Hi Jason, On Fri, 19 Mar 2021 10:54:32 -0300, Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > On Fri, Mar 19, 2021 at 02:41:32PM +0100, Jean-Philippe Brucker wrote: > > On Fri, Mar 19, 2021 at 09:46:45AM -0300, Jason Gunthorpe wrote: > > > On Fri, Mar 19, 2021 at 10:58:41AM +0100, Jean-Philippe Brucker wrote: > > > > > > > Although there is no use for it at the moment (only two upstream > > > > users and it looks like amdkfd always uses current too), I quite > > > > like the client-server model where the privileged process does > > > > bind() and programs the hardware queue on behalf of the client > > > > process. > > > > > > This creates a lot complexity, how do does process A get a secure > > > reference to B? How does it access the memory in B to setup the HW? > > > > mm_access() for example, and passing addresses via IPC > > I'd rather the source process establish its own PASID and then pass > the rights to use it to some other process via FD passing than try to > go the other way. There are lots of security questions with something > like mm_access. > Thank you all for the input, it sounds like we are OK to remove mm argument from iommu_sva_bind_device() and iommu_sva_alloc_pasid() for now? Let me try to summarize PASID allocation as below: Interfaces | Usage | Limit | bind¹ |User visible -------------------------------------------------------------------- /dev/ioasid² | G-SVA/IOVA | cgroup | No |Yes -------------------------------------------------------------------- char dev³ | SVA | cgroup | Yes |No -------------------------------------------------------------------- iommu driver | default PASID| no | No |No -------------------------------------------------------------------- kernel | super SVA | no | yes |No -------------------------------------------------------------------- ¹ Allocated during SVA bind ² PASIDs allocated via /dev/ioasid are not bound to any mm. But its ownership is assigned to the process that does the allocation. ³ Include uacce, other private device driver char dev such as idxd Currently, the proposed /dev/ioasid interface does not map individual PASID with an FD. The FD is at the ioasid_set granularity and bond to the current mm. We could extend the IOCTLs to cover individual PASID-FD passing case when use cases arise. Would this work? Thanks, Jacob
