Xuan Zhuo
2023-Jul-10 03:42 UTC
[PATCH vhost v11 06/10] 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: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
drivers/virtio/virtio_ring.c | 42 ++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 1fb2c6dca9ea..10ee3b7ce571 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -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;
@@ -2765,6 +2778,7 @@ int virtqueue_set_premapped(struct virtqueue *_vq)
return -EINVAL;
vq->premapped = true;
+ vq->do_unmap = false;
return 0;
}
--
2.32.0.3.g01195cf9f
Jason Wang
2023-Jul-13 03:50 UTC
[PATCH vhost v11 06/10] virtio_ring: skip unmap for premapped
On Mon, Jul 10, 2023 at 11:42?AM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:> > 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: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > --- > drivers/virtio/virtio_ring.c | 42 ++++++++++++++++++++++++------------ > 1 file changed, 28 insertions(+), 14 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 1fb2c6dca9ea..10ee3b7ce571 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -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;This seems not straightforward than: if (!vq->use_dma_api) return; if (INDIRECT) { } else if (!vq->premapped) { } ? Thanks> + > 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; > @@ -2765,6 +2778,7 @@ int virtqueue_set_premapped(struct virtqueue *_vq) > return -EINVAL; > > vq->premapped = true; > + vq->do_unmap = false; > > return 0; > } > -- > 2.32.0.3.g01195cf9f >