Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478270568-7902-2-git-send-email-tvrtko.ursulin@linux.intel.com

After this patch only conversion of INTEL_INFO(p)->gen to
INTEL_GEN(dev_priv) remains before the __I915__ macro can
be removed.

v2: Tidy vlv_compute_wm. (David Weinehall)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>

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>

A small selection of macros which can only accept dev_priv from
now on and a resulting trickle of fixups.

v2: Keep original order. (Ville Syrjala)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>

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

Merge tag 'gvt-next-kvmgt-framework' of https://github.com/01org/gvt-linux into drm-intel-next-queued

Zhenyu Wang writes:

gvt-next-kvmgt-framework

This adds initial KVMGT framework based on GVT-g MPT(Mediated Passthrough) interface.
Signed-off-by: NDaniel Vetter <daniel.vetter@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

KVMGT is the MPT implementation based on VFIO/KVM. It provides
a kvmgt_mpt ops to gvt for vGPU access mediation, e.g. to
mediate and emulate the MMIO accesses, to inject interrupts
to vGPU user, to intercept the GTT writing and replace it with
DMA-able address, to write-protect guest PPGTT table for
shadowing synchronization, etc. This patch provides the MPT
implementation for GVT, not yet functional due to theabsence
of mdev.

It's built as kvmgt.ko, depends on vfio.ko, kvm.ko and mdev.ko,
and being required by i915.ko. To not introduce hard dependency
in i915.ko, we used indirect symbol reference. But that means
users have to include kvmgt.ko into init ramdisk if their
i915.ko is included.
Signed-off-by: NKevin Tian <kevin.tian@intel.com>
Signed-off-by: NXiaoguang Chen <xiaoguang.chen@intel.com>
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

There are currently 4 methods in intel_gvt_io_emulation_ops
to emulate CFG/MMIO reading/writing for intel vGPU. A possibly
better scope is: add 3 more methods for vgpu create/destroy/reset
respectively, and rename the ops to 'intel_gvt_ops', then pass
it to the MPT module (say the future kvmgt) to use: they are
all methods for external usage.
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

Hypervisors are different, the MPT ops is a only superset of
all possibly supported hypervisors. There might be other way
out of the MPT to achieve same target. e.g. vfio-based kvmgt
won't provide map_gfn_to_mfn method to establish guest EPT
mapping for aperture, since it will be done in QEMU/KVM, MMIO
is also trapped elsewhere, etc.
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

GVT host needs init/exit hooks to do some initialization/cleanup
work, e.g.: vfio mdev host device register/unregister.
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

Current GVT contains some obsolete logic originally cooked to
support the old, non-vfio kvmgt, which is actually workarounds.
We don't support that anymore, so it's safe to remove it and
make a better framework.
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

By providing predefined vGPU types, users can choose which type a vgpu
to create and use, without specifying detailed parameters.
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NJike Song <jike.song@intel.com>

kmap_atomic doesn't allow sleep until unmapped. However,
it's necessary to allow sleep during reading/writing guest
memory, so use kmap instead.
Signed-off-by: NBing Niu <bing.niu@intel.com>
Signed-off-by: NXiaoguang Chen <xiaoguang.chen@intel.com>
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

On guest writing a PPGTT entry, if it contains value and the old
entry is valid, gvt will read it and find & free the corresponding
old data for it. However, with the KVM write protection provided
by page_track, the guest entry will be written with new value
before gvt handling. To avoid that, we should use the shadow
entry instead.
Signed-off-by: NBing Niu <bing.niu@intel.com>
Signed-off-by: NJike Song <jike.song@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>

Paulo Bonzini writes:

The three KVM patches that KVMGT needs.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

When we need to reset the global seqno on wraparound, we have to wait
until the current rbtrees are drained (or otherwise the next waiter will
be out of sequence). The current mechanism to kick and spin until
complete, may exit too early as it would break if the target thread was
currently running. Instead, we must wake up the threads, but keep
spinning until the trees have been deleted.

In order to appease Tvrtko, busy spin rather than yield().
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161108143719.32215-1-chris@chris-wilson.co.ukReviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

This gets rid of a warning that the connectors are used without locking
when doing a nonblocking modeset.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-11-git-send-email-maarten.lankhorst@linux.intel.com

All of this state should be updated as soon as possible. It shouldn't be
done later because then future updates may not depend on it.

Changes since v1:
- Move the modeset update to before drm_atomic_state_get. (Ville)
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-10-git-send-email-maarten.lankhorst@linux.intel.comReviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>

The only user was i915, which is now gone.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Dave Airlie <airlied@redhat.com> #irc
Cc: dri-devel@lists.freedesktop.org
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-9-git-send-email-maarten.lankhorst@linux.intel.com

drm_select_eld requires mode_config.mutex and connection_mutex
because it looks at the connector list and at the legacy encoders.

