The common iommu_ops is hooked to both device and domain. When a helper
has both device and domain pointer, the way to get the iommu_ops looks
messy in iommu core. This sorts out the way to get iommu_ops. The device
related helpers go through device pointer, while the domain related ones
go through domain pointer.

Signed-off-by: Lu Baolu <[email protected]>
---
 include/linux/iommu.h | 14 ++++++++++++++
 drivers/iommu/iommu.c | 20 +++++++++++---------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9ffa2e88f3d0..eb2684f95018 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -381,6 +381,20 @@ static inline void iommu_iotlb_gather_init(struct 
iommu_iotlb_gather *gather)
        };
 }
 
+static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
+{
+       /*
+        * Assume that valid ops must be installed if iommu_probe_device()
+        * has succeeded. The device ops are essentially for internal use
+        * within the IOMMU subsystem itself, so we should be able to trust
+        * ourselves not to misuse the helper.
+        */
+       WARN_ON(!dev || !dev->iommu || !dev->iommu->iommu_dev ||
+               !dev->iommu->iommu_dev->ops);
+
+       return dev->iommu->iommu_dev->ops;
+}
+
 #define IOMMU_GROUP_NOTIFY_ADD_DEVICE          1 /* Device added */
 #define IOMMU_GROUP_NOTIFY_DEL_DEVICE          2 /* Pre Device removed */
 #define IOMMU_GROUP_NOTIFY_BIND_DRIVER         3 /* Pre Driver bind */
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index df6bd1d58c74..de593a9cc09c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -828,8 +828,10 @@ static int iommu_create_device_direct_mappings(struct 
iommu_group *group,
 static bool iommu_is_attach_deferred(struct iommu_domain *domain,
                                     struct device *dev)
 {
-       if (domain->ops->is_attach_deferred)
-               return domain->ops->is_attach_deferred(domain, dev);
+       const struct iommu_ops *ops = dev_iommu_ops(dev);
+
+       if (ops->is_attach_deferred)
+               return ops->is_attach_deferred(domain, dev);
 
        return false;
 }
@@ -1248,10 +1250,10 @@ int iommu_page_response(struct device *dev,
        struct iommu_fault_event *evt;
        struct iommu_fault_page_request *prm;
        struct dev_iommu *param = dev->iommu;
+       const struct iommu_ops *ops = dev_iommu_ops(dev);
        bool has_pasid = msg->flags & IOMMU_PAGE_RESP_PASID_VALID;
-       struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
 
-       if (!domain || !domain->ops->page_response)
+       if (!ops->page_response)
                return -ENODEV;
 
        if (!param || !param->fault_param)
@@ -1292,7 +1294,7 @@ int iommu_page_response(struct device *dev,
                        msg->pasid = 0;
                }
 
-               ret = domain->ops->page_response(dev, evt, msg);
+               ret = ops->page_response(dev, evt, msg);
                list_del(&evt->list);
                kfree(evt);
                break;
@@ -1755,10 +1757,10 @@ static int __iommu_group_dma_attach(struct iommu_group 
*group)
 
 static int iommu_group_do_probe_finalize(struct device *dev, void *data)
 {
-       struct iommu_domain *domain = data;
+       const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-       if (domain->ops->probe_finalize)
-               domain->ops->probe_finalize(dev);
+       if (ops->probe_finalize)
+               ops->probe_finalize(dev);
 
        return 0;
 }
@@ -2016,7 +2018,7 @@ EXPORT_SYMBOL_GPL(iommu_attach_device);
 
 int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain)
 {
-       const struct iommu_ops *ops = domain->ops;
+       const struct iommu_ops *ops = dev_iommu_ops(dev);
 
        if (ops->is_attach_deferred && ops->is_attach_deferred(domain, dev))
                return __iommu_attach_device(domain, dev);
-- 
2.25.1

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