This is preparatory work for Execlists: we plan to use it later to
allocate our own context objects (since Logical Ring Contexts do
not have the same kind of backing objects).

No functional changes.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We're forgetting to unpin the last_context from the ggtt at GPU reset
time. This leads to the vma pin_count leaking at every reset if the
last context wasn't the ring default context. Further use of the same
context will trigger the pin_count check in i915_gem_object_pin() and
userspace will be faced with EBUSY as a result.

This plaques kms_flip rather badly since it performs lots of resets,
and every fd has its own default context these days.

Fix the problem by properly unpinning the last context at reset.

This regression seems to back to

commit acce9ffa
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:03 2013 -0800

   drm/i915: Better reset handling for contexts

Testcase: igt/gem_ctx_exec/reset-pin-leak
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Fallout from

commit 46470fc9
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Wed May 21 19:01:06 2014 +0300

    drm/i915: Add null state batch to active list

undid the earlier fix of only marking the ctx as initialised after it is
saved by the hardware during a SET_CONTEXT operation:

commit ad1d2199
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date:   Sat Dec 28 13:31:49 2013 -0800

    drm/i915: set ctx->initialized only after RCS
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
[Jani: add reference to the earlier fix in the commit messsage.]
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

The original comment that introduced it said:

commit 0009e46c
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:02 2013 -0800

    drm/i915: Track which ring a context ran on

    Previously we dropped the association of a context to a ring. It is
    however very important to know which ring a context ran on (we could
    have reused the other member, but I was nitpicky).

    This is very important when we switch address spaces, which unlike
    context objects, do change per ring.

    As an example, if we have:

            RCS   BCS
    ctx            A
    ctx      A
    ctx      B
    ctx            B

    Without tracking the last ring B ran on, we wouldn't know to switch the
    address space on BCS in the last row.

But this is not really true, because we are already checking to != from (with
"from" being = ring->last_context) and that should be enough to make sure we
switch to the right address space.

We would have a problem if we switched the context object for every ring (since
then we would fail to do it in some situations) but we only switch it for the
render ring, so we don't care.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

It's barely alive now anyway, so give it the "coup de grâce".
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Up until now, contexts had one (and only one) backing object that was
used by the hardware to save/restore render ring contexts (via the
MI_SET_CONTEXT command). Other rings did not have or need this, so
our i915_hw_context struct had a 1:1 relationship with a a real HW
context.

With Logical Ring Contexts and Execlists, this is not possible anymore:
all rings need a backing object, and it cannot be reused. To prepare
for that, rename our contexts to the more generic term intel_context.

No functional changes.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In the upcoming patches we plan to break the correlation between
engine command streamers (a.k.a. rings) and ringbuffers, so it
makes sense to refactor the code and make the change obvious.

No functional changes.
Signed-off-by: NOscar Mateo <oscar.mateo@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

for proper refcounting to take place as we use
i915_add_request() for it.

i915_add_request() also takes the context for the request
from ring->last_context so move the null state batch
submission after the ring context has been set.

v2: we need to check for correct ring now (Ville Syrjälä)
v3: no need to expose i915_gem_move_object_to_active (Chris Wilson)
v4: cargoculted vma/active/inactive error handling removed (Chris Wilson)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We implement the following workarounds:
* WaDisableAsyncFlipPerfMode:chv
* WaProgramMiArbOnOffAroundMiSetContext:chv

v2: Drop WaDisableSemaphoreAndSyncFlipWait note
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Since commit 691e6415
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Apr 9 09:07:36 2014 +0100

    drm/i915: Always use kref tracking for all contexts.

we have contexts everywhere, and so we must be careful to distinguish
fake contexts, which do not have an associated bo, and real ones, which
do. In particular, we now need to be careful not to dereference NULL
pointers.

This is one such example, as the commit highlighted above failed to move
the unpinning of the default ctx object into the real-context-only
branch.
Reported-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78792Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

HW guys say that it is not a cool idea to let device
go into rc6 without proper 3d pipeline state.

