On Sun, Nov 06, 2022 at 07:46:22PM +0200, Yishai Hadas wrote:
> Enforce a single SAVE command at a time.
>
> As the SAVE command is an asynchronous one, we must enforce running only
> a single command at a time.
>
> This will preserve ordering between multiple calls and protect from
> races on the migration file data structure.
>
> This is a must for the next patches from the series where as part of
> PRE_COPY we may have multiple images to be saved and multiple SAVE
> commands may be issued from different flows.
>
> Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> ---
> drivers/vfio/pci/mlx5/cmd.c | 5 +++++
> drivers/vfio/pci/mlx5/cmd.h | 2 ++
> drivers/vfio/pci/mlx5/main.c | 1 +
> 3 files changed, 8 insertions(+)
This should just use a 'counting completion' instead of open coding
one.
> diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
> index 0848bc905d3e..b9ed2f1c8689 100644
> --- a/drivers/vfio/pci/mlx5/cmd.c
> +++ b/drivers/vfio/pci/mlx5/cmd.c
> @@ -281,6 +281,8 @@ void mlx5vf_mig_file_cleanup_cb(struct work_struct *_work)
> dma_unmap_sgtable(mdev->device, &migf->table.sgt, DMA_FROM_DEVICE, 0);
> mlx5_core_dealloc_pd(mdev, async_data->pdn);
> kvfree(async_data->out);
> + migf->save_cb_active = false;
> + wake_up(&migf->save_wait);
complete()
> fput(migf->filp);
> }
>
> @@ -321,6 +323,7 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
> return -ENOTCONN;
>
> mdev = mvdev->mdev;
> + wait_event(migf->save_wait, !migf->save_cb_active);
wait_for_completion_interruptible()
> err = mlx5_core_alloc_pd(mdev, &pdn);
> if (err)
> return err;
> @@ -353,6 +356,7 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
> get_file(migf->filp);
> async_data->mkey = mkey;
> async_data->pdn = pdn;
> + migf->save_cb_active = true;
> err = mlx5_cmd_exec_cb(&migf->async_ctx, in, sizeof(in),
> async_data->out,
> out_size, mlx5vf_save_callback,
> @@ -371,6 +375,7 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
> dma_unmap_sgtable(mdev->device, &migf->table.sgt, DMA_FROM_DEVICE, 0);
> err_dma_map:
> mlx5_core_dealloc_pd(mdev, pdn);
> + migf->save_cb_active = false;
complete()
> return err;
> }
>
> diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
> index 921d5720a1e5..b1c5dd2ff144 100644
> --- a/drivers/vfio/pci/mlx5/cmd.h
> +++ b/drivers/vfio/pci/mlx5/cmd.h
> @@ -26,6 +26,7 @@ struct mlx5_vf_migration_file {
> struct mutex lock;
> u8 disabled:1;
> u8 is_err:1;
> + u8 save_cb_active:1;
>
> struct sg_append_table table;
> size_t total_length;
> @@ -37,6 +38,7 @@ struct mlx5_vf_migration_file {
> unsigned long last_offset;
> struct mlx5vf_pci_core_device *mvdev;
> wait_queue_head_t poll_wait;
> + wait_queue_head_t save_wait;
> struct mlx5_async_ctx async_ctx;
> struct mlx5vf_async_data async_data;
> };
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> index 4c7a39ffd247..5da278f3c31c 100644
> --- a/drivers/vfio/pci/mlx5/main.c
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -245,6 +245,7 @@ mlx5vf_pci_save_device_data(struct mlx5vf_pci_core_device *mvdev)
> stream_open(migf->filp->f_inode, migf->filp);
> mutex_init(&migf->lock);
> init_waitqueue_head(&migf->poll_wait);
> + init_waitqueue_head(&migf->save_wait);
init_completion()
complete()
Jason
