Re: [PATCH 7/7] iommu: Add iommu_domain::domain_ops

[Lu Baolu]

On 1/24/22 5:58 PM, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Monday, January 24, 2022 3:11 PM
> > +/**
> > + * struct domain_ops - per-domain ops
> > + * @attach_dev: attach an iommu domain to a device
> > + * @detach_dev: detach an iommu domain from a device
>
> What is the criteria about whether an op should be iommu_ops or domain_ops
> when it requires both domain and device pointers like above two (and future
> PASID-based attach)?

Generally ops belong to iommu_ops if they are only device oriented, and
domain_ops if they are only domain oriented. But it's really hard to
judge when both device and domain are involved. Good question. :-)

Perhaps we should leave the attach/detach interfaces in iommu_ops since
they are related to device capabilities. For example, some devices
support attach_dev_pasid, while others not.

> Other examples include:
> 	@apply_resv_region

This will be deprecated.

> 	@is_attach_deferred

Should be at least device centric (domain doesn't play any role here).
Further step is to save the is_attach_deferred at a flag in dev_iommu
and remove the ops (as Robin suggested).

> Thanks
> Kevin

Best regards,
baolu