iommu: Use right way to retrieve iommu_ops

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 <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220216025249.3459465-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: LuBaolu

drivers/iommu/iommu.c

@@ -323,13 +323,14 @@ int iommu_probe_device(struct device *dev)
 
 void iommu_release_device(struct device *dev)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops;
 
 	if (!dev->iommu)
 		return;
 
 	iommu_device_unlink(dev->iommu->iommu_dev, dev);
 
+	ops = dev_iommu_ops(dev);
 	ops->release_device(dev);
 
 	iommu_group_remove_device(dev);
@@ -833,8 +834,10 @@ 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;
 }
@@ -1252,10 +1255,10 @@ 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)
@@ -1296,7 +1299,7 @@ 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;
@@ -1521,7 +1524,7 @@ EXPORT_SYMBOL_GPL(fsl_mc_device_group);
 
 static int iommu_get_def_domain_type(struct device *dev)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
 	if (dev_is_pci(dev) && to_pci_dev(dev)->untrusted)
 		return IOMMU_DOMAIN_DMA;
@@ -1580,17 +1583,14 @@ static int iommu_alloc_default_domain(struct iommu_group *group,
  */
 static struct iommu_group *iommu_group_get_for_dev(struct device *dev)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 	struct iommu_group *group;
 	int ret;
 
 	group = iommu_group_get(dev);
 	if (group)
 		return group;
 
-	if (!ops)
-		return ERR_PTR(-EINVAL);
-
 	group = ops->device_group(dev);
 	if (WARN_ON_ONCE(group == NULL))
 		return ERR_PTR(-EINVAL);
@@ -1759,10 +1759,10 @@ 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;
 }
@@ -2020,7 +2020,7 @@ 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);
@@ -2579,17 +2579,17 @@ EXPORT_SYMBOL_GPL(iommu_set_pgtable_quirks);
 
 void iommu_get_resv_regions(struct device *dev, struct list_head *list)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-	if (ops && ops->get_resv_regions)
+	if (ops->get_resv_regions)
 		ops->get_resv_regions(dev, list);
 }
 
 void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-	if (ops && ops->put_resv_regions)
+	if (ops->put_resv_regions)
 		ops->put_resv_regions(dev, list);
 }
 
@@ -2794,9 +2794,9 @@ iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
 {
 	struct iommu_group *group;
 	struct iommu_sva *handle = ERR_PTR(-EINVAL);
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-	if (!ops || !ops->sva_bind)
+	if (!ops->sva_bind)
 		return ERR_PTR(-ENODEV);
 
 	group = iommu_group_get(dev);
@@ -2837,9 +2837,9 @@ void iommu_sva_unbind_device(struct iommu_sva *handle)
 {
 	struct iommu_group *group;
 	struct device *dev = handle->dev;
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-	if (!ops || !ops->sva_unbind)
+	if (!ops->sva_unbind)
 		return;
 
 	group = iommu_group_get(dev);
@@ -2856,9 +2856,9 @@ EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
 
 u32 iommu_sva_get_pasid(struct iommu_sva *handle)
 {
-	const struct iommu_ops *ops = handle->dev->bus->iommu_ops;
+	const struct iommu_ops *ops = dev_iommu_ops(handle->dev);
 
-	if (!ops || !ops->sva_get_pasid)
+	if (!ops->sva_get_pasid)
 		return IOMMU_PASID_INVALID;
 
 	return ops->sva_get_pasid(handle);

include/linux/iommu.h

@@ -381,6 +381,17 @@ 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.
+	 */
+	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 */