These new tracepoints are emitted once the request is ready to
be submitted to the GPU and once the request is about to
be submitted to the GPU, respectively.

Former condition triggers as soon as all the fences and
dependencies have been resolved, and the latter once the
backend is about to submit it to the GPU.

New tracepoint are enabled via the new
DRM_I915_LOW_LEVEL_TRACEPOINTS Kconfig option which is disabled
by default to alleviate the performance impact concerns.

v2: Move execute tracepoint to __i915_gem_request_submit.
    (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

Provide the same information as the other request event classes.

v2: Pass in flags so we can properly report the blocking status.
    (Chris Wilson)

v3: Log hex with 0x prefix for clarity.

v4: Derive blocking status from flags. (Chris Wilson)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>

If an interrupt has been posted, and we were spinning on the active
seqno waiting for it to advance but it did not, then we can expect that
it will not see its advance in the immediate future and should call into
the irq-seqno barrier. We can stop spinning at this point, and leave the
difficulty of handling the coherency to the caller.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170217151304.16665-3-chris@chris-wilson.co.uk

This removes the usage of intel_ring_emit in favour of
directly writing to the ring buffer.

intel_ring_emit was preventing the compiler for optimising
fetch and increment of the current ring buffer pointer and
therefore generating very verbose code for every write.

It had no useful purpose since all ringbuffer operations
are started and ended with intel_ring_begin and
intel_ring_advance respectively, with no bail out in the
middle possible, so it is fine to increment the tail in
intel_ring_begin and let the code manage the pointer
itself.

Useless instruction removal amounts to approximately
two and half kilobytes of saved text on my build.

Not sure if this has any measurable performance
implications but executing a ton of useless instructions
on fast paths cannot be good.

v2:
 * Change return from intel_ring_begin to error pointer by
   popular demand.
 * Move tail increment to intel_ring_advance to enable some
   error checking.

v3:
 * Move tail advance back into intel_ring_begin.
 * Rebase and tidy.

v4:
 * Complete rebase after a few months since v3.

v5:
 * Remove unecessary cast and fix !debug compile. (Chris Wilson)

v6:
 * Make intel_ring_offset take request as well.
 * Fix recording of request postfix plus a sprinkle of asserts.
   (Chris Wilson)

v7:
 * Use intel_ring_offset to get the postfix. (Chris Wilson)
 * Convert GVT code as well.

v8:
 * Rename *out++ to *cs++.

v9:
 * Fix GVT out to cs conversion in GVT.

v10:
 * Rebase for new intel_ring_begin in selftests.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170214113242.29241-1-tvrtko.ursulin@linux.intel.com

Simple starting point for adding seltests for i915_gem_request, first
mock a device (with engines and contexts) that allows us to construct
and execute a request, along with waiting for the request to complete.
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/20170213171558.20942-10-chris@chris-wilson.co.uk

We first wait for a request to be submitted to hw and assigned a seqno,
before we can wait for the hw to signal completion (otherwise we don't
know the hw id we need to wait upon). Whilst waiting for the request to
be submitted, we may exceed the user's timeout and need to propagate the
error back.

v2: Make ETIME into an error from wait_for_execute for consistent exit
handling.
Reported-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 4680816b ("drm/i915: Wait first for submission, before waiting for request completion")
Testcase: igt/gem_wait/basic-await
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/20170208181238.7232-1-chris@chris-wilson.co.ukReviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

As we now have the ability to directly reset the GPU from the waiter
(and so do not need to drop the lock in order to let the reset proceed)
and also do not lose requests over a reset, we can now simply queue the
request to occur after the reset rather than roundtripping to userspace
(or worse failing with EIO).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170114162334.10271-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

It is an error to start a new request on the same timeline (ringbuffer)
as the current one before the current is submitted. If there are two
requests emitting to the ringbuffer at the same time, the operation is
undefined. We can catch this by checking for the timeline having a later
seqno than ours when we come to submit our request.

