drm/i915: add a context parameter to {en, dis}able zero address mapping

Export a new context parameter that can be set/queried through the
context_{get,set}param ioctls.  This parameter is passed as a context
flag and decides whether or not a GPU address mapping is allowed to
be made at address zero.  The default is to allow such mappings.

Signed-off-by: David Weinehall <david.weinehall@intel.com>
Acked-by: "Zou, Nanhai" <nanhai.zou@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index bd0e4bd..3336e1c 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -676,6 +676,7 @@
 static int
 i915_gem_execbuffer_reserve(struct intel_engine_cs *ring,
 			    struct list_head *vmas,
+			    struct intel_context *ctx,
 			    bool *need_relocs)
 {
 	struct drm_i915_gem_object *obj;
@@ -698,6 +699,9 @@
 		obj = vma->obj;
 		entry = vma->exec_entry;
 
+		if (ctx->flags & CONTEXT_NO_ZEROMAP)
+			entry->flags |= __EXEC_OBJECT_NEEDS_BIAS;
+
 		if (!has_fenced_gpu_access)
 			entry->flags &= ~EXEC_OBJECT_NEEDS_FENCE;
 		need_fence =
@@ -775,7 +779,8 @@
 				  struct drm_file *file,
 				  struct intel_engine_cs *ring,
 				  struct eb_vmas *eb,
-				  struct drm_i915_gem_exec_object2 *exec)
+				  struct drm_i915_gem_exec_object2 *exec,
+				  struct intel_context *ctx)
 {
 	struct drm_i915_gem_relocation_entry *reloc;
 	struct i915_address_space *vm;
@@ -861,7 +866,7 @@
 		goto err;
 
 	need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
-	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, &need_relocs);
+	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, ctx, &need_relocs);
 	if (ret)
 		goto err;
 
@@ -1519,7 +1524,7 @@
 
 	/* Move the objects en-masse into the GTT, evicting if necessary. */
 	need_relocs = (args->flags & I915_EXEC_NO_RELOC) == 0;
-	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, &need_relocs);
+	ret = i915_gem_execbuffer_reserve(ring, &eb->vmas, ctx, &need_relocs);
 	if (ret)
 		goto err;
 
@@ -1529,7 +1534,7 @@
 	if (ret) {
 		if (ret == -EFAULT) {
 			ret = i915_gem_execbuffer_relocate_slow(dev, args, file, ring,
-								eb, exec);
+								eb, exec, ctx);
 			BUG_ON(!mutex_is_locked(&dev->struct_mutex));
 		}
 		if (ret)