[PATCH v5 1/1] iommu-api: Add map_sg/unmap_sg functions

On Mon, Aug 11, 2014 at 03:45:50PM -0700, Olav Haugan wrote:

+int default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			 struct scatterlist *sg, unsigned int nents,
+			 int prot, unsigned long flags)
+{
+	int ret = 0;
+	unsigned long offset = 0;
+	unsigned int i;
+	struct scatterlist *s;
+
+	for_each_sg(sg, s, nents, i) {
+		phys_addr_t phys = page_to_phys(sg_page(s));
+		size_t page_len = s->offset + s->length;
+
+		ret = iommu_map(domain, iova + offset, phys, page_len,
+				prot);

This isn't going to work, iova + offset, phys and page_len need to be
aligned to the minimum page-size the given IOMMU implementation
supports. See the iommu_map implementation for details.

+int default_iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
+			       size_t size, unsigned long flags)

Another asymmentry here, why don't you just pass a scatterlist and nents
like in the map_sg function? if you implement it like this it is just a
duplication of iommu_unmap().

+static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			       struct scatterlist *sg, unsigned int nents,
+			       int prot, unsigned long flags)
+{
+	return domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
+}
+
+static inline int iommu_unmap_sg(struct iommu_domain *domain,
+				 unsigned long iova, size_t size,
+				 unsigned long flags)
+{
+	return domain->ops->unmap_sg(domain, iova, size, flags);
+}

These function pointers need to be checked for != NULL before calling
them.


	Joerg