For each new uninitialized context, generate a
valid null render state to be run on context
creation.

This patch introduces a skeleton with empty states.

v2: - No need to vmap (Chris Wilson)
    - use .c files for state (Daniel Vetter)
    - no need to flush as i915_add_request does it
    - remove parameter for batch alloc size
    - don't wait for the init (Ben Widawsky)

v3: - move to cpu/gpu (Chris Wilson)

Tested-by: Kristen Carlson Accardi <kristen@linux.intel.com> (v1)
Tested-by: NOscar Mateo <oscar.mateo@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If we always initialize kref for the context, even if we are using fake
contexts for hangstats when there is no hw support, we can forgo the
dance to dereference the ctx->obj and inspect whether we are permitted
to use kref inside i915_gem_context_reference() and _unreference().

My ulterior motive here is to improve the debugging of a use-after-free
of ctx->obj. This patch avoids the dereference here and instead forces
the assertion checks associated with kref.

v2: Refactor the fake contexts to being even more like the real
contexts, so that there is much less duplicated and special case code.

v3: Tweaks.
v4: Tweaks, minor.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76671Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Tested-by: Nlu hua <huax.lu@intel.com>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
[Jani: tiny change to backport to drm-intel-fixes.]
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

We don't do CPU access to GPU contexts so making the GPU access snoop
the CPU caches seems silly, and potentially expensive.

v2: Use !IS_VALLEYVIEW instead of HAS_LLC as this is really
    about what the PTEs can represent.
    Add a comment clarifying the situation.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have been setting the bit which was originally BIOS dependent since:
commit f05bb0c7
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Sun Jan 20 16:33:32 2013 +0000

    drm/i915: GFX_MODE Flush TLB Invalidate Mode must be '1' for scanline waits

Therefore, we do not need to try to figure it out dynamically and we can
just always invalidate the TLBs.

It's a partial revert of:
commit 12b0286f
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Mon Jun 4 14:42:50 2012 -0700

    drm/i915: possibly invalidate TLB before context switch

The original commit attempted to only invalidate when necessary
(very much a relic from the old days). Now, we can just always invalidate.

I guess the old TODO still exists. Since we seem to have abandoned ILK
contexts however, there isn't much point in even remembering.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

BSpec seems to tell us we need the MI_ARB_ON_OFF w/a around
MI_SET_CONTEXT on gen8.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The idea of printing objects used by each process is to judge how each
process is using them. This means that we need to evaluate whether the
object is bound for that particular process, rather than just whether it
is bound into the global GTT.

v2: Restore the non-full-ppgtt path for simplicity as we may not even
    create vma with older hardware.

v3: Tweak handling of global entries and default context entries.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We used to have per file descriptor hang stats for the
i915_get_reset_stats_ioctl() and for default context banning.

commit 0eea67eb
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:19 2013 -0800

    drm/i915: Create a per file_priv default context

made having separate hangstats in file_private redundant
as i915_hw_context already contained hangstats. So

commit c482972a
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date:   Fri Dec 6 14:11:20 2013 -0800

    drm/i915: Piggy back hangstats off of contexts

consolidated the hangstats and enabled further improvements.

commit 44e2c070
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Thu Jan 30 16:01:15 2014 +0200

    drm/i915: Use i915_hw_context to set reset stats

tried to reap full benefits of consolidation but fell short
as we never 'switch' to the fake private context on gens
that don't have hw_contexts, so request->ctx remained NULL
on those.

Fix this by 'switching' to fake context so that when
request is submitted to ring, proper context gets assigned
to it.

