[PATCH 09/16] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg

[Logan Gunthorpe]

Add PCI P2PDMA support for dma_direct_map_sg() so that it can map
PCI P2PDMA pages directly without a hack in the callers. This allows
for heterogeneous SGLs that contain both P2PDMA and regular pages.

SGL segments that contain PCI bus addresses are marked with
sg_mark_pci_p2pdma() and are ignored when unmapped.

Signed-off-by: Logan Gunthorpe <logang at deltatee.com>
---
 kernel/dma/direct.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 002268262c9a..108dfb4ecbd5 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -13,6 +13,7 @@
 #include <linux/vmalloc.h>
 #include <linux/set_memory.h>
 #include <linux/slab.h>
+#include <linux/pci-p2pdma.h>
 #include "direct.h"
 
 /*
@@ -387,19 +388,37 @@ void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
 	struct scatterlist *sg;
 	int i;
 
-	for_each_sg(sgl, sg, nents, i)
+	for_each_sg(sgl, sg, nents, i) {
+		if (sg_is_pci_p2pdma(sg)) {
+			sg_unmark_pci_p2pdma(sg);
+			continue;
+		}
+
 		dma_direct_unmap_page(dev, sg->dma_address, sg_dma_len(sg), dir,
 			     attrs);
+	}
 }
 #endif
 
 int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 		enum dma_data_direction dir, unsigned long attrs)
 {
-	int i;
+	struct pci_p2pdma_map_state p2pdma_state = {};
 	struct scatterlist *sg;
+	int i, ret = 0;
 
 	for_each_sg(sgl, sg, nents, i) {
+		if (is_pci_p2pdma_page(sg_page(sg))) {
+			ret = pci_p2pdma_map_segment(&p2pdma_state, dev, sg,
+						     attrs);
+			if (ret < 0) {
+				goto out_unmap;
+			} else if (ret) {
+				ret = 0;
+				continue;
+			}
+		}
+
 		sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
 				sg->offset, sg->length, dir, attrs);
 		if (sg->dma_address == DMA_MAPPING_ERROR)
@@ -411,7 +430,7 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 
 out_unmap:
 	dma_direct_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
-	return 0;
+	return ret;
 }
 
 dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
-- 
2.20.1