[Model Runner V2] Support FLASHINFER_MLA backend (#32709)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

vllm/v1/worker/gpu/attn_utils.py

@@ -57,7 +57,7 @@ def init_attn_backend(
         )
         attn_metadata_builders.append(attn_metadata_builder)  # type: ignore
 
-        if "FLASHINFER" in attn_backend.get_name():
+        if attn_backend.get_name() == "FLASHINFER":
             if flashinfer_workspace is None:
                 flashinfer_workspace = attn_metadata_builder._get_workspace_buffer()
             else:

vllm/v1/worker/gpu/model_runner.py

@@ -248,7 +248,7 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             )
 
         # TODO(woosuk): Support other backends.
-        supported_backends = ("FLASH_ATTN", "FLASHINFER")
+        supported_backends = ("FLASH_ATTN", "FLASHINFER", "FLASHINFER_MLA")
         for backend in self.attn_backends.values():
             backend_name = backend.get_name()
             if backend_name not in supported_backends: