From 187f146d5de65d50d90a4f49157d381d8ae32939 Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Fri, 13 Jun 2025 23:35:18 -0700 Subject: [PATCH] iommu: Introduce get_viommu_size and viommu_init ops So far, a vIOMMU object has been allocated by IOMMU driver and initialized with the driver-level structure, before it returns to the iommufd core for core-level structure initialization. It has been requiring iommufd core to expose some core structure/helpers in its driver.c file, which result in a size increase of this driver module. Meanwhile, IOMMU drivers are now requiring more vIOMMU-base structures for some advanced feature, such as the existing vDEVICE and a future HW_QUEUE. Initializing a core-structure later than driver-structure gives for-driver helpers some trouble, when they are used by IOMMU driver assuming that the new structure (including core) are fully initialized, for example: core: viommu = ops->viommu_alloc(); driver: // my_viommu is successfully allocated driver: my_viommu = iommufd_viommu_alloc(...); driver: // This may crash if it reads viommu->ictx driver: new = iommufd_new_viommu_helper(my_viommu->core ...); core: viommu->ictx = ucmd->ictx; core: ... To ease such a condition, allow the IOMMU driver to report the size of its vIOMMU structure, let the core allocate a vIOMMU object and initialize the core-level structure first, and then hand it over the driver to initialize its driver-level structure. Thus, this requires two new iommu ops, get_viommu_size and viommu_init, so iommufd core can communicate with drivers to replace the viommu_alloc op: core: viommu = ops->get_viommu_size(); driver: return VIOMMU_STRUCT_SIZE(); core: viommu->ictx = ucmd->ictx; // and others core: rc = ops->viommu_init(); driver: // This is safe now as viommu->ictx is inited driver: new = iommufd_new_viommu_helper(my_viommu->core ...); core: ... This also adds a VIOMMU_STRUCT_SIZE macro, for drivers to use, which would statically sanitize the driver structure. Link: https://patch.msgid.link/r/3ab52c5b622dad476c43b1b1f1636c8b902f1692.1749882255.git.nicolinc@nvidia.com Suggested-by: Jason Gunthorpe Signed-off-by: Nicolin Chen Reviewed-by: Jason Gunthorpe Reviewed-by: Lu Baolu Reviewed-by: Kevin Tian Reviewed-by: Pranjal Shrivastava Signed-off-by: Jason Gunthorpe --- include/linux/iommu.h | 15 +++++++++++++++ include/linux/iommufd.h | 6 ++++++ 2 files changed, 21 insertions(+) diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 1567328079945..9be4ff370f1ef 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -14,6 +14,7 @@ #include #include #include +#include #define IOMMU_READ (1 << 0) #define IOMMU_WRITE (1 << 1) @@ -596,6 +597,16 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size, * - IOMMU_DOMAIN_DMA: must use a dma domain * - 0: use the default setting * @default_domain_ops: the default ops for domains + * @get_viommu_size: Get the size of a driver-level vIOMMU structure for a given + * @dev corresponding to @viommu_type. Driver should return 0 + * if vIOMMU isn't supported accordingly. It is required for + * driver to use the VIOMMU_STRUCT_SIZE macro to sanitize the + * driver-level vIOMMU structure related to the core one + * @viommu_init: Init the driver-level struct of an iommufd_viommu on a physical + * IOMMU instance @viommu->iommu_dev, as the set of virtualization + * resources shared/passed to user space IOMMU instance. Associate + * it with a nesting @parent_domain. It is required for driver to + * set @viommu->ops pointing to its own viommu_ops * @viommu_alloc: Allocate an iommufd_viommu on a physical IOMMU instance behind * the @dev, as the set of virtualization resources shared/passed * to user space IOMMU instance. And associate it with a nesting @@ -654,6 +665,10 @@ struct iommu_ops { int (*def_domain_type)(struct device *dev); + size_t (*get_viommu_size)(struct device *dev, + enum iommu_viommu_type viommu_type); + int (*viommu_init)(struct iommufd_viommu *viommu, + struct iommu_domain *parent_domain); struct iommufd_viommu *(*viommu_alloc)( struct device *dev, struct iommu_domain *parent_domain, struct iommufd_ctx *ictx, unsigned int viommu_type); diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h index ac98e49e44feb..423e08963d901 100644 --- a/include/linux/iommufd.h +++ b/include/linux/iommufd.h @@ -229,6 +229,12 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu, } #endif /* CONFIG_IOMMUFD_DRIVER_CORE */ +#define VIOMMU_STRUCT_SIZE(drv_struct, member) \ + (sizeof(drv_struct) + \ + BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) + \ + BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_viommu, \ + ((drv_struct *)NULL)->member))) + /* * Helpers for IOMMU driver to allocate driver structures that will be freed by * the iommufd core. The free op will be called prior to freeing the memory. -- 2.47.2