On Mon, Oct 3, 2011 at 12:58 AM, Ohad Ben-Cohen [off-list ref] wrote:

?int iommu_map(struct iommu_domain *domain, unsigned long iova,
- ? ? ? ? ? ? phys_addr_t paddr, int gfp_order, int prot)
+ ? ? ? ? ? ? phys_addr_t paddr, size_t size, int prot)
?{
- ? ? ? size_t size;
+ ? ? ? int ret = 0;
+
+ ? ? ? /*
+ ? ? ? ?* both the virtual address and the physical one, as well as
+ ? ? ? ?* the size of the mapping, must be aligned (at least) to the
+ ? ? ? ?* size of the smallest page supported by the hardware
+ ? ? ? ?*/
+ ? ? ? if (!IS_ALIGNED(iova | paddr | size, iommu_min_pagesz)) {
+ ? ? ? ? ? ? ? pr_err("unaligned: iova 0x%lx pa 0x%lx size 0x%lx min_pagesz "
+ ? ? ? ? ? ? ? ? ? ? ? "0x%x\n", iova, (unsigned long)paddr,
+ ? ? ? ? ? ? ? ? ? ? ? (unsigned long)size, iommu_min_pagesz);
+ ? ? ? ? ? ? ? return -EINVAL;
+ ? ? ? }

- ? ? ? size ? ? ? ? = 0x1000UL << gfp_order;
+ ? ? ? pr_debug("map: iova 0x%lx pa 0x%lx size 0x%lx\n", iova,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (unsigned long)paddr, (unsigned long)size);

- ? ? ? BUG_ON(!IS_ALIGNED(iova | paddr, size));
+ ? ? ? while (size) {
+ ? ? ? ? ? ? ? unsigned long pgsize, addr_merge = iova | paddr;
+ ? ? ? ? ? ? ? unsigned int pgsize_idx;

- ? ? ? return iommu_ops->map(domain, iova, paddr, gfp_order, prot);
+ ? ? ? ? ? ? ? /* Max page size that still fits into 'size' */
+ ? ? ? ? ? ? ? pgsize_idx = __fls(size);
+
+ ? ? ? ? ? ? ? /* need to consider alignment requirements ? */
+ ? ? ? ? ? ? ? if (likely(addr_merge)) {
+ ? ? ? ? ? ? ? ? ? ? ? /* Max page size allowed by both iova and paddr */
+ ? ? ? ? ? ? ? ? ? ? ? unsigned int align_pgsize_idx = __ffs(addr_merge);
+
+ ? ? ? ? ? ? ? ? ? ? ? pgsize_idx = min(pgsize_idx, align_pgsize_idx);
+ ? ? ? ? ? ? ? }
+
+ ? ? ? ? ? ? ? /* build a mask of acceptable page sizes */
+ ? ? ? ? ? ? ? pgsize = (1UL << (pgsize_idx + 1)) - 1;
+
+ ? ? ? ? ? ? ? /* throw away page sizes not supported by the hardware */
+ ? ? ? ? ? ? ? pgsize &= iommu_pgsize_bitmap;
+
+ ? ? ? ? ? ? ? /* pick the biggest page */
+ ? ? ? ? ? ? ? pgsize_idx = __fls(pgsize);
+ ? ? ? ? ? ? ? pgsize = 1UL << pgsize_idx;
+
+ ? ? ? ? ? ? ? /* convert index to page order */
+ ? ? ? ? ? ? ? pgsize_idx -= PAGE_SHIFT;
+
+ ? ? ? ? ? ? ? pr_debug("mapping: iova 0x%lx pa 0x%lx order %u\n", iova,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (unsigned long)paddr, pgsize_idx);
+
+ ? ? ? ? ? ? ? ret = iommu_ops->map(domain, iova, paddr, pgsize_idx, prot);
+ ? ? ? ? ? ? ? if (ret)
+ ? ? ? ? ? ? ? ? ? ? ? break;
+
+ ? ? ? ? ? ? ? iova += pgsize;
+ ? ? ? ? ? ? ? paddr += pgsize;
+ ? ? ? ? ? ? ? size -= pgsize;
+ ? ? ? }
+
+ ? ? ? return ret;
?}
?EXPORT_SYMBOL_GPL(iommu_map);

Do not we need to unmap all intermediate mappings if iommu_map() is failed?

I think iommu_map() must map the entire given area if it successes.
Otherwise, it should map nothing.

I think it can be simply done with calling iommu_unmap()
with Joerg's previous suggestion about iommu_unmap().

Regards,
KyongHo.