Currently we have this check at the end of __i915_add_request, but
having an early check as well isolates a failure in the caller versus a
failure in sealing the request (i.e. from inside __i915_add_request
itself). For example, CI is currently tripping over this late assertion
on ctg/ilk:

[  100.329399] [IGT] gem_cs_tlb: starting subtest basic-default
[  100.336333] ------------[ cut here ]------------
[  100.336341] kernel BUG at drivers/gpu/drm/i915/i915_gem_request.c:908!
[  100.336347] invalid opcode: 0000 [#1] PREEMPT SMP
[  100.336351] Modules linked in: snd_hda_intel i915 snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core snd_pcm coretemp mei_me lpc_ich mei e1000e ptp pps_core [last unloaded: i915]
[  100.336373] CPU: 0 PID: 6308 Comm: gem_cs_tlb Tainted: G     U          4.10.0-rc3-CI-CI_DRM_2045+ #1
[  100.336380] Hardware name: LENOVO 7465CTO/7465CTO, BIOS 6DET44WW (2.08 ) 04/22/2009
[  100.336386] task: ffff88012b738040 task.stack: ffffc90000560000
[  100.336441] RIP: 0010:__i915_add_request+0x4aa/0x510 [i915]
[  100.336445] RSP: 0018:ffffc90000563ac0 EFLAGS: 00010212
[  100.336451] RAX: 0000000000005d52 RBX: ffff880133bb84c0 RCX: 0000000000000001
[  100.336456] RDX: 0000000080000001 RSI: ffff88012b738860 RDI: 00000000ffffffff
[  100.336461] RBP: ffffc90000563b00 R08: ffff880133bb8780 R09: 0000000000000000
[  100.336466] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88012f53d950
[  100.336472] R13: ffff88012a2b0af8 R14: ffff88012a5b0008 R15: ffff88012f53d960
[  100.336477] FS:  00007f0d19da38c0(0000) GS:ffff88013bc00000(0000) knlGS:0000000000000000
[  100.336483] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  100.336488] CR2: 00007f0d17706000 CR3: 000000012aa3e000 CR4: 00000000000406f0
[  100.336496] Call Trace:
[  100.336527]  i915_gem_switch_to_kernel_context+0x131/0x1b0 [i915]
[  100.336559]  i915_gem_evict_vm+0x202/0x2b0 [i915]
[  100.336590]  i915_gem_execbuffer_reserve.isra.9+0x3ae/0x440 [i915]
[  100.336623]  i915_gem_do_execbuffer.isra.15+0x6d9/0x1b20 [i915]
[  100.336656]  i915_gem_execbuffer2+0xc0/0x250 [i915]
[  100.336666]  drm_ioctl+0x200/0x450
[  100.336697]  ? i915_gem_execbuffer+0x330/0x330 [i915]
[  100.336708]  do_vfs_ioctl+0x90/0x6e0
[  100.336716]  ? up_read+0x1a/0x40
[  100.336723]  ? trace_hardirqs_on_caller+0x122/0x1b0
[  100.336730]  SyS_ioctl+0x3c/0x70
[  100.336738]  entry_SYSCALL_64_fastpath+0x1c/0xb1
[  100.336745] RIP: 0033:0x7f0d187cb357
[  100.336750] RSP: 002b:00007ffe0b2f7c28 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  100.336761] RAX: ffffffffffffffda RBX: 00007ffe0b2f7d60 RCX: 00007f0d187cb357
[  100.336768] RDX: 00007ffe0b2f7d00 RSI: 0000000040406469 RDI: 0000000000000003
[  100.336775] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000022
[  100.336782] R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000002
[  100.336789] R13: 0000000000419101 R14: 00007ffe0b2f7d60 R15: 00007ffe0b2f7d50
[  100.336797] Code: 5f 74 1e e9 d4 fb ff ff e8 bc 1e 9c e0 e9 ae fb ff ff 4c 89 e7 e8 77 22 fd ff e9 88 fd ff ff 0f 0b e8 a3 1e 9c e0 e9 b1 fb ff ff <0f> 0b 0f 0b e8 fd af ab e0 85 c0 75 c2 48 c7 c2 80 2c 71 a0 be
[  100.336877] RIP: __i915_add_request+0x4aa/0x510 [i915] RSP: ffffc90000563ac0
[  100.336886] ---[ end trace 22b36545479e5eb7 ]---
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111140858.1922-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

A fairly trivial move of a matching pair of routines (for preparing a
request for construction) onto an engine vfunc. The ulterior motive is
to be able to create a mock request implementation.
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/20161218153724.8439-7-chris@chris-wilson.co.uk

The requests conversion introduced a nasty bug where we could generate a
new request in the middle of constructing a request if we needed to idle
the system in order to evict space for a context. The request to idle
would be executed (and waited upon) before the current one, creating a
minor havoc in the seqno accounting, as we will consider the current
request to already be completed (prior to deferred seqno assignment) but
ring->last_retired_head would have been updated and still could allow
us to overwrite the current request before execution.

