linux-kernel - [PATCH v1 05/10] iommufd/viommu: Add iommufd_vdev_id_to

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Message-ID: <0079015047db9981c111f09414a863b644c038ef.1724777091.git.nicolinc@nvidia.com>
Date: Tue, 27 Aug 2024 10:02:07 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <will@...nel.org>
CC: <joro@...tes.org>, <suravee.suthikulpanit@....com>,
	<robin.murphy@....com>, <dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>,
	<shuah@...nel.org>, <linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
	<eric.auger@...hat.com>, <jean-philippe@...aro.org>, <mdf@...nel.org>,
	<mshavit@...gle.com>, <shameerali.kolothum.thodi@...wei.com>,
	<smostafa@...gle.com>, <yi.l.liu@...el.com>
Subject: [PATCH v1 05/10] iommufd/viommu: Add iommufd_vdev_id_to_dev helper

This helps drivers to get the dev pointer held by the vdev_id structure.

Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/iommu/iommufd/viommu_api.c | 14 ++++++++++++++
 include/linux/iommufd.h            |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/iommu/iommufd/viommu_api.c b/drivers/iommu/iommufd/viommu_api.c
index 3772a5892a6c..82eb33e047cf 100644
--- a/drivers/iommu/iommufd/viommu_api.c
+++ b/drivers/iommu/iommufd/viommu_api.c
@@ -51,3 +51,17 @@ iommufd_viommu_to_parent_domain(struct iommufd_viommu *viommu)
 	return viommu->hwpt->common.domain;
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_viommu_to_parent_domain, IOMMUFD);
+
+/*
+ * Fetch the dev pointer in the vdev_id structure. Caller must make ensure the
+ * lifecycle of the vdev_id structure, likely by adding a driver-level lock to
+ * protect the passed-in vdev_id for any race against a potential unset_vdev_id
+ * callback.
+ */
+struct device *iommufd_vdev_id_to_dev(struct iommufd_vdev_id *vdev_id)
+{
+	if (!vdev_id || !vdev_id->viommu)
+		return NULL;
+	return vdev_id->idev->dev;
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_vdev_id_to_dev, IOMMUFD);
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index c89583c7c792..88d6586a424f 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -99,6 +99,7 @@ void iommufd_access_unpin_pages(struct iommufd_access *access,
 				unsigned long iova, unsigned long length);
 int iommufd_access_rw(struct iommufd_access *access, unsigned long iova,
 		      void *data, size_t len, unsigned int flags);
+struct device *iommufd_vdev_id_to_dev(struct iommufd_vdev_id *vdev_id);
 int iommufd_vfio_compat_ioas_get_id(struct iommufd_ctx *ictx, u32 *out_ioas_id);
 int iommufd_vfio_compat_ioas_create(struct iommufd_ctx *ictx);
 int iommufd_vfio_compat_set_no_iommu(struct iommufd_ctx *ictx);
@@ -138,6 +139,12 @@ static inline int iommufd_access_rw(struct iommufd_access *access, unsigned long
 	return -EOPNOTSUPP;
 }
 
+static inline struct device *
+iommufd_vdev_id_to_dev(struct iommufd_vdev_id *vdev_id)
+{
+	return NULL;
+}
+
 static inline int iommufd_vfio_compat_ioas_create(struct iommufd_ctx *ictx)
 {
 	return -EOPNOTSUPP;
-- 
2.43.0