[RFC PATCH] iommu: create direct_mapping after device attached

From: honghui.zhang
Date: Wed Jul 20 2016 - 08:49:46 EST


From: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>

For mtk iommu, the domain_finalize was called in device attatch, the mtk
iommu iopgt ops was allocated and initialized in domain_finalize, the
iommu_group_create_direct_mappings would call the map interface to
implement the map. If it's earlier than device attach, there would be NULL
dereference. Move the iommu_group_create_direct_mappings call after device
attached.

Signed-off-by: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
---
drivers/iommu/iommu.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3000051..24c671c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -427,14 +427,19 @@ rename:

dev->iommu_group = group;

- iommu_group_create_direct_mappings(group, dev);
-
mutex_lock(&group->mutex);
list_add_tail(&device->list, &group->devices);
if (group->domain)
__iommu_attach_device(group->domain, dev);
mutex_unlock(&group->mutex);

+ /*
+ * For some iommu driver like mtk iommu, the map callback was assigned
+ * after device attached. The direct_mappings would call iommu map and
+ * dereference NULL if it's called earlier than attach_device.
+ */
+ iommu_group_create_direct_mappings(group, dev);
+
/* Notify any listeners about change to group. */
blocking_notifier_call_chain(&group->notifier,
IOMMU_GROUP_NOTIFY_ADD_DEVICE, dev);
--
1.8.1.1.dirty