We use DRM_DEBUG() when reporting on user actions, to try and keep
intentional errors out of the CI dmesg. Demote the debug from
i915_gem_open() similarly so that it is only apparent with drm.debug & 1
like its brethren.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161109104507.21228-1-chris@chris-wilson.co.ukReviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

Started with removing INTEL_INFO(dev) and cascaded into a quite
big trickle of function prototype changes. Still, I think it is
for the better.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Plus a small cascade of function prototype changes.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Boost the priority of any rendering required to show the next pageflip
as we want to avoid missing the vblank by being delayed by invisible
workload. We prioritise avoiding jank and jitter in the GUI over
starving background tasks.

v2: Descend dma_fence_array when boosting priorities.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-10-chris@chris-wilson.co.uk

Track the priority of each request and use it to determine the order in
which we submit requests to the hardware via execlists.

The priority of the request is determined by the user (eventually via
the context) but may be overridden at any time by the driver. When we set
the priority of the request, we bump the priority of all of its
dependencies to match - so that a high priority drawing operation is not
stuck behind a background task.

When the request is ready to execute (i.e. we have signaled the submit
fence following completion of all its dependencies, including third
party fences), we put the request into a priority sorted rbtree to be
submitted to the hardware. If the request is higher priority than all
pending requests, it will be submitted on the next context-switch
interrupt as soon as the hardware has completed the current request. We
do not currently preempt any current execution to immediately run a very
high priority request, at least not yet.

One more limitation, is that this is first implementation is for
execlists only so currently limited to gen8/gen9.

v2: Replace recursive priority inheritance bumping with an iterative
depth-first search list.
v3: list_next_entry() for walking lists
v4: Explain how the dfs solves the recursion problem with PI.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-8-chris@chris-wilson.co.uk

The scheduler needs to know the dependencies of each request for the
lifetime of the request, as it may choose to reschedule the requests at
any time and must ensure the dependency tree is not broken. This is in
additional to using the fence to only allow execution after all
dependencies have been completed.

One option was to extend the fence to support the bidirectional
dependency tracking required by the scheduler. However the mismatch in
lifetimes between the submit fence and the request essentially meant
that we had to build a completely separate struct (and we could not
simply reuse the existing waitqueue in the fence for one half of the
dependency tracking). The extra dependency tracking simply did not mesh
well with the fence, and keeping it separate both keeps the fence
implementation simpler and allows us to extend the dependency tracking
into a priority tree (whilst maintaining support for reordering the
tree).

To avoid the additional allocations and list manipulations, the use of
the priotree is disabled when there are no schedulers to use it.

v2: Create a dedicated slab for i915_dependency.
    Rename the lists.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-7-chris@chris-wilson.co.uk

The execlist_lock is now completely subsumed by the engine->timeline->lock,
and so we can remove the redundant layer of locking.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-5-chris@chris-wilson.co.uk

In order to simplify the lockdep annotation, as they become more complex
in the future with deferred execution and multiple paths through the
same functions, create a separate lockclass for the user timeline and
the hardware execution timeline.

We should only ever be locking the user timeline and the execution
timeline in parallel so we only need to create two lock classes, rather
than a separate class for every timeline.

v2: Rename the lock classes to be more consistent with other lockdep.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-2-chris@chris-wilson.co.uk

When we release the shmem backing storage, we make sure that the pages
are coherent with the cpu cache. However, our clflush routine was
skipping the flush as the object had no pages at release time. Fix this by
explicitly flushing the sg_table we are decoupling.

Fixes: 03ac84f1 ("drm/i915: Pass around sg_table to get_pages/put_pages backend")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161111145809.9701-2-chris@chris-wilson.co.uk

In order to walk the list of all timelines, we currently require the
struct_mutex. We are sometimes called prior to the struct_mutex being
taken by the caller (i.e !I915_WAIT_LOCKED) in which case we can only
trust the global execution timelines (as these are owned by the device).
This means in the unlocked phase we can only wait upon the currently
executing requests and not all queued.

[  175.743243] general protection fault: 0000 [#1] SMP
[  175.743263] Modules linked in: nls_iso8859_1 intel_rapl x86_pkg_temp_thermal coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel iwlwifi aesni_intel aes_x86_64 lrw snd_soc_rt5640 gf128mul snd_soc_rl6231 snd_soc_core glue_helper snd_compress snd_pcm_dmaengine snd_hda_codec_hdmi ablk_helper snd_hda_codec_realtek cryptd snd_hda_codec_generic serio_raw cfg80211 snd_hda_intel snd_hda_codec ir_lirc_codec snd_hda_core lirc_dev snd_hwdep snd_pcm lpc_ich mei_me mei snd_seq_midi shpchp snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer rc_rc6_mce acpi_als nuvoton_cir kfifo_buf rc_core snd industrialio snd_soc_sst_acpi soundcore snd_soc_sst_match i2c_designware_platform 8250_dw i2c_designware_core dw_dmac spi_pxa2xx_platform mac_hid acpi_pad parport_pc ppdev lp parport
[  175.743509]  autofs4 i915 e1000e psmouse ptp pps_core xhci_pci ehci_pci ahci xhci_hcd ehci_hcd libahci video sdhci_acpi sdhci i2c_hid hid
[  175.743560] CPU: 2 PID: 2386 Comm: wtdg_monitor.sh Tainted: G     U          4.9.0-rc4-nightly+ #2
[  175.743581] Hardware name:                  /NUC5i7RYB, BIOS RYBDWi35.86A.0358.2016.0606.1423 06/06/2016
[  175.743603] task: ffff88024509ba80 task.stack: ffffc9007bd18000
[  175.743618] RIP: 0010:[<ffffffffa01af29b>]  [<ffffffffa01af29b>] i915_gem_wait_for_idle+0x3b/0x140 [i915]
[  175.743660] RSP: 0000:ffffc9007bd1b9b8  EFLAGS: 00010297
[  175.743674] RAX: ffff88024489d248 RBX: 0000000000000000 RCX: 0000000000000000
[  175.743691] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880244898000
[  175.743708] RBP: ffffc9007bd1b9f0 R08: 0000000000000000 R09: 0000000000000001
[  175.743724] R10: 00000028eaf42792 R11: 0000000000000001 R12: dead000000000100
[  175.743741] R13: dead000000000148 R14: ffffc9007bd1ba5f R15: 0000000000000005
[  175.743758] FS:  00007f2638330700(0000) GS:ffff880256d00000(0000) knlGS:0000000000000000
[  175.743777] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  175.743791] CR2: 00007f885c8cea40 CR3: 00000002416b5000 CR4: 00000000003406e0
[  175.743808] Stack:
[  175.743816]  ffff88024489d248 000000004509ba80 ffff880244898000 ffff88024509ba80
[  175.743840]  00000000ffff8b69 ffffc9007bd1ba5f ffffc9007bd1ba5e ffffc9007bd1ba28
[  175.743863]  ffffffffa01b661d 00000000ffffffff 0000000000000000 ffff880244898000
[  175.743886] Call Trace:
[  175.743906]  [<ffffffffa01b661d>] i915_gem_shrinker_lock_uninterruptible.constprop.5+0x5d/0xc0 [i915]
[  175.743937]  [<ffffffffa01b6cd0>] i915_gem_shrinker_oom+0x30/0x1b0 [i915]
[  175.743955]  [<ffffffff8109ca79>] notifier_call_chain+0x49/0x70
[  175.743971]  [<ffffffff8109cd9d>] __blocking_notifier_call_chain+0x4d/0x70
[  175.743988]  [<ffffffff8109cdd6>] blocking_notifier_call_chain+0x16/0x20
[  175.744005]  [<ffffffff811885dc>] out_of_memory+0x22c/0x480
[  175.744020]  [<ffffffff81205542>] __alloc_pages_slowpath+0x851/0x8ec
[  175.744037]  [<ffffffff8118ca51>] __alloc_pages_nodemask+0x2c1/0x310
[  175.744054]  [<ffffffff811d8ea8>] alloc_pages_current+0x88/0x120
[  175.744070]  [<ffffffff811833a4>] __page_cache_alloc+0xb4/0xc0
[  175.744086]  [<ffffffff811865ca>] filemap_fault+0x29a/0x500
[  175.744101]  [<ffffffff81299aa6>] ext4_filemap_fault+0x36/0x50
[  175.744117]  [<ffffffff811b3d4a>] __do_fault+0x6a/0xe0
[  175.744131]  [<ffffffff811b97ee>] handle_mm_fault+0xd0e/0x1330
[  175.744147]  [<ffffffff8106738c>] __do_page_fault+0x23c/0x4d0
[  175.744162]  [<ffffffff81067650>] do_page_fault+0x30/0x80
[  175.744177]  [<ffffffff817ffbe8>] page_fault+0x28/0x30
[  175.744191] Code: 41 57 41 56 41 55 41 54 53 48 83 ec 10 4c 8b a7 48 52 00 00 89 75 d4 48 89 45 c8 49 39 c4 74 78 4d 8d 6c 24 48 41 bf 05 00 00 00 <49> 8b 5d 00 48 85 db 74 50 8b 83 20 01 00 00 85 c0 74 15 48 8b
[  175.744320] RIP  [<ffffffffa01af29b>] i915_gem_wait_for_idle+0x3b/0x140 [i915]
[  175.744351]  RSP <ffffc9007bd1b9b8>

Fixes: 80b204bc ("drm/i915: Enable multiple timelines")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161111145809.9701-1-chris@chris-wilson.co.uk

A small selection of macros which can only accept dev_priv from
now on and a resulting trickle of fixups.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>

As a side product, had to split two other files;
- i915_gem_fence_reg.h
- i915_gem_object.h (only parts that needed immediate untanglement)

I tried to move code in as big chunks as possible, to make review
easier. i915_vma_compare was moved to a header temporarily.

v2:
- Use i915_gem_fence_reg.{c,h}

v3:
- Rebased

v4:
- Fix building when DEBUG_GEM is enabled by reordering a bit.

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478861034-30643-1-git-send-email-joonas.lahtinen@linux.intel.com

At the moment we allocate enough sg table entries assuming we
will not be able to do any coalescing. But since in practice
we most often can, and more so very effectively, this ends up
wasting a lot of memory.

