[PATCH vhost v11 05/10] virtio_ring: introduce virtqueue_dma_dev()

Xuan Zhuo
2023-07-10T03:42:32Z

Added virtqueue_dma_dev() to get DMA device for virtio. Then the
caller can do dma operation in advance. The purpose is to keep memory
mapped across multiple add/get buf operations.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 17 +++++++++++++++++
 include/linux/virtio.h       |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index d471dee3f4f7..1fb2c6dca9ea 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2265,6 +2265,23 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);

+/**
+ * virtqueue_dma_dev - get the dma dev
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * Returns the dma dev. That can been used for dma api.
+ */
+struct device *virtqueue_dma_dev(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (vq->use_dma_api)
+		return vring_dma_dev(vq);
+	else
+		return NULL;
+}
+EXPORT_SYMBOL_GPL(virtqueue_dma_dev);
+
 /**
  * virtqueue_kick_prepare - first half of split virtqueue_kick call.
  * @_vq: the struct virtqueue
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 2efd07b79ecf..35d175121cc6 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -61,6 +61,8 @@ int virtqueue_add_sgs(struct virtqueue *vq,
 		      void *data,
 		      gfp_t gfp);

+struct device *virtqueue_dma_dev(struct virtqueue *vq);
+
 bool virtqueue_kick(struct virtqueue *vq);

 bool virtqueue_kick_prepare(struct virtqueue *vq);
--
2.32.0.3.g01195cf9f