vfio/mlx5: Refactor to use queue based data chunks

Refactor to use queue based data chunks on the migration file.

The SAVE command adds a chunk to the tail of the queue while the read()
API finds the required chunk and returns its data.

In case the queue is empty but the state of the migration file is
MLX5_MIGF_STATE_COMPLETE, read() may not be blocked but will return 0 to
indicate end of file.

This is a step towards maintaining multiple images and their meta data
(i.e. headers) on the migration file as part of next patches from the
series.

Note:
At that point, we still use a single chunk on the migration file but
becomes ready to support multiple.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20221206083438.37807-8-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index fcba12326185..0e36b4c8c816 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -351,6 +351,7 @@ void mlx5vf_mig_file_cleanup_cb(struct work_struct *_work)
 
 	mutex_lock(&migf->lock);
 	if (async_data->status) {
+		migf->buf = async_data->buf;
 		migf->state = MLX5_MIGF_STATE_ERROR;
 		wake_up_interruptible(&migf->poll_wait);
 	}
@@ -368,9 +369,15 @@ static void mlx5vf_save_callback(int status, struct mlx5_async_work *context)
 			struct mlx5_vf_migration_file, async_data);
 
 	if (!status) {
-		WRITE_ONCE(migf->buf->length,
-			   MLX5_GET(save_vhca_state_out, async_data->out,
-				    actual_image_size));
+		unsigned long flags;
+
+		async_data->buf->length =
+			MLX5_GET(save_vhca_state_out, async_data->out,
+				 actual_image_size);
+		spin_lock_irqsave(&migf->list_lock, flags);
+		list_add_tail(&async_data->buf->buf_elm, &migf->buf_list);
+		spin_unlock_irqrestore(&migf->list_lock, flags);
+		migf->state = MLX5_MIGF_STATE_COMPLETE;
 		wake_up_interruptible(&migf->poll_wait);
 	}
 
@@ -407,6 +414,7 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
 	MLX5_SET(save_vhca_state_in, in, size, buf->allocated_length);
 
 	async_data = &migf->async_data;
+	async_data->buf = buf;
 	async_data->out = kvzalloc(out_size, GFP_KERNEL);
 	if (!async_data->out) {
 		err = -ENOMEM;
@@ -479,14 +487,22 @@ void mlx5vf_cmd_dealloc_pd(struct mlx5_vf_migration_file *migf)
 
 void mlx5fv_cmd_clean_migf_resources(struct mlx5_vf_migration_file *migf)
 {
-	lockdep_assert_held(&migf->mvdev->state_mutex);
+	struct mlx5_vhca_data_buffer *entry;
 
+	lockdep_assert_held(&migf->mvdev->state_mutex);
 	WARN_ON(migf->mvdev->mdev_detach);
 
 	if (migf->buf) {
 		mlx5vf_free_data_buffer(migf->buf);
 		migf->buf = NULL;
 	}
+
+	while ((entry = list_first_entry_or_null(&migf->buf_list,
+				struct mlx5_vhca_data_buffer, buf_elm))) {
+		list_del(&entry->buf_elm);
+		mlx5vf_free_data_buffer(entry);
+	}
+
 	mlx5vf_cmd_dealloc_pd(migf);
 }