[RFC PATCH 09/15] nvme-pci: Convert to using dma_map_sg for p2pdma pages

[Logan Gunthorpe <logang@xxxxxxxxxxxx>]

Switch to using sg_dma_p2pdma_len() in places where sg_dma_len() is
used. Then replace the calls to pci_p2pdma_[un]map_sg() with calls
to dma_[un]map_sg() with DMA_ATTR_P2PDMA.

This should be equivalent, though support will be somewhat less
(only dma-direct and dma-iommu are currently supported).

Using DMA_ATTR_P2PDMA is safe because the block layer restricts
requests to be much less than 2GB, thus there's no way for a
segment to be greater than 2GB.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 drivers/nvme/host/pci.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index ef7ce464a48d..26976bdf4af0 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -528,12 +528,8 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
 
 	WARN_ON_ONCE(!iod->nents);
 
-	if (is_pci_p2pdma_page(sg_page(iod->sg)))
-		pci_p2pdma_unmap_sg(dev->dev, iod->sg, iod->nents,
-				    rq_dma_dir(req));
-	else
-		dma_unmap_sg(dev->dev, iod->sg, iod->nents, rq_dma_dir(req));
-
+	dma_unmap_sg_attrs(dev->dev, iod->sg, iod->nents, rq_dma_dir(req),
+			   DMA_ATTR_P2PDMA);
 
 	if (iod->npages == 0)
 		dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
@@ -570,7 +566,7 @@ static void nvme_print_sgl(struct scatterlist *sgl, int nents)
 		pr_warn("sg[%d] phys_addr:%pad offset:%d length:%d "
 			"dma_address:%pad dma_length:%d\n",
 			i, &phys, sg->offset, sg->length, &sg_dma_address(sg),
-			sg_dma_len(sg));
+			sg_dma_p2pdma_len(sg));
 	}
 }
 
@@ -581,7 +577,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
 	struct dma_pool *pool;
 	int length = blk_rq_payload_bytes(req);
 	struct scatterlist *sg = iod->sg;
-	int dma_len = sg_dma_len(sg);
+	int dma_len = sg_dma_p2pdma_len(sg);
 	u64 dma_addr = sg_dma_address(sg);
 	int offset = dma_addr & (NVME_CTRL_PAGE_SIZE - 1);
 	__le64 *prp_list;
@@ -601,7 +597,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
 	} else {
 		sg = sg_next(sg);
 		dma_addr = sg_dma_address(sg);
-		dma_len = sg_dma_len(sg);
+		dma_len = sg_dma_p2pdma_len(sg);
 	}
 
 	if (length <= NVME_CTRL_PAGE_SIZE) {
@@ -650,7 +646,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
 			goto bad_sgl;
 		sg = sg_next(sg);
 		dma_addr = sg_dma_address(sg);
-		dma_len = sg_dma_len(sg);
+		dma_len = sg_dma_p2pdma_len(sg);
 	}
 
 done:
@@ -670,7 +666,7 @@ static void nvme_pci_sgl_set_data(struct nvme_sgl_desc *sge,
 		struct scatterlist *sg)
 {
 	sge->addr = cpu_to_le64(sg_dma_address(sg));
-	sge->length = cpu_to_le32(sg_dma_len(sg));
+	sge->length = cpu_to_le32(sg_dma_p2pdma_len(sg));
 	sge->type = NVME_SGL_FMT_DATA_DESC << 4;
 }
 
@@ -814,14 +810,12 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 	if (!iod->nents)
 		goto out;
 
-	if (is_pci_p2pdma_page(sg_page(iod->sg)))
-		nr_mapped = pci_p2pdma_map_sg_attrs(dev->dev, iod->sg,
-				iod->nents, rq_dma_dir(req), DMA_ATTR_NO_WARN);
-	else
-		nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
-					     rq_dma_dir(req), DMA_ATTR_NO_WARN);
-	if (!nr_mapped)
+	nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
+			rq_dma_dir(req), DMA_ATTR_NO_WARN | DMA_ATTR_P2PDMA);
+	if (!nr_mapped) {
+		ret = BLK_STS_IOERR;
 		goto out;
+	}
 
 	iod->use_sgl = nvme_pci_use_sgls(dev, req);
 	if (iod->use_sgl)
-- 
2.20.1