drm/i915: Kill GTT mappings when moving from GTT domain

In order to force a page-fault on a GTT mapping after we start using it
from the GPU and so enforce correct CPU/GPU synchronisation, we need to
invalidate the mapping.

Pointed out by Owain G. Ainsworth.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index abe6d901f95b..d4d8f888db85 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1314,12 +1314,12 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                 ret = i915_gem_object_bind_to_gtt(obj, 0, true);
                 if (ret)
                         goto unlock;
-
-                ret = i915_gem_object_set_to_gtt_domain(obj, write);
-                if (ret)
-                        goto unlock;
         }
 
+        ret = i915_gem_object_set_to_gtt_domain(obj, write);
+        if (ret)
+                goto unlock;
+
         if (!obj_priv->fault_mappable) {
                 obj_priv->fault_mappable = true;
                 i915_gem_info_update_mappable(dev_priv, obj, true);
@@ -2859,6 +2859,8 @@ i915_gem_object_flush_gtt_write_domain(struct drm_gem_object *obj)
          * to it immediately go to main memory as far as we know, so there's
          * no chipset flush.  It also doesn't land in render cache.
          */
+        i915_gem_release_mmap(obj);
+
         old_write_domain = obj->write_domain;
         obj->write_domain = 0;
 
@@ -3183,6 +3185,10 @@ i915_gem_object_set_to_gpu_domain(struct drm_gem_object *obj,
         if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_CPU)
                 i915_gem_clflush_object(obj);
 
+        /* blow away mappings if mapped through GTT */
+        if ((flush_domains | invalidate_domains) & I915_GEM_DOMAIN_GTT)
+                i915_gem_release_mmap(obj);
+
         /* The actual obj->write_domain will be updated with
          * pending_write_domain after we emit the accumulated flush for all
          * of our domain changes in execbuffers (which clears objects'