vfio/mlx5: Fix the report of dirty_bytes upon pre-copy

Fix the report of dirty_bytes upon pre-copy to include both the existing
data on the migration file and the device extra bytes.

This gives a better close estimation to what can be passed any more as
part of pre-copy.

Fixes: 0dce165b1adf ("vfio/mlx5: Introduce vfio precopy ioctl implementation")
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20230308155723.108218-1-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index e897537..d95fd38 100644 (file)
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -442,16 +442,10 @@ static long mlx5vf_precopy_ioctl(struct file *filp, unsigned int cmd,
        if (migf->pre_copy_initial_bytes > *pos) {
                info.initial_bytes = migf->pre_copy_initial_bytes - *pos;
        } else {
-               buf = mlx5vf_get_data_buff_from_pos(migf, *pos, &end_of_data);
-               if (buf) {
-                       info.dirty_bytes = buf->start_pos + buf->length - *pos;
-               } else {
-                       if (!end_of_data) {
-                               ret = -EINVAL;
-                               goto err_migf_unlock;
-                       }
-                       info.dirty_bytes = inc_length;
-               }
+               info.dirty_bytes = migf->max_pos - *pos;
+               if (!info.dirty_bytes)
+                       end_of_data = true;
+               info.dirty_bytes += inc_length;
        }
 
        if (!end_of_data || !inc_length) {