On Thu, Mar 2, 2023 at 7:59 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> Added virtqueue_get_dma_dev() to get DMA device for virtio. Then the
> caller can do dma operation in advance. The purpose is to keep memory
> mapped across multiple add/get buf operations.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio.c | 6 ++++++
> drivers/virtio/virtio_ring.c | 17 +++++++++++++++++
> include/linux/virtio.h | 2 ++
> 3 files changed, 25 insertions(+)
>
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index b9a80aedee1b..062b6381f5c9 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -1,4 +1,5 @@
> // SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/dma-mapping.h>
> #include <linux/virtio.h>
> #include <linux/spinlock.h>
> #include <linux/virtio_config.h>
> @@ -243,6 +244,11 @@ static int virtio_dev_probe(struct device *_d)
> u64 driver_features;
> u64 driver_features_legacy;
>
> + _d->dma_mask = &_d->coherent_dma_mask;
> + err = dma_set_mask_and_coherent(_d, DMA_BIT_MASK(64));
> + if (err)
> + return err;
> +
> /* We have a driver! */
> virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 53df12a8ab97..9b6a0febae58 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2407,6 +2407,23 @@ int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
> }
> EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_premapped);
>
> +/**
> + * virtqueue_get_dma_dev - expose the dma dev
Nit: I suggest to use "get" instead of "expose", and considering we
had vring_dma_dev() we can simply rename this function as
virtqueue_dma_dev().
Other than this
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Thanks
> + * @_vq: the struct virtqueue we're talking about.
> + *
> + * Returns the dma dev. That can been used for dma api.
> + */
> +struct device *virtqueue_get_dma_dev(struct virtqueue *_vq)
> +{
> + struct vring_virtqueue *vq = to_vvq(_vq);
> +
> + if (vq->use_dma_api)
> + return vring_dma_dev(vq);
> + else
> + return &vq->vq.vdev->dev;
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_get_dma_dev);
> +
> /**
> * virtqueue_kick_prepare - first half of split virtqueue_kick call.
> * @_vq: the struct virtqueue
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 3ebb346ebb7c..ac028b07f684 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -71,6 +71,8 @@ int virtqueue_add_sgs(struct virtqueue *vq,
> void *data,
> gfp_t gfp);
>
> +struct device *virtqueue_get_dma_dev(struct virtqueue *vq);
> +
> bool virtqueue_kick(struct virtqueue *vq);
>
> bool virtqueue_kick_prepare(struct virtqueue *vq);
> --
> 2.32.0.3.g01195cf9f
>
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