Re: [PATCH v5 9/9] iommu/arm-smmu-v3: Support the DS expansion of RIL's SCALE

[Mostafa Saleh <smostafa@google.com>]

On Tue, Sep 01, 2026 at 02:49:58PM -0300, Jason Gunthorpe wrote:
> If DS is supported then SCALE can go up to 39. Compute a scale max that is
> compatible for the entire invs list.

I see in some places scale is still assumed to 32 as in:
- arm_smmu_ril_init_end
- arm_smmu_tlbi_calc_range

Would those need to be updated also?

Thanks,
Mostafa

> 
> Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 15 ++++++++++++---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  2 ++
>  2 files changed, 14 insertions(+), 3 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 b99229a5bbacca..2a159be751891e 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1060,9 +1060,16 @@ static void arm_smmu_invs_update_caps(struct arm_smmu_invs *invs,
>  		invs->has_ats = true;
>  
>  	if (inv->smmu->features & ARM_SMMU_FEAT_RANGE_INV) {
> +		unsigned int scale_max;
> +
>  		invs->has_range_inv = true;
>  		if (inv->smmu->options & ARM_SMMU_OPT_FULL_CONT_RIL)
>  			invs->has_full_cont_ril = true;
> +
> +		scale_max = (inv->smmu->features & ARM_SMMU_FEAT_DS) ? 39 : 31;
> +		if (!invs->range_inv_scale_max ||
> +		    scale_max < invs->range_inv_scale_max)
> +			invs->range_inv_scale_max = scale_max;
>  	}
>  }
>  
> @@ -2625,7 +2632,8 @@ static unsigned int arm_smmu_compute_ttl(u8 leaf_bitmap, u8 table_bitmap,
>   * covered by one command.
>   */
>  static void arm_smmu_tlbi_calc_range(struct arm_smmu_tlbi *tlbi,
> -				     bool single_ril)
> +				     bool single_ril,
> +				     unsigned int scale_max)
>  {
>  	u8 tgsz_lg2 = tlbi->tgsz_lg2;
>  	unsigned int ttl = arm_smmu_compute_ttl(
> @@ -2647,7 +2655,7 @@ static void arm_smmu_tlbi_calc_range(struct arm_smmu_tlbi *tlbi,
>  	 * address beyond alignment to tg (so long as TTL=0).
>  	 */
>  	first.scale = fls64((num_tg - 1) / 32);
> -	if (first.scale > 31) {
> +	if (first.scale > scale_max) {
>  		/* Range too large for a single command do full invalidation */
>  		tlbi->range.use_full_inv = true;
>  		return;
> @@ -2917,7 +2925,8 @@ void arm_smmu_domain_tlbi(struct arm_smmu_tlbi *tlbi,
>  			arm_smmu_tlbi_calc_range(
>  				tlbi,
>  				smmu_domain->stage == ARM_SMMU_DOMAIN_SVA &&
> -					invs->has_full_cont_ril);
> +					invs->has_full_cont_ril,
> +				invs->range_inv_scale_max);
>  		}
>  	}
>  
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index 6582203eb7425f..8b251a188810c9 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -760,6 +760,7 @@ static inline bool arm_smmu_inv_is_ats(const struct arm_smmu_inv *inv)
>   * @has_ats: flag if the array contains an INV_TYPE_ATS or INV_TYPE_ATS_FULL
>   * @has_range_inv: flag if any entry's SMMU supports range invalidation
>   * @has_full_cont_ril: flag if any entry's SMMU requires the CONT RIL workaround
> + * @range_inv_scale_max: max SCALE usable by all range-capable SMMUs
>   * @rcu: rcu head for kfree_rcu()
>   * @inv: flexible invalidation array
>   *
> @@ -791,6 +792,7 @@ struct arm_smmu_invs {
>  	bool has_ats;
>  	bool has_range_inv;
>  	bool has_full_cont_ril;
> +	u8 range_inv_scale_max;
>  	struct rcu_head rcu;
>  	struct arm_smmu_inv inv[] __counted_by(max_invs);
>  };
> -- 
> 2.43.0
>