Re: [PATCH v5 7/9] iommufd: Associate fault object with iommufd_hw_pgtable

[Baolu Lu]

On 5/15/24 4:50 PM, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Tuesday, April 30, 2024 10:57 PM
> >
> > @@ -227,7 +233,7 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx
> > *ictx,
> >   	refcount_inc(&parent->common.obj.users);
> >   	hwpt_nested->parent = parent;
> >
> > -	hwpt->domain = ops->domain_alloc_user(idev->dev, flags,
> > +	hwpt->domain = ops->domain_alloc_user(idev->dev, 0,
> >   					      parent->common.domain,
> > user_data);
>
> it reads slightly better to clear the fault bit and still pass in flags.

Done.

-       hwpt->domain = ops->domain_alloc_user(idev->dev, 0,
+       hwpt->domain = ops->domain_alloc_user(idev->dev,
+                                             flags & 
~IOMMU_HWPT_FAULT_ID_VALID,
                                              parent->common.domain, 
user_data);

> > @@ -308,6 +314,19 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd
> > *ucmd)
> >   		goto out_put_pt;
> >   	}
> >
> > +	if (cmd->flags & IOMMU_HWPT_FAULT_ID_VALID) {
> > +		struct iommufd_fault *fault;
> > +
> > +		fault = iommufd_get_fault(ucmd, cmd->fault_id);
> > +		if (IS_ERR(fault)) {
> > +			rc = PTR_ERR(fault);
> > +			goto out_hwpt;
> > +		}
> > +		hwpt->fault = fault;
> > +		hwpt->domain->iopf_handler = iommufd_fault_iopf_handler;
> > +		hwpt->domain->fault_data = hwpt;
> > +	}
>
> this is nesting specific. why not moving it to the nested_alloc()?

Nesting is currently a use case for userspace I/O page faults, but this
design should be general enough to support other scenarios as well.

Best regards,
baolu