A simple and effective way of trimming the over-allocated
entries is to copy the table over to a new one allocated to the
exact size.

Experiments on my freshly logged and idle desktop (KDE) showed
that by doing this we can save approximately 1 MiB of RAM, or
when running a typical benchmark like gl_manhattan I have
even seen a 6 MiB saving.

More complicated techniques such as only copying the last used
page and freeing the rest are left to the reader.

v2:
 * Update commit message.
 * Use temporary sg_table on stack. (Chris Wilson)

v3:
 * Commit message update.
 * Comment added.
 * Replace memcpy with copy assignment.
   (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1478704423-7447-1-git-send-email-tvrtko.ursulin@linux.intel.com

We always flush the chipset prior to executing with the GPU, so we can
skip the flush during ordinary domain management.

This should help mitigate some of the potential performance regressions,
but likely trivial, from doing the flush unconditionally before execbuf
introduced in commit dcd79934 ("drm/i915: Unconditionally flush any
chipset buffers before execbuf")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161106130001.9509-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

During resume we will reset the SW/HW tracking for each ring head/tail
pointers and so are not prepared to replay any pending requests (as
opposed to GPU reset time). Add an assert for this both to the suspend
and the resume code.

v2:
- Check for ELSP port idle already during suspend and check !gt.awake
  during resume. (Chris)
v3:
- Move the !gt.awake check to i915_gem_resume().
v4:
- s/intel_lr_engines_idle/intel_execlists_idle/ (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1478510405-11799-4-git-send-email-imre.deak@intel.com

We assume that the GPU is idle once receiving the seqno via the last
request's user interrupt. In execlist mode the corresponding context
completed interrupt can be delayed though and until this latter
interrupt arrives we consider the request to be pending on the ELSP
submit port. This can cause a problem during system suspend where this
last request will be seen by the resume code as still pending. Such
pending requests are normally replayed after a GPU reset, but during
resume we reset both SW and HW tracking of the ring head/tail pointers,
so replaying the pending request with its stale tail pointer will leave
the ring in an inconsistent state. A subsequent request submission can
lead then to the GPU executing from uninitialized area in the ring
behind the above stale tail pointer.

Fix this by making sure any pending request on the ELSP port is
completed before suspending. I used a polling wait since the completion
time I measured was <1ms and since normally we only need to wait during
system suspend. GPU idling during runtime suspend is scheduled with a
delay (currently 50-100ms) after the retirement of the last request at
which point the context completed interrupt must have arrived already.

The chance of this bug was increased by

commit 1c777c5d
Author: Imre Deak <imre.deak@intel.com>
Date:   Wed Oct 12 17:46:37 2016 +0300

    drm/i915/hsw: Fix GPU hang during resume from S3-devices state

but it could happen even without the explicit GPU reset, since we
disable interrupts afterwards during the suspend sequence.

v2:
- Do an unlocked poll-wait first. (Chris)
v3-4:
- s/intel_lr_engines_idle/intel_execlists_idle/ and move
  i915.enable_execlists check to the new helper. (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98470Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1478510405-11799-3-git-send-email-imre.deak@intel.com

There is a small race where a new request can be submitted and retired
after the idle worker started to run which leads to idling the GPU too
early. Fix this by deferring the idling to the pending instance of the
worker.

This scenario was pointed out by Chris.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1478510405-11799-2-git-send-email-imre.deak@intel.com

Valleyview appears to be limited to only scanning out from the first 512MiB
of the Global GTT. Lets presume that this behaviour was inherited from the
display block copied from g4x (not Ironlake) and all earlier generations
are similarly affected, though testing suggests different symptoms. For
simplicity, impose that these platforms must scanout from the mappable
region. (For extra simplicity, use HAS_GMCH_DISPLAY even though this
catches Cherryview which does not appear to be limited to the low
aperture for its scanout.)

v2: Use HAS_GMCH_DISPLAY() to more clearly convey my intent about
limiting this workaround to the old style of display engine.

v3: Update changelog to reflect testing by Ville Syrjälä
v4: Include the changes to the comments as well
Reported-by: NLuis Botello <luis.botello.ortega@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98036
Fixes: 2efb813d ("drm/i915: Fallback to using unmappable memory for scanout")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Akash Goel <akash.goel@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.9-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/20161107110128.28762-1-chris@chris-wilson.co.uk
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com

When we split a large object up into chunks for GTT faulting (because we
can't fit the whole object into the aperture) we have to align our cuts
with the fence registers. Each partial VMA must cover a complete set of
tile rows or the offset into each partial VMA is not aligned with the
whole image. Currently we enforce a minimum size on each partial VMA,
but this minimum size itself was not aligned to the tile row causing
distortion.
Reported-by: NAndreas Reis <andreas.reis@gmail.com>
Reported-by: NChris Clayton <chris2553@googlemail.com>
Reported-by: NNorbert Preining <preining@logic.at>
Tested-by: NNorbert Preining <preining@logic.at>
Tested-by: NChris Clayton <chris2553@googlemail.com>
Fixes: 03af84fe ("drm/i915: Choose partial chunksize based on tile row size")
Fixes: a61007a8 ("drm/i915: Fix partial GGTT faulting") # enabling patch
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98402
Testcase: igt/gem_mmap_gtt/medium-copy-odd
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.9-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/20161107105443.27855-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

commit bc0629a7 ("drm/i915: Track pages pinned due to swizzling
quirk") fixed one problem, but revealed a whole lot more. The root cause
of the pin count mismatch for the swizzle quirk (for L-shaped memory on
gen3/4) was that we were incrementing the pages_pin_count upon getting
the backing pages but then overwriting the pages_pin_count to set it to
1 afterwards. With a little bit of adjustment to satisfy the GEM_BUG_ON
sanitychecks, the fix is to replace the explicit atomic_set with an
atomic_inc.

