Re: [PATCH 4/4] pci: export untrusted attribute in sysfs

[Greg Kroah-Hartman]

On Wed, Jun 17, 2020 at 12:53:03PM -0700, Rajat Jain wrote:
> Hi Greg, Christoph,
> 
> On Wed, Jun 17, 2020 at 12:31 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> >
> > On Tue, Jun 16, 2020 at 12:27:35PM -0700, Rajat Jain wrote:
> > > Need clarification. The flag "untrusted" is currently a part of
> > > pci_dev struct, and is populated within the PCI subsystem.
> >
> > Yes, and that is the problem.
> >
> > >
> > > 1) Is your suggestion to move this flag as well as the attribute to
> > > device core (in "struct device")? This would allow other buses to
> > > populate/use this flag if they want. By default it'll be set to 0 for
> > > all devices (PCI subsystem will populate it based on platform info,
> > > like it does today).
> > >
> > > OR
> > >
> > > 2) Are you suggesting to keep the "untrusted" flag within PCI, but
> > > attach the sysfs attribute to the base device? (&pci_dev->dev)?
> >
> > (1).  As for IOMMUs and userspace policy it really should not matter
> > what bus a device is on if it is external and not trustworthy.
> 
> Sure. I can move the flag to the "struct device" (and likely call
> it "external" instead of "untrusted" so as to make it suitable for
> more use cases later).  The buses can fill this up if they know which
> devices are external and which ones are not (otherwise it will be 0 by
> default). The PCI can fill this up like it does today, from platform
> info (ACPI / Device tree). Greg, how does this sound?

That's fine, convert USB over to use it at the same time if you get the
chance :)

thanks,

greg k-h