From: Nicolin Chen <nicolinc@nvidia.com>
To: Ashish Mhetre <amhetre@nvidia.com>
Cc: <catalin.marinas@arm.com>, <will@kernel.org>, <corbet@lwn.net>,
<skhan@linuxfoundation.org>, <robin.murphy@arm.com>,
<joro@8bytes.org>, <jgg@ziepe.ca>,
<linux-arm-kernel@lists.infradead.org>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<iommu@lists.linux.dev>, <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v9 4/4] iommu/arm-smmu-v3: Enable CFGI/TLBI-repeat workaround on Tegra264
Date: Sun, 26 Jul 2026 10:20:10 -0700 [thread overview]
Message-ID: <amZByocd+B+fMk/L@nvidia.com> (raw)
In-Reply-To: <20260726081904.1408859-5-amhetre@nvidia.com>
On Sun, Jul 26, 2026 at 08:19:04AM +0000, Ashish Mhetre wrote:
> Nvidia Tegra264 SMMU is affected by an erratum where a TLB entry can
> survive an invalidation that races with concurrent traffic targeting
> the same entry. The hardware-recommended software workaround is to
> issue every CFGI/TLBI command (each followed by CMD_SYNC) twice, and
> that infrastructure is already in place behind
> arm_smmu_erratum_repeat_tlbi_cfgi_key.
>
> Neither IDR nor IIDR flags this Tegra264-specific bug, so hardware
> detection is not possible. Tegra264 is device-tree-only (no ACPI/IORT
> support) and already has a dedicated "nvidia,tegra264-smmu" compatible,
> so DT-probe is the only viable detection path.
>
> Enable the workaround on instances matching the existing
> "nvidia,tegra264-smmu" compatible by calling static_branch_enable() on
> arm_smmu_erratum_repeat_tlbi_cfgi_key. Document the erratum in
> Documentation/arch/arm64/silicon-errata.rst.
>
> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
prev parent reply other threads:[~2026-07-26 17:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-26 8:19 [PATCH v9 0/4] iommu/arm-smmu-v3: Tegra264 invalidation workaround Ashish Mhetre
2026-07-26 8:19 ` [PATCH v9 1/4] iommu/arm-smmu-v3: Factor out CMDQ batch force-sync conditions Ashish Mhetre
2026-07-26 8:19 ` [PATCH v9 2/4] iommu/arm-smmu-v3: Add CFGI/TLBI-repeat workaround Ashish Mhetre
2026-07-26 8:19 ` [PATCH v9 3/4] iommu/arm-smmu-v3-iommufd: Report CFGI/TLBI-repeat erratum Ashish Mhetre
2026-07-26 16:23 ` Jason Gunthorpe
2026-07-26 17:19 ` Nicolin Chen
2026-07-26 8:19 ` [PATCH v9 4/4] iommu/arm-smmu-v3: Enable CFGI/TLBI-repeat workaround on Tegra264 Ashish Mhetre
2026-07-26 16:23 ` Jason Gunthorpe
2026-07-26 17:20 ` Nicolin Chen [this message]
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