We also employed two different mechanisms to track the active context
until it was switched out. The legacy method allowed for waiting upon an
active context (it could forcibly evict any vma, including context's),
but the execlists method took a step backwards by pinning the vma for
the entire active lifespan of the context (the only way to evict was to
idle the entire GPU, not individual contexts). However, to circumvent
the tricky issue of locking (i.e. we cannot take struct_mutex at the
time of i915_gem_request_submit(), where we would want to move the
previous context onto the active tracker and unpin it), we take the
execlists approach and keep the contexts pinned until retirement.
The benefit of the execlists approach, more important for execlists than
legacy, was the reduction in work in pinning the context for each
request - as the context was kept pinned until idle, it could short
circuit the pinning for all active contexts.

We introduce new engine vfuncs to pin and unpin the context
respectively. The context is pinned at the start of the request, and
only unpinned when the following request is retired (this ensures that
the context is idle and coherent in main memory before we unpin it). We
move the engine->last_context tracking into the retirement itself
(rather than during request submission) in order to allow the submission
to be reordered or unwound without undue difficultly.

And finally an ulterior motive for unifying context handling was to
prepare for mock requests.

v2: Rename to last_retired_context, split out legacy_context tracking
for MI_SET_CONTEXT.
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/20161218153724.8439-3-chris@chris-wilson.co.uk

Currently, we have an active reference for the request until it is
retired. Though it cannot be retired before it has been executed by
hardware, the request may be completed before we have finished
processing the execute fence, i.e. we may continue to process that fence
as we free the request.

Fixes: 5590af3e ("drm/i915: Drive request submission through fence callbacks")
Fixes: 23902e49 ("drm/i915: Split request submit/execute phase into two")
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/20161125131718.20978-3-chris@chris-wilson.co.uk
(cherry picked from commit 48bc2a4a)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

Add the tracking required to enable debugobjects for fences to improve
error detection in BAT. The debugobject interface lets us track the
lifetime and phases of the fences even while being embedded into larger
structs, i.e. to check they are not used after they have been released.

v2: Don't populate the stubs, debugobjects checks for a NULL pointer and
treats it equivalently.
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/20161125131718.20978-4-chris@chris-wilson.co.uk

Currently, we have an active reference for the request until it is
retired. Though it cannot be retired before it has been executed by
hardware, the request may be completed before we have finished
processing the execute fence, i.e. we may continue to process that fence
as we free the request.

Fixes: 5590af3e ("drm/i915: Drive request submission through fence callbacks")
Fixes: 23902e49 ("drm/i915: Split request submit/execute phase into two")
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/20161125131718.20978-3-chris@chris-wilson.co.uk

Before we return the request back to the kmem_cache after a failed
i915_gem_request_alloc(), we should assert that it has not been added to
any global state tracking.
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/20161125131718.20978-2-chris@chris-wilson.co.uk

While we will check that the request is completed prior to being
retired, by placing an assert that the request is complete at the
entrypoint of the function we can more clearly document the function's
preconditions.
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/20161125131718.20978-1-chris@chris-wilson.co.uk

Rename i915_gem_timeline member 'next_seqno' into 'seqno' as
the variable is pre-increment. We've already had two bugs due
to the confusing name, second is fixed as follow-up patch.

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>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161124144750.2610-1-chris@chris-wilson.co.uk

Bannable property, banned status, guilty and active counts are
properties of i915_gem_context. Make them so.

v2: rebase

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479309634-28574-1-git-send-email-mika.kuoppala@intel.com

As hangcheck score was removed, the active decay of score
was removed also. This removed feature for hangcheck to detect
if the gpu client was accidentally or maliciously causing intermittent
hangs. Reinstate the scoring as a per context property, so that if
one context starts to act unfavourably, ban it.

v2: ban_period_secs as a gate to score check (Chris)
v3: decay in proper spot. scores as tunables (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>

Trying to chase an impossible bug (ivb):

