pass(as, old_view, new_view, false);
@@ -906,7 +925,7 @@ static void address_space_update_topology(AddressSpace *as)
 
     /* Writes are protected by the BQL.  */
     atomic_rcu_set(&as->current_map, new_view);
-    call_rcu(old_view, flatview_unref, rcu);
+    flatview_unref(old_view);
 
     /* Note that all the old MemoryRegions are still alive up to this
      * point.  This relieves most MemoryListeners from the need to
@@ -2636,7 +2655,6 @@ 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");
-    as->dispatch = NULL;
     memory_region_update_pending |= root->enabled;
     memory_region_transaction_commit();
 }
@@ -2645,7 +2663,6 @@ static void do_address_space_destroy(AddressSpace *as)
 {
     bool do_free = as->malloced;
 
-    address_space_destroy_dispatch(as);
     assert(QTAILQ_EMPTY(&as->listeners));
 
     flatview_unref(as->current_map);