Re: [PATCH RFCv2 21/24] iommu/arm-smmu-v3: Enable HTTU for stage1 with io-pgtable mapping

[Joao Martins <joao.m.martins@oracle.com>]

On 19/05/2023 14:49, Robin Murphy wrote:
> On 2023-05-18 21:46, Joao Martins wrote:
>> From: Kunkun Jiang <jiangkunkun@huawei.com>
>>
>> As nested mode is not upstreamed now, we just aim to support dirty
>> log tracking for stage1 with io-pgtable mapping (means not support
>> SVA mapping). If HTTU is supported, we enable HA/HD bits in the SMMU
>> CD and transfer ARM_HD quirk to io-pgtable.
>>
>> We additionally filter out HD|HA if not supportted. The CD.HD bit
>> is not particularly useful unless we toggle the DBM bit in the PTE
>> entries.
> 
> ...seeds odd to describe the control which fundamentally enables DBM or not as
> "not particularly useful" to the DBM use-case :/
> 

This is a remnant from v1 where we would just enable the context descriptor HD
bit, but not actually enabling DBM until set_dirty_Tracking(). Which no longer
is the case. Should remove this sentence.

>> Link: https://lore.kernel.org/lkml/20210413085457.25400-6-zhukeqian1@huawei.com/
>> Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
>> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
>> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
>> [joaomart:Convey HD|HA bits over to the context descriptor
>>   and update commit message; original in Link, where this is based on]
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> ---
>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 10 ++++++++++
>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  3 +++
>>   drivers/iommu/io-pgtable-arm.c              | 11 +++++++++--
>>   include/linux/io-pgtable.h                  |  4 ++++
> 
> For the sake of cleanliness, please split the io-pgtable and SMMU additions into
> separate patches (you could perhaps then squash set_dirty_tracking() into the
> SMMU patch as well).
> 
ack