Messages in this thread | | | Subject | Re: [PATCH 1/1] iommu/arm-smmu-v3: add support for BBML | From | Keqian Zhu <> | Date | Thu, 28 Jan 2021 23:18:46 +0800 |
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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.
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-kernel@lists.infradead.org >>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >>> . >>> >> _______________________________________________ >> iommu mailing list >> iommu@lists.linux-foundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/iommu >> > . >
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