tree 2e3311beb25d3bd2e1be8c037aa0cb2d940cbaa8
parent eda2e0a12af1030f95ce224ae23eeb01fcc695c0
author Robert Bragg <robert@sixbynine.org> 1478609508 +0000
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1573582574 +0100

drm/i915: don't whitelist oacontrol in cmd parser

commit 10ff401df041e57afc2b1619cd252b86d0ae5f30 upstream.

Being able to program OACONTROL from a non-privileged batch buffer is
not sufficient to be able to configure the OA unit. This was originally
allowed to help enable Mesa to expose OA counters via the
INTEL_performance_query extension, but the current implementation based
on programming OACONTROL via a batch buffer isn't able to report useable
data without a more complete OA unit configuration. Mesa handles the
possibility that writes to OACONTROL may not be allowed and so only
advertises the extension after explicitly testing that a write to
OACONTROL succeeds. Based on this; removing OACONTROL from the whitelist
should be ok for userspace.

Removing this simplifies adding a new kernel api for configuring the OA
unit without needing to consider the possibility that userspace might
trample on OACONTROL state which we'd like to start managing within
the kernel instead. In particular running any Mesa based GL application
currently results in clearing OACONTROL when initializing which would
disable the capturing of metrics.

v2:
    This bumps the command parser version from 8 to 9, as the change is
    visible to userspace.

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Sourab Gupta <sourab.gupta@intel.com>Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jon Bloomfield <jon.bloomfield@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161108125148.25007-1-robert@sixbynine.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>