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SubjectRe: [PATCHv9 3/8] iommu/arm-smmu: Move non-strict mode to use io_pgtable_domain_attr
On 2020-11-25 03:09, Will Deacon wrote:
> On Mon, Nov 23, 2020 at 10:35:56PM +0530, Sai Prakash Ranjan wrote:
>> Now that we have a struct io_pgtable_domain_attr with quirks,
>> use that for non_strict mode as well thereby removing the need
>> for more members of arm_smmu_domain in the future.
>>
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> ---
>> drivers/iommu/arm/arm-smmu/arm-smmu.c | 8 +++-----
>> drivers/iommu/arm/arm-smmu/arm-smmu.h | 1 -
>> 2 files changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> index 4b9b10fe50ed..f56f266ebdf7 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> @@ -786,9 +786,6 @@ static int arm_smmu_init_domain_context(struct
>> iommu_domain *domain,
>> goto out_clear_smmu;
>> }
>>
>> - 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;
>>
>> @@ -1527,7 +1524,8 @@ static int arm_smmu_domain_get_attr(struct
>> iommu_domain *domain,
>> case IOMMU_DOMAIN_DMA:
>> switch (attr) {
>> case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
>> - *(int *)data = smmu_domain->non_strict;
>> + if (smmu_domain->pgtbl_cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT)
>> + *(int *)data = smmu_domain->pgtbl_cfg.quirks;
>
> I still don't think this is right :(
> We need to set *data to 1 or 0 depending on whether or not the
> non-strict
> quirk is set, i.e:
>
> bool non_strict = smmu_domain->pgtbl_cfg.quirks &
> IO_PGTABLE_QUIRK_NON_STRICT;
> *(int *)data = non_strict;
>
> Your code above leaves *data uninitialised if non_strict is not set.

Ugh sorry, I should have looked at this some more before hurrying up
to post, will fix it.

>
>> return 0;
>> default:
>> return -ENODEV;
>> @@ -1578,7 +1576,7 @@ static int arm_smmu_domain_set_attr(struct
>> iommu_domain *domain,
>> case IOMMU_DOMAIN_DMA:
>> switch (attr) {
>> case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
>> - smmu_domain->non_strict = *(int *)data;
>> + smmu_domain->pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>
> And this is broken because if *data is 0, then you _set_ the quirk,
> which is
> the opposite of what we should be doing.
>
> In other words, although the implementation has changed, the semantics
> have
> not.
>

Will fix this to have quirk set only when *data = 1 and unset in case of
0.

Thanks,
Sai

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