Testcase: igt/drv_hangman
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76055Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

While reading some code, out of boredom, stumbled on a tiny tiny fix.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

GEN8 never freed the PPGTT struct. As GEN8 doesn't use full PPGTT, the
leak is small and only found on a module reload. ie. I don't think this
needs to go to stable.

v2: The very naive, kfree in gen8 ppgtt cleanup, is subject to a double
free on PPGTT initialization failure. (Spotted by Imre). Instead this
patch pulls the ppgtt struct freeing out of the cleanup and leaves it to
the allocators/callers or the one doing the last kref_put as in standard
convention
Reported-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

At one time it was expected to be called in multiple places by kref_put.
At the current time however, it is all contained within
i915_gem_context.c.

This patch makes an upcoming required addition a bit nicer since it too
doesn't need to be defined in a header file.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The i915 driver sets DRIVER_GEM unconditionally, so testing for the
feature will always fail.
Signed-off-by: NThierry Reding <treding@nvidia.com>
[danvet: Fix up conflicts.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Anything more than just one bool parameter is just a pain to read,
symbolic constants are much better.

Split out from Chris' vma-binding rework patch.

v2: Undo the behaviour change in object_pin that Chris spotted.

v3: Split out misplaced hunk to handle set_cache_level errors,
spotted by Jani.

v4: Keep the current over-zealous binding logic in the execbuffer code
working with a quick hack while the overall binding code gets shuffled
around.

v5: Reorder the PIN_ flags for more natural patch splitup.

v6: Pull out the PIN_GLOBAL split-up again.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Found with smatch
Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

If we have stopped rings then we know that test is running
so no need for spam. In addition, only spam when default
context gets banned.

v2: - make sure default context ban gets shown (Chris)
    - use helper for checking for default context, everywhere (Chris)

v3: - dont be quiet when debug is set (Ben, Daniel)

Reference: https://bugs.freedesktop.org/show_bug.cgi?id=73652Signed-off-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

There are cases where we want to know if there is a full, or aliased
PPGTT. Currently, in fact the only distinction we ever need to make is
when we're using full PPGTT.

This patch is simply to promote readability and clarify for the
confusing existing usage where "aliasing" meant aliasing and full.

v2: Remove USES_ALIASING_PPGTT since there are currently no cases where
we need to check if we're using aliasing, but not full PPGTT. (Daniel)

Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

WaMiSetContext_Hang tells us that a MI_NOOP must follow MI_SET_CONTEXT.

The other thing WaMiSetContext_Hang seems to say is that URB_FENCE isn't
allowed to straddle two cachelines. But we don't issue those from the
kernel so we don't care.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Through a twisty and circuituous path it is possible to currently trick
the code into creating a default context and forgetting to pin it
immediately into the GGTT. (This requires a system using contexts without
an aliasing ppgtt, which is currently restricted to Baytrails machines
manually specifying a module parameter to force enable contexts, or
on Sandybridge and later that manually disable the aliasing ppgtt.) The
consequence is that during module unload we attempt to unpin the default
context twice and encounter a BUG remonstrating that we attempt to unpin
an unbound object.

