Re: [PATCH v10 04/12] iommu: Add attach/detach_dev_pasid iommu interface

[Baolu Lu]

On 2022/7/25 15:46, Tian, Kevin wrote:
> > From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Sunday, July 24, 2022 5:14 PM
> >
> > On 2022/7/23 22:11, Jason Gunthorpe wrote:
> > > > +void iommu_detach_device_pasid(struct iommu_domain *domain,
> > struct device *dev,
> > > > +			       ioasid_t pasid)
> > > > +{
> > > > +	struct iommu_group *group = iommu_group_get(dev);
> > > > +
> > > > +	mutex_lock(&group->mutex);
> > > > +	domain->ops->block_dev_pasid(domain, dev, pasid);
> > > I still really this OP, it is nonsense to invoke 'block_dev_pasid' on
> > > a domain, it should be on the iommu ops and it should not take in a
> > > domain parameter. This is why I prefer we write it as
> > >
> > > domain->ops->set_dev_pasid(group->blocking_domain, dev, pasid);
> >
> > I originally plan to refactor this after both Intel and ARM SMMUv3
> > drivers have real blocking domain supports. After revisiting this, it
> > seems that the only difficulty is how to check whether a domain is a
> > blocking domain. I am going to use below checking code:
> >
> > +	/*
> > +	 * Detach the domain if a blocking domain is set. Check the
> > +	 * right domain type once the IOMMU driver supports a real
> > +	 * blocking domain.
> > +	 */
> > +	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
> >
> > Does this work for you?
>
> Or you can call __iommu_group_alloc_blocking_domain() in the sva
> path and then just check whether the domain is equal to
> group->blocking_domain here.

Above check is in the IOMMU driver where group->blocking_domain is not
viable. I ever thought about have something like

struct iommu_domain *iommu_group_blocking_domain(struct iommu_group
*group)

to return group->blocking_domain. But it looks redundant.

Best regards,
baolu