On Wed, Jan 26, 2022 at 09:51:36AM +0800, Lu Baolu wrote: > > > they are fundamentally different things in their own right, and the ideal > > > API should give us the orthogonality to also bind a device to an SVA > > > domain > > > without PASID (e.g. for KVM stage 2, or userspace assignment of simpler > > > fault/stall-tolerant devices), or attach PASIDs to regular iommu_domains. > > > > Yes, these are orthogonal things. A iommu driver that supports PASID > > ideally should support PASID enabled attach/detatch for every > > iommu_domain type it supports. > > > > SVA should not be entangled with PASID beyond that SVA is often used > > with PASID - a SVA iommu_domain should be fully usable with a RID too. > > The prototype of PASID enabled attach/detach ops could look like: > > int (*attach_dev_pasid)(struct iommu_domain *domain, > struct device *dev, ioasid_t id); > void (*detach_dev_pasid)(struct iommu_domain *domain, > struct device *dev, ioasid_t id);
It seems reasonable and straightforward to me.. These would be domain ops? > But the iommu driver should implement different callbacks for > > 1) attaching an IOMMU DMA domain to a PASID on device; > - kernel DMA with PASID > - mdev-like device passthrough > - etc. > 2) attaching a CPU-shared domain to a PASID on device; > - SVA > - guest PASID > - etc. But this you mean domain->ops would be different? Seems fine, up to the driver. I'd hope to see some flow like: domain = device->bus->iommu_ops->alloc_sva_domain(dev) domain->ops->attach_dev_pasid(domain, dev, current->pasid) To duplicate the current SVA APIs Jason _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
