Re: [PATCH 3/7] iommu/vt-d: Enhance compatibility check for paging domain attach

[Jason Gunthorpe]

On Mon, Oct 14, 2024 at 09:25:03AM +0800, Baolu Lu wrote:
> > > +	if (domain->type & __IOMMU_DOMAIN_PAGING) {
> > 
> > It looks like this entire function is already never called for
> > anything but paging?
> > 
> > The only three callers are:
> > 
> > 	.default_domain_ops = &(const struct iommu_domain_ops) {
> > 		.attach_dev		= intel_iommu_attach_device,
> > 		.set_dev_pasid		= intel_iommu_set_dev_pasid,
> > 
> > and
> > 
> > static const struct iommu_domain_ops intel_nested_domain_ops = {
> > 	.attach_dev		= intel_nested_attach_dev,
> > 
> > And none of those cases can be anything except a paging domain by
> > definition.
> 
> A nested domain is not a paging domain. It represents a user-space page
> table that nested on a parent paging domain. Perhaps I overlooked
> anything?

It only calls it on the s2_parent which is always a paging domain?

	ret = prepare_domain_attach_device(&dmar_domain->s2_domain->domain, dev);

Jason