Xuan Zhuo
2023-Mar-08 06:44 UTC
[PATCH vhost v2 01/12] virtio_ring: split: separate dma codes
DMA-related logic is separated from the virtqueue_add_split() to
one new function. DMA address will be saved as sg->dma_address, then
virtqueue_add_split() will use it directly. Unmap operation will be
simpler.
The purpose of this is to facilitate subsequent support to receive
dma address mapped by drivers.
Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 110 ++++++++++++++++++++++++++---------
1 file changed, 82 insertions(+), 28 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 41144b5246a8..8ace2f503953 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -520,6 +520,77 @@ static inline unsigned int virtqueue_add_desc_split(struct
virtqueue *vq,
return next;
}
+static void virtqueue_unmap_sgs(struct vring_virtqueue *vq,
+ struct scatterlist *sgs[],
+ unsigned int total_sg,
+ unsigned int out_sgs,
+ unsigned int in_sgs)
+{
+ struct scatterlist *sg;
+ unsigned int n;
+
+ if (!vq->use_dma_api)
+ return;
+
+ for (n = 0; n < out_sgs; n++) {
+ for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ if (!sg->dma_address)
+ return;
+
+ dma_unmap_page(vring_dma_dev(vq), sg->dma_address,
+ sg->length, DMA_TO_DEVICE);
+ }
+ }
+
+ for (; n < (out_sgs + in_sgs); n++) {
+ for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ if (!sg->dma_address)
+ return;
+
+ dma_unmap_page(vring_dma_dev(vq), sg->dma_address,
+ sg->length, DMA_FROM_DEVICE);
+ }
+ }
+}
+
+static int virtqueue_map_sgs(struct vring_virtqueue *vq,
+ struct scatterlist *sgs[],
+ unsigned int total_sg,
+ unsigned int out_sgs,
+ unsigned int in_sgs)
+{
+ struct scatterlist *sg;
+ unsigned int n;
+
+ for (n = 0; n < out_sgs; n++) {
+ for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
+
+ if (vring_mapping_error(vq, addr))
+ goto err;
+
+ sg->dma_address = addr;
+ }
+ }
+
+ for (; n < (out_sgs + in_sgs); n++) {
+ for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
+
+ if (vring_mapping_error(vq, addr))
+ goto err;
+
+ sg->dma_address = addr;
+ }
+ }
+
+ return 0;
+
+err:
+ virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
+ return -ENOMEM;
+}
+
static inline int virtqueue_add_split(struct virtqueue *_vq,
struct scatterlist *sgs[],
unsigned int total_sg,
@@ -532,9 +603,9 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
struct vring_virtqueue *vq = to_vvq(_vq);
struct scatterlist *sg;
struct vring_desc *desc;
- unsigned int i, n, avail, descs_used, prev, err_idx;
- int head;
+ unsigned int i, n, avail, descs_used, prev;
bool indirect;
+ int head;
START_USE(vq);
@@ -586,32 +657,30 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
return -ENOSPC;
}
+ if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
+ return -ENOMEM;
+
for (n = 0; n < out_sgs; n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
- dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
- if (vring_mapping_error(vq, addr))
- goto unmap_release;
-
prev = i;
/* Note that we trust indirect descriptor
* table since it use stream DMA mapping.
*/
- i = virtqueue_add_desc_split(_vq, desc, i, addr, sg->length,
+ i = virtqueue_add_desc_split(_vq, desc, i,
+ sg->dma_address,
+ sg->length,
VRING_DESC_F_NEXT,
indirect);
}
}
for (; n < (out_sgs + in_sgs); n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
- dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
- if (vring_mapping_error(vq, addr))
- goto unmap_release;
-
prev = i;
/* Note that we trust indirect descriptor
* table since it use stream DMA mapping.