[  207.765411] [drm:i915_reset_and_wakeup [i915]] resetting chip
[  207.765734] [drm:i915_gem_reset [i915]] resetting render ring to restart from tail of request 0x4ee834
[  207.765791] [drm:intel_print_rc6_info [i915]] Enabling RC6 states: RC6 on RC6p on RC6pp off
[  207.767213] [drm:intel_guc_setup [i915]] GuC fw status: path (null), fetch NONE, load NONE
[  207.767515] kernel BUG at drivers/gpu/drm/i915/i915_gem_request.c:203!
[  207.767551] invalid opcode: 0000 [#1] PREEMPT SMP
[  207.767576] Modules linked in: snd_hda_intel i915 cdc_ncm usbnet mii x86_pkg_temp_thermal coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel lpc_ich snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core mei_me mei snd_pcm sdhci_pci sdhci mmc_core e1000e ptp pps_core [last unloaded: i915]
[  207.767808] CPU: 3 PID: 8855 Comm: gem_ringfill Tainted: G     U          4.9.0-rc5-CI-Patchwork_3052+ #1
[  207.767854] Hardware name: LENOVO 2356GCG/2356GCG, BIOS G7ET31WW (1.13 ) 07/02/2012
[  207.767894] task: ffff88012c82a740 task.stack: ffffc9000383c000
[  207.767927] RIP: 0010:[<ffffffffa00a0a3a>]  [<ffffffffa00a0a3a>] i915_gem_request_retire+0x2a/0x4b0 [i915]
[  207.767999] RSP: 0018:ffffc9000383fb20  EFLAGS: 00010293
[  207.768027] RAX: 00000000004ee83c RBX: ffff880135dcb480 RCX: 00000000004ee83a
[  207.768062] RDX: ffff88012fea42a8 RSI: 0000000000000001 RDI: ffff88012c82af68
[  207.768095] RBP: ffffc9000383fb48 R08: 0000000000000000 R09: 0000000000000000
[  207.768129] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880135dcb480
[  207.768163] R13: ffff88012fea42a8 R14: 0000000000000000 R15: 00000000000001d8
[  207.768200] FS:  00007f955f658740(0000) GS:ffff88013e2c0000(0000) knlGS:0000000000000000
[  207.768239] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  207.768258] CR2: 0000555899725930 CR3: 00000001316f6000 CR4: 00000000001406e0
[  207.768286] Stack:
[  207.768299]  ffff880135dcb480 ffff880135dcbe00 ffff88012fea42a8 0000000000000000
[  207.768350]  00000000000001d8 ffffc9000383fb70 ffffffffa00a1339 0000000000000000
[  207.768402]  ffff88012f296c88 00000000000003f0 ffffc9000383fbb0 ffffffffa00b582d
[  207.768453] Call Trace:
[  207.768493]  [<ffffffffa00a1339>] i915_gem_request_retire_upto+0x49/0x90 [i915]
[  207.768553]  [<ffffffffa00b582d>] intel_ring_begin+0x15d/0x2d0 [i915]
[  207.768608]  [<ffffffffa00b59cb>] intel_ring_alloc_request_extras+0x2b/0x40 [i915]
[  207.768667]  [<ffffffffa00a2fd9>] i915_gem_request_alloc+0x359/0x440 [i915]
[  207.768723]  [<ffffffffa008bd03>] i915_gem_do_execbuffer.isra.15+0x783/0x1a10 [i915]
[  207.768766]  [<ffffffff811a6a2e>] ? __might_fault+0x3e/0x90
[  207.768816]  [<ffffffffa008d380>] i915_gem_execbuffer2+0xc0/0x250 [i915]
[  207.768854]  [<ffffffff815532a6>] drm_ioctl+0x1f6/0x480
[  207.768900]  [<ffffffffa008d2c0>] ? i915_gem_execbuffer+0x330/0x330 [i915]
[  207.768939]  [<ffffffff81202f6e>] do_vfs_ioctl+0x8e/0x690
[  207.768972]  [<ffffffff818193ac>] ? retint_kernel+0x2d/0x2d
[  207.769004]  [<ffffffff810d6ef2>] ? trace_hardirqs_on_caller+0x122/0x1b0
[  207.769039]  [<ffffffff812035ac>] SyS_ioctl+0x3c/0x70
[  207.769068]  [<ffffffff818189ae>] entry_SYSCALL_64_fastpath+0x1c/0xb1
[  207.769103] Code: 90 55 48 89 e5 41 57 41 56 41 55 41 54 49 89 fc 53 8b 35 fa 7b e1 e1 85 f6 0f 85 55 03 00 00 41 8b 84 24 80 02 00 00 85 c0 75 02 <0f> 0b 49 8b 94 24 a8 00 00 00 48 8b 8a e0 01 00 00 8b 89 c0 00
[  207.769400] RIP  [<ffffffffa00a0a3a>] i915_gem_request_retire+0x2a/0x4b0 [i915]
[  207.769463]  RSP <ffffc9000383fb20>

Let's add a couple more BUG_ONs before this to ascertain that the request
did make it to hardware. The impossible part of this stacktrace is that
request must have been considered completed by the i915_request_wait()
before we tried to retire it.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161118143412.26508-1-chris@chris-wilson.co.ukReviewed-by: NMatthew Auld <matthew.auld@intel.com>

Since we can retire requests from multiple paths, we cannot assume that
i915_gem_retire_requests() is the sole path on which we can transition
to gt.active_requests == 0. A consequence of this is that we would skip
the function if we had already retired all the requests and not
scheduled the idle worker.

