Re: [PATCH 1/2] iommu/vt-d: Use rbtree to track iommu probed devices

[Baolu Lu]

On 2024/2/19 13:33, Ethan Zhao wrote:
> On 2/19/2024 12:04 PM, Baolu Lu wrote:
> > On 2024/2/19 10:45, Ethan Zhao wrote:
> > > > @@ -4264,25 +4313,34 @@ static struct iommu_device 
> > > > *intel_iommu_probe_device(struct device *dev)
> > > >       }
> > > >       dev_iommu_priv_set(dev, info);
> > > > +    ret = device_rbtree_insert(iommu, info);
> > > > +    if (ret)
> > > > +        goto free;
> > > >       if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev)) {
> > > >           ret = intel_pasid_alloc_table(dev);
> > > >           if (ret) {
> > > >               dev_err(dev, "PASID table allocation failed\n");
> > > > -            kfree(info);
> > > > -            return ERR_PTR(ret);
> > > > +            goto clear_rbtree;
> > > >           }
> > > >       }
> > > >       intel_iommu_debugfs_create_dev(info);
> > > >       return &iommu->iommu;
> > > > +clear_rbtree:
> > > > +    device_rbtree_remove(info);
> > > > +free:
> > > > +    kfree(info);
> > > > +
> > > > +    return ERR_PTR(ret);
> > > >   }
> > > >   static void intel_iommu_release_device(struct device *dev)
> > > >   {
> > > >       struct device_domain_info *info = dev_iommu_priv_get(dev);
> > > > +    device_rbtree_remove(info);
> > >
> > > Perhpas too early here to remove dev from the rbtree, if it is wanted in
> > > devTLB invalidation steps in intel_pasid_tear_down_entry().
> >
> > Perhaps the caller of device_rbtree_find() should not depend on the
>
> I didn't catch up here. seems have to maintain the lifecycle as PCI 
> subsystem
> does, or there would be mutli instances for the same BDF(e.g. the device is
> removed then plugged, again and again.....in the same slot) in the rbtree ?

There should not be multiple instances for a same BDF. The lifecycle of
a device is managed by the device and driver core. The iommu subsystem
registers a notification to the core and take actions on device ADD and
REMOVE events.

Best regards,
baolu