[Intel-gfx] [PATCH 03/11] drm/i915: Allow the sysadmin to override security mitigations

Chris Wilson chris at chris-wilson.co.uk
Mon Jan 11 21:10:59 UTC 2021

Quoting Abodunrin, Akeem G (2021-01-11 20:58:42)
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Chris
> > Wilson
> > Sent: Sunday, January 10, 2021 7:04 AM
> > To: intel-gfx at lists.freedesktop.org
> > Cc: stable at vger.kernel.org; Chris Wilson <chris at chris-wilson.co.uk>
> > Subject: [Intel-gfx] [PATCH 03/11] drm/i915: Allow the sysadmin to override
> > security mitigations
> > 
> > The clear-residuals mitigation is a relatively heavy hammer and under some
> > circumstances the user may wish to forgo the context isolation in order to
> > meet some performance requirement. Introduce a generic module parameter
> > to allow selectively enabling/disabling different mitigations.

> Although this seems like ideal solution - giving users option to choose *potential* performance over security or vice-versa -  However, I would have expected that this patch adds a DRM warning to inform users of the consequences of their action, whenever module parameter is used to disable any kind of mitigations. Well, that is my own perspective, not as a legal expert.

It's marked as unsafe; setting this parameter will issue a notice and
taint the kernel. That should be enough to warn of the consequences of
their actions, without going into the gruesome details.

I very briefly considered a few pr_warn_once() for each disabled
mitigation, but I am not sure what we should say to the user.

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