[bugfix] restore pr-7029 and fix patch error (#7294)

### What this PR does / why we need it?
This PR restores #7029, which adds W8A8C8 support for dsv3.2/glm5 using
the `lightning_indexer_quant` ops in the pd-mix stage.

The original PR was reverted by #7288 because the patch did not work
with the recompute scheduler.

This PR also fixes the patching issue so that it works correctly with
the recompute scheduler.

### Does this PR introduce _any_ user-facing change?
Yes. To enable LI C8, users need to set the `enable_sparse_c8` option to
`"true"` in `additional_config`.

- vLLM version: v0.17.0
- vLLM main:
4034c3d32e
---------
Signed-off-by: rjg-lyh <1318825571@qq.com>

vllm_ascend/core/recompute_scheduler.py

@@ -45,6 +45,30 @@ from vllm.v1.utils import ConstantList, record_function_or_nullcontext
 logger = init_logger(__name__)
 
 
+# `spec_manager_map` in single_type_kv_cache_manager is a module-level dict
+# whose keys are class objects bound at import time.  When the async
+# recompute scheduler is enabled, `recompute_scheduler.py` is imported by
+# `check_and_update_config()` (via AsyncScheduler → scheduler.py →
+# kv_cache_coordinator → single_type_kv_cache_manager) *before*
+# this patch file is executed a second time (e.g. triggered by
+# unpickling an AscendMLAAttentionSpec in the EngineCoreProc subprocess).
+# In that case the dict already contains the original MLAAttentionSpec
+# class as a key, so a subsequent lookup with type(AscendMLAAttentionSpec
+# instance) raises KeyError.
+#
+# Fix: whenever this patch is applied, register AscendMLAAttentionSpec as
+# an additional key in spec_manager_map (if the module is already loaded).
+def register_ascend_mla_spec_in_manager():
+    import sys as _sys
+
+    from vllm.v1.core.single_type_kv_cache_manager import FullAttentionManager
+    from vllm.v1.kv_cache_interface import MLAAttentionSpec as AscendMLAAttentionSpec
+
+    _stm = _sys.modules.get("vllm.v1.core.single_type_kv_cache_manager")
+    if _stm is not None and AscendMLAAttentionSpec not in _stm.spec_manager_map:
+        _stm.spec_manager_map[AscendMLAAttentionSpec] = FullAttentionManager
+
+
 @dataclass
 class RecomputeSchedulerConfig(SchedulerConfig):
     scheduler_cls: str | type[object] = "vllm_ascend.core.recompute_scheduler.RecomputeScheduler"
@@ -82,6 +106,8 @@ class RecomputeScheduler(Scheduler):
     running: list[Request]
 
     def __init__(self, *args, **kwargs):
+        register_ascend_mla_spec_in_manager()
+
         super().__init__(*args, **kwargs)
         # When is_mtp_kv_consumer is true, we will fill request.spec_token_ids
         # with placeholder tokens to enable full graph when decode nodes pull
@@ -993,4 +1019,6 @@ class RecomputeScheduler(Scheduler):
 
 class AsyncRecomputeScheduler(AsyncScheduler, RecomputeScheduler):
     def __init__(self, *args, **kwargs):
+        register_ascend_mla_spec_in_manager()
+
         super().__init__(*args, **kwargs)