v2: Consistently use atomics (not mix atomics and helpers) within the
lowlevel get_pages routines. This makes the atomic operations much
clearer.

Fixes: 1233e2db ("drm/i915: Move object backing storage manipulation")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161104103001.27643-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

We can use the preferred KMEM_CACHE helper for brevity.

Also simplifiy error unwind by only setting the ENOMEM
error code once.

v2: Add forgotten changes. (Joonas Lahtinen)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> (v1)
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478099699-28652-1-git-send-email-tvrtko.ursulin@linux.intel.com

$ sed -i -r 's/\bglobal_list\b/global_link/g' *.c *.h

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1478081764-8058-1-git-send-email-joonas.lahtinen@linux.intel.com

Commit 1bec9b0b ("drm/i915/shrinker: Only shmemfs objects
are backed by swap") stopped considering the userptr objects
in shrinker callbacks.

Restore that so idle userptr objects can be discarded in order
to free up memory.

One change further to what was introduced in 1bec9b0b is
to start considering userptr objects in oom but that should
also be a correct thing to do.

v2: Introduce I915_GEM_OBJECT_IS_SHRINKABLE. (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 1bec9b0b ("drm/i915/shrinker: Only shmemfs objects are backed by swap")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1478011450-6634-1-git-send-email-tvrtko.ursulin@linux.intel.com

Unify our approach to things by passing around dev_priv instead of dev.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1477946245-14134-21-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

The shrinker may appear to recurse into obj->mm.lock as the shrinker may
be called from a direct reclaim path whilst handling get_pages. We
filter out recursing on the same obj->mm.lock by inspecting
obj->mm.pages, but we do want to take the lock on a second object in
order to reap their pages. lockdep spots the recursion on the same
lockclass and needs annotation to avoid a false positive. To keep the
two paths distinct, create an enum to indicate which subclass of
obj->mm.lock we are using. This removes the false positive and avoids
masking real bugs.
Suggested-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101121134.27504-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

With full-ppgtt one of the main bottlenecks is the lookup of the VMA
underneath the object. For execbuf there is merit in having a very fast
direct lookup of ctx:handle to the vma using a hashtree, but that still
leaves a large number of other lookups. One way to speed up the lookup
would be to use a rhashtable, but that requires extra allocations and
may exhibit poor worse case behaviour. An alternative is to use an
embedded rbtree, i.e. no extra allocations and deterministic behaviour,
but at the slight cost of O(lgN) lookups (instead of O(1) for
rhashtable). The major of such tree will be very shallow and so not much
slower, and still scales much, much better than the current unsorted
list.

v2: Bump vma_compare() to return a long, as we return the result of
comparing two pointers.

References: https://bugs.freedesktop.org/show_bug.cgi?id=87726Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101115400.15647-1-chris@chris-wilson.co.uk

If we have a tiled object and an unknown CPU swizzle pattern, we pin the
pages to prevent the object from being swapped out (and us corrupting
the contents as we do not know the access pattern and so cannot convert
it to linear and back to tiled on reuse). This requires us to remember
to drop the extra pinning when freeing the object, or else we trigger
warnings about the pin leak. In commit fbbd37b3 ("drm/i915: Move
object release to a freelist + worker"), the object free path was
deferred to a worker, but the unpinning of the quirk, along with marking
the object as reclaimable, was left on the immediate path (so that if
required we could reclaim the pages under memory pressure as early as
possible). However, this split introduced a bug where the pages were no
longer being unpinned if they were marked as unneeded.

