Rather than reuse the common ctx->mutex for locking the execbuffer LUT,
split it into its own lock to avoid being taken [as part of ctx->mutex]
at inappropriate times. In particular to avoid the inversion from taking
the timeline->mutex for the whole execbuf submission in the next patch.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703004306.11117-1-chris@chris-wilson.co.uk

The obj->lut_list is traversed when the object is closed as the file
table is destroyed during process termination. As this occurs before we
kill any outstanding context if, due to some bug or another, the closure
is blocked, then we fail to shootdown any inflight operations
potentially leaving the GPU spinning forever. As we only need to guard
the list against concurrent closures and insertions, the hold is short
and merits being treated as a simple spinlock.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMichael J. Ruhl <michael.j.ruhl@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701084439.17025-1-chris@chris-wilson.co.uk

Start using device specific parameters instead of module parameters for
most things. The module parameters become the immutable initial values
for i915 parameters. The device specific parameters in i915->params
start life as a copy of i915_modparams. Any later changes are only
reflected in the debugfs.

The stragglers are:

* i915.force_probe and i915.modeset. Needed before dev_priv is
  available. This is fine because the parameters are read-only and never
  modified.

* i915.verbose_state_checks. Passing dev_priv to I915_STATE_WARN and
  I915_STATE_WARN_ON would result in massive and ugly churn. This is
  handled by not exposing the parameter via debugfs, and leaving the
  parameter writable in sysfs. This may be fixed up in follow-up work.

* i915.inject_probe_failure. Only makes sense in terms of the module,
  not the device. This is handled by not exposing the parameter via
  debugfs.

v2: Fix uc i915 lookup code (Michał Winiarski)

Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila@intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: NMichał Winiarski <michal.winiarski@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200618150402.14022-1-jani.nikula@intel.com

Since the removal of the no-semaphore boosting, we rely on timeslicing to
reorder passed inter-dependency hogs across the engines. However, we
require preemption to support timeslicing into user payloads, and not all
machine support preemption so we do not universally enable timeslicing,
even when it would correctly preempt our own inter-engine semaphores.
Since timeslicing and semaphore priority deboosting is now disabled on
Broadwell/Braswell, we have to follow suite and not use semaphores.

Testcase: igt/gem_exec_schedule/semaphore-codependency # bdw/bsw
Fixes: 18e4af04 ("drm/i915: Drop no-semaphore boosting")
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: https://patchwork.freedesktop.org/patch/msgid/20200521140617.30015-1-chris@chris-wilson.co.uk
(cherry picked from commit 0eb670aa)
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Since the removal of the no-semaphore boosting, we rely on timeslicing to
reorder passed inter-dependency hogs across the engines. However, we
require preemption to support timeslicing into user payloads, and not all
machine support preemption so we do not universally enable timeslicing,
even when it would correctly preempt our own inter-engine semaphores.
Since timeslicing and semaphore priority deboosting is now disabled on
Broadwell/Braswell, we have to follow suite and not use semaphores.

Testcase: igt/gem_exec_schedule/semaphore-codependency # bdw/bsw
Fixes: 18e4af04 ("drm/i915: Drop no-semaphore boosting")
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: https://patchwork.freedesktop.org/patch/msgid/20200521140617.30015-1-chris@chris-wilson.co.uk

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The history of i915_vma_close() is confusing, as is its use. As the
lifetime of the i915_vma is currently bounded by the object it is
attached to, we needed a means of identify when a vma was no longer in
use by userspace (via the user's fd). This is further complicated by
that only ppgtt vma should be closed at the user's behest, as the ggtt
were always shared.

Now that we attach the vma to a lut on the user's context, the open
count does indicate how many unique and open context/vm are referencing
this vma from the user. As such, we can and should just use the
open_count to track when the vma is still in use by userspace.

It's a poor man's replacement for reference counting.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1193Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200422190558.30509-1-chris@chris-wilson.co.uk

If we want to percolate information back from the HW, up through the GEM
context, we need to wait until the intel_context is scheduled out for
the last time. This is handled by the retirement of the intel_context's
barrier, i.e. by listening to the pulse after the notional unpin. So
wait until the intel_context is finally retired before releasing the
engine, so that we can inspect the final context state and pass it on.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200406155840.1728-3-chris@chris-wilson.co.uk

