drm/i915/gem: hide new uAPI behind CONFIG_BROKEN

Treat it the same as the fake local-memory stuff, where it is disabled
for normal kernels, in case some random UMD is tempted to use this. Once
we have all the other bits and pieces in place, like the TTM conversion,
we can turn this on for real.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Dave Airlie <airlied@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: mesa-dev@lists.freedesktop.org
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210429103056.407067-9-matthew.auld@intel.com

drivers/gpu/drm/i915/gem/i915_gem_create.c

@@ -335,6 +335,9 @@ static int ext_set_placements(struct i915_user_extension __user *base,
 {
 	struct drm_i915_gem_create_ext_memory_regions ext;
 
+	if (!IS_ENABLED(CONFIG_DRM_I915_UNSTABLE_FAKE_LMEM))
+		return -ENODEV;
+
 	if (copy_from_user(&ext, base, sizeof(ext)))
 		return -EFAULT;
 

drivers/gpu/drm/i915/i915_query.c

@@ -432,6 +432,9 @@ static int query_memregion_info(struct drm_i915_private *i915,
 	u32 total_length;
 	int ret, id, i;
 
+	if (!IS_ENABLED(CONFIG_DRM_I915_UNSTABLE_FAKE_LMEM))
+		return -ENODEV;
+
 	if (query_item->flags != 0)
 		return -EINVAL;