[  231.800401] WARNING: CPU: 1 PID: 90 at drivers/gpu/drm/i915/i915_gem.c:4275 __i915_gem_free_objects+0x326/0x3c0 [i915]
[  231.800403] WARN_ON(i915_gem_object_has_pinned_pages(obj))
[  231.800405] Modules linked in:
[  231.800406]  snd_hda_intel i915 snd_hda_codec_generic mei_me snd_hda_codec coretemp snd_hwdep mei lpc_ich snd_hda_core snd_pcm e1000e ptp pps_core [last unloaded: i915]
[  231.800426] CPU: 1 PID: 90 Comm: kworker/1:4 Tainted: G     U          4.9.0-rc2-CI-CI_DRM_1780+ #1
[  231.800428] Hardware name: LENOVO 7465CTO/7465CTO, BIOS 6DET44WW (2.08 ) 04/22/2009
[  231.800456] Workqueue: events __i915_gem_free_work [i915]
[  231.800459]  ffffc9000034fc80 ffffffff8142dd65 ffffc9000034fcd0 0000000000000000
[  231.800465]  ffffc9000034fcc0 ffffffff8107e4e6 000010b300000001 0000000000001000
[  231.800469]  ffff88011d3db740 ffff880130ef0000 0000000000000000 ffff880130ef5ea0
[  231.800474] Call Trace:
[  231.800479]  [<ffffffff8142dd65>] dump_stack+0x67/0x92
[  231.800484]  [<ffffffff8107e4e6>] __warn+0xc6/0xe0
[  231.800487]  [<ffffffff8107e54a>] warn_slowpath_fmt+0x4a/0x50
[  231.800491]  [<ffffffff811d12ac>] ? kmem_cache_free+0x2dc/0x340
[  231.800520]  [<ffffffffa009ef36>] __i915_gem_free_objects+0x326/0x3c0 [i915]
[  231.800548]  [<ffffffffa009effe>] __i915_gem_free_work+0x2e/0x50 [i915]
[  231.800552]  [<ffffffff8109c27c>] process_one_work+0x1ec/0x6b0
[  231.800555]  [<ffffffff8109c1f6>] ? process_one_work+0x166/0x6b0
[  231.800558]  [<ffffffff8109c789>] worker_thread+0x49/0x490
[  231.800561]  [<ffffffff8109c740>] ? process_one_work+0x6b0/0x6b0
[  231.800563]  [<ffffffff8109c740>] ? process_one_work+0x6b0/0x6b0
[  231.800566]  [<ffffffff810a2aab>] kthread+0xeb/0x110
[  231.800569]  [<ffffffff810a29c0>] ? kthread_park+0x60/0x60
[  231.800573]  [<ffffffff818164a7>] ret_from_fork+0x27/0x40

Moving to a separate flag for tracking the quirked pin is overkill for
the bug (since we only have to interchange the two tests in
i915_gem_free_object) but it does reduce a complicated test on all
objects and provide a sanitycheck for uncommon code paths.

Fixes: fbbd37b3 ("drm/i915: Move object release to a freelist + worker")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101100317.11129-2-chris@chris-wilson.co.uk

Whilst waiting on a request, we may do so without holding any locks or
any guards beyond a reference to the request. In order to avoid taking
locks within request deallocation, we drop references to its timeline
(via the context and ppgtt) upon retirement. We should avoid chasing
such pointers outside of their control, in particular we inspect the
request->timeline to see if we may restore the RPS waitboost for a
client. If we instead look at the engine->timeline, we will have similar
behaviour on both full-ppgtt and !full-ppgtt systems and reduce the
amount of reward we give towards stalling clients (i.e. only if the
client stalls and the GPU is uncontended does it reclaim its boost).
This restores behaviour back to pre-timelines, whilst fixing:

