On Fri, Oct 22, 2021 at 10:45 AM Wu Zongyong
<wuzongyong@xxxxxxxxxxxxxxxxx> wrote:
>
> For the devices which implement the get_vq_num_min callback, the driver
> should not negotiate with virtqueue size with the backend vdpa device if
> the value returned by get_vq_num_min equals to the value returned by
> get_vq_num_max.
> This is useful for vdpa devices based on legacy virtio specfication.
>
> Signed-off-by: Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_vdpa.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index 72eaef2caeb1..e42ace29daa1 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -145,7 +145,8 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> /* Assume split virtqueue, switch to packed if necessary */
> struct vdpa_vq_state state = {0};
> unsigned long flags;
> - u32 align, num;
> + u32 align, max_num, min_num = 0;
> + bool may_reduce_num = true;
> int err;
>
> if (!name)
> @@ -163,22 +164,32 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> if (!info)
> return ERR_PTR(-ENOMEM);
>
> - num = ops->get_vq_num_max(vdpa);
> - if (num == 0) {
> + max_num = ops->get_vq_num_max(vdpa);
> + if (max_num == 0) {
> err = -ENOENT;
> goto error_new_virtqueue;
> }
>
> + if (ops->get_vq_num_min)
> + min_num = ops->get_vq_num_min(vdpa);
> +
> + may_reduce_num = (max_num == min_num) ? false : true;
> +
> /* Create the vring */
> align = ops->get_vq_align(vdpa);
> - vq = vring_create_virtqueue(index, num, align, vdev,
> - true, true, ctx,
> + vq = vring_create_virtqueue(index, max_num, align, vdev,
> + true, may_reduce_num, ctx,
> virtio_vdpa_notify, callback, name);
> if (!vq) {
> err = -ENOMEM;
> goto error_new_virtqueue;
> }
>
> + if (virtqueue_get_vring_size(vq) < min_num) {
> + err = -EINVAL;
> + goto err_vq;
> + }
I wonder under which case can we hit this?
Thanks
> +
> /* Setup virtqueue callback */
> cb.callback = virtio_vdpa_virtqueue_cb;
> cb.private = info;
> --
> 2.31.1
>
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