[Bugfix] fix bug for mtp (#6514)

### What this PR does / why we need it?
fix(mtp): resolve MTP core bugs and enhance eager mode test cases
1. Resolved critical issues in eager mode MTP core execution logic;
2. Fixed functional bugs in the _update_states_after_model_execute
function;
3. Updated and released test_mtp_qwen3_next.py to validate eager mode
acceptance rate.
### Does this PR introduce _any_ user-facing change?
None
### How was this patch tested?

- vLLM version: v0.15.0
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.15.0

Signed-off-by: Bowen-Leee <caoshankuangren@gmail.com>

.github/workflows/scripts/config.yaml

@@ -152,4 +152,3 @@ e2e-multicard-4-cards:
     is_skipped: true
   - name: tests/e2e/multicard/4-cards/spec_decode/test_mtp_qwen3_next.py
     estimated_time: 60
-    is_skipped: true

tests/e2e/multicard/4-cards/spec_decode/test_mtp_qwen3_next.py

@@ -54,7 +54,6 @@ def test_qwen3_next_mtp_acceptance_tp4(model_name):
                     distributed_executor_backend="mp",
                     disable_log_stats=False,
                     speculative_config={
-                        "cudagraph_mode": "FULL_DECODE_ONLY",
                         "method": "qwen3_next_mtp",
                         "num_speculative_tokens": 3,
                     },

vllm_ascend/spec_decode/mtp_proposer.py

@@ -14,7 +14,7 @@ from vllm_ascend.ascend_forward_context import set_ascend_forward_context
 from vllm_ascend.attention.attention_v1 import AscendAttentionState
 from vllm_ascend.attention.utils import AscendCommonAttentionMetadata
 from vllm_ascend.compilation.acl_graph import ACLGraphWrapper
-from vllm_ascend.ops.rotary_embedding import get_cos_and_sin_mla
+from vllm_ascend.ops.rotary_embedding import get_cos_and_sin_mla, update_cos_sin
 from vllm_ascend.spec_decode.eagle_proposer import EagleProposer
 from vllm_ascend.utils import lmhead_tp_enable, vllm_version_is
 
@@ -329,6 +329,7 @@ class MtpProposer(EagleProposer):
         for layer_name in self.attn_layer_names:
             attn_metadata[layer_name] = attn_metadata_mtp
 
+        update_cos_sin(self._get_positions(num_input_tokens))
         for step in range(self.num_speculative_tokens):
             with set_ascend_forward_context(
                 attn_metadata,

vllm_ascend/worker/model_runner_v1.py

@@ -1374,6 +1374,9 @@ class NPUModelRunner(GPUModelRunner):
         with record_function_or_nullcontext("sample_token"):
             sampler_output = self._sample(logits, spec_decode_metadata)
 
+        if self.need_accepted_tokens:
+            self._update_states_after_model_execute(sampler_output.sampled_token_ids, scheduler_output)
+
         def propose_draft_token_ids(sampled_token_ids):
             assert spec_decode_common_attn_metadata is not None
             self._draft_token_ids = self.propose_draft_token_ids(
@@ -1474,8 +1477,6 @@ class NPUModelRunner(GPUModelRunner):
             logits,
             sampling_metadata,
         )
-        if self.need_accepted_tokens:  # TODO remove this if
-            self._update_states_after_model_execute(sampler_output.sampled_token_ids)
         return sampler_output
 
     # TODO: remove this func after eagle_proposer is refactored and