[PULL 03/34] vfio/migration: Add a note about migration rate limiting

[peterx]

From: Avihai Horon <avihaih@nvidia.com>

VFIO migration buffer size is currently limited to 1MB. Therefore, there
is no need to check if migration rate exceeded, as in the worst case it
will exceed by only 1MB.

However, if the buffer size is later changed to a bigger value,
vfio_save_iterate() should enforce migration rate (similar to migration
RAM code).

Add a note about this in vfio_save_iterate() to serve as a reminder.

Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: 20240304105339.20713-4-avihaih@nvidia.com">https://lore.kernel.org/r/20240304105339.20713-4-avihaih@nvidia.com
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/vfio/migration.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 0af783a589..f82dcabc49 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -505,6 +505,12 @@ static bool vfio_is_active_iterate(void *opaque)
     return vfio_device_state_is_precopy(vbasedev);
 }
 
+/*
+ * Note about migration rate limiting: VFIO migration buffer size is currently
+ * limited to 1MB, so there is no need to check if migration rate exceeded (as
+ * in the worst case it will exceed by 1MB). However, if the buffer size is
+ * later changed to a bigger value, migration rate should be enforced here.
+ */
 static int vfio_save_iterate(QEMUFile *f, void *opaque)
 {
     VFIODevice *vbasedev = opaque;
-- 
2.44.0