This is fallout from changing the routine from considering active_engines
(for which it was the only consumer) to active_requests.

v2: Move kicking the idle working to i915_gem_request_retire() otherwise
we could postpone the idle callback everytime we called retire_requests
even though we did no work.
v3: We only need to move the idle work kicking!
v4: Drop the BUG_ON(!awake) as we may be called from the shrinker in the
middle of constructing a request before we have marked the device awake.
v5: Add a BUG_ON() for active_requests underflow upon retirement (Joonas)

Fixes: 28176ef4 ("drm/i915: Reserve space in the global seqno during request allocation")
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/20161115164620.17185-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

With the s390 special case of a yielding cpu_relax() implementation gone,
we can now remove all users of cpu_relax_lowlatency() and replace them
with cpu_relax().
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1477386195-32736-5-git-send-email-borntraeger@de.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

In order to support userspace defining different levels of importance to
different contexts, and in particular the preferred order of execution,
store a priority value on each context. By default, the kernel's
context, which is used for idling and other background tasks, is given
minimum priority (i.e. all user contexts will execute before the kernel).
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/20161114204105.29171-9-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 start of the scheduler, add a hook into request submission for the
scheduler to see the arrival of new requests and prepare its runqueues.
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/20161114204105.29171-6-chris@chris-wilson.co.uk

Defer the transfer from the client's timeline onto the execution
timeline from the point of readiness to the point of actual submission.
For example, in execlists, a request is finally submitted to hardware
when the hardware is ready, and only put onto the hardware queue when
the request is ready. By deferring the transfer, we ensure that the
timeline is maintained in retirement order if we decide to queue the
requests onto the hardware in a different order than fifo.

v2: Rebased onto distinct global/user timeline lock classes.
v3: Play with the position of the spin_lock().
v4: Nesting finally resolved with distinct sw_fence lock classes.
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/20161114204105.29171-4-chris@chris-wilson.co.uk

In order to support deferred scheduling, we need to differentiate
between when the request is ready to run (i.e. the submit fence is
signaled) and when the request is actually run (a new execute fence).
This is typically split between the request itself wanting to wait upon
others (for which we use the submit fence) and the CPU wanting to wait
upon the request, for which we use the execute fence to be sure the
hardware is ready to signal completion.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161114204105.29171-3-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 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>

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

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

Defer the assignment of the global seqno on a request to its submission.
In the next patch, we will only allocate the global seqno at that time,
here we are just enabling the wait-for-submission before wait-for-seqno
paths.
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/20161028125858.23563-34-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

Currently we try to reduce the number of synchronisations (now the
number of requests we need to wait upon) by noting that if we have
earlier waited upon a request, all subsequent requests in the timeline
will be after the wait. This only applies to requests in this timeline,
as other timelines will not be ordered by that waiter.
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/20161028125858.23563-30-chris@chris-wilson.co.uk

Move the actual emission of the breadcrumb for closing the request from
i915_add_request() to the submit callback. (It can be moved later when
required.) This allows us to defer the allocation of the global_seqno
from request construction to actual submission, allowing us to emit the
requests out of order (wrt to the order of their construction, they
still will only be executed one all of their dependencies are resolved
including that all earlier requests on their timeline have been
submitted.) We have to specialise how we then emit the request in order
to write into the preallocated space, rather than at the tail of the
ringbuffer (which will have been advanced by the addition of new
requests).
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/20161028125858.23563-29-chris@chris-wilson.co.uk

In the next patch, we will use deferred breadcrumb emission. That requires
reserving sufficient space in the ringbuffer to emit the breadcrumb, which
first requires us to know how large the breadcrumb is.
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/20161028125858.23563-28-chris@chris-wilson.co.uk

Now that the emission of the request tail and its submission to hardware
are two separate steps, engine->emit_request() is confusing.
engine->emit_request() is called to emit the breadcrumb commands for the
request into the ring, name it such (engine->emit_breadcrumb).
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/20161028125858.23563-27-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

In future patches, we will no longer be able to wait on a static global
seqno and instead have to break our wait up into phases. First we wait
for the global seqno assignment (upon submission to hardware), and once
submitted we wait for the hardware to complete.
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/20161028125858.23563-25-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