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SubjectRe: [PATCH v7 5/6] iommu/arm-smmu-v3: Add support for non-strict mode
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On 2018-09-18 6:10 PM, Will Deacon wrote:
> On Fri, Sep 14, 2018 at 03:30:23PM +0100, Robin Murphy wrote:
>> From: Zhen Lei <thunder.leizhen@huawei.com>
>>
>> Dynamically choose strict or non-strict mode for page table config based
>> on the iommu domain type.
>
> It's the domain type in conjunction with the attribute that determines
> whether we use lazy or strict invalidation.
>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> [rm: convert to domain attribute]
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>> drivers/iommu/arm-smmu-v3.c | 30 ++++++++++++++++++++++++------
>> 1 file changed, 24 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index f10c852479fc..7bbfa5f7ce8e 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -612,6 +612,7 @@ struct arm_smmu_domain {
>> struct mutex init_mutex; /* Protects smmu pointer */
>>
>> struct io_pgtable_ops *pgtbl_ops;
>> + bool non_strict;
>>
>> enum arm_smmu_domain_stage stage;
>> union {
>> @@ -1633,6 +1634,9 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain)
>> if (smmu->features & ARM_SMMU_FEAT_COHERENCY)
>> pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_NO_DMA;
>>
>> + if (smmu_domain->non_strict)
>> + pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>> +
>> pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
>> if (!pgtbl_ops)
>> return -ENOMEM;
>> @@ -1934,13 +1938,17 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
>> {
>> struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>
>> - if (domain->type != IOMMU_DOMAIN_UNMANAGED)
>> - return -EINVAL;
>> -
>> switch (attr) {
>> case DOMAIN_ATTR_NESTING:
>> + if (domain->type != IOMMU_DOMAIN_UNMANAGED)
>> + return -EINVAL;
>> *(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
>> return 0;
>> + case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
>> + if (domain->type != IOMMU_DOMAIN_DMA)
>> + return -EINVAL;
>> + *(int *)data = smmu_domain->non_strict;
>> + return 0;
>> default:
>> return -ENODEV;
>
> Hmm, there's a change in behaviour here (and also in the set function)
> which is that unknown attributes now return -ENODEV for managed domains
> instead of -EINVAL. I don't know if that's a problem, but I'd be inclined
> to switch on the domain type and then have a nested switch for the supported
> attributes.

Sure, a nested switch did actually cross my mind, but I was worried it
might be a little boilerplate-heavy since there's still only one of each
case (and this quick'n'dirty copy-paste job didn't need any thought...)

If that's your preference too, though, I'll respin both driver patches
that way.

Robin.

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