Re: [PATCHv8 2/8] iommu/arm-smmu: Add domain attribute for pagetable configuration

[Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>]

On 2020-11-23 20:48, Will Deacon wrote:
> On Tue, Nov 17, 2020 at 08:00:41PM +0530, Sai Prakash Ranjan wrote:
>> Add iommu domain attribute for pagetable configuration which
>> initially will be used to set quirks like for system cache aka
>> last level cache to be used by client drivers like GPU to set
>> right attributes for caching the hardware pagetables into the
>> system cache and later can be extended to include other page
>> table configuration data.
>> 
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> ---
>>  drivers/iommu/arm/arm-smmu/arm-smmu.c | 25 +++++++++++++++++++++++++
>>  drivers/iommu/arm/arm-smmu/arm-smmu.h |  1 +
>>  include/linux/io-pgtable.h            |  4 ++++
>>  include/linux/iommu.h                 |  1 +
>>  4 files changed, 31 insertions(+)
>> 
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c 
>> b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> index 0f28a8614da3..7b05782738e2 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> @@ -789,6 +789,9 @@ static int arm_smmu_init_domain_context(struct 
>> iommu_domain *domain,
>>  	if (smmu_domain->non_strict)
>>  		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>> 
>> +	if (smmu_domain->pgtbl_cfg.quirks)
>> +		pgtbl_cfg.quirks |= smmu_domain->pgtbl_cfg.quirks;
>> +
>>  	pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
>>  	if (!pgtbl_ops) {
>>  		ret = -ENOMEM;
>> @@ -1511,6 +1514,12 @@ static int arm_smmu_domain_get_attr(struct 
>> iommu_domain *domain,
>>  		case DOMAIN_ATTR_NESTING:
>>  			*(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
>>  			return 0;
>> +		case DOMAIN_ATTR_IO_PGTABLE_CFG: {
>> +			struct domain_attr_io_pgtbl_cfg *pgtbl_cfg = data;
>> +			*pgtbl_cfg = smmu_domain->pgtbl_cfg;
>> +
>> +			return 0;
>> +		}
>>  		default:
>>  			return -ENODEV;
>>  		}
>> @@ -1551,6 +1560,22 @@ static int arm_smmu_domain_set_attr(struct 
>> iommu_domain *domain,
>>  			else
>>  				smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
>>  			break;
>> +		case DOMAIN_ATTR_IO_PGTABLE_CFG: {
>> +			struct domain_attr_io_pgtbl_cfg *pgtbl_cfg = data;
>> +
>> +			if (smmu_domain->smmu) {
>> +				ret = -EPERM;
>> +				goto out_unlock;
>> +			}
>> +
>> +			if (!pgtbl_cfg) {
> 
> Do we really need to check this? If somebody passed us a NULL pointer 
> then
> they have a bug and we don't check this for other domain attributes 
> afaict.
> 

True, I'll drop it.

>> +				ret = -ENODEV;
>> +				goto out_unlock;
>> +			}
>> +
>> +			smmu_domain->pgtbl_cfg = *pgtbl_cfg;
>> +			break;
>> +		}
>>  		default:
>>  			ret = -ENODEV;
>>  		}
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h 
>> b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> index 04288b6fc619..18fbed376afb 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> @@ -364,6 +364,7 @@ enum arm_smmu_domain_stage {
>>  struct arm_smmu_domain {
>>  	struct arm_smmu_device		*smmu;
>>  	struct io_pgtable_ops		*pgtbl_ops;
>> +	struct domain_attr_io_pgtbl_cfg	pgtbl_cfg;
>>  	const struct iommu_flush_ops	*flush_ops;
>>  	struct arm_smmu_cfg		cfg;
>>  	enum arm_smmu_domain_stage	stage;
>> diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
>> index a9a2c59fab37..686b37d48743 100644
>> --- a/include/linux/io-pgtable.h
>> +++ b/include/linux/io-pgtable.h
>> @@ -212,6 +212,10 @@ struct io_pgtable {
>> 
>>  #define io_pgtable_ops_to_pgtable(x) container_of((x), struct 
>> io_pgtable, ops)
>> 
>> +struct domain_attr_io_pgtbl_cfg {
>> +	unsigned long quirks;
>> +};
> 
> nit: Can you rename this to 'struct io_pgtable_domain_attr' please?
> 

Done, thanks.

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