anv/allocator: Add assert and TODO comment for future small BAR uapi

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17349>

src/intel/vulkan/anv_allocator.c

@@ -1706,6 +1706,11 @@ anv_device_alloc_bo(struct anv_device *device,
          regions[nregions++] = device->physical->sys.region;
       }
 
+      /* TODO: Add I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS to flags for
+       * after small BAR uapi is stabilized.
+       */
+      assert(intel_vram_all_mappable(&device->info));
+
       gem_handle = anv_gem_create_regions(device, size + ccs_size,
                                           nregions, regions);
    } else {