This is not required, because when we call audio_codec_enable we know
which connector it was called for, so pass the state.

This also removes having to look at crtc->config.

Changes since v1:
- Use intel_crtc->pipe instead of drm_crtc_index. (Ville)
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-8-git-send-email-maarten.lankhorst@linux.intel.comReviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>

This is the last connector still looking at crtc->config. Fix this.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478609742-13603-7-git-send-email-maarten.lankhorst@linux.intel.com

The newly added assert_kernel_context_is_current introduces a warning
when built with W=1:

drivers/gpu/drm/i915/i915_gem.c: In function ‘assert_kernel_context_is_current’:
drivers/gpu/drm/i915/i915_gem.c:4417:63: error: suggest braces around empty body in an ‘else’ statement [-Werror=empty-body]

Changing the GEM_BUG_ON() macro from an empty definition to "do { } while (0)"
makes the macro more robust to use and avoids the warning.

Fixes: 3033acab ("drm/i915: Queue the idling context switch after all other timelines")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161108135834.2166677-1-arnd@arndb.de

gvt-next-2016-11-07

- Fix regression from e95433c7
- Some MMIO handler fixes
- Add better handling for guest reset control
- stratch page table tree for shadow ppgtt
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

The code to determine the primary plane offset for gen2/3 looks
different than the code for gen4+, but in fact it's doing the same
thing. Let's make it uniform. Allows us to eliminate the 'obj' from
the list of local variables as well.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478550057-24864-6-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

intel_cursor_plane_create() and intel_sprite_plane_create() return
an error pointer, so let's not mistakenly look for a NULL pointer.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: NChris Wilson <chris@chris-wilson.co.uk>
References: https://lists.freedesktop.org/archives/intel-gfx/2016-November/110690.html
Fixes: b079bd17 ("drm/i915: Bail if plane/crtc init fails")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478550057-24864-5-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Use the passed in plane_state instead of plane->state in
vlv_update_plane(). Currently the two are one and the same, but if we
start queuing up multiple plane updates they might not be.

Looks like this was rebase fail on my part.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 8d0deca8 ("drm/i915: Pass 90/270 vs. 0/180 rotation info for intel_gen4_compute_page_offset()")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478550057-24864-4-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

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>

Get rid of sloppy inline functions now that we don't have more users:

i915_gem_request_get_seqno
i915_gem_request_get_engine

v2:
- request->engine is always non-NULL (Chris)
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.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/1478589108-3702-1-git-send-email-joonas.lahtinen@linux.intel.com

Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

On LLC, or even snooped, machines rendering via the GPU ends up in the CPU
cache. This cacheline dirt also needs to be flushed to main memory when
moving to an incoherent domain, such as the display's scanout engine.
Mostly, this happens because either the object is marked as dirty from
its first use or is avoided by setting the object into the display
domain from the start.

v2: Treat WT as not requiring a clflush prior to use on the display
engine as well.

Fixes: 0f71979a ("drm/i915: Performed deferred clflush inside set-cache-level")
References: https://bugs.freedesktop.org/show_bug.cgi?id=95414Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v4.0+
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161107165204.7008-1-chris@chris-wilson.co.uk

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

Atm, in case an idle work handler is already pending but haven't yet
started to run, retiring a new request will not extend the active period
as required, rather simply leaves the pending idle work to be scheduled
at the original expiration time. This may lead to idling the GPU too
early. Fix this by using the delayed-work scheduler alternative which
makes sure the handler's expiration time is extended in this case.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Requested-by: NChris 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/1478510405-11799-1-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>

Currently, the vma is being unlink from the object lookup on destroy.
However, we are meant to be decoupling it upon close so that the user
cannot access the closed vma whilst it remains active on the GPU.

