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,
                                 bool premapped,
                                 gfp_t gfp);

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

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 48 ++++++++++++++++++++++++++++++++++++
 include/linux/virtio.h       | 13 ++++++++++
 2 files changed, 61 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a89295b79e66..525308d82728 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -2272,6 +2272,29 @@ 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).
+ *
+ * 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,
+                                  bool premapped,

+                                  gfp_t gfp)
+{
+       return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, premapped, 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.

@@ -2318,6 +2341,31 @@ 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).
+ *
+ * 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,
+                                 bool premapped,
+                                 gfp_t gfp)
+{
+       return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, premapped, 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..19afa49b92d0 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h

@@ -56,6 +56,19 @@ 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,
+                                 bool premapped,
+                                 gfp_t gfp);
+
+int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
+                                  struct scatterlist *sg, unsigned int num,
+                                  void *data,
+                                  bool premapped,
+                                  gfp_t gfp);
+
 int virtqueue_add_sgs(struct virtqueue *vq,
                      struct scatterlist *sgs[],
                      unsigned int out_sgs,
--

2.32.0.3.g01195cf9f