[PATCH 15/16] RDMA/rw: use dma_map_sg_p2pdma()

[Logan Gunthorpe]

Drop the use of pci_p2pdma_map_sg() in favour of dma_map_sg_p2pdma().

The new interface allows mapping scatterlists that mix both regular
and P2PDMA pages and will verify that the dma device can communicate
with the device the pages are on.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 drivers/infiniband/core/rw.c | 50 ++++++++++--------------------------
 include/rdma/ib_verbs.h      | 32 +++++++++++++++++++++++
 2 files changed, 46 insertions(+), 36 deletions(-)

diff --git a/drivers/infiniband/core/rw.c b/drivers/infiniband/core/rw.c
index 31156e22d3e7..0c6213d9b044 100644
--- a/drivers/infiniband/core/rw.c
+++ b/drivers/infiniband/core/rw.c
@@ -273,26 +273,6 @@ static int rdma_rw_init_single_wr(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
 	return 1;
 }
 
-static void rdma_rw_unmap_sg(struct ib_device *dev, struct scatterlist *sg,
-			     u32 sg_cnt, enum dma_data_direction dir)
-{
-	if (is_pci_p2pdma_page(sg_page(sg)))
-		pci_p2pdma_unmap_sg(dev->dma_device, sg, sg_cnt, dir);
-	else
-		ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
-}
-
-static int rdma_rw_map_sg(struct ib_device *dev, struct scatterlist *sg,
-			  u32 sg_cnt, enum dma_data_direction dir)
-{
-	if (is_pci_p2pdma_page(sg_page(sg))) {
-		if (WARN_ON_ONCE(ib_uses_virt_dma(dev)))
-			return 0;
-		return pci_p2pdma_map_sg(dev->dma_device, sg, sg_cnt, dir);
-	}
-	return ib_dma_map_sg(dev, sg, sg_cnt, dir);
-}
-
 /**
  * rdma_rw_ctx_init - initialize a RDMA READ/WRITE context
  * @ctx:	context to initialize
@@ -315,9 +295,9 @@ int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 	struct ib_device *dev = qp->pd->device;
 	int ret;
 
-	ret = rdma_rw_map_sg(dev, sg, sg_cnt, dir);
-	if (!ret)
-		return -ENOMEM;
+	ret = ib_dma_map_sg_p2pdma(dev, sg, sg_cnt, dir);
+	if (ret < 0)
+		return ret;
 	sg_cnt = ret;
 
 	/*
@@ -354,7 +334,7 @@ int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 	return ret;
 
 out_unmap_sg:
-	rdma_rw_unmap_sg(dev, sg, sg_cnt, dir);
+	ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
 	return ret;
 }
 EXPORT_SYMBOL(rdma_rw_ctx_init);
@@ -394,17 +374,15 @@ int rdma_rw_ctx_signature_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
 		return -EINVAL;
 	}
 
-	ret = rdma_rw_map_sg(dev, sg, sg_cnt, dir);
-	if (!ret)
-		return -ENOMEM;
+	ret = ib_dma_map_sg_p2pdma(dev, sg, sg_cnt, dir);
+	if (ret < 0)
+		return ret;
 	sg_cnt = ret;
 
 	if (prot_sg_cnt) {
-		ret = rdma_rw_map_sg(dev, prot_sg, prot_sg_cnt, dir);
-		if (!ret) {
-			ret = -ENOMEM;
+		ret = ib_dma_map_sg_p2pdma(dev, prot_sg, prot_sg_cnt, dir);
+		if (ret < 0)
 			goto out_unmap_sg;
-		}
 		prot_sg_cnt = ret;
 	}
 
@@ -469,9 +447,9 @@ int rdma_rw_ctx_signature_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
 	kfree(ctx->reg);
 out_unmap_prot_sg:
 	if (prot_sg_cnt)
-		rdma_rw_unmap_sg(dev, prot_sg, prot_sg_cnt, dir);
+		ib_dma_unmap_sg(dev, prot_sg, prot_sg_cnt, dir);
 out_unmap_sg:
-	rdma_rw_unmap_sg(dev, sg, sg_cnt, dir);
+	ib_dma_unmap_sg(dev, sg, sg_cnt, dir);
 	return ret;
 }
 EXPORT_SYMBOL(rdma_rw_ctx_signature_init);
@@ -603,7 +581,7 @@ void rdma_rw_ctx_destroy(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
 		break;
 	}
 
-	rdma_rw_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
+	ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
 }
 EXPORT_SYMBOL(rdma_rw_ctx_destroy);
 
@@ -631,8 +609,8 @@ void rdma_rw_ctx_destroy_signature(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
 	kfree(ctx->reg);
 
 	if (prot_sg_cnt)
-		rdma_rw_unmap_sg(qp->pd->device, prot_sg, prot_sg_cnt, dir);
-	rdma_rw_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
+		ib_dma_unmap_sg(qp->pd->device, prot_sg, prot_sg_cnt, dir);
+	ib_dma_unmap_sg(qp->pd->device, sg, sg_cnt, dir);
 }
 EXPORT_SYMBOL(rdma_rw_ctx_destroy_signature);
 
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index ca28fca5736b..a541ed1702f5 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -4028,6 +4028,17 @@ static inline int ib_dma_map_sg_attrs(struct ib_device *dev,
 				dma_attrs);
 }
 
+static inline int ib_dma_map_sg_p2pdma_attrs(struct ib_device *dev,
+					     struct scatterlist *sg, int nents,
+					     enum dma_data_direction direction,
+					     unsigned long dma_attrs)
+{
+	if (ib_uses_virt_dma(dev))
+		return ib_dma_virt_map_sg(dev, sg, nents);
+	return dma_map_sg_p2pdma_attrs(dev->dma_device, sg, nents, direction,
+				       dma_attrs);
+}
+
 static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
 					 struct scatterlist *sg, int nents,
 					 enum dma_data_direction direction,
@@ -4052,6 +4063,27 @@ static inline int ib_dma_map_sg(struct ib_device *dev,
 	return ib_dma_map_sg_attrs(dev, sg, nents, direction, 0);
 }
 
+/**
+ * ib_dma_map_sg_p2pdma - Map a scatter/gather list to DMA addresses
+ * @dev: The device for which the DMA addresses are to be created
+ * @sg: The array of scatter/gather entries
+ * @nents: The number of scatter/gather entries
+ * @direction: The direction of the DMA
+ *
+ * Map an scatter/gather list that might contain P2PDMA pages.
+ * Unlike ib_dma_map_sg() it will return either a negative errno or
+ * a positive value indicating the number of dma segments. See
+ * dma_map_sg_p2pdma_attrs() for details.
+ *
+ * The resulting list should be unmapped with ib_dma_unmap_sg().
+ */
+static inline int ib_dma_map_sg_p2pdma(struct ib_device *dev,
+				       struct scatterlist *sg, int nents,
+				       enum dma_data_direction direction)
+{
+	return ib_dma_map_sg_p2pdma_attrs(dev, sg, nents, direction, 0);
+}
+
 /**
  * ib_dma_unmap_sg - Unmap a scatter/gather list of DMA addresses
  * @dev: The device for which the DMA addresses were created
-- 
2.20.1