On Mon, Nov 14, 2022 at 09:50:56PM +0100, Eric Auger wrote: > > +IOMMUFD is the user API to control the IOMMU subsystem as it relates to managing > > +IO page tables from userspace using file descriptors. It intends to be general > > +and consumable by any driver that wants to expose DMA to userspace. These > > +drivers are eventually expected to deprecate any internal IOMMU logic if exists > they may already/historically implement (eg. vfio_iommu_type1.c)? Done > > +2. IOMMUFD_OBJ_DEVICE is created when an external driver calls the IOMMUFD kAPI > > + to bind a device to an iommufd. The driver is expected to implement proper a > s/proper/properly? > > + set of ioctls to allow userspace to initiate the binding operation. > > + Successful completion of this operation establishes the desired DMA ownership > > + over the device. The driver must also set the driver_managed_dma flag and > > + must not touch the device until this operation succeeds. I don't know what this was suppose to say, lets delete the word proper > > +3. IOMMUFD_OBJ_HW_PAGETABLE is created when an external driver calls the IOMMUFD > > + kAPI to attach a bound device to an IOAS. Similarly the external driver uAPI > > + allows userspace to initiate the attaching operation. If a compatible > > + pagetable already exists then it is reused for the attachment. Otherwise a > > + new pagetable object and iommu_domain is created. Successful completion of > > + this operation sets up the linkages among IOAS, device and iommu_domain. Once > > + this completes the device could do DMA. > > + > > + Every iommu_domain inside the IOAS is also represented to userspace as a > > + HW_PAGETABLE object. > > + > > + .. note:: > > + > > + Future IOMMUFD updates will provide an API to create and manipulate the > > + HW_PAGETABLE directly. > > + > > +A device can only bind to an iommufd due to DMA ownership claim and attach to at > > +most one IOAS object (no support of PASID yet). > > + > > +Currently only PCI device is allowed to use IOMMUFD. > is it still true? device_bind() now takes a struct device * > > In [PATCH v4 12/17] iommufd: Add kAPI toward external drivers for > physical devices "PCI" is used at several places > but shouldn't it be removed now? Right, gone > > +- struct io_pagetable holding the IOVA map > > +- struct iopt_areas representing populated portions of IOVA > > +- struct iopt_pages representing the storage of PFNs > > +- struct iommu_domain representing the IO page table in the IOMMU > > +- struct iopt_pages_access representing in-kernel users of PFNs > > +- struct xarray pinned_pfns holding a list of pages pinned by in-kernel users > > + > > +Each iopt_pages represents a logical linear array of full PFNs. The PFNs are > > +ultimately derived from userspave VAs via an mm_struct. Once they have been > > +pinned the PFN is stored in IOPTEs of an iommu_domain or inside the pinned_pages > s/is/are Ah it should be "Once they have been pinned the PFNs are stored in IOPTEs" as the whole thing is refering to plural PFNs Thanks, Jason
