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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. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Nicolin Chen > --- > include/linux/iommu.h | 15 +++++++++++++++ > include/linux/iommufd.h | 6 ++++++ > 2 files changed, 21 insertions(+) Reviewed-by: Jason Gunthorpe Jason