Now that we can peek at GEM->engines[] and obtain a reference to them
using RCU, do so for instances where we can safely iterate the
potentially old copy of the engines. For setting, we can do this when we
know the engine properties are copied over before swapping, so we know
the new engines already have the global property and we update the old
before they are discarded. For reading, we only need to be safe; as we
do so on behalf of the user, their races are their own problem.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200402124218.6375-1-chris@chris-wilson.co.uk

I need to keep the GEM context around a bit longer so adding an explicit
flag for syncing execbuf with closed/abandonded contexts.

v2:
 * Use already available context flags. (Chris)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200319170707.8262-1-chris@chris-wilson.co.uk
(cherry picked from commit 207e4a71)
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>

I need to keep the GEM context around a bit longer so adding an explicit
flag for syncing execbuf with closed/abandonded contexts.

v2:
 * Use already available context flags. (Chris)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200319170707.8262-1-chris@chris-wilson.co.uk

On Gen11 powergating half the execution units is a functional
requirement when using the VME samplers. Not fullfilling this
requirement can lead to hangs.

This unfortunately plays fairly poorly with the NOA requirements. NOA
requires a stable power configuration to maintain its configuration.

As a result using OA (and NOA feeding into it) so far has required us
to use a power configuration that can work for all contexts. The only
power configuration fullfilling this is powergating half the execution
units.

This makes performance analysis for 3D workloads somewhat pointless.

Failing to find a solution that would work for everybody, this change
introduces a new i915-perf stream open parameter that punts the
decision off to userspace. If this parameter is omitted, the existing
Gen11 behavior remains (half EU array powergating).

This change takes the initiative to move all perf related sseu
configuration into i915_perf.c

v2: Make parameter priviliged if different from default

v3: Fix context modifying its sseu config while i915-perf is enabled

v4: Always consider global sseu a privileged operation (Tvrtko)
    Override req_sseu point in intel_sseu_make_rpcs() (Tvrtko)
    Remove unrelated changes (Tvrtko)

v5: Some typos (Tvrtko)
    Process sseu param in read_properties_unlocked() (Tvrtko)

v6: Actually commit the bits from v5...
    Fixup some checkpath warnings

v7: Only compare engine uabi field (Chris)
Signed-off-by: NLionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200317132222.2638719-3-lionel.g.landwerlin@intel.com

During driver unload, we have many asserts that we have released our
bookkeeping structs and are idle. In some cases, these struct are
protected by RCU and we do not release them until after an RCU grace
period.
Reported-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 130a95e9 ("drm/i915/gem: Consolidate ctx->engines[] release")
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>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200312115307.16460-1-chris@chris-wilson.co.uk

When applying the context-barrier, we only care about the current
engines, as the next set of engines will be naturally after the barrier.
So we can skip holding the ctx->engines_mutex while constructing the
request by taking a sneaky reference to the i915_gem_engines instead.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200311221739.30375-2-chris@chris-wilson.co.uk

The sw-fence notify function requires to be at least 4-byte aligned so
that we can use the low bits in the function pointer for internal fence
flags. Make it so.

References: https://gitlab.freedesktop.org/drm/intel/issues/1433
Fixes: 42fb60de ("drm/i915/gem: Don't leak non-persistent requests on changing engines")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200311221739.30375-1-chris@chris-wilson.co.uk

Use the same engine_idle_release() routine for cleaning all old
ctx->engine[] state, closing any potential races with concurrent execbuf
submission.

v2ish: Use the ce->pin_count to close the execbuf gap.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1241Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200303080546.1140508-1-chris@chris-wilson.co.uk

The #include has been splattered all over the place, but there are
precious few places, all .c files, that actually need it.

v2: remove leftover double newlines
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200225133131.3301-1-jani.nikula@intel.com

No good reason why we must always use a static ringsize, so let
userspace select one during construction.

Link: https://github.com/intel/compute-runtime/pull/261Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Steve Carbonari <steven.carbonari@intel.com>
Reviewed-by: NJanusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200225192206.1107336-2-chris@chris-wilson.co.uk

use intel_uc_uses_guc_submission() directly instead, to be consistent in
the way we check what we want to do with the GuC.

v2: do not go through ctx->vm->gt, use i915->gt instead
Signed-off-by: NDaniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com> #v1
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200218223327.11058-3-daniele.ceraolospurio@intel.com

To enable non-persistent contexts, we require a means of cancelling any
inflight work from that context. This is first done "gracefully" by
using preemption to kick the active context off the engine, and then
forcefully by resetting the engine if it is active. If we are unable to
reset the engine to remove hostile userspace, we should not allow
userspace to opt into using non-persistent contexts.

