[PATCH v3 3/7] migration: Introduce postcopy incoming setup and cleanup functions

[Juraj Marcin <jmarcin@redhat.com>]

From: Juraj Marcin <jmarcin@redhat.com>

After moving postcopy_ram_listen_thread() to postcopy file, this patch
introduces a pair of functions, postcopy_incoming_setup() and
postcopy_incoming_cleanup(). These functions encapsulate setup and
cleanup of all incoming postcopy resources, postcopy-ram and postcopy
listen thread.

Furthermore, this patch also renames the postcopy_ram_listen_thread to
postcopy_listen_thread, as this thread handles not only postcopy-ram,
but also dirty-bitmaps and in the future it could handle other
postcopiable devices.

Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
---
 migration/migration.c    |  2 +-
 migration/postcopy-ram.c | 46 ++++++++++++++++++++++++++++++++++++----
 migration/postcopy-ram.h |  3 ++-
 migration/savevm.c       | 25 ++--------------------
 4 files changed, 47 insertions(+), 29 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 6e647c7c4a..9a367f717e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -892,7 +892,7 @@ process_incoming_migration_co(void *opaque)
              * but managed to complete within the precopy period, we can use
              * the normal exit.
              */
-            postcopy_ram_incoming_cleanup(mis);
+            postcopy_incoming_cleanup(mis);
         } else if (ret >= 0) {
             /*
              * Postcopy was started, cleanup should happen at the end of the
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 36d5415554..b47c955763 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -2082,10 +2082,8 @@ bool postcopy_is_paused(MigrationStatus status)
  * Triggered by a postcopy_listen command; this thread takes over reading
  * the input stream, leaving the main thread free to carry on loading the rest
  * of the device state (from RAM).
- * (TODO:This could do with being in a postcopy file - but there again it's
- * just another input loop, not that postcopy specific)
  */
-void *postcopy_ram_listen_thread(void *opaque)
+static void *postcopy_listen_thread(void *opaque)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
     QEMUFile *f = mis->from_src_file;
@@ -2151,7 +2149,7 @@ void *postcopy_ram_listen_thread(void *opaque)
          */
         qemu_event_wait(&mis->main_thread_load_event);
     }
-    postcopy_ram_incoming_cleanup(mis);
+    postcopy_incoming_cleanup(mis);
 
     if (load_res < 0) {
         /*
@@ -2184,3 +2182,43 @@ void *postcopy_ram_listen_thread(void *opaque)
 
     return NULL;
 }
+
+int postcopy_incoming_setup(MigrationIncomingState *mis, Error **errp)
+{
+    /*
+     * Sensitise RAM - can now generate requests for blocks that don't exist
+     * However, at this point the CPU shouldn't be running, and the IO
+     * shouldn't be doing anything yet so don't actually expect requests
+     */
+    if (migrate_postcopy_ram()) {
+        if (postcopy_ram_incoming_setup(mis)) {
+            postcopy_ram_incoming_cleanup(mis);
+            error_setg(errp, "Failed to setup incoming postcopy RAM blocks");
+            return -1;
+        }
+    }
+
+    trace_loadvm_postcopy_handle_listen("after uffd");
+
+    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, errp)) {
+        return -1;
+    }
+
+    mis->have_listen_thread = true;
+    postcopy_thread_create(mis, &mis->listen_thread,
+                           MIGRATION_THREAD_DST_LISTEN,
+                           postcopy_listen_thread, QEMU_THREAD_DETACHED);
+
+    return 0;
+}
+
+int postcopy_incoming_cleanup(MigrationIncomingState *mis)
+{
+    int rc = 0;
+
+    if (migrate_postcopy_ram()) {
+        rc = postcopy_ram_incoming_cleanup(mis);
+    }
+
+    return rc;
+}
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 3e26db3e6b..a080dd65a7 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -199,6 +199,7 @@ bool postcopy_is_paused(MigrationStatus status);
 void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
                                    RAMBlock *rb);
 
-void *postcopy_ram_listen_thread(void *opaque);
+int postcopy_incoming_setup(MigrationIncomingState *mis, Error **errp);
+int postcopy_incoming_cleanup(MigrationIncomingState *mis);
 
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 97fdd08c08..6ae3f740b5 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2112,32 +2112,11 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis,
 
     trace_loadvm_postcopy_handle_listen("after discard");
 
-    /*
-     * Sensitise RAM - can now generate requests for blocks that don't exist
-     * However, at this point the CPU shouldn't be running, and the IO
-     * shouldn't be doing anything yet so don't actually expect requests
-     */
-    if (migrate_postcopy_ram()) {
-        if (postcopy_ram_incoming_setup(mis)) {
-            postcopy_ram_incoming_cleanup(mis);
-            error_setg(errp, "Failed to setup incoming postcopy RAM blocks");
-            return -1;
-        }
-    }
+    int rc = postcopy_incoming_setup(mis, errp);
 
-    trace_loadvm_postcopy_handle_listen("after uffd");
-
-    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, errp)) {
-        return -1;
-    }
-
-    mis->have_listen_thread = true;
-    postcopy_thread_create(mis, &mis->listen_thread,
-                           MIGRATION_THREAD_DST_LISTEN,
-                           postcopy_ram_listen_thread, QEMU_THREAD_DETACHED);
     trace_loadvm_postcopy_handle_listen("return");
 
-    return 0;
+    return rc;
 }
 
 static void loadvm_postcopy_handle_run_bh(void *opaque)
-- 
2.51.0