memory: support stateless memory listeners

Current memory listeners are incremental; that is, they are expected to
maintain their own state, and receive callbacks for changes to that state.

This patch adds support for stateless listeners; these work by receiving
a ->begin() callback (which tells them that new state is coming), a
sequence of ->region_add() and ->region_nop() callbacks, and then a
->commit() callback which signifies the end of the new state.  They should
ignore ->region_del() callbacks.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/xen-all.c b/xen-all.c
index a58a397ca4..6a11342665 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -394,6 +394,14 @@ static void xen_set_memory(struct MemoryListener *listener,
     }
 }
 
+static void xen_begin(MemoryListener *listener)
+{
+}
+
+static void xen_commit(MemoryListener *listener)
+{
+}
+
 static void xen_region_add(MemoryListener *listener,
                            MemoryRegionSection *section)
 {
@@ -406,6 +414,11 @@ static void xen_region_del(MemoryListener *listener,
     xen_set_memory(listener, section, false);
 }
 
+static void xen_region_nop(MemoryListener *listener,
+                           MemoryRegionSection *section)
+{
+}
+
 static void xen_sync_dirty_bitmap(XenIOState *state,
                                   target_phys_addr_t start_addr,
                                   ram_addr_t size)
@@ -500,8 +513,11 @@ static void xen_eventfd_del(MemoryListener *listener,
 }
 
 static MemoryListener xen_memory_listener = {
+    .begin = xen_begin,
+    .commit = xen_commit,
     .region_add = xen_region_add,
     .region_del = xen_region_del,
+    .region_nop = xen_region_nop,
     .log_start = xen_log_start,
     .log_stop = xen_log_stop,
     .log_sync = xen_log_sync,