| Message ID | 20230602092206.50108-7-xuanzhuo@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | virtio core prepares for AF_XDP | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Fri, Jun 02, 2023 at 05:22:02PM +0800, Xuan Zhuo wrote: > Under the premapped mode, the driver needs to unmap the DMA address > after receiving the buffer. The virtio core records the DMA address, > so the driver needs a way to get the dma info from the virtio core. > > A straightforward approach is to pass an array to the virtio core when > calling virtqueue_get_buf(). However, it is not feasible when there are > multiple DMA addresses in the descriptor chain, and the array size is > unknown. > > To solve this problem, a helper be introduced. After calling > virtqueue_get_buf(), the driver can call the helper to > retrieve a dma info. If the helper function returns -EAGAIN, it means > that there are more DMA addresses to be processed, and the driver should > call the helper function again. Please, keep error codes for when an actual error occurs. A common pattern would be: <0 - error 0 - success, done >0 - success, more to do > To keep track of the current position in > the chain, a cursor must be passed to the helper function, which is > initialized by virtqueue_get_buf(). > > Some processes are done inside this helper, so this helper MUST be > called under the premapped mode. > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > --- > drivers/virtio/virtio_ring.c | 105 ++++++++++++++++++++++++++++++++--- > include/linux/virtio.h | 9 ++- > 2 files changed, 103 insertions(+), 11 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index cdc4349f6066..cbc22daae7e1 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -1695,8 +1695,85 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) > return needs_kick; > } > > +static void detach_cursor_init_packed(struct vring_virtqueue *vq, > + struct virtqueue_detach_cursor *cursor, u16 id) > +{ > + struct vring_desc_state_packed *state = NULL; > + u32 len; > + > + state = &vq->packed.desc_state[id]; > + > + /* Clear data ptr. */ > + state->data = NULL; > + > + vq->packed.desc_extra[state->last].next = vq->free_head; > + vq->free_head = id; > + vq->vq.num_free += state->num; > + > + /* init cursor */ > + cursor->curr = id; > + cursor->done = 0; > + cursor->pos = 0; > + > + if (vq->packed.desc_extra[id].flags & VRING_DESC_F_INDIRECT) { > + len = vq->split.desc_extra[id].len; > + > + cursor->num = len / sizeof(struct vring_packed_desc); > + cursor->indirect = true; > + > + vring_unmap_extra_packed(vq, &vq->packed.desc_extra[id]); > + } else { > + cursor->num = state->num; > + cursor->indirect = false; > + } > +} > + > +static int virtqueue_detach_packed(struct virtqueue *_vq, struct virtqueue_detach_cursor *cursor, > + dma_addr_t *addr, u32 *len, enum dma_data_direction *dir) > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + > + if (unlikely(cursor->done)) > + return -EINVAL; > + > + if (!cursor->indirect) { > + struct vring_desc_extra *extra; > + > + extra = &vq->packed.desc_extra[cursor->curr]; > + cursor->curr = extra->next; > + > + *addr = extra->addr; > + *len = extra->len; > + *dir = (extra->flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; > + > + if (++cursor->pos == cursor->num) { > + cursor->done = true; > + return 0; > + } > + } else { > + struct vring_packed_desc *indir_desc, *desc; > + u16 flags; > + > + indir_desc = vq->packed.desc_state[cursor->curr].indir_desc; > + desc = &indir_desc[cursor->pos]; > + > + flags = le16_to_cpu(desc->flags); > + *addr = le64_to_cpu(desc->addr); > + *len = le32_to_cpu(desc->len); > + *dir = (flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; > + > + if (++cursor->pos == cursor->num) { > + kfree(indir_desc); > + cursor->done = true; > + return 0; > + } > + } > + > + return -EAGAIN; > +} > + > static void detach_buf_packed(struct vring_virtqueue *vq, > - unsigned int id, void **ctx) > + unsigned int id) > { > struct vring_desc_state_packed *state = NULL; > struct vring_packed_desc *desc; > @@ -1736,8 +1813,6 @@ static void detach_buf_packed(struct vring_virtqueue *vq, > } > kfree(desc); > state->indir_desc = NULL; > - } else if (ctx) { > - *ctx = state->indir_desc; > } > } > > @@ -1768,7 +1843,8 @@ static bool more_used_packed(const struct vring_virtqueue *vq) > > static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq, > unsigned int *len, > - void **ctx) > + void **ctx, > + struct virtqueue_detach_cursor *cursor) > { > struct vring_virtqueue *vq = to_vvq(_vq); > u16 last_used, id, last_used_idx; > @@ -1808,7 +1884,14 @@ 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); > + > + if (!vq->indirect && ctx) > + *ctx = vq->packed.desc_state[id].indir_desc; > + > + if (vq->premapped) > + detach_cursor_init_packed(vq, cursor, id); > + else > + detach_buf_packed(vq, id); > > last_used += vq->packed.desc_state[id].num; > if (unlikely(last_used >= vq->packed.vring.num)) { > @@ -1960,7 +2043,8 @@ static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq) > return true; > } > > -static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq) > +static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq, > + struct virtqueue_detach_cursor *cursor) > { > struct vring_virtqueue *vq = to_vvq(_vq); > unsigned int i; > @@ -1973,7 +2057,10 @@ 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); > + if (vq->premapped) > + detach_cursor_init_packed(vq, cursor, i); > + else > + detach_buf_packed(vq, i); > END_USE(vq); > return buf; > } > @@ -2458,7 +2545,7 @@ 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) : > + return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx, NULL) : > virtqueue_get_buf_ctx_split(_vq, len, ctx, NULL); > } > EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx); > @@ -2590,7 +2677,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq) > { > struct vring_virtqueue *vq = to_vvq(_vq); > > - return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) : > + return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq, NULL) : > virtqueue_detach_unused_buf_split(_vq, NULL); > } > EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index eb4a4e4329aa..7f137c7a9034 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -43,8 +43,13 @@ struct virtqueue_detach_cursor { > unsigned done:1; > unsigned hole:14; > > - /* for split head */ > - unsigned head:16; > + union { > + /* for split head */ > + unsigned head:16; > + > + /* for packed id */ > + unsigned curr:16; > + }; > unsigned num:16; > unsigned pos:16; > }; > -- > 2.32.0.3.g01195cf9f
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index cdc4349f6066..cbc22daae7e1 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1695,8 +1695,85 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) return needs_kick; } +static void detach_cursor_init_packed(struct vring_virtqueue *vq, + struct virtqueue_detach_cursor *cursor, u16 id) +{ + struct vring_desc_state_packed *state = NULL; + u32 len; + + state = &vq->packed.desc_state[id]; + + /* Clear data ptr. */ + state->data = NULL; + + vq->packed.desc_extra[state->last].next = vq->free_head; + vq->free_head = id; + vq->vq.num_free += state->num; + + /* init cursor */ + cursor->curr = id; + cursor->done = 0; + cursor->pos = 0; + + if (vq->packed.desc_extra[id].flags & VRING_DESC_F_INDIRECT) { + len = vq->split.desc_extra[id].len; + + cursor->num = len / sizeof(struct vring_packed_desc); + cursor->indirect = true; + + vring_unmap_extra_packed(vq, &vq->packed.desc_extra[id]); + } else { + cursor->num = state->num; + cursor->indirect = false; + } +} + +static int virtqueue_detach_packed(struct virtqueue *_vq, struct virtqueue_detach_cursor *cursor, + dma_addr_t *addr, u32 *len, enum dma_data_direction *dir) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + + if (unlikely(cursor->done)) + return -EINVAL; + + if (!cursor->indirect) { + struct vring_desc_extra *extra; + + extra = &vq->packed.desc_extra[cursor->curr]; + cursor->curr = extra->next; + + *addr = extra->addr; + *len = extra->len; + *dir = (extra->flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + if (++cursor->pos == cursor->num) { + cursor->done = true; + return 0; + } + } else { + struct vring_packed_desc *indir_desc, *desc; + u16 