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SubjectRe: [PATCH v2 3/3] vdpa/mlx5: defer clear_virtqueues to until DRIVER_OK
On Wed, Feb 10, 2021 at 01:48:00PM -0800, Si-Wei Liu wrote:
> While virtq is stopped, get_vq_state() is supposed to
> be called to get sync'ed with the latest internal
> avail_index from device. The saved avail_index is used
> to restate the virtq once device is started. Commit
> b35ccebe3ef7 introduced the clear_virtqueues() routine
> to reset the saved avail_index, however, the index
> gets cleared a bit earlier before get_vq_state() tries
> to read it. This would cause consistency problems when
> virtq is restarted, e.g. through a series of link down
> and link up events. We could defer the clearing of
> avail_index to until the device is to be started,
> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
> set_status().
>
> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
> Acked-by: Jason Wang <jasowang@redhat.com>

Acked-by: Eli Cohen <elic@nvidia.com>

> ---
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 7c1f789..ce6aae8 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1777,7 +1777,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> if (!status) {
> mlx5_vdpa_info(mvdev, "performing device reset\n");
> teardown_driver(ndev);
> - clear_virtqueues(ndev);
> mlx5_vdpa_destroy_mr(&ndev->mvdev);
> ndev->mvdev.status = 0;
> ++mvdev->generation;
> @@ -1786,6 +1785,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>
> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> + clear_virtqueues(ndev);
> err = setup_driver(ndev);
> if (err) {
> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
> --
> 1.8.3.1
>

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