[PATCH v2 12/14] iommu: Consolidate the default_domain setup to one function

[Jason Gunthorpe <jgg@nvidia.com>]

The default_domain setup flow requires
 - Determining the default type
 - Allocating a default_domain
 - Attaching it to devices
 - Doing iommu_create_device_direct_mappings()

This is sprinkled around three places written in two different ways. Make
it all the same in one function.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommu.c | 256 ++++++++++++++++--------------------------
 1 file changed, 96 insertions(+), 160 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 79e3fa80d0f6cc..26129423fa7b95 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -91,8 +91,6 @@ static const char * const iommu_group_resv_type_string[] = {
 
 static int iommu_bus_notifier(struct notifier_block *nb,
 			      unsigned long action, void *data);
-static int iommu_alloc_default_domain(struct iommu_group *group,
-				      struct device *dev);
 static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
 						 unsigned type);
 static int __iommu_attach_device(struct iommu_domain *domain,
@@ -124,7 +122,9 @@ static void __iommu_group_set_domain_nofail(struct iommu_group *group,
 		group, new_domain, IOMMU_SET_DOMAIN_MUST_SUCCEED));
 }
 
-static int iommu_create_device_direct_mappings(struct iommu_group *group,
+static int iommu_setup_default_domain(struct iommu_group *group,
+				      int target_type);
+static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
 					       struct device *dev);
 static struct iommu_group *iommu_group_get_for_dev(struct device *dev);
 static ssize_t iommu_group_store_type(struct iommu_group *group,
@@ -436,29 +436,14 @@ int iommu_probe_device(struct device *dev)
 
 	if (group->domain) {
 		ret = iommu_group_do_dma_first_attach(group, dev);
+		if (ret)
+			goto err_unlock;
+		iommu_create_device_direct_mappings(group->domain, dev);
 	} else if (!group->default_domain) {
-		/*
-		 * Try to allocate a default domain - needs support from the
-		 * IOMMU driver. There are still some drivers which don't
-		 * support default domains, so the return value is not yet
-		 * checked.
-		 */
-		iommu_alloc_default_domain(group, dev);
-		if (group->default_domain)
-			ret = __iommu_group_set_domain_internal(
-				group, group->default_domain,
-				IOMMU_SET_DOMAIN_WITH_DEFERRED);
-
-		/*
-		 * We assume that the iommu driver starts up the device in
-		 * 'set_platform_dma_ops' mode if it does not support default
-		 * domains.
-		 */
+		ret = iommu_setup_default_domain(group, 0);
+		if (ret)
+			goto err_unlock;
 	}
-	if (ret)
-		goto err_unlock;
-
-	iommu_create_device_direct_mappings(group, dev);
 
 	mutex_unlock(&group->mutex);
 	iommu_group_put(group);
@@ -1004,16 +989,15 @@ int iommu_group_set_name(struct iommu_group *group, const char *name)
 }
 EXPORT_SYMBOL_GPL(iommu_group_set_name);
 
-static int iommu_create_device_direct_mappings(struct iommu_group *group,
+static int iommu_create_device_direct_mappings(struct iommu_domain *domain,
 					       struct device *dev)
 {
-	struct iommu_domain *domain = group->default_domain;
 	struct iommu_resv_region *entry;
 	struct list_head mappings;
 	unsigned long pg_size;
 	int ret = 0;
 
-	if (!domain || !iommu_is_dma_domain(domain))
+	if (!iommu_is_dma_domain(domain))
 		return 0;
 
 	BUG_ON(!domain->pgsize_bitmap);
@@ -1696,37 +1680,6 @@ static int iommu_get_def_domain_type(struct device *dev)
 	return 0;
 }
 
