From ada14b9f1aab5b60d50dec14c17eb84a55c0f682 Mon Sep 17 00:00:00 2001 From: Yi Liu Date: Fri, 21 Mar 2025 10:19:23 -0700 Subject: [PATCH] iommu: Require passing new handles to APIs supporting handle Add kdoc to highligt the caller of iommu_[attach|replace]_group_handle() and iommu_attach_device_pasid() should always provide a new handle. This can avoid race with lockless reference to the handle. e.g. the find_fault_handler() and iommu_report_device_fault() in the PRI path. Link: https://patch.msgid.link/r/20250321171940.7213-2-yi.l.liu@intel.com Reviewed-by: Lu Baolu Reviewed-by: Jason Gunthorpe Signed-off-by: Yi Liu Tested-by: Nicolin Chen Signed-off-by: Jason Gunthorpe --- drivers/iommu/iommu.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index d96e6fabb4dae..34ea7e5e7d00d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3365,6 +3365,9 @@ static void __iommu_remove_group_pasid(struct iommu_group *group, * @pasid: the pasid of the device. * @handle: the attach handle. * + * Caller should always provide a new handle to avoid race with the paths + * that have lockless reference to handle if it intends to pass a valid handle. + * * Return: 0 on success, or an error. */ int iommu_attach_device_pasid(struct iommu_domain *domain, @@ -3525,6 +3528,9 @@ EXPORT_SYMBOL_NS_GPL(iommu_attach_handle_get, "IOMMUFD_INTERNAL"); * This is a variant of iommu_attach_group(). It allows the caller to provide * an attach handle and use it when the domain is attached. This is currently * used by IOMMUFD to deliver the I/O page faults. + * + * Caller should always provide a new handle to avoid race with the paths + * that have lockless reference to handle. */ int iommu_attach_group_handle(struct iommu_domain *domain, struct iommu_group *group, @@ -3594,6 +3600,9 @@ EXPORT_SYMBOL_NS_GPL(iommu_detach_group_handle, "IOMMUFD_INTERNAL"); * * If the currently attached domain is a core domain (e.g. a default_domain), * it will act just like the iommu_attach_group_handle(). + * + * Caller should always provide a new handle to avoid race with the paths + * that have lockless reference to handle. */ int iommu_replace_group_handle(struct iommu_group *group, struct iommu_domain *new_domain, -- 2.39.5