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Date:   Thu, 18 Jun 2020 08:18:21 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Rajat Jain <rajatja@google.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        David Woodhouse <dwmw2@infradead.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>, iommu@lists.linux-foundation.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        linux-acpi@vger.kernel.org, Raj Ashok <ashok.raj@intel.com>,
        "Krishnakumar, Lalithambika" <lalithambika.krishnakumar@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Prashant Malani <pmalani@google.com>,
        Benson Leung <bleung@google.com>,
        Todd Broch <tbroch@google.com>,
        Alex Levin <levinale@google.com>,
        Mattias Nissler <mnissler@google.com>,
        Rajat Jain <rajatxjain@gmail.com>,
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        Christian Kellner <christian@kellner.me>,
        Alex Williamson <alex.williamson@redhat.com>,
        Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH 4/4] pci: export untrusted attribute in sysfs
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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@infradead.org> 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