Re: [PATCH rc v7 3/6] iommu: Fix pasid attach in pci_dev_reset_iommu_prepare/done()

[Nicolin Chen]

On Fri, Apr 24, 2026 at 01:49:52PM +0800, Baolu Lu wrote:
> On 4/19/26 07:41, Nicolin Chen wrote:
> > -	xa_for_each_start(&group->pasid_array, pasid, entry, 1)
> > -		WARN_ON(__iommu_set_group_pasid(
> > -			pasid_array_entry_to_domain(entry), group, pasid,
> > -			group->blocking_domain));
> > +	if (pdev->dev.iommu->max_pasids > 0) {
> > +		xa_for_each_start(&group->pasid_array, pasid, entry, 1) {
> > +			struct iommu_domain *pasid_dom =
> > +				pasid_array_entry_to_domain(entry);
> > +
> > +			WARN_ON(pasid_dom->ops->set_dev_pasid(
> > +				pasid_dom, &pdev->dev, pasid,
> > +				group->blocking_domain));
> > +		}
> > +	}
> >   	if (!WARN_ON(group->recovery_cnt == 0))
> >   		group->recovery_cnt--;
> 
> I don’t think this patch fixes a real-world issue though it has the
> "Fixes:" tag. Logically, if pdev->dev.iommu->max_pasids == 0, there
> should be no domains attached to any pasid. Consequently,
> group->pasid_array should be empty, and the xa_for_each loop is just a
> no-op.
> 
> I understand this was a result of Sashko's review comments, but I don't
> think it worth a formal fix. I admit I might be overlooking something,
> so please correct me if I am wrong.

The max_pasids check is a small thing, to match other callers.

The fix is replacing __iommu_set_group_pasid() with set_dev_pasid(),
because this path shouldn't change the group-level pasid domains.

Thanks
Nicolin