From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

This way both the start and end points of migrating a particular VFIO
device are known.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 include/hw/vfio/vfio-common.h | 2 ++
 hw/vfio/migration.c           | 9 +++++++++
 hw/vfio/trace-events          | 2 ++
 3 files changed, 13 insertions(+)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index fed499b199f09bbd8da90e3df7eb6c904c11a466..282eadf4ebf5a27a3f7168868fbc2a20d94252c0 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -73,6 +73,8 @@ typedef struct VFIOMigration {
     uint64_t precopy_init_size;
     uint64_t precopy_dirty_size;
     bool initial_data_sent;
+
+    bool event_save_iterate_started;
 } VFIOMigration;
 
 struct VFIOGroup;
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 992dc3b1025729877d9fbe6ce9a4dbaf4dbd8a07..87ddc210578f4ecbaf30fa5d8816ce182cbcbcb0 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -472,6 +472,8 @@ static int vfio_save_setup(QEMUFile *f, void *opaque, Error **errp)
         return -ENOMEM;
     }
 
+    migration->event_save_iterate_started = false;
+
     if (vfio_precopy_supported(vbasedev)) {
         switch (migration->device_state) {
         case VFIO_DEVICE_STATE_RUNNING:
@@ -602,6 +604,11 @@ static int vfio_save_iterate(QEMUFile *f, void *opaque)
     VFIOMigration *migration = vbasedev->migration;
     ssize_t data_size;
 
+    if (!migration->event_save_iterate_started) {
+        trace_vfio_save_iterate_start(vbasedev->name);
+        migration->event_save_iterate_started = true;
+    }
+
     data_size = vfio_save_block(f, migration);
     if (data_size < 0) {
         return data_size;
@@ -630,6 +637,8 @@ static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
     int ret;
     Error *local_err = NULL;
 
+    trace_vfio_save_complete_precopy_start(vbasedev->name);
+
     /* We reach here with device state STOP or STOP_COPY only */
     ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_STOP_COPY,
                                    VFIO_DEVICE_STATE_STOP, &local_err);
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 29789e8d276dcd39270edb3636d7f329452e9186..032a51a10592fdab3dd9b2be6506d034275678e7 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -159,8 +159,10 @@ vfio_migration_state_notifier(const char *name, int state) " (%s) state %d"
 vfio_save_block(const char *name, int data_size) " (%s) data_size %d"
 vfio_save_cleanup(const char *name) " (%s)"
 vfio_save_complete_precopy(const char *name, int ret) " (%s) ret %d"
+vfio_save_complete_precopy_start(const char *name) " (%s)"
 vfio_save_device_config_state(const char *name) " (%s)"
 vfio_save_iterate(const char *name, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy initial size %"PRIu64" precopy dirty size %"PRIu64
+vfio_save_iterate_start(const char *name) " (%s)"
 vfio_save_setup(const char *name, uint64_t data_buffer_size) " (%s) data buffer size %"PRIu64
 vfio_state_pending_estimate(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy %"PRIu64" postcopy %"PRIu64" precopy initial size %"PRIu64" precopy dirty size %"PRIu64
 vfio_state_pending_exact(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t stopcopy_size, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy %"PRIu64" postcopy %"PRIu64" stopcopy size %"PRIu64" precopy initial size %"PRIu64" precopy dirty size %"PRIu64
-- 
2.47.0