If the per-engine reset fails, we still do a full GPU reset, but that is
rare and usually indicative of much deeper issues. The damage is already
done. However, the goal of the interface to allow long running compute
jobs without causing collateral damage elsewhere, and if we are unable
to support that we should make that known by not providing the
interface (and falsely pretending we can).

Fixes: a0e04715 ("drm/i915/gem: Make context persistence optional")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200130164553.1937718-1-chris@chris-wilson.co.uk
(cherry picked from commit d1b9b5f1)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

If we have a set of active engines marked as being non-persistent, we
lose track of those if the user replaces those engines with
I915_CONTEXT_PARAM_ENGINES. As part of our uABI contract is that
non-persistent requests are terminated if they are no longer being
tracked by the user's context (in order to prevent a lost request
causing an untracked and so unstoppable GPU hang), we need to apply the
same context cancellation upon changing engines.

v2: Track stale engines[] so we only reap at context closure.
v3: Tvrtko spotted races with closing contexts and set-engines, so add a
veneer of kill-everything paranoia to clean up after losing a race.

Fixes: a0e04715 ("drm/i915/gem: Make context persistence optional")
Testcase: igt/gem_ctx_peristence/replace
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211144831.1011498-1-chris@chris-wilson.co.uk

If a request is being re-run after an innocent reset, it is marked as
-EAGAIN. So only skip an engine reset if the request is marked as -EIO.

Testcase: igt/gem_ctx_exec/basic-nohangcheck
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200207161602.2838218-1-chris@chris-wilson.co.uk

Lift the routines to emit a request to update the SSEU on the
intel_context out of i915_gem_context.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200131104548.2451485-6-chris@chris-wilson.co.uk

To enable non-persistent contexts, we require a means of cancelling any
inflight work from that context. This is first done "gracefully" by
using preemption to kick the active context off the engine, and then
forcefully by resetting the engine if it is active. If we are unable to
reset the engine to remove hostile userspace, we should not allow
userspace to opt into using non-persistent contexts.

If the per-engine reset fails, we still do a full GPU reset, but that is
rare and usually indicative of much deeper issues. The damage is already
done. However, the goal of the interface to allow long running compute
jobs without causing collateral damage elsewhere, and if we are unable
to support that we should make that known by not providing the
interface (and falsely pretending we can).

Fixes: a0e04715 ("drm/i915/gem: Make context persistence optional")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200130164553.1937718-1-chris@chris-wilson.co.uk

Convert most of the remaining uses of the printk based logging macros to
the new struct drm_device based logging macros in drm/i915/gem.
This also involves extracting the struct drm_i915_private device
from various types, and using it in the various macros.
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NWambui Karuga <wambui.karugax@gmail.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200122125750.9737-3-wambui.karugax@gmail.com

First pass of conversion to the new struct drm_based device logging
macros in the drm/i915/gem directory. This conversion was achieved using
the following coccinelle script that transforms based on the existence
of a straightforward struct drm_i915_private device:

@rule1@
identifier fn, T;
@@

fn(struct drm_i915_private *T,...) {
<+...
(
-DRM_INFO(
+drm_info(&T->drm,
...)
|
-DRM_ERROR(
+drm_err(&T->drm,
...)
|
-DRM_WARN(
+drm_warn(&T->drm,
...)
|
-DRM_DEBUG(
+drm_dbg(&T->drm,
...)
|
-DRM_DEBUG_DRIVER(
+drm_dbg(&T->drm,
...)
|
-DRM_DEBUG_KMS(
+drm_dbg_kms(&T->drm,
...)
|
-DRM_DEBUG_ATOMIC(
+drm_dbg_atomic(&T->drm,
...)
)
...+>
}

@rule2@
identifier fn, T;
@@

fn(...) {
...
struct drm_i915_private *T = ...;
<+...
(
-DRM_INFO(
+drm_info(&T->drm,
...)
|
-DRM_ERROR(
+drm_err(&T->drm,
...)
|
-DRM_WARN(
+drm_warn(&T->drm,
...)
|
-DRM_DEBUG(
+drm_dbg(&T->drm,
...)
|
-DRM_DEBUG_KMS(
+drm_dbg_kms(&T->drm,
...)
|
-DRM_DEBUG_DRIVER(
+drm_dbg(&T->drm,
...)
|
-DRM_DEBUG_ATOMIC(
+drm_dbg_atomic(&T->drm,
...)
)
...+>
}

