linux-kernel - Re: [PATCH v2 2/7] PCI: Set "untrusted" flag for truly external devices only

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Date:   Mon, 6 Jul 2020 20:48:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Rajat Jain <rajatja@...gle.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-acpi@...r.kernel.org, Raj Ashok <ashok.raj@...el.com>,
        lalithambika.krishnakumar@...el.com,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Prashant Malani <pmalani@...gle.com>,
        Benson Leung <bleung@...gle.com>,
        Todd Broch <tbroch@...gle.com>,
        Alex Levin <levinale@...gle.com>,
        Mattias Nissler <mnissler@...gle.com>,
        Rajat Jain <rajatxjain@...il.com>,
        Bernie Keany <bernie.keany@...el.com>,
        Aaron Durbin <adurbin@...gle.com>,
        Diego Rivas <diegorivas@...gle.com>,
        Duncan Laurie <dlaurie@...gle.com>,
        Furquan Shaikh <furquan@...gle.com>,
        Jesse Barnes <jsbarnes@...gle.com>,
        Christian Kellner <christian@...lner.me>,
        Alex Williamson <alex.williamson@...hat.com>, oohall@...il.com,
        Saravana Kannan <saravanak@...gle.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v2 2/7] PCI: Set "untrusted" flag for truly external
 devices only

On Mon, Jul 06, 2020 at 11:41:26AM -0500, Bjorn Helgaas wrote:
> On Tue, Jun 30, 2020 at 09:55:54AM +0200, Greg Kroah-Hartman wrote:
> > On Mon, Jun 29, 2020 at 09:49:38PM -0700, Rajat Jain wrote:
> > > The "ExternalFacing" devices (root ports) are still internal devices that
> > > sit on the internal system fabric and thus trusted. Currently they were
> > > being marked untrusted.
> > > 
> > > This patch uses the platform flag to identify the external facing devices
> > > and then use it to mark any downstream devices as "untrusted". The
> > > external-facing devices themselves are left as "trusted". This was
> > > discussed here: https://lkml.org/lkml/2020/6/10/1049
> > 
> > {sigh}
> > 
> > First off, please use lore.kernel.org links, we don't control lkml.org
> > and it often times has been down.
> > 
> > Also, you need to put all of the information in the changelog, referring
> > to another place isn't always the best thing, considering you will be
> > looking this up in 20+ years to try to figure out why people came up
> > with such a crazy design.
> > 
> > But, the main point is, no, we did not decide on this.  "trust" is a
> > policy decision to make by userspace, it is independant of "location",
> > while you are tieing it directly here, which is what I explicitly said
> > NOT to do.
> > 
> > So again, no, I will NAK this patch as-is, sorry, you are mixing things
> > together in a way that it should not do at this point in time.
> 
> What do you see being mixed together here?  I acknowledge that the
> name of "pdev->untrusted" is probably a mistake.  But this patch
> doesn't change anything there.  It only changes the treatment of the
> edge case of the "ExternalFacing" ports.  Previously we treated them
> as being external themselves, which does seem wrong.

I don't see the patch here, and it's been a while but I think there is a
mixture of "location" and "trust" happening here with a single value
when they should be separate.

Hopefully the next round of this patch series will be better.

thanks,

greg k-h