virtio core only supports virtual addresses, dma is completed in virtio
core.
In some scenarios (such as the AF_XDP), the memory is allocated
and DMA mapping is completed in advance, so it is necessary for us to
support passing the DMA address to virtio core.
Drives can use sg->dma_address to pass the mapped dma address to virtio
core. If one sg->dma_address is used then all sgs must use
sg->dma_address, otherwise all must be null when passing it to the APIs
of virtio.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 31 +++++++++++++++++++++++--------
1 file changed, 23 insertions(+), 8 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 62db16a15ae7..055c1c069fff 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -67,9 +67,13 @@
#define LAST_ADD_TIME_INVALID(vq)
#endif
+#define VRING_STATE_F_MAP_INTERNAL BIT(0)
+
struct vring_desc_state_split {
void *data; /* Data for callback. */
struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
+ u32 flags; /* State flags. */
+ u32 padding;
};
struct vring_desc_state_packed {
@@ -448,7 +452,7 @@ 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_internal)
{
struct vring_desc_extra *extra = vq->split.desc_extra;
u16 flags;
@@ -465,6 +469,9 @@ 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_internal)
+ goto out;
+
dma_unmap_page(vring_dma_dev(vq),
extra[i].addr,
extra[i].len,
@@ -615,7 +622,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
struct scatterlist *sg;
struct vring_desc *desc;
unsigned int i, n, avail, descs_used, prev;
- bool indirect;
+ bool indirect, dma_map_internal;
int head;
START_USE(vq);
@@ -668,7 +675,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
return -ENOSPC;
}
- if (virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
+ dma_map_internal = !sgs[0]->dma_address;
+ if (dma_map_internal && virtqueue_map_sgs(vq, sgs, total_sg, out_sgs, in_sgs))
goto err_map;
for (n = 0; n < out_sgs; n++) {
@@ -735,6 +743,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
else
vq->split.desc_state[head].indir_desc = ctx;
+ vq->split.desc_state[head].flags = dma_map_internal ? VRING_STATE_F_MAP_INTERNAL : 0;
+
/* Put entry in available array (but don't update avail->idx until they
* do sync). */
avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1);
@@ -759,7 +769,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
return 0;
unmap_release:
- virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
+ if (dma_map_internal)
+ virtqueue_unmap_sgs(vq, sgs, total_sg, out_sgs, in_sgs);
err_map:
if (indirect)
@@ -805,20 +816,22 @@ 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_internal;
/* Clear data ptr. */
vq->split.desc_state[head].data = NULL;
+ dma_map_internal = !!(vq->split.desc_state[head].flags & VRING_STATE_F_MAP_INTERNAL);
/* 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_internal);
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_internal);
vq->split.desc_extra[i].next = vq->free_head;
vq->free_head = head;
@@ -840,8 +853,10 @@ 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_internal) {
+ 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;
--
2.32.0.3.g01195cf9f
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