[tests] Fix bnb cpu error

src/accelerate/accelerator.py

@@ -1471,8 +1471,11 @@ def prepare_model(self, model: torch.nn.Module, device_placement: bool = None, e
                             "You can't train a model that has been loaded in 8-bit or 4-bit precision on a different device than the one "
                             "you're training on. Make sure you loaded the model on the correct device using for example `device_map={'':torch.cuda.current_device()}` or `device_map={'':torch.xpu.current_device()}`"
                         )
-
-            if ("cpu" in model_devices and not is_bitsandbytes_multi_backend_available()) or "disk" in model_devices:
+            if (
+                ("cpu" in model_devices and not is_bitsandbytes_multi_backend_available())
+                or ("cpu" in model_devices and is_xpu_available())
+                or "disk" in model_devices
+            ):
                 raise ValueError(
                     "You can't train a model that has been loaded in 8-bit or 4-bit precision with CPU or disk offload. "
                     "If you want train the 8-bit or 4-bit model in CPU, please install bitsandbytes with multi-backend, see https://huggingface.co/docs/bitsandbytes/main/en/installation#multi-backend"

tests/test_accelerator.py

@@ -470,7 +470,7 @@ def test_accelerator_bnb(self):
         # This should work
         model = accelerator.prepare(model)
 
-    @require_cuda
+    @require_cuda_or_xpu
     @slow
     @require_bnb
     def test_accelerator_bnb_cpu_error(self):