linux-kernel - [PATCH v3 07/10] iommu: Use right way to retrieve iommu

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Date:   Mon, 14 Feb 2022 09:55:35 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Cc:     Alex Williamson <alex.williamson@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v3 07/10] 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@...ux.intel.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
---
 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 7cf073c56036..d290d8be6133 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -833,8 +833,10 @@ 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 +1254,10 @@ 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 +1298,7 @@ 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;
@@ -1759,10 +1761,10 @@ 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 +2022,7 @@ 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