drm/i915: Fix eviction when the GGTT is idle but full

[mirror_ubuntu-bionic-kernel.git] / drivers / gpu / drm / i915 / i915_gem_evict.c

diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index a5a5b7e6daae355b9f5a80e39ea2cbaac9173e90..ee4811ffb7aafe619a83ee7b1aad1672cbd32ea5 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -33,21 +33,20 @@
 #include "intel_drv.h"
 #include "i915_trace.h"
 
-static bool ggtt_is_idle(struct drm_i915_private *dev_priv)
+static bool ggtt_is_idle(struct drm_i915_private *i915)
 {
-       struct i915_ggtt *ggtt = &dev_priv->ggtt;
-       struct intel_engine_cs *engine;
-       enum intel_engine_id id;
+       struct intel_engine_cs *engine;
+       enum intel_engine_id id;
 
-       for_each_engine(engine, dev_priv, id) {
-               struct intel_timeline *tl;
+       if (i915->gt.active_requests)
+              return false;
 
-               tl = &ggtt->base.timeline.engine[engine->id];
-               if (i915_gem_active_isset(&tl->last_request))
-                       return false;
-       }
+       for_each_engine(engine, i915, id) {
+              if (engine->last_retired_context != i915->kernel_context)
+                      return false;
+       }
 
-       return true;
+       return true;
 }
 
 static int ggtt_flush(struct drm_i915_private *i915)
@@ -157,7 +156,8 @@ i915_gem_evict_something(struct i915_address_space *vm,
                                    min_size, alignment, cache_level,
                                    start, end, mode);
 
-       /* Retire before we search the active list. Although we have
+       /*
+        * Retire before we search the active list. Although we have
         * reasonable accuracy in our retirement lists, we may have
         * a stray pin (preventing eviction) that can only be resolved by
         * retiring.
@@ -182,7 +182,8 @@ search_again:
                BUG_ON(ret);
        }
 
-       /* Can we unpin some objects such as idle hw contents,
+       /*
+        * Can we unpin some objects such as idle hw contents,
         * or pending flips? But since only the GGTT has global entries
         * such as scanouts, rinbuffers and contexts, we can skip the
         * purge when inspecting per-process local address spaces.
@@ -190,19 +191,33 @@ search_again:
        if (!i915_is_ggtt(vm) || flags & PIN_NONBLOCK)
                return -ENOSPC;
 
-       if (ggtt_is_idle(dev_priv)) {
-               /* If we still have pending pageflip completions, drop
-                * back to userspace to give our workqueues time to
-                * acquire our locks and unpin the old scanouts.
-                */
-               return intel_has_pending_fb_unpin(dev_priv) ? -EAGAIN : -ENOSPC;
-       }
+       /*
+        * Not everything in the GGTT is tracked via VMA using
+        * i915_vma_move_to_active(), otherwise we could evict as required
+        * with minimal stalling. Instead we are forced to idle the GPU and
+        * explicitly retire outstanding requests which will then remove
+        * the pinning for active objects such as contexts and ring,
+        * enabling us to evict them on the next iteration.
+        *
+        * To ensure that all user contexts are evictable, we perform
+        * a switch to the perma-pinned kernel context. This all also gives
+        * us a termination condition, when the last retired context is
+        * the kernel's there is no more we can evict.
+        */
+       if (!ggtt_is_idle(dev_priv)) {
+               ret = ggtt_flush(dev_priv);
+               if (ret)
+                       return ret;
 
-       ret = ggtt_flush(dev_priv);
-       if (ret)
-               return ret;
+               goto search_again;
+       }
 
-       goto search_again;
+       /*
+        * If we still have pending pageflip completions, drop
+        * back to userspace to give our workqueues time to
+        * acquire our locks and unpin the old scanouts.
+        */
+       return intel_has_pending_fb_unpin(dev_priv) ? -EAGAIN : -ENOSPC;
 
 found:
        /* drm_mm doesn't allow any other other operations while