-static int iommu_group_alloc_default_domain(struct bus_type *bus,
-					    struct iommu_group *group,
-					    unsigned int type)
-{
-	struct iommu_domain *dom;
-
-	dom = __iommu_domain_alloc(bus, type);
-	if (!dom && type != IOMMU_DOMAIN_DMA) {
-		dom = __iommu_domain_alloc(bus, IOMMU_DOMAIN_DMA);
-		if (dom)
-			pr_warn("Failed to allocate default IOMMU domain of type %u for group %s - Falling back to IOMMU_DOMAIN_DMA",
-				type, group->name);
-	}
-
-	if (!dom)
-		return -ENOMEM;
-
-	group->default_domain = dom;
-	return 0;
-}
-
-static int iommu_alloc_default_domain(struct iommu_group *group,
-				      struct device *dev)
-{
-	unsigned int type;
-
-	type = iommu_get_def_domain_type(dev) ? : iommu_def_domain_type;
-
-	return iommu_group_alloc_default_domain(dev->bus, group, type);
-}
-
 /**
  * iommu_group_get_for_dev - Find or create the IOMMU group for a device
  * @dev: target device
@@ -1848,6 +1801,84 @@ static int iommu_get_default_domain_type(struct iommu_group *group,
 	return best_type;
 }
 
+/**
+ * iommu_setup_default_domain - Set the default_domain for the group
+ * @group: Group to change
+ * @target_type: Domain type to set as the default_domain
+ *
+ * Allocate a default domain and set it as the current domain on the group. If
+ * the group already has a default domain it will be changed to the target_type.
+ * When target_type is 0 the default domain is selected based on driver and
+ * system preferences.
+ */
+static int iommu_setup_default_domain(struct iommu_group *group,
+				      int target_type)
+{
+	struct group_device *gdev;
+	struct iommu_domain *dom;
+	struct bus_type *bus =
+		list_first_entry(&group->devices, struct group_device, list)
+			->dev->bus;
+	int ret;
+
+	lockdep_assert_held(&group->mutex);
+
+	target_type = iommu_get_default_domain_type(group, target_type);
+	if (target_type < 0)
+		return -EINVAL;
+
+	if (group->default_domain && group->default_domain->type == target_type)
+		return 0;
+
+	dom = __iommu_domain_alloc(bus, target_type);
+	if (!dom && target_type != IOMMU_DOMAIN_DMA) {
+		dom = __iommu_domain_alloc(bus, IOMMU_DOMAIN_DMA);
+		if (dom)
+			pr_warn("Failed to allocate default IOMMU domain of type %u for group %s - Falling back to IOMMU_DOMAIN_DMA",
+				target_type, group->name);
+	}
+
+	/*
+	 * There are still some drivers which don't support default domains, so
+	 * we ignore the failure and leave group->default_domain NULL.
+	 *
+	 * We assume that the iommu driver starts up the device in
+	 * 'set_platform_dma_ops' mode if it does not support default domains.
+	 */
+	if (!dom) {
+		ret = 0;
+		goto out_set;
+	}
+
+	ret = __iommu_group_set_domain_internal(group, dom,
+						IOMMU_SET_DOMAIN_WITH_DEFERRED);
+	if (ret) {
+		/*
+		 * An attach_dev failure may result in some devices being left
+		 * attached to dom. This is not cleaned up until release_device
+		 * is called. Thus we can't always free dom on failure, we have
+		 * no choice but to stick the broken domain into
+		 * group->default_domain to defer the free and try to continue.
+		 */
+		if (list_count_nodes(&group->devices) > 1)
+			goto out_set;
+
+		iommu_domain_free(dom);
+		dom = NULL;
+		goto out_set;
+	}
+
+	/* The domain must be attached before we can establish any mappings */
+	for_each_group_device(group, gdev)
+		iommu_create_device_direct_mappings(dom, gdev->dev);
+
+out_set:
+	if (group->default_domain)
+		iommu_domain_free(group->default_domain);
+	group->default_domain = dom;
+	return ret;
+}
+
 static int iommu_group_do_probe_finalize(struct device *dev, void *data)
 {
 	const struct iommu_ops *ops = dev_iommu_ops(dev);
@@ -1864,21 +1895,6 @@ static void __iommu_group_dma_finalize(struct iommu_group *group)
 				   iommu_group_do_probe_finalize);
 }
 
