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

Logan Gunthorpe
2021-04-08T17:01:53Z

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@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