fix: add validation for expert parallelism settings

Add validation to prevent simultaneous use of `--enable-expert-parallel` and `expert-tensor-parallel-size` configurations. These settings are mutually exclusive. Implementing this check prevents unexpected behavior and improves error tracing.

If both settings are enabled concurrently, the system now throws an error, making it easier to identify and resolve configuration issues.

Signed-off-by: Jade Zheng <[email protected]>

Author: jianzs

vllm_ascend/ascend_config.py

@@ -13,11 +13,14 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Optional
+from typing import Optional, TYPE_CHECKING
 
 import vllm.envs as envs
 from vllm.logger import logger
 
+if TYPE_CHECKING:
+    from vllm.config import VllmConfig
+
 
 class AscendConfig:
     """
@@ -112,7 +115,7 @@ def get_ascend_config():
     return _ASCEND_CONFIG
 
 
-def check_ascend_config(vllm_config, enforce_eager):
+def check_ascend_config(vllm_config: "VllmConfig", enforce_eager):
     ascend_config = get_ascend_config()
 
     # for v0 engine
@@ -164,3 +167,11 @@ def check_ascend_config(vllm_config, enforce_eager):
                             "ACL Graph is currently experimental. Please "
                             "raise an issue on https://github.com/vllm-project/vllm-ascend/issues"
                             " if you encourage any Error")
+
+        # for expert parallelism
+        if vllm_config.parallel_config.enable_expert_parallel and \
+            ascend_config.expert_tensor_parallel_size > 0:
+            raise RuntimeError(
+                "Cannot set `--enable-expert-parallel` and "
+                "`expert_tensor_parallel_size` at the same time. "
+            )