Hi Jean, Just realized I should send this to your Linaro account instead of ARM. So Hi again :)
On Wed, 1 Jul 2020 23:29:16 -0700 Jacob Pan <jacob.jun....@linux.intel.com> wrote: > Hi Jean, > > Have a question for you on whether we can have a fixed token type for > ioasid_set. > > Currently, ioasid_set has an arbitrary token. For VT-d vSVA usage, we > choose mm as ioasid_set token to identify PASIDs within a guest. We > have multiple in-kernel users of PASIDs such as VFIO, KVM, and VDCM. > When an IOASID set is created, there is not a good way to communicate > about the token choices. So we have to let VDCM and KVM *assume* mm > is used as token, then retrieve ioasid_set based on the token. > > This assumption of "mm as token" is not a reliable SW architecture. So > we are thinking if we can have an explicit ioasid_set token type where > mm is used. After all, PASID and mm are closely related. > > The code change might be the following: > 1. add a flag to indicate token type when ioasid_set is allocated, > e.g. IOASID_SET_TYPE_MM > IOASID_SET_TYPE_ANY > 2. other users of the ioasid_set can query if an mm token exists based > on the flag IOASID_SET_TYPE_MM, then retrieve the ioasid_set. > > Existing ioasid_set user can still use arbitrary token under the flag > IOASID_SET_TYPE_ANY > > Would this be an issue for ARM usage? > > Thanks, > > Jacob [Jacob Pan] _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
