iommu: Decouple iommu_map_sg from CPU page size (18f23409) · Commits · 戴 / test

If the IOMMU supports pages smaller than the CPU page size, segments which lie at offsets within the CPU page may be mapped based on the finer-grained IOMMU page boundaries. This minimises the amount of non-buffer memory between the CPU page boundary and the start of the segment which must be mapped and therefore exposed to the device, and brings the default iommu_map_sg implementation in line with iommu_map/unmap with respect to alignment. Signed-off-by:

Robin Murphy <robin.murphy@arm.com> Signed-off-by:

Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

+15 −5

Original line number	Diff line number	Diff line
		@@ -1143,14 +1143,24 @@ size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
		{
		struct scatterlist *s;
		size_t mapped = 0;
		unsigned int i;
		unsigned int i, min_pagesz;
		int ret;

		if (unlikely(domain->ops->pgsize_bitmap == 0UL))
		return 0;

		min_pagesz = 1 << __ffs(domain->ops->pgsize_bitmap);

		for_each_sg(sg, s, nents, i) {
		phys_addr_t phys = page_to_phys(sg_page(s));
		phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;

		/* We are mapping on page boundarys, so offset must be 0 */
		if (s->offset)
		/*
		* We are mapping on IOMMU page boundaries, so offset within
		* the page must be 0. However, the IOMMU may support pages
		* smaller than PAGE_SIZE, so s->offset may still represent
		* an offset of that boundary within the CPU page.
		*/
		if (!IS_ALIGNED(s->offset, min_pagesz))
		goto out_err;

		ret = iommu_map(domain, iova + mapped, phys, s->length, prot);

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