flags; + + indir_desc = vq->packed.desc_state[cursor->curr].indir_desc; + desc = &indir_desc[cursor->pos]; + + flags = le16_to_cpu(desc->flags); + *addr = le64_to_cpu(desc->addr); + *len = le32_to_cpu(desc->len); + *dir = (flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + if (++cursor->pos == cursor->num) { + kfree(indir_desc); + cursor->done = true; + return 0; + } + } + + return -EAGAIN; +} + static void detach_buf_packed(struct vring_virtqueue *vq, - unsigned int id, void **ctx) + unsigned int id) { struct vring_desc_state_packed *state = NULL; struct vring_packed_desc *desc; @@ -1736,8 +1813,6 @@ static void detach_buf_packed(struct vring_virtqueue *vq, } kfree(desc); state->indir_desc = NULL; - } else if (ctx) { - *ctx = state->indir_desc; } } @@ -1768,7 +1843,8 @@ static bool more_used_packed(const struct vring_virtqueue *vq) static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq, unsigned int *len, - void **ctx) + void **ctx, + struct virtqueue_detach_cursor *cursor) { struct vring_virtqueue *vq = to_vvq(_vq); u16 last_used, id, last_used_idx; @@ -1808,7 +1884,14 @@ 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); + + if (!vq->indirect && ctx) + *ctx = vq->packed.desc_state[id].indir_desc; + + if (vq->premapped) + detach_cursor_init_packed(vq, cursor, id); + else + detach_buf_packed(vq, id); last_used += vq->packed.desc_state[id].num; if (unlikely(last_used >= vq->packed.vring.num)) { @@ -1960,7 +2043,8 @@ static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq) return true; } -static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq) +static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq, + struct virtqueue_detach_cursor *cursor) { struct vring_virtqueue *vq = to_vvq(_vq); unsigned int i; @@ -1973,7 +2057,10 @@ 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); + if (vq->premapped) + detach_cursor_init_packed(vq, cursor, i); + else + detach_buf_packed(vq, i); END_USE(vq); return buf; } @@ -2458,7 +2545,7 @@ 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) : + return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx, NULL) : virtqueue_get_buf_ctx_split(_vq, len, ctx, NULL); } EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx); @@ -2590,7 +2677,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); - return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) : + return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq, NULL) : virtqueue_detach_unused_buf_split(_vq, NULL); } EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); diff --git a/include/linux/virtio.h b/include/linux/virtio.h index eb4a4e4329aa..7f137c7a9034 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -43,8 +43,13 @@ struct virtqueue_detach_cursor { unsigned done:1; unsigned hole:14; - /* for split head */ - unsigned head:16; + union { + /* for split head */ + unsigned head:16; + + /* for packed id */ + unsigned curr:16; + }; unsigned num:16; unsigned pos:16; };
Under the premapped mode, the driver needs to unmap the DMA address after receiving the buffer. The virtio core records the DMA address, so the driver needs a way to get the dma info from the virtio core. A straightforward approach is to pass an array to the virtio core when calling virtqueue_get_buf(). However, it is not feasible when there are multiple DMA addresses in the descriptor chain, and the array size is unknown. To solve this problem, a helper be introduced. After calling virtqueue_get_buf(), the driver can call the helper to retrieve a dma info. If the helper function returns -EAGAIN, it means that there are more DMA addresses to be processed, and the driver should call the helper function again. To keep track of the current position in the chain, a cursor must be passed to the helper function, which is initialized by virtqueue_get_buf(). Some processes are done inside this helper, so this helper MUST be called under the premapped mode. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- drivers/virtio/virtio_ring.c | 105 ++++++++++++++++++++++++++++++++--- include/linux/virtio.h | 9 ++- 2 files changed, 103 insertions(+), 11 deletions(-)