[PATCH vhost v1 08/12] virtio_ring: introduce virtqueue_add_inbuf_premapped()

Xuan Zhuo
Thu, 02 Mar 2023 11:59:04 -0000

Introduce virtqueue_add_inbuf_premapped() to submit premapped sgs.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 25 +++++++++++++++++++++++++
 include/linux/virtio.h       |  5 +++++
 2 files changed, 30 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5e98f828236d..53df12a8ab97 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2382,6 +2382,31 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);

+/**
+ * virtqueue_add_inbuf_premapped - expose input buffers with dma address to
other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: scatterlist (must be well-formed and terminated!)
+ * @num: the number of entries in @sg writable by other side
+ * @data: the token identifying the buffer.
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * It is required that all addrs have completed DMA operations. And use
+ * sg->dma_address, sg->length to pass addr and length.
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
+				  struct scatterlist *sg, unsigned int num,
+				  void *data,
+				  gfp_t gfp)
+{
+	return virtqueue_add_premapped(vq, &sg, num, 0, 1, data, NULL, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_premapped);
+
 /**
  * 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 d8b472a7dcae..3ebb346ebb7c 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -59,6 +59,11 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
 			    void *ctx,
 			    gfp_t gfp);

+int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
+				  struct scatterlist *sg, unsigned int num,
+				  void *data,
+				  gfp_t gfp);
+
 int virtqueue_add_sgs(struct virtqueue *vq,
 		      struct scatterlist *sgs[],
 		      unsigned int out_sgs,
--
2.32.0.3.g01195cf9f