We make use of the top bit of the dma_length to indicate a P2PDMA
segment. Code that uses this will need to use sg_dma_p2pdma_len() to
get the length and ensure no lengths exceed 2GB.
An sg_dma_is_p2pdma() helper is included to check if a particular
segment is p2pdma().
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
include/linux/scatterlist.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 36c47e7e66a2..e738159d56f9 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -39,6 +39,10 @@ struct scatterlist {
#define sg_dma_len(sg) ((sg)->length)
#endif
+#define SG_P2PDMA_FLAG (1U << 31)
+#define sg_dma_p2pdma_len(sg) (sg_dma_len(sg) & ~SG_P2PDMA_FLAG)
+#define sg_dma_is_p2pdma(sg) (sg_dma_len(sg) & SG_P2PDMA_FLAG)
+
struct sg_table {
struct scatterlist *sgl; /* the list */
unsigned int nents; /* number of mapped entries */
--
2.20.1
