On Mon, 20 Feb 2023 13:38:13 +0800, Jason Wang <[email protected]> wrote:
> On Tue, Feb 14, 2023 at 3:27 PM Xuan Zhuo <[email protected]> wrote:
> >
> > virtqueue_add_split() only supports virtual addresses, dma is completed
> > in virtqueue_add_split().
> >
> > In some scenarios (such as the AF_XDP scenario), the memory is allocated
> > and DMA is completed in advance, so it is necessary for us to support
> > passing the DMA address to virtio core.
> >
> > Signed-off-by: Xuan Zhuo <[email protected]>
> > ---
> > drivers/virtio/virtio_ring.c | 100 +++++++++++++++++++++++++++++++++--
> > include/linux/virtio.h | 5 ++
> > 2 files changed, 100 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 47b6f9152f9f..a31155abe101 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 premapped;
>
> Better with a comment.
>
> Not native speaker, but "dma_addr" might be better?
>
> > };
> >
> > struct vring_desc_state_packed {
> > @@ -440,7 +441,7 @@ 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 premapped)
> > {
> > struct vring_desc_extra *extra = vq->split.desc_extra;
> > u16 flags;
> > @@ -457,6 +458,9 @@ 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 (premapped)
> > + goto out;
> > +
> > dma_unmap_page(vring_dma_dev(vq),
> > extra[i].addr,
> > extra[i].len,
> > @@ -788,6 +792,47 @@ static inline int virtqueue_add_split(struct virtqueue
> > *_vq,
> > return err;
> > }
> >
> > +static inline int virtqueue_add_split_premapped(struct virtqueue *_vq,
> > + struct scatterlist *sgs[],
> > + unsigned int total_sg,
> > + unsigned int out_sgs,
> > + unsigned int in_sgs,
> > + void *data,
> > + void *ctx,
> > + gfp_t gfp)
> > +{
> > + struct vring_virtqueue *vq = to_vvq(_vq);
> > + struct vring_desc *desc;
> > + int head;
> > + int err;
> > +
> > + START_USE(vq);
> > +
> > + /* check vq state and try to alloc desc for indirect. */
> > + err = virtqueue_add_split_prepare(vq, total_sg, out_sgs, data, ctx,
> > gfp, &desc);
> > + if (err)
> > + goto end;
> > +
> > + head = vq->free_head;
> > + err = virtqueue_add_split_vring(vq, sgs, total_sg, out_sgs, in_sgs,
> > desc);
> > + if (err)
> > + goto err;
> > +
> > + /* Store token and indirect buffer state. */
> > + vq->split.desc_state[head].data = data;
> > + vq->split.desc_state[head].indir_desc = desc ? desc : ctx;
> > + vq->split.desc_state[head].premapped = true;
>
> This function duplicates most of the logic of virtqueue_add_split()
> let's unify it.
I want to know that the __virtqueue_add_split is the original
virtqueue_add_split or my refactor virtqueue_add_split?
>
> probably:
>
> __virtqueue_add_split(..., bool premapped);
> virtqueue_add_split()
> {
> __virtqueue_add_split(..., false);
> }
>
> virtqueue_add_split_premapped()
> {
> __virtqueue_add_split(..., true);
> }
I am trying to reduce the inspection of premapped.
In fact, this is Michael's request, although I am not particularly sure that my
implementation has met his requirements.
https://lore.kernel.org/all/[email protected]/
Thanks.
>
> ?
>
> And so did for packed (patch 5).
>
> Thanks
>
>
>
> > +
> > + goto end;
> > +
> > +err:
> > + kfree(desc);
> > +
> > +end:
> > + END_USE(vq);
> > + return err;
> > +}
> > +
> > static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
> > {
> > struct vring_virtqueue *vq = to_vvq(_vq);
> > @@ -824,20 +869,23 @@ 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 premapped;
> >
> > /* Clear data ptr. */
> > vq->split.desc_state[head].data = NULL;
> >
> > + premapped = vq->split.desc_state[head].premapped;
> > +
> > /* 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, premapped);
> > i = vq->split.desc_extra[i].next;
> > vq->vq.num_free++;
> > }
> >
> > - vring_unmap_one_split(vq, i);
> > + vring_unmap_one_split(vq, i, premapped);
> > vq->split.desc_extra[i].next = vq->free_head;
> > vq->free_head = head;
> >
> > @@ -859,8 +907,10 @@ 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 (!premapped) {
> > + 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;
> > @@ -2204,6 +2254,21 @@ static inline int virtqueue_add(struct virtqueue
> > *_vq,
> > out_sgs, in_sgs, data, ctx, gfp);
> > }
> >
> > +static inline int virtqueue_add_premapped(struct virtqueue *_vq,
> > + struct scatterlist *sgs[],
> > + unsigned int total_sg,
> > + unsigned int out_sgs,
> > + unsigned int in_sgs,
> > + void *data,
> > + void *ctx,
> > + gfp_t gfp)
> > +{
> > + struct vring_virtqueue *vq = to_vvq(_vq);
> > +
> > + return virtqueue_add_split_premapped(_vq, sgs, total_sg, out_sgs,
> > + in_sgs, data, ctx, gfp);
> > +}
> > +
> > /**
> > * virtqueue_add_sgs - expose buffers to other end
> > * @_vq: the struct virtqueue we're talking about.
> > @@ -2261,6 +2326,31 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
> > }
> > EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
> >
> > +/**
> > + * virtqueue_add_outbuf_premapped - expose output buffers to other end
> > + * @vq: the struct virtqueue we're talking about.
> > + * @sg: scatterlist (must be well-formed and terminated!)
> > + * @num: the number of entries in @sg readable by other side
> > + * @data: the token identifying the buffer.
> > + * @gfp: how to do memory allocations (if necessary).
> > + *
> > + * Caller must ensure we don't call this with other virtqueue operations
> > + * at the same time (except where noted).
> > + *
> > + * It is required that all addrs have completed DMA operations. And use
> > + * sg->dma_address, sg->length to pass addr and length.
> > + *
> > + * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
> > + */
> > +int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
> > + struct scatterlist *sg, unsigned int num,
> > + void *data,
> > + gfp_t gfp)
> > +{
> > + return virtqueue_add_premapped(vq, &sg, num, 1, 0, data, NULL, gfp);
> > +}
> > +EXPORT_SYMBOL_GPL(virtqueue_add_outbuf_premapped);
> > +
> > /**
> > * virtqueue_add_inbuf - expose input buffers to other end
> > * @vq: the struct virtqueue we're talking about.
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index dcab9c7e8784..d8b472a7dcae 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -43,6 +43,11 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
> > void *data,
> > gfp_t gfp);
> >
> > +int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
> > + struct scatterlist *sg, unsigned int num,
> > + void *data,
> > + gfp_t gfp);
> > +
> > int virtqueue_add_inbuf(struct virtqueue *vq,
> > struct scatterlist sg[], unsigned int num,
> > void *data,
> > --
> > 2.32.0.3.g01195cf9f
> >
>
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