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>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index abe6d90..d4d8f88 100644 (file)
--- 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'