Checkpatch warnings were addressed manually.
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NWambui Karuga <wambui.karugax@gmail.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200122125750.9737-2-wambui.karugax@gmail.com

If the ctx->vm is freed before we can acquire a local reference to it,
we proceed to call i915_vm_put(NULL), which is invalid.
Reported-by: NColin Ian King <colin.king@canonical.com>
Fixes: 5dbd2b7b ("drm/i915/gem: Convert vm idr to xarray")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Colin Ian King <colin.king@canonical.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123152602.1432282-1-chris@chris-wilson.co.uk

Replace the vm_idr + vm_idr_mutex to an XArray. The XArray data
structure is now used to implement IDRs, and provides its own locking.
We can simply remove the IDR wrapper and in the process also remove our
extra mutex.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NMichael J. Ruhl <michael.j.ruhl@intel.com>
Acked-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200122161531.508903-1-chris@chris-wilson.co.uk

Since we now allow the intel_context_unpin() to run unserialised, we
risk our operations under the intel_context_lock_pinned() being run as
the context is unpinned (and thus invalidating our state). We can
atomically acquire the pin, testing to see if it is pinned in the
process, thus ensuring that the state remains consistent during the
course of the whole operation.

Fixes: 84135022 ("drm/i915/gt: Drop mutex serialisation between context pin/unpin")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200109085142.871563-1-chris@chris-wilson.co.uk

Attempt to split i915_gem_gtt.[ch] into more manageable chunks.
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NMatthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200107134009.3255354-1-chris@chris-wilson.co.uk

IDR internally uses xarray so we can use it directly which simplifies our
code by removing the need to do external locking.
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191224095920.2386297-1-chris@chris-wilson.co.uk

The only protection for intel_context.gem_cotext is granted by RCU, so
annotate it as a rcu protected pointer and carefully dereference it in
the few occasions we need to use it.

Fixes: 9f3ccd40 ("drm/i915: Drop GEM context as a direct link from i915_request")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Acked-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191222233558.2201901-1-chris@chris-wilson.co.uk

Allocate only an internal intel_context for the kernel_context, forgoing
a global GEM context for internal use as we only require a separate
address space (for our own protection).

Now having weaned GT from requiring ce->gem_context, we can stop
referencing it entirely. This also means we no longer have to create random
and unnecessary GEM contexts for internal use.

GEM contexts are now entirely for tracking GEM clients, and intel_context
the execution environment on the GPU.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Acked-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191221160324.1073045-1-chris@chris-wilson.co.uk

Instead of rummaging through the intel_context to peek at the GEM
context in the middle of request submission to decide whether to use
semaphores, store that information on the intel_context itself.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191220101230.256839-2-chris@chris-wilson.co.uk

Keep the intel_context as being the primary state for i915_request, with
the GEM context a backpointer from the low level state for the rarer
cases we need client information. Our goal is to remove such references
to clients from the backend, and leave the HW submission agnostic to
client interfaces and self-contained.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191220101230.256839-1-chris@chris-wilson.co.uk

Get_pid_task() needs to be paired with a put_pid or we leak a pid
reference every time a banned client tries to create a context.

v2:
 * task_pid_nr helper exists! (Chris)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: b083a087 ("drm/i915: Add per client max context ban limit")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217170933.8108-1-tvrtko.ursulin@linux.intel.com
(cherry picked from commit ba16a48a)
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Get_pid_task() needs to be paired with a put_pid or we leak a pid
reference every time a banned client tries to create a context.

v2:
 * task_pid_nr helper exists! (Chris)
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: b083a087 ("drm/i915: Add per client max context ban limit")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217170933.8108-1-tvrtko.ursulin@linux.intel.com

All pinning must be done prior to i915_request_create, to avoid
timeline->mutex inversions.

Here we slightly abuse the context_barrier_task stages to utilise the
'skip' decision as an opportunity to acquire the pin on the new ppgtt.
Consider it s/skip/prepare/. At the moment, we only have on user of
context_barrier_task, so it might be worth breaking it down for the
specific task of set-vm and refactor it later if we find a second
purpose.

<4> [402.377487] WARNING: possible circular locking dependency detected
<4> [402.377493] 5.4.0-rc8-CI-CI_DRM_7491+ #1 Tainted: G     U
<4> [402.377497] ------------------------------------------------------
<4> [402.377502] gem_exec_parall/2506 is trying to acquire lock:
<4> [402.377507] ffff888403cdac70 (&kernel#2){+.+.}, at: i915_request_create+0x16/0x1c0 [i915]
<4> [402.377593]
but task is already holding lock:
<4> [402.377597] ffff88835efad550 (&ppgtt->pin_mutex){+.+.}, at: gen6_ppgtt_pin+0x4d/0x110 [i915]
<4> [402.377660]
which lock already depends on the new lock.

