From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> To: Robin Murphy <robin.murphy@arm.com> Cc: Krishna Reddy <vdumpa@nvidia.com>, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org, Thierry Reding <treding@nvidia.com> Subject: Re: [PATCH] iommu/io-pgtable-arm: Optimize partial walk flush for large scatter-gather list Date: Wed, 16 Jun 2021 12:28:03 +0530 [thread overview] Message-ID: <8535b6c757a5584b495f135f4377053c@codeaurora.org> (raw) In-Reply-To: <da62ff1c-9b49-34d3-69a1-1a674e4a30f7@arm.com> Hi Robin, On 2021-06-15 19:23, Robin Murphy wrote: > On 2021-06-15 12:51, Sai Prakash Ranjan wrote: <snip>... >> Hi @Robin, from these discussions it seems they are not ok with the >> change >> for all SoC vendor implementations and do not have any data on such >> impact. >> As I mentioned above, on QCOM platforms we do have several >> optimizations in HW >> for TLBIs and would like to make use of it and reduce the unmap >> latency. >> What do you think, should this be made implementation specific? > > Yes, it sounds like there's enough uncertainty for now that this needs > to be an opt-in feature. However, I still think that non-strict mode > could use it generically, since that's all about over-invalidating to > save time on individual unmaps - and relatively non-deterministic - > already. > > So maybe we have a second set of iommu_flush_ops, or just a flag > somewhere to control the tlb_flush_walk functions internally, and the > choice can be made in the iommu_get_dma_strict() test, but also forced > on all the time by your init_context hook. What do you reckon? > Sounds good to me. Since you mentioned non-strict mode using it generically, can't we just set tlb_flush_all() in io_pgtable_tlb_flush_walk() like below based on quirk so that we don't need to add any check in iommu_get_dma_strict() and just force the new flush_ops in init_context hook? if (iop->cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT) { iop->cfg.tlb->tlb_flush_all(iop->cookie); return; } Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
WARNING: multiple messages have this Message-ID (diff)
From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> To: Robin Murphy <robin.murphy@arm.com> Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Thierry Reding <treding@nvidia.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] iommu/io-pgtable-arm: Optimize partial walk flush for large scatter-gather list Date: Wed, 16 Jun 2021 12:28:03 +0530 [thread overview] Message-ID: <8535b6c757a5584b495f135f4377053c@codeaurora.org> (raw) In-Reply-To: <da62ff1c-9b49-34d3-69a1-1a674e4a30f7@arm.com> Hi Robin, On 2021-06-15 19:23, Robin Murphy wrote: > On 2021-06-15 12:51, Sai Prakash Ranjan wrote: <snip>... >> Hi @Robin, from these discussions it seems they are not ok with the >> change >> for all SoC vendor implementations and do not have any data on such >> impact. >> As I mentioned above, on QCOM platforms we do have several >> optimizations in HW >> for TLBIs and would like to make use of it and reduce the unmap >> latency. >> What do you think, should this be made implementation specific? > > Yes, it sounds like there's enough uncertainty for now that this needs > to be an opt-in feature. However, I still think that non-strict mode > could use it generically, since that's all about over-invalidating to > save time on individual unmaps - and relatively non-deterministic - > already. > > So maybe we have a second set of iommu_flush_ops, or just a flag > somewhere to control the tlb_flush_walk functions internally, and the > choice can be made in the iommu_get_dma_strict() test, but also forced > on all the time by your init_context hook. What do you reckon? > Sounds good to me. Since you mentioned non-strict mode using it generically, can't we just set tlb_flush_all() in io_pgtable_tlb_flush_walk() like below based on quirk so that we don't need to add any check in iommu_get_dma_strict() and just force the new flush_ops in init_context hook? if (iop->cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT) { iop->cfg.tlb->tlb_flush_all(iop->cookie); return; } Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-06-16 6:58 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-09 14:53 [PATCH] iommu/io-pgtable-arm: Optimize partial walk flush for large scatter-gather list Sai Prakash Ranjan 2021-06-09 14:53 ` Sai Prakash Ranjan 2021-06-09 18:44 ` Robin Murphy 2021-06-09 18:44 ` Robin Murphy 2021-06-09 18:44 ` Robin Murphy 2021-06-10 5:24 ` Sai Prakash Ranjan 2021-06-10 5:24 ` Sai Prakash Ranjan 2021-06-10 9:08 ` Robin Murphy 2021-06-10 9:08 ` Robin Murphy 2021-06-10 9:08 ` Robin Murphy 2021-06-10 9:36 ` Sai Prakash Ranjan 2021-06-10 9:36 ` Sai Prakash Ranjan 2021-06-10 11:33 ` Robin Murphy 2021-06-10 11:33 ` Robin Murphy 2021-06-10 11:33 ` Robin Murphy 2021-06-10 11:54 ` Sai Prakash Ranjan 2021-06-10 11:54 ` Sai Prakash Ranjan 2021-06-10 15:29 ` Robin Murphy 2021-06-10 15:29 ` Robin Murphy 2021-06-10 15:29 ` Robin Murphy 2021-06-10 15:51 ` Sai Prakash Ranjan 2021-06-10 15:51 ` Sai Prakash Ranjan 2021-06-11 0:37 ` Krishna Reddy 2021-06-11 0:37 ` Krishna Reddy 2021-06-11 0:37 ` Krishna Reddy 2021-06-11 0:54 ` Sai Prakash Ranjan 2021-06-11 0:54 ` Sai Prakash Ranjan 2021-06-11 16:49 ` Krishna Reddy 2021-06-11 16:49 ` Krishna Reddy 2021-06-11 16:49 ` Krishna Reddy 2021-06-12 2:46 ` Sai Prakash Ranjan 2021-06-12 2:46 ` Sai Prakash Ranjan 2021-06-14 17:48 ` Krishna Reddy 2021-06-14 17:48 ` Krishna Reddy 2021-06-14 17:48 ` Krishna Reddy 2021-06-15 11:51 ` Sai Prakash Ranjan 2021-06-15 11:51 ` Sai Prakash Ranjan 2021-06-15 13:53 ` Robin Murphy 2021-06-15 13:53 ` Robin Murphy 2021-06-15 13:53 ` Robin Murphy 2021-06-16 6:58 ` Sai Prakash Ranjan [this message] 2021-06-16 6:58 ` Sai Prakash Ranjan 2021-06-16 9:03 ` Sai Prakash Ranjan 2021-06-16 9:03 ` Sai Prakash Ranjan 2021-06-17 21:18 ` Krishna Reddy 2021-06-17 21:18 ` Krishna Reddy 2021-06-17 21:18 ` Krishna Reddy 2021-06-18 2:47 ` Sai Prakash Ranjan 2021-06-18 2:47 ` Sai Prakash Ranjan 2021-06-18 4:04 ` Sai Prakash Ranjan 2021-06-18 4:04 ` Sai Prakash Ranjan 2021-06-10 12:03 ` Thierry Reding 2021-06-10 12:03 ` Thierry Reding 2021-06-10 12:03 ` Thierry Reding
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