On Wed, Oct 11, 2023 at 05:27:07PM +0800, Xuan Zhuo wrote:
> virtqueue_set_dma_premapped() adds a new parameter to disable the
> virtqueue premapped mode.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 2 +-
> drivers/virtio/virtio_ring.c | 11 ++++++++---
> include/linux/virtio.h | 2 +-
> 3 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index fe7f314d65c9..6b5f47ebf9b2 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -737,7 +737,7 @@ static void virtnet_rq_set_premapped(struct virtnet_info *vi)
> return;
>
> for (i = 0; i < vi->max_queue_pairs; i++) {
> - if (virtqueue_set_dma_premapped(vi->rq[i].vq))
> + if (virtqueue_set_dma_premapped(vi->rq[i].vq, true))
> continue;
>
> vi->rq[i].do_dma = true;
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 51d8f3299c10..b3ded56722f4 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2784,7 +2784,7 @@ EXPORT_SYMBOL_GPL(virtqueue_resize);
> * 0: success.
> * -EINVAL: vring does not use the dma api, so we can not enable premapped mode.
> */
> -int virtqueue_set_dma_premapped(struct virtqueue *_vq)
> +int virtqueue_set_dma_premapped(struct virtqueue *_vq, bool mode)
> {
> struct vring_virtqueue *vq = to_vvq(_vq);
> u32 num;
> @@ -2803,8 +2803,13 @@ int virtqueue_set_dma_premapped(struct virtqueue *_vq)
> return -EINVAL;
> }
>
> - vq->premapped = true;
> - vq->do_unmap = false;
> + if (mode) {
> + vq->premapped = true;
> + vq->do_unmap = false;
> + } else {
> + vq->premapped = false;
> + vq->do_unmap = vq->use_dma_api;
> + }
>
> END_USE(vq);
>
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 4cc614a38376..1cf7b004348b 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -81,7 +81,7 @@ bool virtqueue_enable_cb(struct virtqueue *vq);
>
> unsigned virtqueue_enable_cb_prepare(struct virtqueue *vq);
>
> -int virtqueue_set_dma_premapped(struct virtqueue *_vq);
> +int virtqueue_set_dma_premapped(struct virtqueue *_vq, bool mode);
>
> bool virtqueue_poll(struct virtqueue *vq, unsigned);
Wait a sec I thought we never change premapped. If you make this
dynamic don't you need a bunch of locking?
Or maybe queue is empty when you change this?
If yes pls add a bunch of BUG_ON checks to make sure this is not misused.
> --
> 2.32.0.3.g01195cf9f
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