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Message-Id: <20230810123057.43407-7-xuanzhuo@linux.alibaba.com>
Date: Thu, 10 Aug 2023 20:30:51 +0800
From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To: virtualization@...ts.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
netdev@...r.kernel.org,
bpf@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>
Subject: [PATCH vhost v13 06/12] 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@...ux.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 bb3d73d221cd..7973814b6e31 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;
@@ -2771,6 +2784,7 @@ int virtqueue_set_dma_premapped(struct virtqueue *_vq)
}
vq->premapped = true;
+ vq->do_unmap = false;
END_USE(vq);
--
2.32.0.3.g01195cf9f
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