[Bug 86766] New: [ILK/PNV Bisected]c211a47 drm/i915: Disallow pin ioctl completely for kms drivers

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=86766

            Bug ID: 86766
           Summary: [ILK/PNV Bisected]c211a47 drm/i915: Disallow pin ioctl
                    completely for kms drivers
           Product: DRI
           Version: DRI git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: jinxianx.guo at intel.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

==System Environment==
--------------------------
Regression: Yes

Non-working platforms: ILK PNV

==kernel==
--------------------------
origin/drm-intel-nightly: 904b8529cd69f98b98d33b533a211003f99fb1cd(fails)
    drm-intel-nightly: 2014y-11m-26d-20h-40m-01s UTC integration manifest

==Bug detailed description==
(PNV)igt/gem_pin PASS->NSPT
(ILK)igt/gem_pin PASS->NSPT

==Reproduce steps==
---------------------------- 
1. ./gem_pin

==Bisect results from PRTS==
----------------------------
Bisect shows: c211a47c2c28562f8a3fff9e027be1a3ed9e154a is the first bad commit
commit c211a47c2c28562f8a3fff9e027be1a3ed9e154a
Author:     Daniel Vetter <daniel.vetter at ffwll.ch>
AuthorDate: Mon Nov 24 11:12:42 2014 +0100
Commit:     Daniel Vetter <daniel.vetter at ffwll.ch>
CommitDate: Mon Nov 24 22:36:55 2014 +0100

    drm/i915: Disallow pin ioctl completely for kms drivers

    The problem here is that SNA pins batchbuffers to etch out a bit more
    performance. Iirc it started out as a w/a for i830M (which we've
    implemented in the kernel since a long time already). The problem is
    that the pin ioctl wasn't added in

    commit d23db88c3ab233daed18709e3a24d6c95344117f
    Author: Chris Wilson <chris at chris-wilson.co.uk>
    Date:   Fri May 23 08:48:08 2014 +0200

        drm/i915: Prevent negative relocation deltas from wrapping

    Fix this by simply disallowing pinning from userspace so that the
    kernel is in full control of batch placement again. Especially since
    distros are moving towards running X as non-root, so most users won't
    even be able to see any benefits.

    UMS support is dead now, but we need this minimal patch for
    backporting. Follow-up patch will remove the pin ioctl code
    completely.

    Note to backporters: You must have both

    commit b45305fce5bb1abec263fcff9d81ebecd6306ede
    Author: Daniel Vetter <daniel.vetter at ffwll.ch>
    Date:   Mon Dec 17 16:21:27 2012 +0100

        drm/i915: Implement workaround for broken CS tlb on i830/845

    which laned in 3.8 and

    commit c4d69da167fa967749aeb70bc0e94a457e5d00c1
    Author: Chris Wilson <chris at chris-wilson.co.uk>
    Date:   Mon Sep 8 14:25:41 2014 +0100

        drm/i915: Evict CS TLBs between batches

    which is also marked cc: stable. Otherwise this could introduce a
    regression by disabling the userspace w/a without the kernel w/a being
    fully functional on i830/45.

    References: https://bugs.freedesktop.org/show_bug.cgi?id=76554#c116
    Cc: stable at vger.kernel.org # requires c4d69da167fa967749a and v3.8
    Cc: Chris Wilson <chris at chris-wilson.co.uk>
    Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>

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