On Tue, 27 Jun 2023 16:03:26 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> On Fri, Jun 2, 2023 at 5:22 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
> >
> > If the vq is the premapped mode, use the sg_dma_address() directly.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/virtio/virtio_ring.c | 46 ++++++++++++++++++++++--------------
> > 1 file changed, 28 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 2afdfb9e3e30..18212c3e056b 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -598,8 +598,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> > dma_addr_t addr;
> >
> > - if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
> > - goto unmap_release;
> > + if (vq->premapped) {
> > + addr = sg_dma_address(sg);
> > + } else {
> > + if (vring_map_one_sg(vq, sg, DMA_TO_DEVICE, &addr))
> > + goto unmap_release;
> > + }
>
> Btw, I wonder whether or not it would be simple to implement the
> vq->premapped check inside vring_map_one_sg() assuming the
> !use_dma_api is done there as well.
YES,
That will more simple for the caller.
But we will have things like:
int func(bool do)
{
if (!do)
return;
}
I like this way, but you don't like it in last version.
>
> >
> > prev = i;
> > /* Note that we trust indirect descriptor
> > @@ -614,8 +618,12 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > for (sg = sgs[n]; sg; sg = sg_next(sg)) {
> > dma_addr_t addr;
> >
> > - if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
> > - goto unmap_release;
> > + if (vq->premapped) {
> > + addr = sg_dma_address(sg);
> > + } else {
> > + if (vring_map_one_sg(vq, sg, DMA_FROM_DEVICE, &addr))
> > + goto unmap_release;
> > + }
> >
> > prev = i;
> > /* Note that we trust indirect descriptor
> > @@ -689,21 +697,23 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > return 0;
> >
> > unmap_release:
> > - err_idx = i;
> > + if (!vq->premapped) {
>
> Can vq->premapped be true here? The label is named as "unmap_relase"
> which implies "map" beforehand which seems not the case for
> premapping.
I see.
Rethink about this, there is a better way.
I will fix in next version.
Thanks.
>
> Thanks
>
>
> > + err_idx = i;
> >
> > - if (indirect)
> > - i = 0;
> > - else
> > - i = head;
> > -
> > - for (n = 0; n < total_sg; n++) {
> > - if (i == err_idx)
> > - break;
> > - if (indirect) {
> > - vring_unmap_one_split_indirect(vq, &desc[i]);
> > - i = virtio16_to_cpu(_vq->vdev, desc[i].next);
> > - } else
> > - i = vring_unmap_one_split(vq, i);
> > + if (indirect)
> > + i = 0;
> > + else
> > + i = head;
> > +
> > + for (n = 0; n < total_sg; n++) {
> > + if (i == err_idx)
> > + break;
> > + if (indirect) {
> > + vring_unmap_one_split_indirect(vq, &desc[i]);
> > + i = virtio16_to_cpu(_vq->vdev, desc[i].next);
> > + } else
> > + i = vring_unmap_one_split(vq, i);
> > + }
> > }
> >
> > if (indirect)
> > --
> > 2.32.0.3.g01195cf9f
> >
>
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