Commit b319940f authored by Xuan Zhuo's avatar Xuan Zhuo Committed by Michael S. Tsirkin
Browse files

virtio_ring: skip unmap for premapped 



Now we add a case where we skip dma unmap, the vq->premapped is true.

We can't just rely on use_dma_api to determine whether to skip the dma
operation. For convenience, I introduced the "do_unmap". By default, it
is the same as use_dma_api. If the driver is configured with premapped,
then do_unmap is false.

So as long as do_unmap is false, for addr of desc, we should skip dma
unmap operation.

Signed-off-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-7-xuanzhuo@linux.alibaba.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 2df64759

drivers/virtio/virtio_ring.c

+28 −14
Original line number Diff line number Diff line
@@ -175,6 +175,11 @@ struct vring_virtqueue { 
	/* Do DMA mapping by driver */

	bool premapped;



	/* Do unmap or not for desc. Just when premapped is False and

	 * use_dma_api is true, this is true.

	 */

	bool do_unmap;



	/* Head of free buffer list. */

	unsigned int free_head;

	/* Number we've added since last sync. */
@@ -440,7 +445,7 @@ static void vring_unmap_one_split_indirect(const struct vring_virtqueue *vq, 
{

	u16 flags;



	if (!vq->use_dma_api)

	if (!vq->do_unmap)

		return;



	flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
@@ -458,18 +463,21 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq, 
	struct vring_desc_extra *extra = vq->split.desc_extra;

	u16 flags;



	if (!vq->use_dma_api)

		goto out;



	flags = extra[i].flags;



	if (flags & VRING_DESC_F_INDIRECT) {

		if (!vq->use_dma_api)

			goto out;



		dma_unmap_single(vring_dma_dev(vq),

				 extra[i].addr,

				 extra[i].len,

				 (flags & VRING_DESC_F_WRITE) ?

				 DMA_FROM_DEVICE : DMA_TO_DEVICE);

	} else {

		if (!vq->do_unmap)

			goto out;



		dma_unmap_page(vring_dma_dev(vq),

			       extra[i].addr,

			       extra[i].len,
@@ -635,7 +643,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, 
	}

	/* Last one doesn't continue. */

	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);

	if (!indirect && vq->use_dma_api)

	if (!indirect && vq->do_unmap)

		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &=

			~VRING_DESC_F_NEXT;
@@ -794,7 +802,7 @@ 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->use_dma_api) {

		if (vq->do_unmap) {

			for (j = 0; j < len / sizeof(struct vring_desc); j++)

				vring_unmap_one_split_indirect(vq, &indir_desc[j]);

		}
@@ -1217,17 +1225,20 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq, 
{

	u16 flags;



	if (!vq->use_dma_api)

		return;



	flags = extra->flags;



	if (flags & VRING_DESC_F_INDIRECT) {

		if (!vq->use_dma_api)

			return;



		dma_unmap_single(vring_dma_dev(vq),

				 extra->addr, extra->len,

				 (flags & VRING_DESC_F_WRITE) ?

				 DMA_FROM_DEVICE : DMA_TO_DEVICE);

	} else {

		if (!vq->do_unmap)

			return;



		dma_unmap_page(vring_dma_dev(vq),

			       extra->addr, extra->len,

			       (flags & VRING_DESC_F_WRITE) ?
@@ -1240,7 +1251,7 @@ static void vring_unmap_desc_packed(const struct vring_virtqueue *vq, 
{

	u16 flags;



	if (!vq->use_dma_api)

	if (!vq->do_unmap)

		return;



	flags = le16_to_cpu(desc->flags);
@@ -1329,7 +1340,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, 
				sizeof(struct vring_packed_desc));

	vq->packed.vring.desc[head].id = cpu_to_le16(id);



	if (vq->use_dma_api) {

	if (vq->do_unmap) {

		vq->packed.desc_extra[id].addr = addr;

		vq->packed.desc_extra[id].len = total_sg *

				sizeof(struct vring_packed_desc);
@@ -1470,7 +1481,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, 
			desc[i].len = cpu_to_le32(sg->length);

			desc[i].id = cpu_to_le16(id);



			if (unlikely(vq->use_dma_api)) {

			if (unlikely(vq->do_unmap)) {

				vq->packed.desc_extra[curr].addr = addr;

				vq->packed.desc_extra[curr].len = sg->length;

				vq->packed.desc_extra[curr].flags =
@@ -1604,7 +1615,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, 
	vq->free_head = id;

	vq->vq.num_free += state->num;



	if (unlikely(vq->use_dma_api)) {

	if (unlikely(vq->do_unmap)) {

		curr = id;

		for (i = 0; i < state->num; i++) {

			vring_unmap_extra_packed(vq,
@@ -1621,7 +1632,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq, 
		if (!desc)

			return;



		if (vq->use_dma_api) {

		if (vq->do_unmap) {

			len = vq->packed.desc_extra[id].len;

			for (i = 0; i < len / sizeof(struct vring_packed_desc);

					i++)
@@ -2080,6 +2091,7 @@ static struct virtqueue *vring_create_virtqueue_packed( 
	vq->dma_dev = dma_dev;

	vq->use_dma_api = vring_use_dma_api(vdev);

	vq->premapped = false;

	vq->do_unmap = vq->use_dma_api;



	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&

		!context;
@@ -2587,6 +2599,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, 
	vq->dma_dev = dma_dev;

	vq->use_dma_api = vring_use_dma_api(vdev);

	vq->premapped = false;

	vq->do_unmap = vq->use_dma_api;



	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&

		!context;
@@ -2771,6 +2784,7 @@ int virtqueue_set_dma_premapped(struct virtqueue *_vq) 
	}



	vq->premapped = true;

	vq->do_unmap = false;



	END_USE(vq);