Xuan Zhuo
2023-Jul-13 04:02 UTC
[PATCH vhost v11 06/10] virtio_ring: skip unmap for premapped
On Thu, 13 Jul 2023 11:50:57 +0800, Jason Wang <jasowang at redhat.com> wrote:> On Mon, Jul 10, 2023 at 11:42?AM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > Now we add a case where we skip dma unmap, the vq->premapped is true. > > > > We can't just rely on use_dma_api to determine whether to skip the dma > > operation. For convenience, I introduced the "do_unmap". By default, it > > is the same as use_dma_api. If the driver is configured with premapped, > > then do_unmap is false. > > > > So as long as do_unmap is false, for addr of desc, we should skip dma > > unmap operation. > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > --- > > drivers/virtio/virtio_ring.c | 42 ++++++++++++++++++++++++------------ > > 1 file changed, 28 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 1fb2c6dca9ea..10ee3b7ce571 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -175,6 +175,11 @@ struct vring_virtqueue { > > /* Do DMA mapping by driver */ > > bool premapped; > > > > + /* Do unmap or not for desc. Just when premapped is False and > > + * use_dma_api is true, this is true. > > + */ > > + bool do_unmap; > > + > > /* Head of free buffer list. */ > > unsigned int free_head; > > /* Number we've added since last sync. */ > > @@ -440,7 +445,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq, > > { > > u16 flags; > > > > - if (!vq->use_dma_api) > > + if (!vq->do_unmap) > > return; > > > > flags = virtio16_to_cpu(vq->vq.vdev, desc->flags); > > @@ -458,18 +463,21 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq, > > struct vring_desc_extra *extra = vq->split.desc_extra; > > u16 flags; > > > > - if (!vq->use_dma_api) > > - goto out; > > - > > flags = extra[i].flags; > > > > if (flags & VRING_DESC_F_INDIRECT) { > > + if (!vq->use_dma_api) > > + goto out; > > + > > dma_unmap_single(vring_dma_dev(vq), > > extra[i].addr, > > extra[i].len, > > (flags & VRING_DESC_F_WRITE) ? > > DMA_FROM_DEVICE : DMA_TO_DEVICE); > > } else { > > + if (!vq->do_unmap) > > + goto out; > > + > > dma_unmap_page(vring_dma_dev(vq), > > extra[i].addr, > > extra[i].len, > > @@ -635,7 +643,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > } > > /* Last one doesn't continue. */ > > desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT); > > - if (!indirect && vq->use_dma_api) > > + if (!indirect && vq->do_unmap) > > vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &> > ~VRING_DESC_F_NEXT; > > > > @@ -794,7 +802,7 @@ 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)); > > > > - if (vq->use_dma_api) { > > + if (vq->do_unmap) { > > for (j = 0; j < len / sizeof(struct vring_desc); j++) > > vring_unmap_one_split_indirect(vq, &indir_desc[j]); > > } > > @@ -1217,17 +1225,20 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq, > > { > > u16 flags; > > > > - if (!vq->use_dma_api) > > - return; > > - > > flags = extra->flags; > > > > if (flags & VRING_DESC_F_INDIRECT) { > > + if (!vq->use_dma_api) > > + return; > > + > > dma_unmap_single(vring_dma_dev(vq), > > extra->addr, extra->len, > > (flags & VRING_DESC_F_WRITE) ? > > DMA_FROM_DEVICE : DMA_TO_DEVICE); > > } else { > > + if (!vq->do_unmap) > > + return; > > This seems not straightforward than: > > if (!vq->use_dma_api) > return; > > if (INDIRECT) { > } else if (!vq->premapped) { > } > > ?My logic here is that for the real buffer, we use do_unmap to judge uniformly. And indirect still use use_dma_api to judge.>From this point of view, how do you feel?Thanks.> > Thanks > > > + > > dma_unmap_page(vring_dma_dev(vq), > > extra->addr, extra->len, > > (flags & VRING_DESC_F_WRITE) ? > > @@ -1240,7 +1251,7 @@ static void vring_unmap_desc_packed(const struct vring_virtqueue *vq, > > { > > u16 flags; > > > > - if (!vq->use_dma_api) > > + if (!vq->do_unmap) > > return; > > > > flags = le16_to_cpu(desc->flags); > > @@ -1329,7 +1340,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, > > sizeof(struct vring_packed_desc)); > > vq->packed.vring.desc[head].id = cpu_to_le16(id); > > > > - if (vq->use_dma_api) { > > + if (vq->do_unmap) { > > vq->packed.desc_extra[id].addr = addr; > > vq->packed.desc_extra[id].len = total_sg * > > sizeof(struct vring_packed_desc); > > @@ -1470,7 +1481,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > desc[i].len = cpu_to_le32(sg->length); > > desc[i].id = cpu_to_le16(id); > > > > - if (unlikely(vq->use_dma_api)) { > > + if (unlikely(vq->do_unmap)) { > > vq->packed.desc_extra[curr].addr = addr; > > vq->packed.desc_extra[curr].len = sg->length; > > vq->packed.desc_extra[curr].flags > > @@ -1604,7 +1615,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > > vq->free_head = id; > > vq->vq.num_free += state->num; > > > > - if (unlikely(vq->use_dma_api)) { > > + if (unlikely(vq->do_unmap)) { > > curr = id; > > for (i = 0; i < state->num; i++) { > > vring_unmap_extra_packed(vq, > > @@ -1621,7 +1632,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > > if (!desc) > > return; > > > > - if (vq->use_dma_api) { > > + if (vq->do_unmap) { > > len = vq->packed.desc_extra[id].len; > > for (i = 0; i < len / sizeof(struct vring_packed_desc); > > i++) > > @@ -2080,6 +2091,7 @@ static struct virtqueue *vring_create_virtqueue_packed( > > vq->dma_dev = dma_dev; > > vq->use_dma_api = vring_use_dma_api(vdev); > > vq->premapped = false; > > + vq->do_unmap = vq->use_dma_api; > > > > vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && > > !context; > > @@ -2587,6 +2599,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > vq->dma_dev = dma_dev; > > vq->use_dma_api = vring_use_dma_api(vdev); > > vq->premapped = false; > > + vq->do_unmap = vq->use_dma_api; > > > > vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && > > !context; > > @@ -2765,6 +2778,7 @@ int virtqueue_set_premapped(struct virtqueue *_vq) > > return -EINVAL; > > > > vq->premapped = true; > > + vq->do_unmap = false; > > > > return 0; > > } > > -- > > 2.32.0.3.g01195cf9f > > >
Jason Wang
2023-Jul-13 04:21 UTC
[PATCH vhost v11 06/10] virtio_ring: skip unmap for premapped
On Thu, Jul 13, 2023 at 12:06?PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:> > On Thu, 13 Jul 2023 11:50:57 +0800, Jason Wang <jasowang at redhat.com> wrote: > > On Mon, Jul 10, 2023 at 11:42?AM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > Now we add a case where we skip dma unmap, the vq->premapped is true. > > > > > > We can't just rely on use_dma_api to determine whether to skip the dma > > > operation. For convenience, I introduced the "do_unmap". By default, it > > > is the same as use_dma_api. If the driver is configured with premapped, > > > then do_unmap is false. > > > > > > So as long as do_unmap is false, for addr of desc, we should skip dma > > > unmap operation. > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > > > --- > > > drivers/virtio/virtio_ring.c | 42 ++++++++++++++++++++++++------------ > > > 1 file changed, 28 insertions(+), 14 deletions(-) > > > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > > index 1fb2c6dca9ea..10ee3b7ce571 100644 > > > --- a/drivers/virtio/virtio_ring.c > > > +++ b/drivers/virtio/virtio_ring.c > > > @@ -175,6 +175,11 @@ struct vring_virtqueue { > > > /* Do DMA mapping by driver */ > > > bool premapped; > > > > > > + /* Do unmap or not for desc. Just when premapped is False and > > > + * use_dma_api is true, this is true. > > > + */ > > > + bool do_unmap; > > > + > > > /* Head of free buffer list. */ > > > unsigned int free_head; > > > /* Number we've added since last sync. */ > > > @@ -440,7 +445,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq, > > > { > > > u16 flags; > > > > > > - if (!vq->use_dma_api) > > > + if (!vq->do_unmap) > > > return; > > > > > > flags = virtio16_to_cpu(vq->vq.vdev, desc->flags); > > > @@ -458,18 +463,21 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq, > > > struct vring_desc_extra *extra = vq->split.desc_extra; > > > u16 flags; > > > > > > - if (!vq->use_dma_api) > > > - goto out; > > > - > > > flags = extra[i].flags; > > > > > > if (flags & VRING_DESC_F_INDIRECT) { > > > + if (!vq->use_dma_api) > > > + goto out; > > > + > > > dma_unmap_single(vring_dma_dev(vq), > > > extra[i].addr, > > > extra[i].len, > > > (flags & VRING_DESC_F_WRITE) ? > > > DMA_FROM_DEVICE : DMA_TO_DEVICE); > > > } else { > > > + if (!vq->do_unmap) > > > + goto out; > > > + > > > dma_unmap_page(vring_dma_dev(vq), > > > extra[i].addr, > > > extra[i].len, > > > @@ -635,7 +643,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > > } > > > /* Last one doesn't continue. */ > > > desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT); > > > - if (!indirect && vq->use_dma_api) > > > + if (!indirect && vq->do_unmap) > > > vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &> > > ~VRING_DESC_F_NEXT; > > > > > > @@ -794,7 +802,7 @@ 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)); > > > > > > - if (vq->use_dma_api) { > > > + if (vq->do_unmap) { > > > for (j = 0; j < len / sizeof(struct vring_desc); j++) > > > vring_unmap_one_split_indirect(vq, &indir_desc[j]); > > > } > > > @@ -1217,17 +1225,20 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq, > > > { > > > u16 flags; > > > > > > - if (!vq->use_dma_api) > > > - return; > > > - > > > flags = extra->flags; > > > > > > if (flags & VRING_DESC_F_INDIRECT) { > > > + if (!vq->use_dma_api) > > > + return; > > > + > > > dma_unmap_single(vring_dma_dev(vq), > > > extra->addr, extra->len, > > > (flags & VRING_DESC_F_WRITE) ? > > > DMA_FROM_DEVICE : DMA_TO_DEVICE); > > > } else { > > > + if (!vq->do_unmap) > > > + return; > > > > This seems not straightforward than: > > > > if (!vq->use_dma_api) > > return; > > > > if (INDIRECT) { > > } else if (!vq->premapped) { > > } > > > > ? > > > My logic here is that for the real buffer, we use do_unmap to judge uniformly. > And indirect still use use_dma_api to judge. > > From this point of view, how do you feel?We can hear from others but a state machine with three booleans seems not easy for me to read. Thanks> > Thanks. > > > > > > Thanks > > > > > + > > > dma_unmap_page(vring_dma_dev(vq), > > > extra->addr, extra->len, > > > (flags & VRING_DESC_F_WRITE) ? > > > @@ -1240,7 +1251,7 @@ static void vring_unmap_desc_packed(const struct vring_virtqueue *vq, > > > { > > > u16 flags; > > > > > > - if (!vq->use_dma_api) > > > + if (!vq->do_unmap) > > > return; > > > > > > flags = le16_to_cpu(desc->flags); > > > @@ -1329,7 +1340,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, > > > sizeof(struct vring_packed_desc)); > > > vq->packed.vring.desc[head].id = cpu_to_le16(id); > > > > > > - if (vq->use_dma_api) { > > > + if (vq->do_unmap) { > > > vq->packed.desc_extra[id].addr = addr; > > > vq->packed.desc_extra[id].len = total_sg * > > > sizeof(struct vring_packed_desc); > > > @@ -1470,7 +1481,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, > > > desc[i].len = cpu_to_le32(sg->length); > > > desc[i].id = cpu_to_le16(id); > > > > > > - if (unlikely(vq->use_dma_api)) { > > > + if (unlikely(vq->do_unmap)) { > > > vq->packed.desc_extra[curr].addr = addr; > > > vq->packed.desc_extra[curr].len = sg->length; > > > vq->packed.desc_extra[curr].flags > > > @@ -1604,7 +1615,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > > > vq->free_head = id; > > > vq->vq.num_free += state->num; > > > > > > - if (unlikely(vq->use_dma_api)) { > > > + if (unlikely(vq->do_unmap)) { > > > curr = id; > > > for (i = 0; i < state->num; i++) { > > > vring_unmap_extra_packed(vq, > > > @@ -1621,7 +1632,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > > > if (!desc) > > > return; > > > > > > - if (vq->use_dma_api) { > > > + if (vq->do_unmap) { > > > len = vq->packed.desc_extra[id].len; > > > for (i = 0; i < len / sizeof(struct vring_packed_desc); > > > i++) > > > @@ -2080,6 +2091,7 @@ static struct virtqueue *vring_create_virtqueue_packed( > > > vq->dma_dev = dma_dev; > > > vq->use_dma_api = vring_use_dma_api(vdev); > > > vq->premapped = false; > > > + vq->do_unmap = vq->use_dma_api; > > > > > > vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && > > > !context; > > > @@ -2587,6 +2599,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, > > > vq->dma_dev = dma_dev; > > > vq->use_dma_api = vring_use_dma_api(vdev); > > > vq->premapped = false; > > > + vq->do_unmap = vq->use_dma_api; > > > > > > vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && > > > !context; > > > @@ -2765,6 +2778,7 @@ int virtqueue_set_premapped(struct virtqueue *_vq) > > > return -EINVAL; > > > > > > vq->premapped = true; > > > + vq->do_unmap = false; > > > > > > return 0; > > > } > > > -- > > > 2.32.0.3.g01195cf9f > > > > > >