On 2021/1/29 0:17, Robin Murphy wrote: > On 2021-01-28 15:18, Keqian Zhu wrote: >> >> >> On 2021/1/27 17:39, Robin Murphy wrote: >>> On 2021-01-27 07:36, Keqian Zhu wrote: >>>> >>>> >>>> On 2021/1/27 10:01, Leizhen (ThunderTown) wrote: >>>>> >>>>> >>>>> On 2021/1/26 18:12, Will Deacon wrote: >>>>>> On Mon, Jan 25, 2021 at 08:23:40PM +0000, Robin Murphy wrote: >>>>>>> Now we probably will need some degreee of BBML feature awareness for the >>>>>>> sake of SVA if and when we start using it for CPU pagetables, but I >>>>>>> still >>>>>>> cannot see any need to consider it in io-pgtable. >>>>>> >>>>>> Agreed; I don't think this is something that io-pgtable should have to >>>>>> care >>>>>> about. >>>> Hi, >>>> >>>> I have a question here :-). >>>> If the old table is not live, then the break procedure seems unnecessary. >>>> Do I miss something? >>> >>> The MMU is allowed to prefetch translations at any time, so not following >>> the proper update procedure could still potentially lead to a TLB conflict, >>> even if there's no device traffic to worry about disrupting. >>> >>> Robin. >> >> Thanks. Does the MMU you mention here includes MMU and SMMU? I know that at >> SMMU side, ATS can prefetch translation. > > Yes, both - VMSAv8 allows speculative translation table walks, so SMMUv3 > inherits from there (per 3.21.1 "Translation tables and TLB invalidation > completion behavior"). OK, I Get it. Thanks. Keqian. > > Robin. > >> >> Keqian >>> >>>> Thanks, >>>> Keqian >>>> >>>>> >>>>> Yes, the SVA works in stall mode, and the failed device access requests >>>>> are not >>>>> discarded. >>>>> >>>>> Let me look for examples. The BBML usage scenario was told by a former >>>>> colleague. >>>>> >>>>>> >>>>>> Will >>>>>> >>>>>> . >>>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> linux-arm-kernel mailing list >>>>> linux-arm-ker...@lists.infradead.org >>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >>>>> . >>>>> >>>> _______________________________________________ >>>> iommu mailing list >>>> io...@lists.linux-foundation.org >>>> https://lists.linuxfoundation.org/mailman/listinfo/iommu >>>> >>> . >>> > . >