iommu: Add def_domain_type() callback in iommu_ops

Some devices are reqired to use a specific type (identity or dma)
of default domain when they are used with a vendor iommu. When the
system level default domain type is different from it, the vendor
iommu driver has to request a new default domain with
iommu_request_dma_domain_for_dev() and iommu_request_dm_for_dev()
in the add_dev() callback. Unfortunately, these two helpers only
work when the group hasn't been assigned to any other devices,
hence, some vendor iommu driver has to use a private domain if
it fails to request a new default one.

This adds def_domain_type() callback in the iommu_ops, so that
any special requirement of default domain for a device could be
aware by the iommu generic layer.
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
[ jroedel@suse.de: Added iommu_get_def_domain_type() function and use
                   it to allocate the default domain ]
Co-developed-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200429133712.31431-3-joro@8bytes.orgSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -1361,21 +1361,35 @@ struct iommu_group *fsl_mc_device_group(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(fsl_mc_device_group);
 
+static int iommu_get_def_domain_type(struct device *dev)
+{
+	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	unsigned int type = 0;
+
+	if (ops->def_domain_type)
+		type = ops->def_domain_type(dev);
+
+	return (type == 0) ? iommu_def_domain_type : type;
+}
+
 static int iommu_alloc_default_domain(struct device *dev,
 				      struct iommu_group *group)
 {
 	struct iommu_domain *dom;
+	unsigned int type;
 
 	if (group->default_domain)
 		return 0;
 
-	dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
-	if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) {
+	type = iommu_get_def_domain_type(dev);
+
+	dom = __iommu_domain_alloc(dev->bus, type);
+	if (!dom && type != IOMMU_DOMAIN_DMA) {
 		dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA);
 		if (dom) {
 			dev_warn(dev,
 				 "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
-				 iommu_def_domain_type);
+				 type);
 		}
 	}
 

include/linux/iommu.h

@@ -248,6 +248,10 @@ struct iommu_iotlb_gather {
  * @cache_invalidate: invalidate translation caches
  * @sva_bind_gpasid: bind guest pasid and mm
  * @sva_unbind_gpasid: unbind guest pasid and mm
+ * @def_domain_type: device default domain type, return value:
+ *		- IOMMU_DOMAIN_IDENTITY: must use an identity domain
+ *		- IOMMU_DOMAIN_DMA: must use a dma domain
+ *		- 0: use the default setting
  * @pgsize_bitmap: bitmap of all possible supported page sizes
  * @owner: Driver module providing these ops
  */
@@ -318,6 +322,8 @@ struct iommu_ops {
 
 	int (*sva_unbind_gpasid)(struct device *dev, int pasid);
 
+	int (*def_domain_type)(struct device *dev);
+
 	unsigned long pgsize_bitmap;
 	struct module *owner;
 };