introduce virtqueue_get_buf_ctx_dma() to collect the dma info when
get buf from virtio core for premapped mode.
If the virtio queue is premapped mode, the virtio-net send buf may
have many desc. Every desc dma address need to be unmap. So here we
introduce a new helper to collect the dma address of the buffer from
the virtio core.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 148 ++++++++++++++++++++++++++---------
include/linux/virtio.h | 2 +
2 files changed, 115 insertions(+), 35 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 51d8f3299c10..0b3caee4ef9d 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -362,6 +362,20 @@ static struct device *vring_dma_dev(const struct vring_virtqueue *vq)
return vq->dma_dev;
}
+static void store_dma_to_sg(struct scatterlist **sgp, dma_addr_t addr, unsigned int length)
+{
+ struct scatterlist *sg;
+
+ sg = *sgp;
+
+ sg->dma_address = addr;
+ sg->length = length;
+
+ sg = sg_next(sg);
+
+ *sgp = sg;
+}
+
/* Map one sg entry. */
static int vring_map_one_sg(const struct vring_virtqueue *vq, struct scatterlist *sg,
enum dma_data_direction direction, dma_addr_t *addr)
@@ -441,12 +455,18 @@ static void virtqueue_init(struct vring_virtqueue *vq, u32 num)
*/
static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq,
- const struct vring_desc *desc)
+ const struct vring_desc *desc,
+ struct scatterlist **sg)
{
u16 flags;
- if (!vq->do_unmap)
+ if (!vq->do_unmap) {
+ if (*sg)
+ store_dma_to_sg(sg,
+ virtio64_to_cpu(vq->vq.vdev, desc->addr),
+ virtio32_to_cpu(vq->vq.vdev, desc->len));
return;
+ }
flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
@@ -458,7 +478,7 @@ 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, struct scatterlist **sg)
{
struct vring_desc_extra *extra = vq->split.desc_extra;
u16 flags;
@@ -475,8 +495,11 @@ 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 (!vq->do_unmap)
+ if (!vq->do_unmap) {
+ if (*sg)
+ store_dma_to_sg(sg, extra[i].addr, extra[i].len);
goto out;
+ }
dma_unmap_page(vring_dma_dev(vq),
extra[i].addr,
@@ -717,10 +740,10 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
if (i == err_idx)
break;
if (indirect) {
- vring_unmap_one_split_indirect(vq, &desc[i]);
+ vring_unmap_one_split_indirect(vq, &desc[i], NULL);
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
} else
- i = vring_unmap_one_split(vq, i);
+ i = vring_unmap_one_split(vq, i, NULL);
}
free_indirect:
@@ -763,7 +786,7 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
}
static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
- void **ctx)
+ struct scatterlist *sg, void **ctx)
{
unsigned int i, j;
__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
@@ -775,12 +798,12 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
i = head;
while (vq->split.vring.desc[i].flags & nextflag) {
- vring_unmap_one_split(vq, i);
+ vring_unmap_one_split(vq, i, &sg);
i = vq->split.desc_extra[i].next;
vq->vq.num_free++;
}
- vring_unmap_one_split(vq, i);
+ vring_unmap_one_split(vq, i, &sg);
vq->split.desc_extra[i].next = vq->free_head;
vq->free_head = head;
@@ -794,7 +817,7 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
/* Free the indirect table, if any, now that it's unmapped. */
if (!indir_desc)
- return;
+ goto end;
len = vq->split.desc_extra[head].len;
@@ -802,9 +825,10 @@ 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));
- if (vq->do_unmap) {
+ if (vq->do_unmap || sg) {
for (j = 0; j < len / sizeof(struct vring_desc); j++)
- vring_unmap_one_split_indirect(vq, &indir_desc[j]);
+ vring_unmap_one_split_indirect(vq, &indir_desc[j], &sg);
+
}
kfree(indir_desc);
@@ -812,6 +836,11 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
} else if (ctx) {
*ctx = vq->split.desc_state[head].indir_desc;
}
+
+end:
+ /* sg point to the next. So we mark the last one as the end. */
+ if (!vq->do_unmap && sg)
+ sg_mark_end(sg - 1);
}
static bool more_used_split(const struct vring_virtqueue *vq)
@@ -822,6 +851,7 @@ static bool more_used_split(const struct vring_virtqueue *vq)
static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
unsigned int *len,
+ struct scatterlist *sg,
void **ctx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
@@ -862,7 +892,7 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
/* detach_buf_split clears data, so grab it now. */
ret = vq->split.desc_state[i].data;
- detach_buf_split(vq, i, ctx);
+ detach_buf_split(vq, i, sg, ctx);
vq->last_used_idx++;
/* If we expect an interrupt for the next entry, tell host
* by writing event index and flush out the write before
@@ -984,7 +1014,7 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
continue;
/* detach_buf_split clears data, so grab it now. */
buf = vq->split.desc_state[i].data;
- detach_buf_split(vq, i, NULL);
+ detach_buf_split(vq, i, NULL, NULL);
vq->split.avail_idx_shadow--;
vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
vq->split.avail_idx_shadow);
@@ -1221,7 +1251,8 @@ static u16 packed_last_used(u16 last_used_idx)
}
static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
- const struct vring_desc_extra *extra)
+ const struct vring_desc_extra *extra,
+ struct scatterlist **sg)
{
u16 flags;
@@ -1236,8 +1267,11 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
- if (!vq->do_unmap)
+ if (!vq->do_unmap) {
+ if (*sg)
+ store_dma_to_sg(sg, extra->addr, extra->len);
return;
+ }
dma_unmap_page(vring_dma_dev(vq),
extra->addr, extra->len,
@@ -1247,12 +1281,17 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq,
}
static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
- const struct vring_packed_desc *desc)
