Re: [PATCH 2/2] iommu/arm-smmu-v3: Override for Inst/Data attribute

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Incorrect parenthesis placement in `arm_smmu_make_cdtable_ste()` causes the `STRTAB_STE_1_INSTCFG` bitfield to be evaluated outside the `cpu_to_le64()` macro. On big-endian platforms, this mixes little-endian data with host-endian data, leading to corruption of the Stream Table Entry.
--

--- Patch [2]: [PATCH 2/2] iommu/arm-smmu-v3: Override for Inst/Data attribute ---
commit af569c8fadcbad6c95ec600eb667d4a653e847dd
Author: Peter Griffin <peter.griffin@linaro.org>

iommu/arm-smmu-v3: Override for Inst/Data attribute

This commit adds an option to override the instruction/data attribute of
incoming traffic to Data by setting the INSTCFG override in all Stream Table
Entries. The option is configurable via the arm,instdata-override device tree
property.

> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 57b750ebcd3d6..2b39cb5aa49d0 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
[ ... ]
> @@ -1835,7 +1838,11 @@ void arm_smmu_make_cdtable_ste(struct arm_smmu_ste *target,
>  			 STRTAB_STE_1_S1STALLD :
>  			 0) |
>  		FIELD_PREP(STRTAB_STE_1_EATS,
> -			   ats_enabled ? STRTAB_STE_1_EATS_TRANS : 0));
> +			   ats_enabled ? STRTAB_STE_1_EATS_TRANS : 0)) |
> +		FIELD_PREP(STRTAB_STE_1_INSTCFG,
> +			   smmu->options & ARM_SMMU_OPT_OVR_INSTCFG_DATA ?
> +				   STRTAB_STE_1_INSTCFG_DATA :
> +				   STRTAB_STE_1_INSTCFG_INCOMING);

[Severity: High]
Does this prematurely close the cpu_to_le64() macro?

By having the extra parenthesis after 0, the STRTAB_STE_1_INSTCFG field
appears to be bitwise-ORed in host endianness rather than being
little-endian swapped along with the rest of the fields.

On big-endian platforms, could this mix little-endian and host-endian data,
leading to corruption of the Stream Table Entry?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260724-arm-smmu-v3-instcfg-override-v1-0-e7acf4a8a525@linaro.org?part=2