Here is the presentation, any comments is welcome. https://docs.google.com/presentation/d/1sc295JznVAfDIPieAqzjcyUkcHnNFQsK8FFqdoCY854/edit?usp=sharing
On Fri, Sep 13, 2019 at 3:13 PM Guo Ren <guo...@kernel.org> wrote: > > Another idea is seperate remote TLB invalidate into two instructions: > > - sfence.vma.b.asyc > - sfence.vma.b.barrier // wait all async TLB invalidate operations finished > for all harts. > > (I remember who mentioned me separate them into two instructions after > session. Anup? Is the idea right ?) > > Actually, I never consider asyc TLB invalidate before, because current our > light iommu did not need it. > > Thx all people attend the session :) Let's continue the talk. > > > Guo Ren <guo...@kernel.org> 于 2019年9月12日周四 22:59写道： >> >> Thx Will for reply. >> >> On Thu, Sep 12, 2019 at 3:03 PM Will Deacon <w...@kernel.org> wrote: >> > >> > On Sun, Sep 08, 2019 at 07:52:55AM +0800, Guo Ren wrote: >> > > On Mon, Jun 24, 2019 at 6:40 PM Will Deacon <w...@kernel.org> wrote: >> > > > > I'll keep my system use the same ASID for SMP + IOMMU :P >> > > > >> > > > You will want a separate allocator for that: >> > > > >> > > > https://lkml.kernel.org/r/20190610184714.6786-2-jean-philippe.bruc...@arm.com >> > > >> > > Yes, it is hard to maintain ASID between IOMMU and CPUMMU or different >> > > system, because it's difficult to synchronize the IO_ASID when the CPU >> > > ASID is rollover. >> > > But we could still use hardware broadcast TLB invalidation instruction >> > > to uniformly manage the ASID and IO_ASID, or OTHER_ASID in our IOMMU. >> > >> > That's probably a bad idea, because you'll likely stall execution on the >> > CPU until the IOTLB has completed invalidation. In the case of ATS, I think >> > an endpoint ATC is permitted to take over a minute to respond. In reality, >> > I >> > suspect the worst you'll ever see would be in the msec range, but that's >> > still an unacceptable period of time to hold a CPU. >> Just as I've said in the session that IOTLB invalidate delay is >> another topic, My main proposal is to introduce stage1.pgd and >> stage2.pgd as address space identifiers between different TLB systems >> based on vmid, asid. My last part of sildes will show you how to >> translate stage1/2.pgd to as/vmid in PCI ATS system and the method >> could work with SMMU-v3 and intel Vt-d. (It's regret for me there is >> no time to show you the whole slides.) >> >> In our light IOMMU implementation, there's no IOTLB invalidate delay >> problem. Becasue IOMMU is very close to CPU MMU and interconnect's >> delay is the same with SMP CPUs MMU (no PCI, VM supported). >> >> To solve the problem, we could define a async mode in sfence.vma.b to >> slove the problem and finished with per_cpu_irq/exception. >> >> -- >> Best Regards >> Guo Ren >> >> ML: https://lore.kernel.org/linux-csky/ -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/ _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
