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 <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 74 +++++++++++++++++++++++++++++++-----
include/linux/virtio.h | 5 +++
2 files changed, 69 insertions(+), 10 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 17520f0d7649..5b186ce73d35 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 dma_map; /* Addr is mapped by virtio core or not. */
};
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 dma_map)
{
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 (!dma_map)
+ goto out;
+
dma_unmap_page(vring_dma_dev(vq),
extra[i].addr,
extra[i].len,
@@ -751,6 +755,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
unsigned int in_sgs,
void *data,
void *ctx,
+ bool dma_map,
gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
@@ -767,9 +772,11 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
goto end;
}
- err = virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
- if (err)
- goto err;
+ if (dma_map) {
+ err = virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
+ if (err)
+ goto err;
+ }
head = vq->free_head;
err = virtqueue_add_vring_split(vq, sgs, total_sg, out_sgs, in_sgs, desc);
@@ -779,11 +786,13 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
/* 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].dma_map = dma_map;
goto end;
err:
- virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
+ if (dma_map)
+ virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
kfree(desc);
@@ -828,20 +837,23 @@ 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 dma_map;
/* Clear data ptr. */
vq->split.desc_state[head].data = NULL;
+ dma_map = vq->split.desc_state[head].dma_map;
+
/* 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, dma_map);
i = vq->split.desc_extra[i].next;
vq->vq.num_free++;
}
- vring_unmap_one_split(vq, i);
+ vring_unmap_one_split(vq, i, dma_map);
vq->split.desc_extra[i].next = vq->free_head;
vq->free_head = head;
@@ -863,8 +875,10 @@ 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 (dma_map) {
+ 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;
@@ -2204,7 +2218,22 @@ static inline int virtqueue_add(struct virtqueue *_vq,
return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
out_sgs, in_sgs, data, ctx, gfp) :
virtqueue_add_split(_vq, sgs, total_sg,
- out_sgs, in_sgs, data, ctx, gfp);
+ out_sgs, in_sgs, data, ctx, true, 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(_vq, sgs, total_sg, out_sgs, in_sgs, data,
+ ctx, false, gfp);
}
/**
@@ -2264,6 +2293,31 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
}
EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
+/**
+ * virtqueue_add_outbuf_premapped - expose output buffers with dma address 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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