iommu: Decouple iommu_map_sg from CPU page size

index 08c53c5..5c4101a 100644
@@ -1129,14 +1129,24 @@ 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);