Xuan Zhuo
2022-Jan-07 06:33 UTC
[PATCH 4/6] virtio: split: virtqueue_add_split() support dma address
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 virtqueue_add_split().
This patch stipulates that if sg->dma_address is not NULL, use this
address as the DMA address. And record this information in extra->flags,
which can be skipped when executing dma unmap.
extra->flags |= VRING_DESC_F_PREDMA;
This relies on the previous patch, in the indirect scenario, for each
desc allocated, an extra is allocated at the same time.
Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 7420741cb750..add8430d9678 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -66,6 +66,9 @@
#define LAST_ADD_TIME_INVALID(vq)
#endif
+/* This means the buffer dma is pre-alloc. Just used by vring_desc_extra */
+#define VRING_DESC_F_PREDMA (1 << 15)
+
struct vring_desc_extra {
dma_addr_t addr; /* Descriptor DMA addr. */
u32 len; /* Descriptor length. */
@@ -336,11 +339,19 @@ static inline struct device *vring_dma_dev(const struct
vring_virtqueue *vq)
return vq->vq.vdev->dev.parent;
}
+static inline bool sg_is_predma(struct scatterlist *sg)
+{
+ return !!sg->dma_address;
+}
+
/* Map one sg entry. */
static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
struct scatterlist *sg,
enum dma_data_direction direction)
{
+ if (sg_is_predma(sg))
+ return sg_dma_address(sg);
+
if (!vq->use_dma_api)
return (dma_addr_t)sg_phys(sg);
@@ -396,6 +407,9 @@ 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 (flags & VRING_DESC_F_PREDMA)
+ goto out;
+
dma_unmap_page(vring_dma_dev(vq),
extra->addr,
extra->len,
@@ -441,7 +455,8 @@ static inline unsigned int virtqueue_add_desc_split(struct
virtqueue *vq,
unsigned int i,
dma_addr_t addr,
unsigned int len,
- u16 flags)
+ u16 flags,
+ bool predma)
{
struct vring_virtqueue *vring = to_vvq(vq);
struct vring_desc_extra *extra;
@@ -468,6 +483,9 @@ static inline unsigned int virtqueue_add_desc_split(struct
virtqueue *vq,
extra->len = len;
extra->flags = flags;
+ if (predma)
+ extra->flags |= VRING_DESC_F_PREDMA;
+
return next;
}
@@ -547,7 +565,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
* table since it use stream DMA mapping.
*/
i = virtqueue_add_desc_split(_vq, in, i, addr, sg->length,
- VRING_DESC_F_NEXT);
+ VRING_DESC_F_NEXT,
+ sg_is_predma(sg));
}
}
for (; n < (out_sgs + in_sgs); n++) {
@@ -563,7 +582,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
i = virtqueue_add_desc_split(_vq, in, i, addr,
sg->length,
VRING_DESC_F_NEXT |
- VRING_DESC_F_WRITE);
+ VRING_DESC_F_WRITE,
+ sg_is_predma(sg));
}
}
/* Last one doesn't continue. */
@@ -582,7 +602,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
virtqueue_add_desc_split(_vq, NULL, head, addr,
total_sg * sizeof(struct vring_desc),
- VRING_DESC_F_INDIRECT);
+ VRING_DESC_F_INDIRECT, false);
}
/* We're using some buffers from the free list. */
--
2.31.0
Jason Wang
2022-Jan-10 06:45 UTC
[PATCH 4/6] virtio: split: virtqueue_add_split() support dma address
? 2022/1/7 ??2:33, Xuan Zhuo ??:> 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 virtqueue_add_split(). > > This patch stipulates that if sg->dma_address is not NULL, use this > address as the DMA address. And record this information in extra->flags, > which can be skipped when executing dma unmap. > > extra->flags |= VRING_DESC_F_PREDMA;I think we need another name other than the VRING_DESC_F prefix since it's for the flag defined in the spec. May VIRTIO_DESC_F_PREDMA. Thanks> > This relies on the previous patch, in the indirect scenario, for each > desc allocated, an extra is allocated at the same time. > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > --- > drivers/virtio/virtio_ring.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 7420741cb750..add8430d9678 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -66,6 +66,9 @@ > #define LAST_ADD_TIME_INVALID(vq) > #endif > > +/* This means the buffer dma is pre-alloc. Just used by vring_desc_extra */ > +#define VRING_DESC_F_PREDMA (1 << 15) > + > struct vring_desc_extra { > dma_addr_t addr; /* Descriptor DMA addr. */ > u32 len; /* Descriptor length. */ > @@ -336,11 +339,19 @@ static inline struct device *vring_dma_dev(const struct vring_virtqueue *vq) > return vq->vq.vdev->dev.parent; > } > > +static inline bool sg_is_predma(struct scatterlist *sg) > +{ > + return !!sg->dma_address; > +} > + > /* Map one sg entry. */ > static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq, > struct scatterlist *sg, > enum dma_data_direction direction) > { > + if (sg_is_predma(sg)) > + return sg_dma_address(sg); > + > if (!vq->use_dma_api) > return (dma_addr_t)sg_phys(sg); > > @@ -396,6 +407,9 @@ 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 (flags & VRING_DESC_F_PREDMA) > + goto out; > + > dma_unmap_page(vring_dma_dev(vq), > extra->addr, > extra->len, > @@ -441,7 +455,8 @@ static inline unsigned int virtqueue_add_desc_split(struct virtqueue *vq, > unsigned int i, > dma_addr_t addr, > unsigned int len, > - u16 flags) > + u16 flags, > + bool predma) > { > struct vring_virtqueue *vring = to_vvq(vq); > struct vring_desc_extra *extra; > @@ -468,6 +483,9 @@ static inline unsigned int virtqueue_add_desc_split(struct virtqueue *vq, > extra->len = len; > extra->flags = flags; > > + if (predma) > + extra->flags |= VRING_DESC_F_PREDMA; > + > return next; > } > > @@ -547,7 +565,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > * table since it use stream DMA mapping. > */ > i = virtqueue_add_desc_split(_vq, in, i, addr, sg->length, > - VRING_DESC_F_NEXT); > + VRING_DESC_F_NEXT, > + sg_is_predma(sg)); > } > } > for (; n < (out_sgs + in_sgs); n++) { > @@ -563,7 +582,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > i = virtqueue_add_desc_split(_vq, in, i, addr, > sg->length, > VRING_DESC_F_NEXT | > - VRING_DESC_F_WRITE); > + VRING_DESC_F_WRITE, > + sg_is_predma(sg)); > } > } > /* Last one doesn't continue. */ > @@ -582,7 +602,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > virtqueue_add_desc_split(_vq, NULL, head, addr, > total_sg * sizeof(struct vring_desc), > - VRING_DESC_F_INDIRECT); > + VRING_DESC_F_INDIRECT, false); > } > > /* We're using some buffers from the free list. */