[   34.074858] kernel BUG at drivers/gpu/drm/i915/i915_gem_gtt.c:3561!
[   34.074875] invalid opcode: 0000 [#1] PREEMPT SMP
[   34.074888] Modules linked in: snd_hda_intel i915 x86_pkg_temp_thermal coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel lpc_ich mei_me mei snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi snd_hda_codec snd_hwdep snd_hda_core i2c_designware_platform i2c_designware_core snd_pcm e1000e ptp pps_core sdhci_acpi sdhci mmc_core i2c_hid [last unloaded: i915]
[   34.075010] CPU: 1 PID: 6224 Comm: gem_close_race Tainted: G     U          4.9.0-rc3-CI-CI_DRM_1800+ #1
[   34.075034] Hardware name:                  /NUC5i7RYB, BIOS RYBDWi35.86A.0355.2016.0224.1501 02/24/2016
[   34.075057] task: ffff8802459a8040 task.stack: ffffc90000524000
[   34.075074] RIP: 0010:[<ffffffffa0392cbc>]  [<ffffffffa0392cbc>] i915_gem_obj_lookup_or_create_vma+0x8c/0xc0 [i915]
[   34.075118] RSP: 0018:ffffc90000527b68  EFLAGS: 00010202
[   34.075135] RAX: ffff8802426c5e40 RBX: 0000000000000000 RCX: ffff8802447fc2a8
[   34.075158] RDX: 0000000000000000 RSI: ffff8802447fc2a8 RDI: ffff880248a4a880
[   34.075181] RBP: ffffc90000527b88 R08: 0000000000000008 R09: 0000000000000000
[   34.075203] R10: 0000000000000001 R11: 0000000000000000 R12: ffff880248a4a880
[   34.075225] R13: ffff8802447fc2a8 R14: ffff880243e9afa8 R15: ffff880248a4a9c8
[   34.075248] FS:  00007f9b43e59740(0000) GS:ffff880256c80000(0000) knlGS:0000000000000000
[   34.075273] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   34.075292] CR2: 00007f9b43419140 CR3: 000000024455d000 CR4: 00000000003406e0
[   34.075314] Stack:
[   34.075323]  0000000000000000 ffffc90000527bd0 ffff880243cb8008 ffff880243e9afa8
[   34.075353]  ffffc90000527c08 ffffffffa03874c7 ffffc90000527bb8 ffff880243e9afa8
[   34.075383]  ffff880243e9afb0 ffffc90000527e10 ffff8802447fc2a8 ffff880243cb8040
[   34.075414] Call Trace:
[   34.075435]  [<ffffffffa03874c7>] eb_lookup_vmas.isra.7+0x247/0x330 [i915]
[   34.075468]  [<ffffffffa0388c34>] i915_gem_do_execbuffer.isra.15+0x604/0x1a10 [i915]
[   34.075507]  [<ffffffffa039c957>] ? i915_gem_object_get_sg+0x347/0x380 [i915]
[   34.075532]  [<ffffffff811a69ce>] ? __might_fault+0x3e/0x90
[   34.075562]  [<ffffffffa038a430>] i915_gem_execbuffer2+0xc0/0x250 [i915]
[   34.075585]  [<ffffffff81552926>] drm_ioctl+0x1f6/0x480
[   34.075604]  [<ffffffff8100107a>] ? trace_hardirqs_on_thunk+0x1a/0x1c
[   34.075635]  [<ffffffffa038a370>] ? i915_gem_execbuffer+0x330/0x330 [i915]
[   34.075658]  [<ffffffff81202d2e>] do_vfs_ioctl+0x8e/0x690
[   34.075677]  [<ffffffff8181582d>] ? _raw_spin_unlock_irqrestore+0x3d/0x60
[   34.075700]  [<ffffffff810fcd51>] ? SyS_timer_settime+0x141/0x1e0
[   34.075721]  [<ffffffff810d6de2>] ? trace_hardirqs_on_caller+0x122/0x1b0
[   34.075742]  [<ffffffff8120336c>] SyS_ioctl+0x3c/0x70
[   34.075760]  [<ffffffff8181602e>] entry_SYSCALL_64_fastpath+0x1c/0xb1
[   34.075781] Code: 44 a0 48 c7 c2 9a 7e 43 a0 be e0 0d 00 00 48 c7 c7 a0 45 44 a0 e8 55 b8 ce e0 48 85 db 74 a3 49 83 bd f8 03 00 00 00 74 99 0f 0b <0f> 0b 48 89 da 4c 89 ee 4c 89 e7 e8 04 a9 ff ff 48 89 da 49 89
[   34.075955] RIP  [<ffffffffa0392cbc>] i915_gem_obj_lookup_or_create_vma+0x8c/0xc0 [i915]
[   34.075994]  RSP <ffffc90000527b68>

Testcase: igt/gem_close_race/basic-threads
Fixes: db6c2b41 ("drm/i915: Store the vma in an rbtree...")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161104161241.25871-1-chris@chris-wilson.co.ukReviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

All the unused entries in the page table tree(PML4E->PDPE->PDE->PTE)
should point to scratch page table/scratch page to avoid page walk error
due to the page prefetching.
When removing an entry in shadow PPGTT,  it need map to scratch page
also, the older implementation use single scratch page to assign to all
level entries, it doesn't align the page walk behavior when removed
entry is in PML, PDP, PD.  To avoid potential page walk error this patch
implement a scratch page tree to replace the single scratch page.

v2: more details in commit message address Kevin's comments.
Signed-off-by: NPing Gao <ping.a.gao@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>