RE: [PATCH 1/4] iommu/vt-d: Implement set device pasid op for default domain

[Tian, Kevin]

> From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Thursday, March 2, 2023 10:07 PM
> > +
> > +	if (!sm_supported(iommu) || !info)
> 
> @info has been referenced. !info check makes no sense.
> 
> Add pasid_supported(iommu).
> 
> Do you need to check whether the domain is compatible for this rid
> pasid?

what kind of compatibility is concerned here? In concept a pasid
can be attached to any domain if it has been successfully attached
to rid. Probably we can add a check here that RID2PASID must
point to the domain already.

> 
> > +		return -ENODEV;
> > +
> > +	if (WARN_ON(pasid == PASID_RID2PASID))
> > +		return -EINVAL;
> 
> Add a call to domain_attach_iommu() here to get a refcount of the domain
> ID. And call domain_detach_iommu() in intel_iommu_remove_dev_pasid().
> 

Is it necessary? iommu core doesn't allow taking ownership
if !xa_empty(&group->pasid_array) so if this pasid attach succeeds
this device cannot be attached to another domain before pasid
detach is done on the current domain.