iommu: Create direct mappings in default domains

Use the information exported by the IOMMU drivers to create
direct mapped regions in the default domains.
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -325,6 +325,52 @@ int iommu_group_set_name(struct iommu_group *group, const char *name)
 }
 EXPORT_SYMBOL_GPL(iommu_group_set_name);
 
+static int iommu_group_create_direct_mappings(struct iommu_group *group,
+					      struct device *dev)
+{
+	struct iommu_domain *domain = group->default_domain;
+	struct iommu_dm_region *entry;
+	struct list_head mappings;
+	unsigned long pg_size;
+	int ret = 0;
+
+	if (!domain || domain->type != IOMMU_DOMAIN_DMA)
+		return 0;
+
+	BUG_ON(!domain->ops->pgsize_bitmap);
+
+	pg_size = 1UL << __ffs(domain->ops->pgsize_bitmap);
+	INIT_LIST_HEAD(&mappings);
+
+	iommu_get_dm_regions(dev, &mappings);
+
+	/* We need to consider overlapping regions for different devices */
+	list_for_each_entry(entry, &mappings, list) {
+		dma_addr_t start, end, addr;
+
+		start = ALIGN(entry->start, pg_size);
+		end   = ALIGN(entry->start + entry->length, pg_size);
+
+		for (addr = start; addr < end; addr += pg_size) {
+			phys_addr_t phys_addr;
+
+			phys_addr = iommu_iova_to_phys(domain, addr);
+			if (phys_addr)
+				continue;
+
+			ret = iommu_map(domain, addr, addr, pg_size, entry->prot);
+			if (ret)
+				goto out;
+		}
+
+	}
+
+out:
+	iommu_put_dm_regions(dev, &mappings);
+
+	return ret;
+}
+
 /**
  * iommu_group_add_device - add a device to an iommu group
  * @group: the group into which to add the device (reference should be held)
@@ -381,6 +427,8 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
 
 	dev->iommu_group = group;
 
+	iommu_group_create_direct_mappings(group, dev);
+
 	mutex_lock(&group->mutex);
 	list_add_tail(&device->list, &group->devices);
 	if (group->domain)