Re: [PATCH] iommu/arm-smmu-v3: Declare eats_s1chk and eats_trans as host-endian u64

[Pranjal Shrivastava <praan@google.com>]

On Mon, Jun 15, 2026 at 12:45:33PM -0700, Nicolin Chen wrote:
> arm_smmu_get_ste_update_safe() declares the eats_s1chk and eats_trans
> locals as __le64, but initializes them from FIELD_PREP(), which returns a
> host-endian value, and passes them through cpu_to_le64() at the use sites.
> 
> Sparse reports the following warnings:
> 
> >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:1122:38: sparse: sparse: cast from restricted __le64
>    drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:1124:33: sparse: sparse: cast from restricted __le64
> 
> Declare both locals as u64 so the type matches FIELD_PREP() and the
> existing cpu_to_le64() at the use sites performs the host-to-little-endian
> conversion. No functional change.
> 
> Fixes: 7cad80048595 ("iommu/arm-smmu-v3: Mark EATS_TRANS safe when computing the update sequence")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/all/202606151017.QU0evpH9-lkp@intel.com/
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> 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 8ce3e801eda3b..4c0f7b17b1f37 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1240,9 +1240,9 @@ VISIBLE_IF_KUNIT
>  void arm_smmu_get_ste_update_safe(const __le64 *cur, const __le64 *target,
>  				  __le64 *safe_bits)
>  {
> -	const __le64 eats_s1chk =
> +	const u64 eats_s1chk =
>  		FIELD_PREP(STRTAB_STE_1_EATS, STRTAB_STE_1_EATS_S1CHK);
> -	const __le64 eats_trans =
> +	const u64 eats_trans =
>  		FIELD_PREP(STRTAB_STE_1_EATS, STRTAB_STE_1_EATS_TRANS);

Reviewed-by: Pranjal Shrivastava <praan@google.com>

Thanks,
Praan