From: Will Deacon <will@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Stephan Gerhold <stephan.gerhold@linaro.org>
Cc: catalin.marinas@arm.com, kernel-team@android.com,
Will Deacon <will@kernel.org>,
Rob Clark <robin.clark@oss.qualcomm.com>,
Manivannan Sadhasivam <mani@kernel.org>,
Johan Hovold <johan@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
iommu@lists.linux.dev, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/arm-smmu-qcom: Enable use of all SMR groups when running bare-metal
Date: Tue, 25 Nov 2025 18:05:40 +0000 [thread overview]
Message-ID: <176408774799.1871149.15645186594285769855.b4-ty@kernel.org> (raw)
In-Reply-To: <20250821-arm-smmu-qcom-all-smr-v1-1-7f5cbbceac3e@linaro.org>
On Thu, 21 Aug 2025 10:33:53 +0200, Stephan Gerhold wrote:
> Some platforms (e.g. SC8280XP and X1E) support more than 128 stream
> matching groups. This is more than what is defined as maximum by the ARM
> SMMU architecture specification. Commit 122611347326 ("iommu/arm-smmu-qcom:
> Limit the SMR groups to 128") disabled use of the additional groups because
> they don't exhibit the same behavior as the architecture supported ones.
>
> It seems like this is just another quirk of the hypervisor: When running
> bare-metal without the hypervisor, the additional groups appear to behave
> just like all others. The boot firmware uses some of the additional groups,
> so ignoring them in this situation leads to stream match conflicts whenever
> we allocate a new SMR group for the same SID.
>
> [...]
Applied to iommu (arm/smmu/updates), thanks!
[1/1] iommu/arm-smmu-qcom: Enable use of all SMR groups when running bare-metal
https://git.kernel.org/iommu/c/5583a55e074b
I chatted off-list with Robin about this and we agreed that it's the best
approach for now.
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
prev parent reply other threads:[~2025-11-25 18:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-21 8:33 [PATCH] iommu/arm-smmu-qcom: Enable use of all SMR groups when running bare-metal Stephan Gerhold
2025-09-09 12:57 ` Will Deacon
2025-09-09 15:35 ` Stephan Gerhold
2025-09-17 18:02 ` Robin Murphy
2025-09-17 19:16 ` Stephan Gerhold
2025-09-19 7:51 ` Will Deacon
2025-10-28 10:53 ` Stephan Gerhold
2025-11-25 18:05 ` Will Deacon [this message]
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