<4> [402.377664]
the existing dependency chain (in reverse order) is:
<4> [402.377668]
-> #1 (&ppgtt->pin_mutex){+.+.}:
<4> [402.377674]        __mutex_lock+0x9a/0x9d0
<4> [402.377713]        gen6_ppgtt_pin+0x4d/0x110 [i915]
<4> [402.377756]        emit_ppgtt_update+0x1dc/0x370 [i915]
<4> [402.377801]        context_barrier_task+0x176/0x310 [i915]
<4> [402.377844]        ctx_setparam+0x400/0xb10 [i915]
<4> [402.377886]        i915_gem_context_setparam_ioctl+0xc8/0x160 [i915]
<4> [402.377891]        drm_ioctl_kernel+0xa7/0xf0
<4> [402.377895]        drm_ioctl+0x2e1/0x390
<4> [402.377899]        do_vfs_ioctl+0xa0/0x6f0
<4> [402.377903]        ksys_ioctl+0x35/0x60
<4> [402.377906]        __x64_sys_ioctl+0x11/0x20
<4> [402.377910]        do_syscall_64+0x4f/0x210
<4> [402.377914]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4> [402.377917]
-> #0 (&kernel#2){+.+.}:
<4> [402.377923]        __lock_acquire+0x1328/0x15d0
<4> [402.377926]        lock_acquire+0xa7/0x1c0
<4> [402.377930]        __mutex_lock+0x9a/0x9d0
<4> [402.377977]        i915_request_create+0x16/0x1c0 [i915]
<4> [402.378013]        intel_engine_flush_barriers+0x4c/0x100 [i915]
<4> [402.378062]        i915_ggtt_pin+0x7d/0x130 [i915]
<4> [402.378108]        gen6_ppgtt_pin+0x9c/0x110 [i915]
<4> [402.378148]        ring_context_pin+0x2e/0xc0 [i915]
<4> [402.378183]        __intel_context_do_pin+0x6b/0x190 [i915]
<4> [402.378226]        i915_gem_do_execbuffer+0x180c/0x26b0 [i915]
<4> [402.378268]        i915_gem_execbuffer2_ioctl+0x11b/0x460 [i915]
<4> [402.378272]        drm_ioctl_kernel+0xa7/0xf0
<4> [402.378275]        drm_ioctl+0x2e1/0x390
<4> [402.378279]        do_vfs_ioctl+0xa0/0x6f0
<4> [402.378282]        ksys_ioctl+0x35/0x60
<4> [402.378286]        __x64_sys_ioctl+0x11/0x20
<4> [402.378289]        do_syscall_64+0x4f/0x210
<4> [402.378292]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4> [402.378295]
other info that might help us debug this:

<4> [402.378299]  Possible unsafe locking scenario:

<4> [402.378302]        CPU0                    CPU1
<4> [402.378305]        ----                    ----
<4> [402.378307]   lock(&ppgtt->pin_mutex);
<4> [402.378310]                                lock(&kernel#2);
<4> [402.378314]                                lock(&ppgtt->pin_mutex);
<4> [402.378317]   lock(&kernel#2);
<4> [402.378320]
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NAndi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191206105527.1130413-4-chris@chris-wilson.co.uk

Though the context is closed and so no more requests can be added to the
timeline, retirement can still be removing requests. It can even be
removing the very request we are inspecting and so cause us to wander
into dead links.

Serialise with the retirement by taking the timeline->mutex used for
guarding the timeline->requests list.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112404
Fixes: 4a317415 ("drm/i915/gem: Refine occupancy test in kill_context()")
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>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191129151845.1092933-1-chris@chris-wilson.co.uk
(cherry picked from commit 7ce596a8)
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Though the context is closed and so no more requests can be added to the
timeline, retirement can still be removing requests. It can even be
removing the very request we are inspecting and so cause us to wander
into dead links.

Serialise with the retirement by taking the timeline->mutex used for
guarding the timeline->requests list.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112404
Fixes: 4a317415 ("drm/i915/gem: Refine occupancy test in kill_context()")
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>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191129151845.1092933-1-chris@chris-wilson.co.uk