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Date:   Wed, 17 Jun 2020 00:31:00 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Rajat Jain <rajatja@google.com>
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Subject: Re: [PATCH 4/4] pci: export untrusted attribute in sysfs
Message-ID: <20200617073100.GA14424@infradead.org>
References: <20200616011742.138975-1-rajatja@google.com>
 <20200616011742.138975-4-rajatja@google.com>
 <20200616073249.GB30385@infradead.org>
 <CACK8Z6ELaM8KxbwPor=BUquWN7pALQmmHu5geSOc71P3KoJ1QA@mail.gmail.com>
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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.