[PATCH net-next v4 05/13] virtio_ring: introduce add api for premapped

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

Two APIs are introduced to submit premapped per-buffers.

int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
                                 struct scatterlist *sg, unsigned int num,
                                 void *data,
                                 void *ctx,
                                 gfp_t gfp);

int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
                                  struct scatterlist *sg, unsigned int num,
                                  void *data,
                                  gfp_t gfp);

Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 48 ++++++++++++++++++++++++++++++++++++
 include/linux/virtio.h       | 11 +++++++++
 2 files changed, 59 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index fefa85a5e6b6..0842d27886e5 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2276,6 +2276,29 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
 
+/**
+ * virtqueue_add_outbuf_premapped - expose output buffers 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 readable 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).
+ *
+ * Return:
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
+				   struct scatterlist *sg, unsigned int num,
+				   void *data,
+				   gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, true, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_outbuf_premapped);
+
 /**
  * virtqueue_add_inbuf - expose input buffers to other end
  * @vq: the struct virtqueue we're talking about.
@@ -2322,6 +2345,31 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
 
+/**
+ * virtqueue_add_inbuf_premapped - expose input buffers 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.
+ * @ctx: extra context for the token
+ * @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).
+ *
+ * Return:
+ * 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,
+				  void *ctx,
+				  gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, true, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_premapped);
+
 /**
  * virtqueue_dma_dev - get the dma dev
  * @_vq: the struct virtqueue we're talking about.
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 306137a15d07..13b3f55abca3 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -56,6 +56,17 @@ 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,
+				  void *ctx,
+				  gfp_t gfp);
+
+int virtqueue_add_outbuf_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