[  645.078485] BUG: KASAN: use-after-free in i915_gem_object_wait_fence+0x1ee/0x2e0 at addr ffff8802335643a0
[  645.078577] Read of size 4 by task gem_exec_schedu/28408
[  645.078638] CPU: 1 PID: 28408 Comm: gem_exec_schedu Not tainted 4.9.0-rc2+ #64
[  645.078724] Hardware name:                  /        , BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
[  645.078816]  ffff88022daef9a0 ffffffff8143d059 ffff880235402a80 ffff880233564200
[  645.078998]  ffff88022daef9c8 ffffffff81229c5c ffff88022daefa48 ffff880233564200
[  645.079172]  ffff880235402a80 ffff88022daefa38 ffffffff81229ef0 000000008110a796
[  645.079345] Call Trace:
[  645.079404]  [<ffffffff8143d059>] dump_stack+0x68/0x9f
[  645.079467]  [<ffffffff81229c5c>] kasan_object_err+0x1c/0x70
[  645.079534]  [<ffffffff81229ef0>] kasan_report_error+0x1f0/0x4b0
[  645.079601]  [<ffffffff8122a244>] kasan_report+0x34/0x40
[  645.079676]  [<ffffffff81634f5e>] ? i915_gem_object_wait_fence+0x1ee/0x2e0
[  645.079741]  [<ffffffff81229951>] __asan_load4+0x61/0x80
[  645.079807]  [<ffffffff81634f5e>] i915_gem_object_wait_fence+0x1ee/0x2e0
[  645.079876]  [<ffffffff816364bf>] i915_gem_object_wait+0x19f/0x590
[  645.079944]  [<ffffffff81636320>] ? i915_gem_object_wait_priority+0x500/0x500
[  645.080016]  [<ffffffff8110fb30>] ? debug_show_all_locks+0x1e0/0x1e0
[  645.080084]  [<ffffffff8110abdc>] ? check_chain_key+0x14c/0x210
[  645.080157]  [<ffffffff8110a796>] ? __lock_is_held+0x46/0xc0
[  645.080226]  [<ffffffff8163bc61>] ? i915_gem_set_domain_ioctl+0x141/0x690
[  645.080296]  [<ffffffff8163bcc2>] i915_gem_set_domain_ioctl+0x1a2/0x690
[  645.080366]  [<ffffffff811f8f85>] ? __might_fault+0x75/0xe0
[  645.080433]  [<ffffffff815a55f7>] drm_ioctl+0x327/0x640
[  645.080508]  [<ffffffff8163bb20>] ? i915_gem_obj_prepare_shmem_write+0x3a0/0x3a0
[  645.080603]  [<ffffffff815a52d0>] ? drm_ioctl_permit+0x120/0x120
[  645.080670]  [<ffffffff8110abdc>] ? check_chain_key+0x14c/0x210
[  645.080738]  [<ffffffff81275717>] do_vfs_ioctl+0x127/0xa20
[  645.080804]  [<ffffffff8120268c>] ? do_mmap+0x47c/0x580
[  645.080871]  [<ffffffff811da567>] ? vm_mmap_pgoff+0x117/0x140
[  645.080938]  [<ffffffff812755f0>] ? ioctl_preallocate+0x150/0x150
[  645.081011]  [<ffffffff81108c53>] ? up_write+0x23/0x50
[  645.081078]  [<ffffffff811da567>] ? vm_mmap_pgoff+0x117/0x140
[  645.081145]  [<ffffffff811da450>] ? vma_is_stack_for_current+0x90/0x90
[  645.081214]  [<ffffffff8110d853>] ? mark_held_locks+0x23/0xc0
[  645.082030]  [<ffffffff81288408>] ? __fget+0x168/0x250
[  645.082106]  [<ffffffff819ad517>] ? entry_SYSCALL_64_fastpath+0x5/0xb1
[  645.082176]  [<ffffffff81288592>] ? __fget_light+0xa2/0xc0
[  645.082242]  [<ffffffff8127604c>] SyS_ioctl+0x3c/0x70
[  645.082309]  [<ffffffff819ad52e>] entry_SYSCALL_64_fastpath+0x1c/0xb1
[  645.082374] Object at ffff880233564200, in cache kmalloc-8192 size: 8192
[  645.082431] Allocated:
[  645.082480] PID = 28408
[  645.082535]  [  645.082566] [<ffffffff8103ae66>] save_stack_trace+0x16/0x20
[  645.082623]  [  645.082656] [<ffffffff81228b06>] save_stack+0x46/0xd0
[  645.082716]  [  645.082756] [<ffffffff812292fd>] kasan_kmalloc+0xad/0xe0
[  645.082817]  [  645.082848] [<ffffffff81631752>] i915_ppgtt_create+0x52/0x220
[  645.082908]  [  645.082941] [<ffffffff8161db96>] i915_gem_create_context+0x396/0x560
[  645.083027]  [  645.083059] [<ffffffff8161f857>] i915_gem_context_create_ioctl+0x97/0xf0
[  645.083152]  [  645.083183] [<ffffffff815a55f7>] drm_ioctl+0x327/0x640
[  645.083243]  [  645.083274] [<ffffffff81275717>] do_vfs_ioctl+0x127/0xa20
[  645.083334]  [  645.083372] [<ffffffff8127604c>] SyS_ioctl+0x3c/0x70
[  645.083432]  [  645.083464] [<ffffffff819ad52e>] entry_SYSCALL_64_fastpath+0x1c/0xb1
[  645.083551] Freed:
[  645.083599] PID = 27629
[  645.083648]  [  645.083676] [<ffffffff8103ae66>] save_stack_trace+0x16/0x20
[  645.083738]  [  645.083770] [<ffffffff81228b06>] save_stack+0x46/0xd0
[  645.083830]  [  645.083862] [<ffffffff81229203>] kasan_slab_free+0x73/0xc0
[  645.083922]  [  645.083961] [<ffffffff812279c9>] kfree+0xa9/0x170
[  645.084021]  [  645.084053] [<ffffffff81629f60>] i915_ppgtt_release+0x100/0x180
[  645.084139]  [  645.084171] [<ffffffff8161d414>] i915_gem_context_free+0x1b4/0x230
[  645.084257]  [  645.084288] [<ffffffff816537b2>] intel_lr_context_unpin+0x192/0x230
[  645.084380]  [  645.084413] [<ffffffff81645250>] i915_gem_request_retire+0x620/0x630
[  645.084500]  [  645.085226] [<ffffffff816473d1>] i915_gem_retire_requests+0x181/0x280
[  645.085313]  [  645.085352] [<ffffffff816352ba>] i915_gem_retire_work_handler+0xca/0xe0
[  645.085440]  [  645.085471] [<ffffffff810c725b>] process_one_work+0x4fb/0x920
[  645.085532]  [  645.085562] [<ffffffff810c770d>] worker_thread+0x8d/0x840
[  645.085622]  [  645.085653] [<ffffffff810d21e5>] kthread+0x185/0x1b0
[  645.085718]  [  645.085750] [<ffffffff819ad7a7>] ret_from_fork+0x27/0x40
[  645.085811] Memory state around the buggy address:
[  645.085869]  ffff880233564280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  645.085956]  ffff880233564300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  645.086053] >ffff880233564380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  645.086138]                                ^
[  645.086193]  ffff880233564400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  645.086283]  ffff880233564480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

v2: Add a comment to document the hint like nature of
 intel_engine_last_submit()

Fixes: 73cb9701 ("drm/i915: Combine seqno + tracking into a global timeline struct")
Fixes: 80b204bc ("drm/i915: Enable multiple timelines")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101100317.11129-1-chris@chris-wilson.co.uk

