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iommu: add generic helper for mapping sgtable objects 

struct sg_table is a common structure used for describing a memory
buffer. It consists of a scatterlist with memory pages and DMA addresses
(sgl entry), as well as the number of scatterlist entries: CPU pages
(orig_nents entry) and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling mapping functions with a wrong number of entries.

To avoid such issues, lets introduce a common wrapper operating directly
on the struct sg_table objects, which take care of the proper use of
the nents and orig_nents entries.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Marek Szyprowski 2020-05-13 15:32:10 +02:00 committed by Christoph Hellwig
parent 709d6d73c7
commit 48530d9fab
1 changed files with 16 additions and 0 deletions
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16
include/linux/iommu.h
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@ -466,6 +466,22 @@ extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t io
extern void iommu_set_fault_handler(struct iommu_domain *domain,
iommu_fault_handler_t handler, void *token);
/**
* iommu_map_sgtable - Map the given buffer to the IOMMU domain
* @domain: The IOMMU domain to perform the mapping
* @iova: The start address to map the buffer
* @sgt: The sg_table object describing the buffer
* @prot: IOMMU protection bits
*
* Creates a mapping at @iova for the buffer described by a scatterlist
* stored in the given sg_table object in the provided IOMMU domain.
*/
static inline size_t iommu_map_sgtable(struct iommu_domain *domain,
unsigned long iova, struct sg_table *sgt, int prot)
{
return iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, prot);
}
extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
extern void generic_iommu_put_resv_regions(struct device *dev,