vfio-iommufd: No need to record iommufd_ctx in vfio_device

iommufd_ctx is stored in vfio_device for emulated devices per bind_iommufd.
However, as iommufd_access is created in bind, no more need to stored it
since iommufd_access implicitly stores it.

Link: https://lore.kernel.org/r/20230327093351.44505-4-yi.l.liu@intel.comReviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/vfio/iommufd.c

@@ -142,14 +142,10 @@ int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
 
 	lockdep_assert_held(&vdev->dev_set->lock);
 
-	iommufd_ctx_get(ictx);
 	user = iommufd_access_create(ictx, &vfio_user_ops, vdev);
-	if (IS_ERR(user)) {
-		iommufd_ctx_put(ictx);
+	if (IS_ERR(user))
 		return PTR_ERR(user);
-	}
 	vdev->iommufd_access = user;
-	vdev->iommufd_ictx = ictx;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_bind);
@@ -163,8 +159,6 @@ void vfio_iommufd_emulated_unbind(struct vfio_device *vdev)
 		vdev->iommufd_attached = false;
 		vdev->iommufd_access = NULL;
 	}
-	iommufd_ctx_put(vdev->iommufd_ictx);
-	vdev->iommufd_ictx = NULL;
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_unbind);
 

include/linux/vfio.h

@@ -60,7 +60,6 @@ struct vfio_device {
 	void (*put_kvm)(struct kvm *kvm);
 #if IS_ENABLED(CONFIG_IOMMUFD)
 	struct iommufd_device *iommufd_device;
-	struct iommufd_ctx *iommufd_ictx;
 	bool iommufd_attached;
 #endif
 };