-static int iommu_do_create_direct_mappings(struct device *dev, void *data)
-{
-	struct iommu_group *group = data;
-
-	iommu_create_device_direct_mappings(group, dev);
-
-	return 0;
-}
-
-static int iommu_group_create_direct_mappings(struct iommu_group *group)
-{
-	return __iommu_group_for_each_dev(group, group,
-					  iommu_do_create_direct_mappings);
-}
-
 int bus_iommu_probe(struct bus_type *bus)
 {
 	struct iommu_group *group, *next;
@@ -1900,30 +1916,18 @@ int bus_iommu_probe(struct bus_type *bus)
 		/* Remove item from the list */
 		list_del_init(&group->entry);
 
-		/* Try to allocate default domain */
-		iommu_group_alloc_default_domain(
-			bus, group, iommu_get_default_domain_type(group, 0));
-
 		if (!group->default_domain) {
-			mutex_unlock(&group->mutex);
-			continue;
+			ret = iommu_setup_default_domain(group, 0);
+			if (ret) {
+				mutex_unlock(&group->mutex);
+				return ret;
+			}
 		}
-
-		iommu_group_create_direct_mappings(group);
-
-		ret = __iommu_group_set_domain_internal(
-			group, group->default_domain,
-			IOMMU_SET_DOMAIN_WITH_DEFERRED);
-
 		mutex_unlock(&group->mutex);
-
-		if (ret)
-			break;
-
 		__iommu_group_dma_finalize(group);
 	}
 
-	return ret;
+	return 0;
 }
 
 bool iommu_present(struct bus_type *bus)
@@ -2905,69 +2909,6 @@ int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 }
 EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
 
-/*
- * Changes the default domain of an iommu group
- *
- * @group: The group for which the default domain should be changed
- * @dev: The first device in the group
- * @type: The type of the new default domain that gets associated with the group
- *
- * Returns 0 on success and error code on failure
- *
- * Note:
- * 1. Presently, this function is called only when user requests to change the
- *    group's default domain type through /sys/kernel/iommu_groups/<grp_id>/type
- *    Please take a closer look if intended to use for other purposes.
- */
-static int iommu_change_dev_def_domain(struct iommu_group *group,
-				       struct device *dev, int type)
-{
-	struct iommu_domain *prev_dom;
-	int ret;
-
-	lockdep_assert_held(&group->mutex);
-
-	prev_dom = group->default_domain;
-	type = iommu_get_default_domain_type(group, type);
-	if (type < 0)
-		return -EINVAL;
-
-	/*
-	 * Switch to a new domain only if the requested domain type is different
-	 * from the existing default domain type
-	 */
-	if (prev_dom->type == type)
-		return 0;
-
-	group->default_domain = NULL;
-	group->domain = NULL;
-
-	/* Sets group->default_domain to the newly allocated domain */
-	ret = iommu_group_alloc_default_domain(dev->bus, group, type);
-	if (ret)
-		goto restore_old_domain;
-
-	group->domain = prev_dom;
-	ret = iommu_create_device_direct_mappings(group, dev);
-	if (ret)
-		goto free_new_domain;
-
-	ret = __iommu_group_set_domain(group, group->default_domain);
-	if (ret)
-		goto free_new_domain;
-
-	iommu_domain_free(prev_dom);
-
-	return 0;
-
-free_new_domain:
-	iommu_domain_free(group->default_domain);
-restore_old_domain:
-	group->default_domain = prev_dom;
-
-	return ret;
-}
-
 /*
  * Changing the default domain through sysfs requires the users to unbind the
  * drivers from the devices in the iommu group, except for a DMA -> DMA-FQ
@@ -2980,8 +2921,6 @@ static int iommu_change_dev_def_domain(struct iommu_group *group,
 static ssize_t iommu_group_store_type(struct iommu_group *group,
 				      const char *buf, size_t count)
 {
-	struct group_device *grp_dev;
-	struct device *dev;
 	int ret, req_type;
 
 	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
@@ -3019,10 +2958,7 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
 		return -EPERM;
 	}
 
-	grp_dev = list_first_entry(&group->devices, struct group_device, list);
-	dev = grp_dev->dev;
-
-	ret = iommu_change_dev_def_domain(group, dev, req_type);
+	ret = iommu_setup_default_domain(group, req_type);
 
 	/*
 	 * Release the mutex here because ops->probe_finalize() call-back of
-- 
2.40.0