Re: [PATCH v2 1/5] iommu/vt-d: Separate page request queue from SVM

Baolu Lu
2024-09-14T01:22:37Z

On 9/14/24 8:52 AM, Tian, Kevin wrote:
>> From: Joel Granados via B4 Relay
>> <devnull+j.granados.samsung.com@kernel.org>
>>
>> From: Joel Granados<j.granados@samsung.com>
>>
>> IO page faults are no longer dependent on CONFIG_INTEL_IOMMU_SVM.
>> Move
>> all Page Request Queue (PRQ) functions that handle prq events to a new
>> file in drivers/iommu/intel/prq.c. The page_req_des struct is now
>> declared in drivers/iommu/intel/prq.c.
>>
>> No functional changes are intended. This is a preparation patch to
>> enable the use of IO page faults outside the SVM/PASID use cases.
> Do we want to guard it under a new config option e.g.
> CONFIG_INTEL_IOMMU_IOPF? it's unnecessary to allocate resources
> for the majority usages which don't require IOPF.
>
> Baolu?

The OS builder doesn't know if Linux will run on a platform with PRI-
capable devices. They'll probably always enable this option if we
provide it.

This option could be useful for embedded systems, but I'm not sure if
any embedded systems have VT-d hardware, which is mainly for high-end
PCs or cloud servers.

So, maybe we could leave it as is for now and add it later if we see a
real use case.

Thanks,
baolu