From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Krishna Reddy <vdumpa@nvidia.com>
Cc: Sachin Nikam <Snikam@nvidia.com>,
"fenghua.yu@intel.com" <fenghua.yu@intel.com>,
Yu-Huan Hsu <YHsu@nvidia.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
Alistair Popple <apopple@nvidia.com>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
Pritesh Raithatha <praithatha@nvidia.com>,
Vikram Sethi <vsethi@nvidia.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
Jason Gunthorpe <jgg@nvidia.com>,
"zhangfei.gao@linaro.org" <zhangfei.gao@linaro.org>,
"will@kernel.org" <will@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v10 10/13] iommu/arm-smmu-v3: Check for SVA features
Date: Mon, 14 Dec 2020 10:32:47 +0100 [thread overview]
Message-ID: <X9cxP8g5JgAGS2wD@myrica> (raw)
In-Reply-To: <BY5PR12MB376486BC4F0789F81F1E9963B3CC0@BY5PR12MB3764.namprd12.prod.outlook.com>
On Wed, Dec 09, 2020 at 07:49:09PM +0000, Krishna Reddy wrote:
> Hi Jean,
> > > Why is BTM mandated for SVA? I couldn't find this requirement in
> > > SMMU spec (Sorry if I missed it or this got discussed earlier). But
> > > if performance is the
> > only concern here,
> > > is it better just to allow it with a warning rather than limiting
> > > SMMUs without
> > BTM?
> >
> > It's a performance concern and requires to support multiple
> > configurations, but the spec allows it. Are there SMMUs without BTM
> > that need it?
>
> The Tegra Next Generation SOC uses arm-smmu-v3, but it doesn't have support for BTM.
> Do you have plan to get your earlier patch to handle invalidate notifications into upstream sometime soon?
> Can the dependency on BTM be relaxed with the patch?
>
> PATCH v9 13/13] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops
> https://www.spinics.net/lists/arm-kernel/msg825099.html
This patch (which should be in 5.11) only takes care of sending ATC
invalidations to PCIe endpoints. With this, BTM is still required to
invalidate SMMU TLBs.
However we could enable command-queue invalidation when ARM_SMMU_FEAT_BTM
isn't set. Invalidations are still a relatively rare event so it may not
be outrageously slow. I can add a patch to my tree if you have hardware to
test. This could also be a first step for enabling SVA on other systems as
well, because I'm not finding time to work on BTM at the moment (requires
pinning VMIDs in KVM).
Thanks,
Jean
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next prev parent reply other threads:[~2020-12-14 9:33 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-18 10:18 [PATCH v10 00/13] iommu: Shared Virtual Addressing for SMMUv3 (PT sharing part) Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 01/13] mm: Define pasid in mm Jean-Philippe Brucker
2020-09-28 22:22 ` Will Deacon
2020-09-28 22:43 ` Fenghua Yu
2020-09-30 9:13 ` Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 02/13] iommu/ioasid: Add ioasid references Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 03/13] iommu/sva: Add PASID helpers Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 04/13] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 05/13] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 06/13] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 07/13] iommu/arm-smmu-v3: Move definitions to a header Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 08/13] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-09-18 10:18 ` [PATCH v10 09/13] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-09-18 13:07 ` Jonathan Cameron
2020-09-18 10:18 ` [PATCH v10 10/13] iommu/arm-smmu-v3: Check for SVA features Jean-Philippe Brucker
2020-09-21 8:59 ` Shameerali Kolothum Thodi
2020-09-24 10:13 ` Jean-Philippe Brucker
2020-09-24 11:13 ` Shameerali Kolothum Thodi
2020-12-09 19:49 ` Krishna Reddy
2020-12-09 20:07 ` Will Deacon
2020-12-09 20:38 ` Krishna Reddy
2020-12-14 9:32 ` Jean-Philippe Brucker [this message]
2020-12-14 23:23 ` Krishna Reddy
2020-09-18 10:18 ` [PATCH v10 11/13] iommu/arm-smmu-v3: Add SVA device feature Jean-Philippe Brucker
2020-12-15 1:09 ` Krishna Reddy
2021-01-06 10:09 ` Jean-Philippe Brucker
2021-01-06 17:23 ` Krishna Reddy
2020-09-18 10:18 ` [PATCH v10 12/13] iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind() Jean-Philippe Brucker
2020-11-24 23:58 ` Jason Gunthorpe
2020-11-25 9:27 ` Jean-Philippe Brucker
2020-11-26 0:37 ` Jason Gunthorpe
2020-09-18 10:18 ` [PATCH v10 13/13] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-09-18 13:15 ` [PATCH v10 00/13] iommu: Shared Virtual Addressing for SMMUv3 (PT sharing part) Jonathan Cameron
2020-09-28 16:47 ` Jean-Philippe Brucker
2020-09-28 17:23 ` Will Deacon
2020-09-28 22:39 ` Will Deacon
2020-09-30 9:12 ` Jean-Philippe Brucker
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