Hello,
On 2013-09-27 00:36, Andreas Herrmann wrote:
... otherwise it is impossible for the low level iommu driver to
figure out which pte flags should be used.
In __map_sg_chunk we can derive the flags from dma_data_direction.
In __iommu_create_mapping we should treat the memory like
DMA_BIDIRECTIONAL and pass both IOMMU_READ and IOMMU_WRITE to
iommu_map.
__iommu_create_mapping is used during dma_alloc_coherent (via
arm_iommu_alloc_attrs). AFAIK dma_alloc_coherent is responsible for
allocation _and_ mapping. I think this implies that access to the
mapped pages should be allowed.
Cc: Marek Szyprowski <[email protected]>
Signed-off-by: Andreas Herrmann <[email protected]>
Thanks pointing the issue and preparing the patch. I will push it to the
dma-mapping fixes branch.
---
arch/arm/mm/dma-mapping.c | 43 ++++++++++++++++++++++++++++---------------
1 file changed, 28 insertions(+), 15 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f5e1a84..1272ed2 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1232,7 +1232,8 @@ __iommu_create_mapping(struct device *dev, struct page
**pages, size_t size)
break;
len = (j - i) << PAGE_SHIFT;
- ret = iommu_map(mapping->domain, iova, phys, len, 0);
+ ret = iommu_map(mapping->domain, iova, phys, len,
+ IOMMU_READ|IOMMU_WRITE);
if (ret < 0)
goto fail;
iova += len;
@@ -1431,6 +1432,27 @@ static int arm_iommu_get_sgtable(struct device *dev,
struct sg_table *sgt,
GFP_KERNEL);
}
+static int __dma_direction_to_prot(enum dma_data_direction dir)
+{
+ int prot;
+
+ switch (dir) {
+ case DMA_BIDIRECTIONAL:
+ prot = IOMMU_READ | IOMMU_WRITE;
+ break;
+ case DMA_TO_DEVICE:
+ prot = IOMMU_READ;
+ break;
+ case DMA_FROM_DEVICE:
+ prot = IOMMU_WRITE;
+ break;
+ default:
+ prot = 0;
+ }
+
+ return prot;
+}
+
/*
* Map a part of the scatter-gather list into contiguous io address space
*/
@@ -1444,6 +1466,7 @@ static int __map_sg_chunk(struct device *dev, struct
scatterlist *sg,
int ret = 0;
unsigned int count;
struct scatterlist *s;
+ int prot;
size = PAGE_ALIGN(size);
*handle = DMA_ERROR_CODE;
@@ -1460,7 +1483,9 @@ static int __map_sg_chunk(struct device *dev, struct
scatterlist *sg,
!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
__dma_page_cpu_to_dev(sg_page(s), s->offset, s->length,
dir);
- ret = iommu_map(mapping->domain, iova, phys, len, 0);
+ prot = __dma_direction_to_prot(dir);
+
+ ret = iommu_map(mapping->domain, iova, phys, len, prot);
if (ret < 0)
goto fail;
count += len >> PAGE_SHIFT;
@@ -1665,19 +1690,7 @@ static dma_addr_t arm_coherent_iommu_map_page(struct
device *dev, struct page *p
if (dma_addr == DMA_ERROR_CODE)
return dma_addr;
- switch (dir) {
- case DMA_BIDIRECTIONAL:
- prot = IOMMU_READ | IOMMU_WRITE;
- break;
- case DMA_TO_DEVICE:
- prot = IOMMU_READ;
- break;
- case DMA_FROM_DEVICE:
- prot = IOMMU_WRITE;
- break;
- default:
- prot = 0;
- }
+ prot = __dma_direction_to_prot(dir);
ret = iommu_map(mapping->domain, dma_addr, page_to_phys(page), len, prot);
if (ret < 0)
Best regards
--
Marek Szyprowski
Samsung R&D Institute Poland
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