Re: [PATCH 1/1] iommu/vt-d: Enable PASID during iommu device probe

[Baolu Lu]

On 2022/9/16 10:40, Ethan Zhao wrote:
> > I may not get you exactly. 😄 Some IOMMU features reply on PASID
> > capabilities on both IOMMU and device. The IOMMU drivers enumerate the
> > capabilities and enable them if they are supported.
> I might not express it straightforward,  I mean with this patch iommu 
> deals with
>
> the complexity of enabling PASID (globally?)  or not at probing stage , 
> instead
>
> of other device driver side decision to request IOMMU PASID enabling during
>
> their setup state.  if so you move the decision to iommu probe stage. 
> hmmm...

I am sorry that the commit message was a bit confusing. Actually we
always enable PASID at iommu probe path w/ or w/o this patch.

> Pros,  iommu driver controls everything about PASID enabling.
>
> Cons,  iommu driver handles all possible complexity about capability 
> matching

Do device drivers need to configure PCI PASID without IOMMU? I searched
the tree and found nothing.

Best regards,
baolu