On Thu, 23 Jun 2022 08:46:45 +0000 "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote: > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Sent: Thursday, June 23, 2022 6:17 AM > > > > > > > > ret = -EIO; > > > - domain->domain = iommu_domain_alloc(bus); > > > + domain->domain = iommu_domain_alloc(iommu_api_dev->dev- > > >bus); > > > > It makes sense to move away from a bus centric interface to iommu ops > > and I can see that having a device interface when we have device level > > address-ability within a group makes sense, but does it make sense to > > only have that device level interface? For example, if an iommu_group > > is going to remain an aspect of the iommu subsystem, shouldn't we be > > able to allocate a domain and test capabilities based on the group and > > the iommu driver should have enough embedded information reachable > > from > > the struct iommu_group to do those things? This "perform group level > > operations based on an arbitrary device in the group" is pretty klunky. > > Thanks, > > > > This sounds a right thing to do. > > btw another alternative which I'm thinking of is whether vfio_group > can record the bus info when the first device is added to it in > __vfio_register_dev(). Then we don't need a group interface from > iommu to test if vfio is the only user having such requirement. That might be more simple, but it's just another variation on vfio picking an arbitrary device from a group to satisfy the iommu interface rather than operating on an iommu subsystem provided object. Thanks, Alex
