iommu: Introduce iommu_group_mutex_assert()

Add function to check iommu group mutex lock. So that device drivers can
rely on group mutex lock instead of adding another driver level lock
before modifying driver specific device data structure.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240205115615.6053-10-vasant.hegde@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d14413916f93a01626e850aa72ee0c919c1f72bd..8309e634977e2a7a228c5931c752db8af58e5931 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1248,6 +1248,25 @@ void iommu_group_remove_device(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(iommu_group_remove_device);
 
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API)
+/**
+ * iommu_group_mutex_assert - Check device group mutex lock
+ * @dev: the device that has group param set
+ *
+ * This function is called by an iommu driver to check whether it holds
+ * group mutex lock for the given device or not.
+ *
+ * Note that this function must be called after device group param is set.
+ */
+void iommu_group_mutex_assert(struct device *dev)
+{
+       struct iommu_group *group = dev->iommu_group;
+
+       lockdep_assert_held(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_group_mutex_assert);
+#endif
+
 static struct device *iommu_group_first_dev(struct iommu_group *group)
 {
        lockdep_assert_held(&group->mutex);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32bb121e8032c148381fdd88aab8a517cfe1cde4..8141a37556d5fcddd2268dd8b087043e3d1a68d8 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1356,6 +1356,14 @@ static inline ioasid_t iommu_alloc_global_pasid(struct device *dev)
 static inline void iommu_free_global_pasid(ioasid_t pasid) {}
 #endif /* CONFIG_IOMMU_API */
 
+#if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API)
+void iommu_group_mutex_assert(struct device *dev);
+#else
+static inline void iommu_group_mutex_assert(struct device *dev)
+{
+}
+#endif
+
 /**
  * iommu_map_sgtable - Map the given buffer to the IOMMU domain
  * @domain:    The IOMMU domain to perform the mapping