To flush all call_rcu() tasks (here from i915_gem_free_object()) we need
to call rcu_barrier() (not synchronize_rcu()). If we don't then we may
still have objects being freed as we continue to teardown the driver -
in particular, the recently released rings may race with the memory
manager shutdown resulting in sporadic:

[  142.217186] WARNING: CPU: 7 PID: 6185 at drivers/gpu/drm/drm_mm.c:932 drm_mm_takedown+0x2e/0x40
[  142.217187] Memory manager not clean during takedown.
[  142.217187] Modules linked in: i915(-) x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel lpc_ich snd_hda_codec_realtek snd_hda_codec_generic mei_me mei snd_hda_codec_hdmi snd_hda_codec snd_hwdep snd_hda_core snd_pcm e1000e ptp pps_core [last unloaded: snd_hda_intel]
[  142.217199] CPU: 7 PID: 6185 Comm: rmmod Not tainted 4.9.0-rc2-CI-Trybot_242+ #1
[  142.217199] Hardware name: LENOVO 10AGS00601/SHARKBAY, BIOS FBKT34AUS 04/24/2013
[  142.217200]  ffffc90002ecfce0 ffffffff8142dd65 ffffc90002ecfd30 0000000000000000
[  142.217202]  ffffc90002ecfd20 ffffffff8107e4e6 000003a40778c2a8 ffff880401355c48
[  142.217204]  ffff88040778c2a8 ffffffffa040f3c0 ffffffffa040f4a0 00005621fbf8b1f0
[  142.217206] Call Trace:
[  142.217209]  [<ffffffff8142dd65>] dump_stack+0x67/0x92
[  142.217211]  [<ffffffff8107e4e6>] __warn+0xc6/0xe0
[  142.217213]  [<ffffffff8107e54a>] warn_slowpath_fmt+0x4a/0x50
[  142.217214]  [<ffffffff81559e3e>] drm_mm_takedown+0x2e/0x40
[  142.217236]  [<ffffffffa035c02a>] i915_gem_cleanup_stolen+0x1a/0x20 [i915]
[  142.217246]  [<ffffffffa034c581>] i915_ggtt_cleanup_hw+0x31/0xb0 [i915]
[  142.217253]  [<ffffffffa0310311>] i915_driver_cleanup_hw+0x31/0x40 [i915]
[  142.217260]  [<ffffffffa0312001>] i915_driver_unload+0x141/0x1a0 [i915]
[  142.217268]  [<ffffffffa031c2c4>] i915_pci_remove+0x14/0x20 [i915]
[  142.217269]  [<ffffffff8147d214>] pci_device_remove+0x34/0xb0
[  142.217271]  [<ffffffff8157b14c>] __device_release_driver+0x9c/0x150
[  142.217272]  [<ffffffff8157bcc6>] driver_detach+0xb6/0xc0
[  142.217273]  [<ffffffff8157abe3>] bus_remove_driver+0x53/0xd0
[  142.217274]  [<ffffffff8157c787>] driver_unregister+0x27/0x50
[  142.217276]  [<ffffffff8147c265>] pci_unregister_driver+0x25/0x70
[  142.217287]  [<ffffffffa03d764c>] i915_exit+0x1a/0x71 [i915]
[  142.217289]  [<ffffffff811136b3>] SyS_delete_module+0x193/0x1e0
[  142.217291]  [<ffffffff818174ae>] entry_SYSCALL_64_fastpath+0x1c/0xb1
[  142.217292] ---[ end trace 6fd164859c154772 ]---
[  142.217505] [drm:show_leaks] *ERROR* node [6b6b6b6b6b6b6b6b + 6b6b6b6b6b6b6b6b]: inserted at
                [<ffffffff81559ff3>] save_stack.isra.1+0x53/0xa0
                [<ffffffff8155a98d>] drm_mm_insert_node_in_range_generic+0x2ad/0x360
                [<ffffffffa035bf23>] i915_gem_stolen_insert_node_in_range+0x93/0xe0 [i915]
                [<ffffffffa035c855>] i915_gem_object_create_stolen+0x75/0xb0 [i915]
                [<ffffffffa036a51a>] intel_engine_create_ring+0x9a/0x140 [i915]
                [<ffffffffa036a921>] intel_init_ring_buffer+0xf1/0x440 [i915]
                [<ffffffffa036be1b>] intel_init_render_ring_buffer+0xab/0x1b0 [i915]
                [<ffffffffa0363d08>] intel_engines_init+0xc8/0x210 [i915]
                [<ffffffffa0355d7c>] i915_gem_init+0xac/0xf0 [i915]
                [<ffffffffa0311454>] i915_driver_load+0x9c4/0x1430 [i915]
                [<ffffffffa031c2f8>] i915_pci_probe+0x28/0x40 [i915]
                [<ffffffff8147d315>] pci_device_probe+0x85/0xf0
                [<ffffffff8157b7ff>] driver_probe_device+0x21f/0x430
                [<ffffffff8157baee>] __driver_attach+0xde/0xe0

In particular note that the node was being poisoned as we inspected the
list, a  clear indication that the object is being freed as we make the
assertion.

v2: Don't loop, just assert that we do all the work required as that
will be better at detecting further errors.

