Re: [RFC PATCH v2 5/6] PCI/TSM: Authenticate devices via platform TSM

[Dan Williams <dan.j.williams@intel.com>]

Xu Yilun wrote:
> > > > +
> > > > +/* collect TSM capable devices to rendezvous with the tsm driver */
> > > > +static DEFINE_XARRAY(pci_tsm_devs);
> > > 
> > > imho either this or pci_dev::tsm is enough but not necessarily both.
> > 
> > You mean:
> > 
> > s/pci_tsm_devs/tsm_devs/
> > 
> > ?
> 
> I don't think the concern is just a renaming. My understanding is, we
> already have a struct pci_tsm embedded in struct pci_dev, we could loop
> and find all TSM capable devices by:
> 
> 	for_each_pci_dev(pdev) {
> 		if (pdev->tsm)
> 			pci_tsm_add/del(pdev);
> 	}
> A dedicated list for TSM capable devices seems not necessary.

Not the first time this criticism has been raised against pci_tsm_devs.
I think for_each_pci_dev() is potentially wasteful, but it is trivial to
add back if for_each_pci_dev() scanning becomes too expensive.

> But my concern is about VFs.  VFs are as well TSM capable but not
> applicable for tsm_ops->exec(TSM_EXEC_CONNECT), maybe not applicable
> for tsm_ops->add() either.  One way to distinguish PF/VFs is we only
> collect PFs in pci_tsm_devs, but all TSM capable devices have
> valid pci_dev::tsm pointer.
> 
> TSM capable devices in Guest should not been collected in pci_tsm_devs
> either.

Yes, for this initial phase of the enabling only PF operations are
relevant.