[vhost,11/17] virtio_ring: export premapped to driver by struct virtqueue

Commit Message

Xuan Zhuo Jan. 30, 2024, 11:42 a.m. UTC

Export the premapped to drivers, then drivers can check
the vq premapped mode after the find_vqs().
Because the find_vqs() just try to enable the vq premapped mode,
the driver must check that after find_vqs().

Signed-off-by: Xuan Zhuo <[e-mail]>
---
 drivers/virtio/virtio_ring.c | 13 +++++--------
 include/linux/virtio.h       |  1 +
 2 files changed, 6 insertions(+), 8 deletions(-)

Comments

Jason Wang Jan. 31, 2024, 9:12 a.m. UTC | #1

On Tue, Jan 30, 2024 at 7:43 PM Xuan Zhuo <[e-mail]> wrote:
>
> Export the premapped to drivers, then drivers can check
> the vq premapped mode after the find_vqs().

This looks odd, it's the charge of the driver to set premapped, so it
should know it?

Thanks

Xuan Zhuo Feb. 1, 2024, 3:17 a.m. UTC | #2

On Wed, 31 Jan 2024 17:12:43 +0800, Jason Wang <[e-mail]> wrote:
> On Tue, Jan 30, 2024 at 7:43 PM Xuan Zhuo <[e-mail]> wrote:
> >
> > Export the premapped to drivers, then drivers can check
> > the vq premapped mode after the find_vqs().
> 
> This looks odd, it's the charge of the driver to set premapped, so it
> should know it?

If the use_dma_api is false, we can not enable the premapped mode.
Though we wrapped dma apis, but the AF_XDP use the default dma api directly.
As we discussed, we just work in premapped mode when the use_dma_api is true.

Thanks.


> 
> Thanks
>

Patch

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e5e9672b4ab2..e7badc81642d 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -191,9 +191,6 @@  struct vring_virtqueue {
 	/* Host publishes avail event idx */
 	bool event;
 
-	/* Do DMA mapping by driver */
-	bool premapped;
-
 	/* Head of free buffer list. */
 	unsigned int free_head;
 	/* Number we've added since last sync. */
@@ -311,7 +308,7 @@  static bool vring_use_dma_api(const struct virtio_device *vdev)
 
 static bool vring_need_unmap_buffer(const struct vring_virtqueue *vring)
 {
-	return vring->use_dma_api && !vring->premapped;
+	return vring->use_dma_api && !vring->vq.premapped;
 }
 
 size_t virtio_max_dma_size(const struct virtio_device *vdev)
@@ -383,7 +380,7 @@  static struct device *vring_dma_dev(const struct vring_virtqueue *vq)
 static int vring_map_one_sg(const struct vring_virtqueue *vq, struct scatterlist *sg,
 			    enum dma_data_direction direction, dma_addr_t *addr)
 {
-	if (vq->premapped) {
+	if (vq->vq.premapped) {
 		*addr = sg_dma_address(sg);
 		return 0;
 	}
@@ -2145,7 +2142,7 @@  static struct virtqueue *vring_create_virtqueue_packed(struct virtio_device *vde
 	vq->packed_ring = true;
 	vq->dma_dev = dma_dev;
 	vq->use_dma_api = vring_use_dma_api(vdev);
-	vq->premapped = vq->use_dma_api && cfg_vq_get(cfg, premapped);
+	vq->vq.premapped = vq->use_dma_api && cfg_vq_get(cfg, premapped);
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
 		!cfg_vq_get(cfg, ctx);
@@ -2687,7 +2684,7 @@  static struct virtqueue *__vring_new_virtqueue(struct virtio_device *vdev,
 #endif
 	vq->dma_dev = tp_cfg->dma_dev;
 	vq->use_dma_api = vring_use_dma_api(vdev);
-	vq->premapped = vq->use_dma_api && cfg_vq_get(cfg, premapped);
+	vq->vq.premapped = vq->use_dma_api && cfg_vq_get(cfg, premapped);
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
 		!cfg_vq_get(cfg, ctx);
@@ -2818,7 +2815,7 @@  int virtqueue_set_dma_premapped(struct virtqueue *_vq)
 		return -EINVAL;
 	}
 
-	vq->premapped = true;
+	vq->vq.premapped = true;
 
 	if (vq->packed_ring) {
 		kfree(vq->packed.desc_dma);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 4cc614a38376..37ba44dc34de 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -36,6 +36,7 @@  struct virtqueue {
 	unsigned int num_free;
 	unsigned int num_max;
 	bool reset;
+	bool premapped;
 	void *priv;
 };