[Qemu-devel] [PATCH 1/3] Finish non-postcopiable iterative devices before package

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Where we have iterable, but non-postcopiable devices (e.g. htab
or block migration), complete them before forming the 'package'
but with the CPUs stopped.  This stops them filling up the package.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/sysemu/sysemu.h |  2 +-
 migration/migration.c   | 10 ++++++++--
 migration/savevm.c      | 10 ++++++++--
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index f992494..3bb8897 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -112,7 +112,7 @@ void qemu_savevm_state_header(QEMUFile *f);
 int qemu_savevm_state_iterate(QEMUFile *f, bool postcopy);
 void qemu_savevm_state_cleanup(void);
 void qemu_savevm_state_complete_postcopy(QEMUFile *f);
-void qemu_savevm_state_complete_precopy(QEMUFile *f);
+void qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only);
 void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
                                uint64_t *res_non_postcopiable,
                                uint64_t *res_postcopiable);
diff --git a/migration/migration.c b/migration/migration.c
index c5c977e..5df490a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1429,6 +1429,12 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
     }
 
     /*
+     * Cause any non-postcopiable, but iterative devices to
+     * send out their final data.
+     */
+    qemu_savevm_state_complete_precopy(ms->file, true);
+
+    /*
      * in Finish migrate and with the io-lock held everything should
      * be quiet, but we've potentially still got dirty pages and we
      * need to tell the destination to throw any pages it's already received
@@ -1471,7 +1477,7 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
      */
     qemu_savevm_send_postcopy_listen(fb);
 
-    qemu_savevm_state_complete_precopy(fb);
+    qemu_savevm_state_complete_precopy(fb, false);
     qemu_savevm_send_ping(fb, 3);
 
     qemu_savevm_send_postcopy_run(fb);
@@ -1538,7 +1544,7 @@ static void migration_completion(MigrationState *s, int current_active_state,
             ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
             if (ret >= 0) {
                 qemu_file_set_rate_limit(s->file, INT64_MAX);
-                qemu_savevm_state_complete_precopy(s->file);
+                qemu_savevm_state_complete_precopy(s->file, false);
             }
         }
         qemu_mutex_unlock_iothread();
diff --git a/migration/savevm.c b/migration/savevm.c
index be52314..d90e228 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1026,7 +1026,7 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f)
     qemu_fflush(f);
 }
 
-void qemu_savevm_state_complete_precopy(QEMUFile *f)
+void qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only)
 {
     QJSON *vmdesc;
     int vmdesc_len;
@@ -1041,9 +1041,11 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f)
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
         if (!se->ops ||
             (in_postcopy && se->ops->save_live_complete_postcopy) ||
+            (in_postcopy && !iterable_only) ||
             !se->ops->save_live_complete_precopy) {
             continue;
         }
+
         if (se->ops && se->ops->is_active) {
             if (!se->ops->is_active(se->opaque)) {
                 continue;
@@ -1062,6 +1064,10 @@ void qemu_savevm_state_complete_precopy(QEMUFile *f)
         }
     }
 
+    if (iterable_only) {
+        return;
+    }
+
     vmdesc = qjson_new();
     json_prop_int(vmdesc, "page_size", TARGET_PAGE_SIZE);
     json_start_array(vmdesc, "devices");
@@ -1176,7 +1182,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
 
     ret = qemu_file_get_error(f);
     if (ret == 0) {
-        qemu_savevm_state_complete_precopy(f);
+        qemu_savevm_state_complete_precopy(f, false);
         ret = qemu_file_get_error(f);
     }
     qemu_savevm_state_cleanup();
-- 
2.5.0