[  161.002869] Kernel BUG at f84861f8 [verbose debug info unavailable]
[  161.002875] invalid opcode: 0000 [#1] SMP
[  161.002882] Modules linked in: coretemp kvm_intel kvm crc32_pclmul aesni_intel aes_i586 xts lrw gf128mul ablk_helper cryptd hid_sensor_accel_3d hid_sensor_gyro_3d hid_sensor_magn_3d hid_sensor_trigger industrialio_triggered_buffer kfifo_buf industrialio hid_sensor_iio_common snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi snd_seq_midi_event dm_multipath scsi_dh asix ppdev usbnet snd_rawmidi mii hid_sensor_hub microcode snd_seq rfcomm bnep snd_seq_device bluetooth snd_timer snd parport_pc binfmt_misc soundcore dw_dmac_pci dw_dmac_core mac_hid lp parport dm_mirror dm_region_hash dm_log hid_generic usbhid hid i915(O-) drm_kms_helper(O) igb dca ptp pps_core i2c_algo_bit drm(O) ahci libahci video
[  161.002991] CPU: 0 PID: 2114 Comm: rmmod Tainted: G        W  O 3.13.0-rc8+ #2
[  161.002997] Hardware name: NEXCOM VTC1010/Aptio CRB, BIOS 5.6.5 09/24/2013
[  161.003004] task: dbdd6800 ti: dbe0e000 task.ti: dbe0e000
[  161.003010] EIP: 0060:[<f84861f8>] EFLAGS: 00010246 CPU: 0
[  161.003044] EIP is at i915_gem_object_ggtt_unpin+0x88/0x90 [i915]
[  161.003050] EAX: dfce3840 EBX: 00000000 ECX: dfafd690 EDX: dfce3874
[  161.003056] ESI: c0086b40 EDI: df962e00 EBP: dbe0fe1c ESP: dbe0fe0c
[  161.003062]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[  161.003068] CR0: 8005003b CR2: b7718000 CR3: 1bec0000 CR4: 001007f0
[  161.003076] Stack:
[  161.003081]  00afc014 00000004 c0086b40 dfafc000 dbe0fe38 f8487e5a dfaa5400 c0086b40
[  161.003099]  dfafc000 dfaa5400 dfaa5414 dbe0fe58 f84741aa 00000000 f89c34b9 dfaa5414
[  161.003117]  dfaa5400 dfaa5400 f644b000 dbe0fe6c f89a5443 dfaa5400 f8505000 f644b000
[  161.003134] Call Trace:
[  161.003169]  [<f8487e5a>] i915_gem_context_fini+0xba/0x1c0 [i915]
[  161.003202]  [<f84741aa>] i915_driver_unload+0x1fa/0x2f0 [i915]
[  161.003232]  [<f89a5443>] drm_dev_unregister+0x23/0x90 [drm]
[  161.003259]  [<f89a54ed>] drm_put_dev+0x3d/0x70 [drm]
[  161.003294]  [<f8470615>] i915_pci_remove+0x15/0x20 [i915]
[  161.003306]  [<c1338a6f>] pci_device_remove+0x2f/0xa0
[  161.003317]  [<c140c871>] __device_release_driver+0x61/0xc0
[  161.003328]  [<c140d12f>] driver_detach+0x8f/0xa0
[  161.003341]  [<c140c54f>] bus_remove_driver+0x4f/0xc0
[  161.003353]  [<c140d708>] driver_unregister+0x28/0x60
[  161.003362]  [<c10cee42>] ? stop_cpus+0x32/0x40
[  161.003372]  [<c10bd510>] ? module_refcount+0x90/0x90
[  161.003383]  [<c13378c5>] pci_unregister_driver+0x15/0x60
[  161.003413]  [<f89a739f>] drm_pci_exit+0x9f/0xb0 [drm]
[  161.003458]  [<f84e624a>] i915_exit+0x1b/0x1d [i915]
[  161.003468]  [<c10bf8a8>] SyS_delete_module+0x158/0x1f0
[  161.003480]  [<c1173d5d>] ? ____fput+0xd/0x10
[  161.003488]  [<c106f0fe>] ? task_work_run+0x7e/0xb0
[  161.003499]  [<c165a68d>] sysenter_do_call+0x12/0x28
[  161.003505] Code: 0f b6 4d f3 8d 51 0f 83 e1 f0 83 e2 0f 09 d1 84 d2 88 48 54 75 07 80 a7 91 00 00 00 7f 83 c4 04 5b 5e 5f 5d c3 8d b6 00 00 00 00 <0f> 0b 8d b6 00 00 00 00 55 89 e5 57 56 53 83 ec 64 3e 8d 74 26
[  161.003586] EIP: [<f84861f8>] i915_gem_object_ggtt_unpin+0x88/0x90 [i915] SS:ESP 0068:dbe0fe0c

v2: Rename the local variable (is_default_ctx) to avoid confusion with
the function is_default_ctx(). And correct Jesse's email address.
Reported-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73985Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Tested-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NBen Widawsky <benjamin.widawsky@intel.com>
[danvet: Fix up the rebase fail from my first attempt, thankfully
pointed out by Ville.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The initialized flag is used to specify a context has been initialized
and it's context is safe to load, ie. the 3d state is setup properly.
With full PPGTT, we emit the address space loads during context switch
and this currently marks a context as initialized. With full PPGTT
patches, if a client first emits a batch to !RCS, then later, RCS, the
code will mistake the context as initialized and try to reload an
uninitialized context.

