sid2groups keeps track of which stream id combinations belong to a iommu_group to assign those correctly to devices. When a iommu_group is freed a stale pointer will however remain in sid2groups. This prevents devices with the same stream id combination to ever be attached again (see below). Fix that by creating a shadow copy of the stream id configuration when a group is allocated for the first time and clear the sid2group entry when that group is freed.
# echo 1 >/sys/bus/pci/devices/0000\:03\:00.0/remove pci 0000:03:00.0: Removing from iommu group 1 # echo 1 >/sys/bus/pci/rescan [...] pci 0000:03:00.0: BAR 0: assigned [mem 0x6a0000000-0x6a000ffff 64bit pref] pci 0000:03:00.0: BAR 2: assigned [mem 0x6a0010000-0x6a001ffff 64bit pref] pci 0000:03:00.0: BAR 6: assigned [mem 0x6c0100000-0x6c01007ff pref] tg3 0000:03:00.0: Failed to add to iommu group 1: -2 [...] Fixes: 46d1fb072e76b161 ("iommu/dart: Add DART iommu driver") Reported-by: Marc Zyngier <m...@kernel.org> Signed-off-by: Sven Peter <s...@svenpeter.dev> --- drivers/iommu/apple-dart.c | 38 +++++++++++++++++++++++++++++++++++--- 1 file changed, 35 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c index 47ffe9e49abb..f82b2c46493a 100644 --- a/drivers/iommu/apple-dart.c +++ b/drivers/iommu/apple-dart.c @@ -636,16 +636,34 @@ static int apple_dart_of_xlate(struct device *dev, struct of_phandle_args *args) return -EINVAL; } +static DEFINE_MUTEX(apple_dart_groups_lock); + +static void apple_dart_release_group(void *iommu_data) +{ + int i, sid; + struct apple_dart_stream_map *stream_map; + struct apple_dart_master_cfg *group_master_cfg = iommu_data; + + mutex_lock(&apple_dart_groups_lock); + + for_each_stream_map(i, group_master_cfg, stream_map) + for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS) + stream_map->dart->sid2group[sid] = NULL; + + kfree(iommu_data); + mutex_unlock(&apple_dart_groups_lock); +} + static struct iommu_group *apple_dart_device_group(struct device *dev) { - static DEFINE_MUTEX(lock); int i, sid; struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev); struct apple_dart_stream_map *stream_map; + struct apple_dart_master_cfg *group_master_cfg; struct iommu_group *group = NULL; struct iommu_group *res = ERR_PTR(-EINVAL); - mutex_lock(&lock); + mutex_lock(&apple_dart_groups_lock); for_each_stream_map(i, cfg, stream_map) { for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS) { @@ -673,6 +691,20 @@ static struct iommu_group *apple_dart_device_group(struct device *dev) #endif group = generic_device_group(dev); + res = ERR_PTR(-ENOMEM); + if (!group) + goto out; + + group_master_cfg = kzalloc(sizeof(*group_master_cfg), GFP_KERNEL); + if (!group_master_cfg) { + iommu_group_put(group); + goto out; + } + + memcpy(group_master_cfg, cfg, sizeof(*group_master_cfg)); + iommu_group_set_iommudata(group, group_master_cfg, + apple_dart_release_group); + for_each_stream_map(i, cfg, stream_map) for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS) stream_map->dart->sid2group[sid] = group; @@ -680,7 +712,7 @@ static struct iommu_group *apple_dart_device_group(struct device *dev) res = group; out: - mutex_unlock(&lock); + mutex_unlock(&apple_dart_groups_lock); return res; } -- 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu