[PATCH 13/42][SRU][U] UBUNTU: SAUCE: iommu: Export bus_iommu_probe() and make is safe for re-probing

[You-Sheng Yang]

From: Joerg Roedel <jroedel at suse.de>

BugLink: https://bugs.launchpad.net/bugs/1876707

Add a check to the bus_iommu_probe() call-path to make sure it ignores
devices which have already been successfully probed. Then export the
bus_iommu_probe() function so it can be used by IOMMU drivers.

Signed-off-by: Joerg Roedel <jroedel at suse.de>
Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski at samsung.com>
Link: https://lore.kernel.org/r/20200429133712.31431-14-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel at suse.de>
(cherry picked from commit 5012c3968537e2ffecbdb2eba3479bf9fb9e5597
iommu/next)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 drivers/iommu/iommu.c | 10 +++++++++-
 include/linux/iommu.h |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 874bd6e72f29..517faae131aa 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1611,11 +1611,19 @@ static int probe_iommu_group(struct device *dev, void *data)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 	struct list_head *group_list = data;
+	struct iommu_group *group;
 	int ret;
 
 	if (!dev_iommu_get(dev))
 		return -ENOMEM;
 
+	/* Device is probed already if in a group */
+	group = iommu_group_get(dev);
+	if (group) {
+		iommu_group_put(group);
+		return 0;
+	}
+
 	if (!try_module_get(ops->owner)) {
 		ret = -EINVAL;
 		goto err_free_dev_iommu;
@@ -1784,7 +1792,7 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group)
 					  iommu_do_create_direct_mappings);
 }
 
-static int bus_iommu_probe(struct bus_type *bus)
+int bus_iommu_probe(struct bus_type *bus)
 {
 	const struct iommu_ops *ops = bus->iommu_ops;
 	int ret;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 30170d191e5e..fea1622408ad 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -445,6 +445,7 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 #define IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER	6 /* Post Driver unbind */
 
 extern int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops);
+extern int bus_iommu_probe(struct bus_type *bus);
 extern bool iommu_present(struct bus_type *bus);
 extern bool iommu_capable(struct bus_type *bus, enum iommu_cap cap);
 extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
-- 
2.25.1