iommu: Keep a list of allocated groups in __iommu_probe_device()

This is needed to defer default_domain allocation for new IOMMU groups
until all devices have been added to the group.

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/20200429133712.31431-10-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -44,6 +44,7 @@ struct iommu_group {
 	int id;
 	struct iommu_domain *default_domain;
 	struct iommu_domain *domain;
+	struct list_head entry;
 };
 
 struct group_device {
@@ -184,7 +185,7 @@ static void dev_iommu_free(struct device *dev)
 	dev->iommu = NULL;
 }
 
-static int __iommu_probe_device(struct device *dev)
+static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 	struct iommu_device *iommu_dev;
@@ -204,6 +205,9 @@ static int __iommu_probe_device(struct device *dev)
 	}
 	iommu_group_put(group);
 
+	if (group_list && !group->default_domain && list_empty(&group->entry))
+		list_add_tail(&group->entry, group_list);
+
 	iommu_device_link(iommu_dev, dev);
 
 	return 0;
@@ -234,7 +238,7 @@ int iommu_probe_device(struct device *dev)
 	if (ops->probe_device) {
 		struct iommu_group *group;
 
-		ret = __iommu_probe_device(dev);
+		ret = __iommu_probe_device(dev, NULL);
 
 		/*
 		 * Try to allocate a default domain - needs support from the
@@ -567,6 +571,7 @@ struct iommu_group *iommu_group_alloc(void)
 	group->kobj.kset = iommu_group_kset;
 	mutex_init(&group->mutex);
 	INIT_LIST_HEAD(&group->devices);
+	INIT_LIST_HEAD(&group->entry);
 	BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);
 
 	ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);