1. context 1 blit // context marked as initialized, but isn't
2. context 1 render // loads random state from step 2

It is really easy to hit this with a planned upcoming patch which makes
default context reuse possible.

NOTE: This should only effect full PPGTT branches, ie. current
drm-intel-nightly.

Thanks to Chris for helping me track this down.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Simplify the failure scenario in the commit message according
to Chris' review a bit.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This was an accidental "ABI" change introduced during PPGTT:

commit 0eea67eb
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Fri Dec 6 14:11:19 2013 -0800

    drm/i915: Create a per file_priv default context

The failure test application actually tests the return type. The other
option is to simply change the test.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Without this fix the ioctls silently succeeded (but actually did
nothing).

It makes all the code which calls into this function way too confusing.

v2: Fix destroy IOCTL as well

v3: Clarify the other two callers of i915_gem_context_get() to never
check for NULL. (Mika)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72903Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Testcase: igt/gem_ctx_exec/basic
[danvet: Fix up the commit message and actually bother to mention the
testcase this fixes.]
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

As with processes which run on the CPU, the goal of multiple VMs is to
provide process isolation. Specific to GEN, there is also the ability to
map more objects per process (2GB each instead of 2Gb-2k total).

For the most part, all the pipes have been laid, and all we need to do
is remove asserts and actually start changing address spaces with the
context switch. Since prior to this we've converted the setting of the
page tables to a streamed version, this is quite easy.

One important thing to point out (since it'd been hotly contested) is
that with this patch, every context created will have it's own address
space (provided the HW can do it).

v2: Disable BDW on rebase

NOTE: I tried to make this commit as small as possible. I needed one
place where I could "turn everything on" and that is here. It could be
split into finer commits, but I didn't really see much point.

Cc: Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We need to have the address space when reserving space for the objects.
Since the address space and context are tied together, and reserve
occurs before context switch (for good reason), we must lookup our
context earlier in the process.

This leaves some room for optimizations where we no longer need to use
ctx_id in certain places. This will be addressed in a subsequent patch.

Important tricky bit:
Because slow relocations during execbuffer drop struct_mutex

Perhaps it would be best to acquire the reference when we get the
context, but I'll save that for another day (note I have written the
patch before, and I found the changes required to be uglier than this).

Note that since we currently access everything via context id, and not
the data structure this is fine, though not desirable. The next change
attempts to get the context only once via the context ID idr lookup, and
as such, the following can happen:

CTX-A is created, refcount = 1
CTX-A execbuf, mutex dropped
close IOCTL called on CTX-A, refcount = 0
CTX-A resumes in execbuf.

v2: Rebased on top of
commit b6359918
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Wed Oct 30 15:44:16 2013 +0200

    drm/i915: add i915_get_reset_stats_ioctl

v3: Rebased on top of
commit 25b3dfc8
Author: Mika Westerberg <mika.westerberg@linux.intel.com>
Date:   Tue Nov 12 11:57:30 2013 +0200

Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Tue Nov 26 16:14:33 2013 +0200

    drm/i915: check context reset stats before relocations
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

To simplify the codepaths somewhat, we can simply always create a
context. Contexts already keep hangstat information. This prevents us
from having to differentiate at other parts in the code.

