[PATCH v2 05/22] iommufd: Add iommufd_struct_destroy to revert iommufd_viommu_alloc

Nicolin Chen
2025-04-26T06:10:25Z

An IOMMU driver that allocated a vIOMMU may want to revert the allocation,
if it encounters an internal error after the allocation. So, there needs a
destroy helper for drivers to use.

Move iommufd_object_abort() to the driver.c file and the public header, to
introduce common iommufd_struct_destroy() helper that will abort all kinds
of driver structures, not confined to iommufd_viommu but also the new ones
being added in the future.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/iommufd_private.h | 1 -
include/linux/iommufd.h | 15 +++++++++++++++
drivers/iommu/iommufd/driver.c | 14 ++++++++++++++
drivers/iommu/iommufd/main.c | 13 -------------
4 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 5c69ac05c029..8d96aa514033 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -180,7 +180,6 @@ static inline void iommufd_put_object(struct iommufd_ctx *ictx,
wake_up_interruptible_all(&ictx->destroy_wait);
}

-void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj);
void iommufd_object_abort_and_destroy(struct iommufd_ctx *ictx,
struct iommufd_object *obj);
void iommufd_object_finalize(struct iommufd_ctx *ictx,
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 83e5c4dff121..ef0d3c4765cf 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -211,6 +211,7 @@ static inline int iommufd_vfio_compat_set_no_iommu(struct iommufd_ctx *ictx)
struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
size_t size,
enum iommufd_object_type type);
+void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj);
struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
unsigned long vdev_id);
int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
@@ -226,6 +227,11 @@ _iommufd_object_alloc(struct iommufd_ctx *ictx, size_t size,
return ERR_PTR(-EOPNOTSUPP);
}

+static inline void iommufd_object_abort(struct iommufd_ctx *ictx,
+ struct iommufd_object *obj)
+{
+}
+
static inline struct device *
iommufd_viommu_find_dev(struct iommufd_viommu *viommu, unsigned long vdev_id)
{
@@ -279,4 +285,13 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
ret->member.viommu = viommu; \
ret; \
})
+
+/* Helper for IOMMU driver to destroy structures created by allocators above */
+#define iommufd_struct_destroy(ictx, drv_struct, member) \
+ ({ \
+ static_assert(__same_type(struct iommufd_object, \
+ drv_struct->member.obj)); \
+ static_assert(offsetof(typeof(*drv_struct), member.obj) == 0); \
+ iommufd_object_abort(ictx, &drv_struct->member.obj); \
+ })
#endif
diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index 922cd1fe7ec2..7980a09761c2 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -36,6 +36,20 @@ struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
}
EXPORT_SYMBOL_NS_GPL(_iommufd_object_alloc, "IOMMUFD");

+/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */
+void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj)
+{
+ XA_STATE(xas, &ictx->objects, obj->id);
+ void *old;
+
+ xa_lock(&ictx->objects);
+ old = xas_store(&xas, NULL);
+ xa_unlock(&ictx->objects);
+ WARN_ON(old != XA_ZERO_ENTRY);
+ kfree(obj);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_object_abort, "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)
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 3df468f64e7d..2b9ee9b4a424 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -51,19 +51,6 @@ void iommufd_object_finalize(struct iommufd_ctx *ictx,
WARN_ON(old != XA_ZERO_ENTRY);
}

-/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */
-void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj)
-{
- XA_STATE(xas, &ictx->objects, obj->id);
- void *old;
-
- xa_lock(&ictx->objects);
- old = xas_store(&xas, NULL);
- xa_unlock(&ictx->objects);
- WARN_ON(old != XA_ZERO_ENTRY);
- kfree(obj);
-}
-
/*
* Abort an object that has been fully initialized and needs destroy, but has
* not been finalized.
--
2.43.0