Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
 tools/virtio/linux/virtio.h | 45 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/tools/virtio/linux/virtio.h b/tools/virtio/linux/virtio.h
index 390c4cb..0426a75 100644
--- a/tools/virtio/linux/virtio.h
+++ b/tools/virtio/linux/virtio.h
@@ -11,6 +11,13 @@
 #include <linux/types.h>
 #include <errno.h>
 
+# ifndef likely
+#  define likely(x)    (__builtin_expect(!!(x), 1))
+# endif
+# ifndef unlikely
+#  define unlikely(x)  (__builtin_expect(!!(x), 0))
+# endif
+
 typedef unsigned long long dma_addr_t;
 
 struct scatterlist {
@@ -43,6 +50,10 @@ static inline void sg_mark_end(struct scatterlist *sg)
        sg->page_link |= 0x02;
        sg->page_link &= ~0x01;
 }
+static inline void sg_unmark_end(struct scatterlist *sg)
+{
+       sg->page_link &= ~0x02;
+}
 static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
 {
        memset(sgl, 0, sizeof(*sgl) * nents);
@@ -79,6 +90,26 @@ static inline void sg_init_one(struct scatterlist *sg, const 
void *buf, unsigned
        sg_init_table(sg, 1);
        sg_set_buf(sg, buf, buflen);
 }
+/*
+ * We overload the LSB of the page pointer to indicate whether it's
+ * a valid sg entry, or whether it points to the start of a new scatterlist.
+ * Those low bits are there for everyone! (thanks mason :-)
+ */
+#define sg_is_chain(sg)                ((sg)->page_link & 0x01)
+#define sg_is_last(sg)         ((sg)->page_link & 0x02)
+#define sg_chain_ptr(sg)       \
+       ((struct scatterlist *) ((sg)->page_link & ~0x03))
+static inline struct scatterlist *sg_next(struct scatterlist *sg)
+{
+       if (sg_is_last(sg))
+               return NULL;
+
+       sg++;
+       if (unlikely(sg_is_chain(sg)))
+               sg = sg_chain_ptr(sg);
+
+       return sg;
+}
 
 typedef __u16 u16;
 
@@ -109,13 +140,6 @@ static inline void kfree(void *p)
 
 #define uninitialized_var(x) x = x
 
-# ifndef likely
-#  define likely(x)    (__builtin_expect(!!(x), 1))
-# endif
-# ifndef unlikely
-#  define unlikely(x)  (__builtin_expect(!!(x), 0))
-# endif
-
 #define pr_err(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
 #ifdef DEBUG
 #define pr_debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
@@ -200,6 +224,13 @@ int virtqueue_add_buf(struct virtqueue *vq,
                      void *data,
                      gfp_t gfp);
 
+int virtqueue_add_sgs(struct virtqueue *vq,
+                     struct scatterlist *sgs[],
+                     unsigned int out_sgs,
+                     unsigned int in_sgs,
+                     void *data,
+                     gfp_t gfp);
+
 void virtqueue_kick(struct virtqueue *vq);
 
 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
-- 
MST
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