There is allocation overhead, but it should not be measurable.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Every file will get it's own context, and we use this context instead of
the default context. The default context still exists for future
shrinker usage as well as reset handling.

v2: Updated to address Mika's recent context guilty changes
Some more changes around this come up in later patches as well.

v3: Use a fake context to avoid allocation for the !HAS_HW_CONTEXT case.
I've tried the alternatives. This looks the best to me.
Removed hangstat stuff from v2 - for a separate patch
Demote failed PPGTT set to DRM_DEBUG_DRIVER since it can now be invoked
easily from userspace.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have a default context which suits the aliasing PPGTT well. Tie them
together so it looks like any other context/PPGTT pair. This makes the
code cleaner as it won't have to special case aliasing as often.

The patch has one slightly tricky part in the default context creation
function. In the future (and on aliased setup) we create a new VM for a
context (potentially). However, if we have aliasing PPGTT, which occurs
at this point in time for all platforms GEN6+, we can simply manage the
refcounting to allow things to behave as normal. Now is a good time to
recall that the aliasing_ppgtt doesn't have a real VM, it uses the GGTT
drm_mm.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Pretty straightforward so far except for the bit about the refcounting.
The PPGTT will potentially be shared amongst multiple contexts. Because
contexts themselves have a refcounted lifecycle, the easiest way to
manage this will be to refcount the PPGTT. To acheive this, we piggy
back off of the existing context refcount, and will increment and
decrement the PPGTT refcount with context creation, and destruction.

To put it more clearly, if context A, and context B both use PPGTT 0, we
can't free the PPGTT until both A, and B are destroyed.

Note that because the PPGTT is permanently pinned (for now), it really
just matters for the PPGTT destruction, as opposed to making space under
memory pressure.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The plan to to make every file descriptor have a default context. To
accommodate this, generalize out default context setup function so it
can be used at file open time.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We **need** to do this for exactly 1 reason, because we want to embed a
PPGTT into the context, but we don't want to special case the default
context.

To achieve that, we must be able to initialize contexts after the GTT is
setup (so we can allocate and pin the default context's BO), but before
the PPGTT and rings are initialized. This is because, currently, context
initialization requires ring usage. We don't have rings until after the
GTT is setup. If we split the enabling part of context initialization,
the part requiring the ringbuffer, we can untangle this, and then later
embed the PPGTT

Incidentally this allows us to also adhere to the original design of
context init/fini in future patches: they were only ever meant to be
called at driver load and unload.

v2: Move hw_contexts_disabled test in i915_gem_context_enable() (Chris)

v3: BUG_ON after checking for disabled contexts. Or else it blows up pre
gen6 (Ben)

v4: Forward port
Modified enable for each ring, since that patch is earlier in the series
Dropped ring arg from create_default_context so it can be used by others
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

This patch adds to changes for contexts on reset:
Sets last context to default - this will prevent the context switch
happening after a reset. That switch is not possible because the
rings are hung during reset and context switch requires reset. This
behavior will need to be reworked in the future, but this is what we
want for now.

In the future, we'll also want to reset the guilty context to
uninitialized. We should wait for ARB_Robustness related code to land
for that.

This is somewhat for paranoia.  Because we really don't know what the
GPU was doing when it hung, or the state it was in (mid context write,
for example), later restoring the context is a bad idea. By setting the
flag to not initialized, the next load of that context will not restore
the state, and thus on the subsequent switch away from the context will
overwrite the old data.

NOTE: This code needs a fixup when we actually have multiple VMs. The
issue that can occur is inactive objects in a VM will need to be
destroyed before the last context unref. This can now happen via the
fake switch introduced in this patch (and it other ways in the future)
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Previously we dropped the association of a context to a ring. It is
however very important to know which ring a context ran on (we could
have reused the other member, but I was nitpicky).

This is very important when we switch address spaces, which unlike
context objects, do change per ring.

As an example, if we have:

        RCS   BCS
ctx            A
ctx      A
ctx      B
ctx            B

Without tracking the last ring B ran on, we wouldn't know to switch the
address space on BCS in the last row.

As a result, we no longer need to track which ring a context "belongs"
to, as it never really made much sense anyway.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>