+ const struct vring_packed_desc *desc,
+ struct scatterlist **sg)
{
u16 flags;
- if (!vq->do_unmap)
+ if (!vq->do_unmap) {
+ if (*sg)
+ store_dma_to_sg(sg, le64_to_cpu(desc->addr),
+ le32_to_cpu(desc->len));
return;
+ }
flags = le16_to_cpu(desc->flags);
@@ -1389,7 +1428,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
err_idx = i;
for (i = 0; i < err_idx; i++)
- vring_unmap_desc_packed(vq, &desc[i]);
+ vring_unmap_desc_packed(vq, &desc[i], NULL);
free_desc:
kfree(desc);
@@ -1539,7 +1578,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
for (n = 0; n < total_sg; n++) {
if (i == err_idx)
break;
- vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr]);
+ vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr], NULL);
curr = vq->packed.desc_extra[curr].next;
i++;
if (i >= vq->packed.vring.num)
@@ -1600,7 +1639,9 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
}
static void detach_buf_packed(struct vring_virtqueue *vq,
- unsigned int id, void **ctx)
+ unsigned int id,
+ struct scatterlist *sg,
+ void **ctx)
{
struct vring_desc_state_packed *state = NULL;
struct vring_packed_desc *desc;
@@ -1615,13 +1656,10 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
vq->free_head = id;
vq->vq.num_free += state->num;
- if (unlikely(vq->do_unmap)) {
- curr = id;
- for (i = 0; i < state->num; i++) {
- vring_unmap_extra_packed(vq,
- &vq->packed.desc_extra[curr]);
- curr = vq->packed.desc_extra[curr].next;
- }
+ curr = id;
+ for (i = 0; i < state->num; i++) {
+ vring_unmap_extra_packed(vq, &vq->packed.desc_extra[curr], &sg);
+ curr = vq->packed.desc_extra[curr].next;
}
if (vq->indirect) {
@@ -1630,19 +1668,24 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
/* Free the indirect table, if any, now that it's unmapped. */
desc = state->indir_desc;
if (!desc)
- return;
+ goto end;
- if (vq->do_unmap) {
+ if (vq->do_unmap || sg) {
len = vq->packed.desc_extra[id].len;
for (i = 0; i < len / sizeof(struct vring_packed_desc);
i++)
- vring_unmap_desc_packed(vq, &desc[i]);
+ vring_unmap_desc_packed(vq, &desc[i], &sg);
}
kfree(desc);
state->indir_desc = NULL;
} else if (ctx) {
*ctx = state->indir_desc;
}
+
+end:
+ /* sg point to the next. So we mark the last one as the end. */
+ if (!vq->do_unmap && sg)
+ sg_mark_end(sg - 1);
}
static inline bool is_used_desc_packed(const struct vring_virtqueue *vq,
@@ -1672,6 +1715,7 @@ static bool more_used_packed(const struct vring_virtqueue *vq)
static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
unsigned int *len,
+ struct scatterlist *sg,
void **ctx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
@@ -1712,7 +1756,7 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
/* detach_buf_packed clears data, so grab it now. */
ret = vq->packed.desc_state[id].data;
- detach_buf_packed(vq, id, ctx);
+ detach_buf_packed(vq, id, sg, ctx);
last_used += vq->packed.desc_state[id].num;
if (unlikely(last_used >= vq->packed.vring.num)) {
@@ -1877,7 +1921,7 @@ static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
continue;
/* detach_buf clears data, so grab it now. */
buf = vq->packed.desc_state[i].data;
- detach_buf_packed(vq, i, NULL);
+ detach_buf_packed(vq, i, NULL, NULL);
END_USE(vq);
return buf;
}
@@ -2417,11 +2461,45 @@ void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
{
struct vring_virtqueue *vq = to_vvq(_vq);
- return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
- virtqueue_get_buf_ctx_split(_vq, len, ctx);
+ return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, NULL, ctx) :
+ virtqueue_get_buf_ctx_split(_vq, len, NULL, ctx);
}
EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
+/**
+ * virtqueue_get_buf_ctx_dma - get the next used buffer with the dma info
+ * @_vq: the struct virtqueue we're talking about.
+ * @len: the length written into the buffer
+ * @sg: scatterlist array to store the dma info
+ * @ctx: extra context for the token
+ *
+ * If the device wrote data into the buffer, @len will be set to the
+ * amount written. This means you don't need to clear the buffer
+ * beforehand to ensure there's no data leakage in the case of short
+ * writes.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ *
+ * Only when the vq is in premapped mode and the sg is not null, we store the
+ * dma info of every descriptor of this buf to the sg array. The sg array must
+ * point to a scatterlist array, with the last element marked as the sg last.
+ * Once the function is done, we mark the last sg stored with dma info as the
+ * last one. If the sg array size is too small, some dma info may be missed.
+ *
+ * Returns NULL if there are no used buffers, or the "data" token
+ * handed to virtqueue_add_*().
+ */
+void *virtqueue_get_buf_ctx_dma(struct virtqueue *_vq, unsigned int *len,
+ struct scatterlist *sg, void **ctx)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, sg, ctx) :
+ virtqueue_get_buf_ctx_split(_vq, len, sg, ctx);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx_dma);
+
void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
{
return virtqueue_get_buf_ctx(_vq, len, NULL);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 4cc614a38376..0b919786ade5 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -74,6 +74,8 @@ void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
void *virtqueue_get_buf_ctx(struct virtqueue *vq, unsigned int *len,
void **ctx);
+void *virtqueue_get_buf_ctx_dma(struct virtqueue *_vq, unsigned int *len,
+ struct scatterlist *sg, void **ctx);
void virtqueue_disable_cb(struct virtqueue *vq);
--
2.32.0.3.g01195cf9f
