ACK: [SRU][F][PATCH 0/1] Backport "iommu/arm-smmu-v3: Don't reserve implementation defined register space"

[Kuba Pawlak]

On 2.04.2025 16:13, Magali Lemes wrote:
> BugLink: https://bugs.launchpad.net/bugs/2067864
>
> [Impact]
> With certain bare-metal ARM instance types running the 5.4 kernels, there is a
> conflict error during the ioremap operation while loading the ARM SMMUv3
> driver, causing boot issues.
> This can be solved by backporting upstream commit 52f3fab0067d
> ("iommu/arm-smmu-v3: Don't reserve implementation defined register space").
>
> [Fix]
> There was a conflict when adding arm_smmu_ioremap() due to the current
> context missing ab246774713e ("iommu/arm-smmu-v3: Unregister IOMMU and
> bus ops on device removal").
>
> [Test]
> Compiled and boot tested.
> It's been further tested by the bug reporter that the bare-metal ARM instance
> running a 5.4 kernel with this patch applied can boot.
>
> [Where problems could occur]
> This touches probing of the ARM SMMUv3 driver, which might lead to boot
> failures or system instability.
>
> [Other info]
> This has been initially submitted for the F:linux-aws kernel, but since this
> issue can happen on other similar hardware configurations, it makes sense to
> target the generic kernel as well.
>
> Jean-Philippe Brucker (1):
>    iommu/arm-smmu-v3: Don't reserve implementation defined register space
>
>   drivers/iommu/arm-smmu-v3.c | 35 +++++++++++++++++++++++++++++++----
>   1 file changed, 31 insertions(+), 4 deletions(-)
Acked-by: Kuba Pawlak <kuba.pawlak at canonical.com>
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