Fixes: fbbd37b3 ("drm/i915: Move object release to a freelist + worker")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161101084843.3961-1-chris@chris-wilson.co.uk

With the infrastructure converted over to tracking multiple timelines in
the GEM API whilst preserving the efficiency of using a single execution
timeline internally, we can now assign a separate timeline to every
context with full-ppgtt.

v2: Add a comment to indicate the xfer between timelines upon submission.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-35-chris@chris-wilson.co.uk

A restriction on our global seqno is that they cannot wrap, and that we
cannot use the value 0. This allows us to detect when a request has not
yet been submitted, its global seqno is still 0, and ensures that
hardware semaphores are monotonic as required by older hardware. To
meet these restrictions when we defer the assignment of the global
seqno, we must check that we have an available slot in the global seqno
space during request construction. If that test fails, we wait for all
requests to be completed and reset the hardware back to 0.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-33-chris@chris-wilson.co.uk

Though we will have multiple timelines, we still have a single timeline
of execution. This we can use to provide an execution and retirement order
of requests. This keeps tracking execution of requests simple, and vital
for preserving a single waiter (i.e. so that we can order the waiters so
that only the earliest to wakeup need be woken). To accomplish this we
distinguish the seqno used to order requests per-context (external) and
that used internally for execution.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-26-chris@chris-wilson.co.uk

Before suspend, we wait for the switch to the kernel context. In order
for all the other context images to be complete upon suspend, that
switch must be the last operation by the GPU (i.e. this idling request
must not overtake any pending requests). To make this request execute last,
we make it depend on every other inflight request.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-24-chris@chris-wilson.co.uk

Our timelines are more than just a seqno. They also provide an ordered
list of requests to be executed. Due to the restriction of handling
individual address spaces, we are limited to a timeline per address
space but we use a fence context per engine within.

Our first step to introducing independent timelines per context (i.e. to
allow each context to have a queue of requests to execute that have a
defined set of dependencies on other requests) is to provide a timeline
abstraction for the global execution queue.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-23-chris@chris-wilson.co.uk

In preparation to support many distinct timelines, we need to expand the
activity tracking on the GEM object to handle more than just a request
per engine. We already use the struct reservation_object on the dma-buf
to handle many fence contexts, so integrating that into the GEM object
itself is the preferred solution. (For example, we can now share the same
reservation_object between every consumer/producer using this buffer and
skip the manual import/export via dma-buf.)

v2: Reimplement busy-ioctl (by walking the reservation object), postpone
the ABI change for another day. Similarly use the reservation object to
find the last_write request (if active and from i915) for choosing
display CS flips.

Caveats:

 * busy-ioctl: busy-ioctl only reports on the native fences, it will not
warn of stalls (in set-domain-ioctl, pread/pwrite etc) if the object is
being rendered to by external fences. It also will not report the same
busy state as wait-ioctl (or polling on the dma-buf) in the same
circumstances. On the plus side, it does retain reporting of which
*i915* engines are engaged with this object.

 * non-blocking atomic modesets take a step backwards as the wait for
render completion blocks the ioctl. This is fixed in a subsequent
patch to use a fence instead for awaiting on the rendering, see
"drm/i915: Restore nonblocking awaits for modesetting"

 * dynamic array manipulation for shared-fences in reservation is slower
than the previous lockless static assignment (e.g. gem_exec_lut_handle
runtime on ivb goes from 42s to 66s), mainly due to atomic operations
(maintaining the fence refcounts).

 * loss of object-level retirement callbacks, emulated by VMA retirement
tracking.

 * minor loss of object-level last activity information from debugfs,
could be replaced with per-vma information if desired
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-21-chris@chris-wilson.co.uk

Having moved the locked phase of freeing an object to a separate worker,
we can now declare to the core that we only need the unlocked variant of
driver->gem_free_object, and can use the simple unreference internally.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-20-chris@chris-wilson.co.uk

We want to hide the latency of releasing objects and their backing
storage from the submission, so we move the actual free to a worker.
This allows us to switch to struct_mutex freeing of the object in the
next patch.

Furthermore, if we know that the object we are dereferencing remains valid
for the duration of our access, we can forgo the usual synchronisation
barriers and atomic reference counting. To ensure this we defer freeing
an object til after an RCU grace period, such that any lookup of the
object within an RCU read critical section will remain valid until
after we exit that critical section. We also employ this delay for
rate-limiting the serialisation on reallocation - we have to slow down
object creation in order to prevent resource starvation (in particular,
files).

v2: Return early in i915_gem_tiling() ioctl to skip over superfluous
work on error.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-19-chris@chris-wilson.co.uk

As we can locklessly (well struct_mutex-lessly) acquire the backing
storage, do so in set-domain-ioctl to reduce the contention on the
struct_mutex.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-18-chris@chris-wilson.co.uk

We only need struct_mutex within pwrite for a brief window where we need
to serialise with rendering and control our cache domains. Elsewhere we
can rely on the backing storage being pinned, and forgive userspace any
races against us.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-17-chris@chris-wilson.co.uk