iommu: Add API to request DMA domain for device

Normally during iommu probing a device, a default doamin will
be allocated and attached to the device. The domain type of
the default domain is statically defined, which results in a
situation where the allocated default domain isn't suitable
for the device due to some limitations. We already have API
iommu_request_dm_for_dev() to replace a DMA domain with an
identity one. This adds iommu_request_dma_domain_for_dev()
to request a dma domain if an allocated identity domain isn't
suitable for the device in question.

Signed-off-by: Lu Baolu <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>

Author: LuBaolu

drivers/iommu/iommu.c

@@ -1907,10 +1907,10 @@ struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
 	return region;
 }
 
-/* Request that a device is direct mapped by the IOMMU */
-int iommu_request_dm_for_dev(struct device *dev)
+static int
+request_default_domain_for_dev(struct device *dev, unsigned long type)
 {
-	struct iommu_domain *dm_domain;
+	struct iommu_domain *domain;
 	struct iommu_group *group;
 	int ret;
 
@@ -1923,8 +1923,7 @@ int iommu_request_dm_for_dev(struct device *dev)
 
 	/* Check if the default domain is already direct mapped */
 	ret = 0;
-	if (group->default_domain &&
-	    group->default_domain->type == IOMMU_DOMAIN_IDENTITY)
+	if (group->default_domain && group->default_domain->type == type)
 		goto out;
 
 	/* Don't change mappings of existing devices */
@@ -1934,23 +1933,26 @@ int iommu_request_dm_for_dev(struct device *dev)
 
 	/* Allocate a direct mapped domain */
 	ret = -ENOMEM;
-	dm_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_IDENTITY);
-	if (!dm_domain)
+	domain = __iommu_domain_alloc(dev->bus, type);
+	if (!domain)
 		goto out;
 
 	/* Attach the device to the domain */
-	ret = __iommu_attach_group(dm_domain, group);
+	ret = __iommu_attach_group(domain, group);
 	if (ret) {
-		iommu_domain_free(dm_domain);
+		iommu_domain_free(domain);
 		goto out;
 	}
 
+	iommu_group_create_direct_mappings(group, dev);
+
 	/* Make the direct mapped domain the default for this group */
 	if (group->default_domain)
 		iommu_domain_free(group->default_domain);
-	group->default_domain = dm_domain;
+	group->default_domain = domain;
 
-	dev_info(dev, "Using iommu direct mapping\n");
+	dev_info(dev, "Using iommu %s mapping\n",
+		 type == IOMMU_DOMAIN_DMA ? "dma" : "direct");
 
 	ret = 0;
 out:
@@ -1960,6 +1962,18 @@ int iommu_request_dm_for_dev(struct device *dev)
 	return ret;
 }
 
+/* Request that a device is direct mapped by the IOMMU */
+int iommu_request_dm_for_dev(struct device *dev)
+{
+	return request_default_domain_for_dev(dev, IOMMU_DOMAIN_IDENTITY);
+}
+
+/* Request that a device can't be direct mapped by the IOMMU */
+int iommu_request_dma_domain_for_dev(struct device *dev)
+{
+	return request_default_domain_for_dev(dev, IOMMU_DOMAIN_DMA);
+}
+
 const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
 {
 	const struct iommu_ops *ops = NULL;

include/linux/iommu.h

@@ -362,6 +362,7 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
 extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
 extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
 extern int iommu_request_dm_for_dev(struct device *dev);
+extern int iommu_request_dma_domain_for_dev(struct device *dev);
 extern struct iommu_resv_region *
 iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot,
 			enum iommu_resv_type type);
@@ -626,6 +627,11 @@ static inline int iommu_request_dm_for_dev(struct device *dev)
 	return -ENODEV;
 }
 
+static inline int iommu_request_dma_domain_for_dev(struct device *dev)
+{
+	return -ENODEV;
+}
+
 static inline int iommu_attach_group(struct iommu_domain *domain,
 				     struct iommu_group *group)
 {