On Tue, 21 Mar 2023 16:45:21 -0400, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> On Tue, Mar 21, 2023 at 05:34:59PM +0800, Xuan Zhuo wrote:
> > virtio core only supports virtual addresses, dma is completed in virtio
> > core.
> >
> > In some scenarios (such as the AF_XDP), the memory is allocated
> > and DMA mapping is completed in advance, so it is necessary for us to
> > support passing the DMA address to virtio core.
> >
> > Drives can use sg->dma_address to pass the mapped dma address to virtio
> > core. If one sg->dma_address is used then all sgs must use
> > sg->dma_address, otherwise all must be null when passing it to the APIs
> > of virtio.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/virtio/virtio_ring.c | 27 +++++++++++++++++++--------
> > 1 file changed, 19 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index c8ed4aef9462..be2ff96964c3 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -70,6 +70,7 @@
> > struct vring_desc_state_split {
> > void *data; /* Data for callback. */
> > struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
> > + bool map_inter; /* Do dma map internally. */
>
> I prefer a full name. E.g. "dma_map_internal". Eschew abbreviation.
Will fix.
Thanks.
>
>
> > };
> >
> > struct vring_desc_state_packed {
> > @@ -448,7 +449,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq,
> > }
> >
> > static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq,
> > - unsigned int i)
> > + unsigned int i, bool map_inter)
> > {
> > struct vring_desc_extra *extra = vq->split.desc_extra;
> > u16 flags;
> > @@ -465,6 +466,9 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq,
> > (flags & VRING_DESC_F_WRITE) ?
> > DMA_FROM_DEVICE : DMA_TO_DEVICE);
> > } else {
> > + if (!map_inter)
> > + goto out;
> > +
> > dma_unmap_page(vring_dma_dev(vq),
> > extra[i].addr,
> > extra[i].len,
> > @@ -615,7 +619,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > struct scatterlist *sg;
> > struct vring_desc *desc;
> > unsigned int i, n, avail, descs_used, prev;
> > - bool indirect;
> > + bool indirect, map_inter;
> > int head;
> >
> > START_USE(vq);
> > @@ -668,7 +672,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > return -ENOSPC;
> > }
> >
> > - if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
> > + map_inter = !sgs[0]->dma_address;
> > + if (map_inter && virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
> > return -ENOMEM;
> >
> > for (n = 0; n < out_sgs; n++) {
> > @@ -734,6 +739,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > vq->split.desc_state[head].indir_desc = desc;
> > else
> > vq->split.desc_state[head].indir_desc = ctx;
> > + vq->split.desc_state[head].map_inter = map_inter;
> >
> > /* Put entry in available array (but don't update avail->idx until they
> > * do sync). */
> > @@ -759,7 +765,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > return 0;
> >
> > unmap_release:
> > - virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
> > + if (map_inter)
> > + virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
> >
> > if (indirect)
> > kfree(desc);
> > @@ -804,20 +811,22 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
> > {
> > unsigned int i, j;
> > __virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
> > + bool map_inter;
> >
> > /* Clear data ptr. */
> > vq->split.desc_state[head].data = NULL;
> > + map_inter = vq->split.desc_state[head].map_inter;
> >
> > /* Put back on free list: unmap first-level descriptors and find end */
> > i = head;
> >
> > while (vq->split.vring.desc[i].flags & nextflag) {
> > - vring_unmap_one_split(vq, i);
> > + vring_unmap_one_split(vq, i, map_inter);
> > i = vq->split.desc_extra[i].next;
> > vq->vq.num_free++;
> > }
> >
> > - vring_unmap_one_split(vq, i);
> > + vring_unmap_one_split(vq, i, map_inter);
> > vq->split.desc_extra[i].next = vq->free_head;
> > vq->free_head = head;
> >
> > @@ -839,8 +848,10 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
> > VRING_DESC_F_INDIRECT));
> > BUG_ON(len == 0 || len % sizeof(struct vring_desc));
> >
> > - for (j = 0; j < len / sizeof(struct vring_desc); j++)
> > - vring_unmap_one_split_indirect(vq, &indir_desc[j]);
> > + if (map_inter) {
> > + for (j = 0; j < len / sizeof(struct vring_desc); j++)
> > + vring_unmap_one_split_indirect(vq, &indir_desc[j]);
> > + }
> >
> > kfree(indir_desc);
> > vq->split.desc_state[head].indir_desc = NULL;
> > --
> > 2.32.0.3.g01195cf9f
>
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