drm/i915: Remove has-kernel-context

We can no longer assume execution ordering, and in particular we cannot
assume which context will execute last. One side-effect of this is that
we cannot determine if the kernel-context is resident on the GPU, so
remove the routines that claimed to do so.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190308093657.8640-4-chris@chris-wilson.co.uk

5 files changed, 4 insertions, 78 deletions

diff --git a/drivers/gpu/drm/i915/i915_active.h b/drivers/gpu/drm/i915/i915_active.h
index 8142a334b37b..7d758719ce39 100644
--- a/drivers/gpu/drm/i915/i915_active.h
+++ b/drivers/gpu/drm/i915/i915_active.h
@@ -108,19 +108,6 @@ i915_active_request_set_retire_fn(struct i915_active_request *active,
         active->retire = fn ?: i915_active_retire_noop;
 }
 
-static inline struct i915_request *
-__i915_active_request_peek(const struct i915_active_request *active)
-{
-        /*
-         * Inside the error capture (running with the driver in an unknown
-         * state), we want to bend the rules slightly (a lot).
-         *
-         * Work is in progress to make it safer, in the meantime this keeps
-         * the known issue from spamming the logs.
-         */
-        return rcu_dereference_protected(active->request, 1);
-}
-
 /**
  * i915_active_request_raw - return the active request
  * @active - the active tracker
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 961237b90b40..1f1849f90606 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2828,23 +2828,6 @@ i915_gem_retire_work_handler(struct work_struct *work)
                                    round_jiffies_up_relative(HZ));
 }
 
-static void assert_kernel_context_is_current(struct drm_i915_private *i915)
-{
-        struct intel_engine_cs *engine;
-        enum intel_engine_id id;
-
-        if (i915_reset_failed(i915))
-                return;
-
-        i915_retire_requests(i915);
-
-        for_each_engine(engine, i915, id) {
-                GEM_BUG_ON(__i915_active_request_peek(&engine->timeline.last_request));
-                GEM_BUG_ON(engine->last_retired_context !=
-                           to_intel_context(i915->kernel_context, engine));
-        }
-}
-
 static bool switch_to_kernel_context_sync(struct drm_i915_private *i915,
                                           unsigned long mask)
 {
@@ -2864,9 +2847,7 @@ static bool switch_to_kernel_context_sync(struct drm_i915_private *i915,
                                    I915_GEM_IDLE_TIMEOUT))
                 result = false;
 
-        if (result) {
-                assert_kernel_context_is_current(i915);
-        } else {
+        if (!result) {
                 /* Forcibly cancel outstanding work and leave the gpu quiet. */
                 dev_err(i915->drm.dev,
                         "Failed to idle engines, declaring wedged!\n");
diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index 7d8e90dfca84..060f5903544a 100644
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -38,25 +38,15 @@ I915_SELFTEST_DECLARE(static struct igt_evict_ctl {
 
 static bool ggtt_is_idle(struct drm_i915_private *i915)
 {
-       struct intel_engine_cs *engine;
-       enum intel_engine_id id;
-
-       if (i915->gt.active_requests)
-               return false;
-
-       for_each_engine(engine, i915, id) {
-               if (!intel_engine_has_kernel_context(engine))
-                       return false;
-       }
-
-       return true;
+        return !i915->gt.active_requests;
 }
 
 static int ggtt_flush(struct drm_i915_private *i915)
 {
         int err;
 
-        /* Not everything in the GGTT is tracked via vma (otherwise we
+        /*
+         * Not everything in the GGTT is tracked via vma (otherwise we
          * could evict as required with minimal stalling) so we are forced
          * to idle the GPU and explicitly retire outstanding requests in
          * the hopes that we can then remove contexts and the like only
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 18174f808fd8..8e326556499e 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1090,37 +1090,6 @@ bool intel_engines_are_idle(struct drm_i915_private *i915)
         return true;
 }
 
-/**
- * intel_engine_has_kernel_context:
- * @engine: the engine
- *
- * Returns true if the last context to be executed on this engine, or has been
- * executed if the engine is already idle, is the kernel context
- * (#i915.kernel_context).
- */
-bool intel_engine_has_kernel_context(const struct intel_engine_cs *engine)
-{
-        const struct intel_context *kernel_context =
-                to_intel_context(engine->i915->kernel_context, engine);
-        struct i915_request *rq;
-
-        lockdep_assert_held(&engine->i915->drm.struct_mutex);
-
-        if (!engine->context_size)
-                return true;
-
-        /*
-         * Check the last context seen by the engine. If active, it will be
-         * the last request that remains in the timeline. When idle, it is
-         * the last executed context as tracked by retirement.
-         */
-        rq = __i915_active_request_peek(&engine->timeline.last_request);
-        if (rq)
-                return rq->hw_context == kernel_context;
-        else
-                return engine->last_retired_context == kernel_context;
-}
-
 void intel_engines_reset_default_submission(struct drm_i915_private *i915)
 {
         struct intel_engine_cs *engine;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 84b7047e2df5..9ccbe63d46e3 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -935,7 +935,6 @@ void intel_engines_sanitize(struct drm_i915_private *i915, bool force);
 bool intel_engine_is_idle(struct intel_engine_cs *engine);
 bool intel_engines_are_idle(struct drm_i915_private *dev_priv);
 
-bool intel_engine_has_kernel_context(const struct intel_engine_cs *engine);
 void intel_engine_lost_context(struct intel_engine_cs *engine);
 
 void intel_engines_park(struct drm_i915_private *i915);