*/
- i = virtqueue_add_desc_split(_vq, desc, i, addr,
+ i = virtqueue_add_desc_split(_vq, desc, i,
+ sg->dma_address,
sg->length,
VRING_DESC_F_NEXT |
VRING_DESC_F_WRITE,
@@ -679,22 +748,7 @@ static inline int virtqueue_add_split(struct virtqueue
*_vq,
return 0;
unmap_release:
- 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);
- }
+ virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
if (indirect)
kfree(desc);
--
2.32.0.3.g01195cf9f
Jason Wang
2023-Mar-14 07:05 UTC
[PATCH vhost v2 01/12] virtio_ring: split: separate dma codes
On Wed, Mar 8, 2023 at 2:44?PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:> > DMA-related logic is separated from the virtqueue_add_split() to > one new function. DMA address will be saved as sg->dma_address, then > virtqueue_add_split() will use it directly. Unmap operation will be > simpler. > > The purpose of this is to facilitate subsequent support to receive > dma address mapped by drivers. > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > --- > drivers/virtio/virtio_ring.c | 110 ++++++++++++++++++++++++++--------- > 1 file changed, 82 insertions(+), 28 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 41144b5246a8..8ace2f503953 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -520,6 +520,77 @@ static inline unsigned int virtqueue_add_desc_split(struct virtqueue *vq, > return next; > } > > +static void virtqueue_unmap_sgs(struct vring_virtqueue *vq, > + struct scatterlist *sgs[], > + unsigned int total_sg, > + unsigned int out_sgs, > + unsigned int in_sgs) > +{ > + struct scatterlist *sg; > + unsigned int n; > + > + if (!vq->use_dma_api) > + return; > + > + for (n = 0; n < out_sgs; n++) { > + for (sg = sgs[n]; sg; sg = sg_next(sg)) { > + if (!sg->dma_address) > + return; > + > + dma_unmap_page(vring_dma_dev(vq), sg->dma_address, > + sg->length, DMA_TO_DEVICE); > + } > + } > + > + for (; n < (out_sgs + in_sgs); n++) { > + for (sg = sgs[n]; sg; sg = sg_next(sg)) { > + if (!sg->dma_address) > + return; > + > + dma_unmap_page(vring_dma_dev(vq), sg->dma_address, > + sg->length, DMA_FROM_DEVICE); > + } > + } > +} > + > +static int virtqueue_map_sgs(struct vring_virtqueue *vq, > + struct scatterlist *sgs[], > + unsigned int total_sg, > + unsigned int out_sgs, > + unsigned int in_sgs) > +{ > + struct scatterlist *sg; > + unsigned int n; > +So we have a use_dma_api check in the unmap path but not here. More below.> + for (n = 0; n < out_sgs; n++) { > + for (sg = sgs[n]; sg; sg = sg_next(sg)) { > + dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE); > + > + if (vring_mapping_error(vq, addr)) > + goto err; > + > + sg->dma_address = addr;When KMSAN is not enabled (should be the case for production environments), the only work that is done here is to assign the dma_address. And there will be another loop after the mapping to add descriptors, this seems to slow down the performance. Any benchmark for this patch? Or can we: 1) return early when use_dma_api is false 2) have a helper like vring_sg_address() { if (!sg->dma_address) return sg_phys(sg); return sg->dma_address; } Thanks> + } > + } > + > + for (; n < (out_sgs + in_sgs); n++) { > + for (sg = sgs[n]; sg; sg = sg_next(sg)) { > + dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE); > + > + if (vring_mapping_error(vq, addr)) > + goto err; > + > + sg->dma_address = addr; > + } > + } > + > + return 0; > + > +err: > + virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs); > + return -ENOMEM; > +} > + > static inline int virtqueue_add_split(struct virtqueue *_vq, > struct scatterlist *sgs[], > unsigned int total_sg, > @@ -532,9 +603,9 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > struct vring_virtqueue *vq = to_vvq(_vq); > struct scatterlist *sg; > struct vring_desc *desc; > - unsigned int i, n, avail, descs_used, prev, err_idx; > - int head; > + unsigned int i, n, avail, descs_used, prev; > bool indirect; > + int head; > > START_USE(vq); > > @@ -586,32 +657,30 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > return -ENOSPC; > } > > + if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs)) > + return -ENOMEM; > + > for (n = 0; n < out_sgs; n++) { > for (sg = sgs[n]; sg; sg = sg_next(sg)) { > - dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE); > - if (vring_mapping_error(vq, addr)) > - goto unmap_release; > - > prev = i; > /* Note that we trust indirect descriptor > * table since it use stream DMA mapping. > */ > - i = virtqueue_add_desc_split(_vq, desc, i, addr, sg->length, > + i = virtqueue_add_desc_split(_vq, desc, i, > + sg->dma_address, > + sg->length, > VRING_DESC_F_NEXT, > indirect); > } > } > for (; n < (out_sgs + in_sgs); n++) { > for (sg = sgs[n]; sg; sg = sg_next(sg)) { > - dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE); > - if (vring_mapping_error(vq, addr)) > - goto unmap_release; > - > prev = i; > /* Note that we trust indirect descriptor > * table since it use stream DMA mapping. > */ > - i = virtqueue_add_desc_split(_vq, desc, i, addr, > + i = virtqueue_add_desc_split(_vq, desc, i, > + sg->dma_address, > sg->length, > VRING_DESC_F_NEXT | > VRING_DESC_F_WRITE, > @@ -679,22 +748,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > return 0; > > unmap_release: > - 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); > - } > + virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs); > > if (indirect) > kfree(desc); > -- > 2.32.0.3.g01195cf9f >