linux-kernel - [PATCH v6 5/8] iommufd/vdevice: Remove struct device reference from struct vdevice

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Message-Id: <20250716070349.1807226-6-yilun.xu@linux.intel.com>
Date: Wed, 16 Jul 2025 15:03:46 +0800
From: Xu Yilun <yilun.xu@...ux.intel.com>
To: jgg@...dia.com,
	jgg@...pe.ca,
	kevin.tian@...el.com,
	will@...nel.org,
	aneesh.kumar@...nel.org
Cc: iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	joro@...tes.org,
	robin.murphy@....com,
	shuah@...nel.org,
	nicolinc@...dia.com,
	aik@....com,
	dan.j.williams@...el.com,
	baolu.lu@...ux.intel.com,
	yilun.xu@...el.com
Subject: [PATCH v6 5/8] iommufd/vdevice: Remove struct device reference from struct vdevice

Remove struct device *dev from struct vdevice.

The dev pointer is the Plan B for vdevice to reference the physical
device. As now vdev->idev is added without refcounting concern, just
use vdev->idev->dev when needed. To avoid exposing
struct iommufd_device in the public header, export a
iommufd_vdevice_to_device() helper.

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Reviewed-by: Kevin Tian <kevin.tian@...el.com>
Reviewed-by: Nicolin Chen <nicolinc@...dia.com>
Co-developed-by: Nicolin Chen <nicolinc@...dia.com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
Tested-by: Nicolin Chen <nicolinc@...dia.com>
Signed-off-by: Xu Yilun <yilun.xu@...ux.intel.com>
---
 drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c |  3 ++-
 drivers/iommu/iommufd/driver.c                 | 10 ++++++++--
 drivers/iommu/iommufd/viommu.c                 |  3 ---
 include/linux/iommufd.h                        |  8 +++++++-
 4 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index eb90af5093d8..4c86eacd36b1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -1218,7 +1218,8 @@ static void tegra241_vintf_destroy_vsid(struct iommufd_vdevice *vdev)
 
 static int tegra241_vintf_init_vsid(struct iommufd_vdevice *vdev)
 {
-	struct arm_smmu_master *master = dev_iommu_priv_get(vdev->dev);
+	struct device *dev = iommufd_vdevice_to_device(vdev);
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 	struct tegra241_vintf *vintf = viommu_to_vintf(vdev->viommu);
 	struct tegra241_vintf_sid *vsid = vdev_to_vsid(vdev);
 	struct arm_smmu_stream *stream = &master->streams[0];
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index e4eae20bcd4e..6f1010da221c 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -83,6 +83,12 @@ void _iommufd_destroy_mmap(struct iommufd_ctx *ictx,
 }
 EXPORT_SYMBOL_NS_GPL(_iommufd_destroy_mmap, "IOMMUFD");
 
+struct device *iommufd_vdevice_to_device(struct iommufd_vdevice *vdev)
+{
+	return vdev->idev->dev;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_vdevice_to_device, "IOMMUFD");
+
 /* Caller should xa_lock(&viommu->vdevs) to protect the return value */
 struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 				       unsigned long vdev_id)
@@ -92,7 +98,7 @@ struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 	lockdep_assert_held(&viommu->vdevs.xa_lock);
 
 	vdev = xa_load(&viommu->vdevs, vdev_id);
-	return vdev ? vdev->dev : NULL;
+	return vdev ? iommufd_vdevice_to_device(vdev) : NULL;
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_viommu_find_dev, "IOMMUFD");
 
@@ -109,7 +115,7 @@ int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
 
 	xa_lock(&viommu->vdevs);
 	xa_for_each(&viommu->vdevs, index, vdev) {
-		if (vdev->dev == dev) {
+		if (iommufd_vdevice_to_device(vdev) == dev) {
 			*vdev_id = vdev->virt_id;
 			rc = 0;
 			break;
diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index ecbae5091ffe..6cf0bd5d8f08 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -125,7 +125,6 @@ void iommufd_vdevice_abort(struct iommufd_object *obj)
 	xa_cmpxchg(&viommu->vdevs, vdev->virt_id, vdev, NULL, GFP_KERNEL);
 	refcount_dec(&viommu->obj.users);
 	idev->vdev = NULL;
-	put_device(vdev->dev);
 }
 
 void iommufd_vdevice_destroy(struct iommufd_object *obj)
@@ -203,8 +202,6 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
 	}
 
 	vdev->virt_id = virt_id;
-	vdev->dev = idev->dev;
-	get_device(idev->dev);
 	vdev->viommu = viommu;
 	refcount_inc(&viommu->obj.users);
 	/*
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index b88911026bc4..810e4d8ac912 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -109,7 +109,6 @@ struct iommufd_vdevice {
 	struct iommufd_object obj;
 	struct iommufd_viommu *viommu;
 	struct iommufd_device *idev;
-	struct device *dev;
 
 	/*
 	 * Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
@@ -261,6 +260,7 @@ int _iommufd_alloc_mmap(struct iommufd_ctx *ictx, struct iommufd_object *owner,
 			unsigned long *offset);
 void _iommufd_destroy_mmap(struct iommufd_ctx *ictx,
 			   struct iommufd_object *owner, unsigned long offset);
+struct device *iommufd_vdevice_to_device(struct iommufd_vdevice *vdev);
 struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
 				       unsigned long vdev_id);
 int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
@@ -295,6 +295,12 @@ static inline void _iommufd_destroy_mmap(struct iommufd_ctx *ictx,
 {
 }
 
+static inline struct device *
+iommufd_vdevice_to_device(struct iommufd_vdevice *vdev)
+{
+	return NULL;
+}
+
 static inline struct device *
 iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
 {
-- 
2.25.1