From 894928a9512440974032ce49e058d8c2c169b1cf Mon Sep 17 00:00:00 2001
From: Ananya <91440435+DotSlash-A@users.noreply.github.com>
Date: Sat, 24 Jan 2026 08:59:52 +0530
Subject: [PATCH] Refactor: Extract DeepSeek common utilities into shared
 module (#16969)

---
 .../srt/models/deepseek_common/utils.py       | 42 ++++++++++++++++++-
 python/sglang/srt/models/deepseek_v2.py       | 25 ++---------
 2 files changed, 45 insertions(+), 22 deletions(-)

diff --git a/python/sglang/srt/models/deepseek_common/utils.py b/python/sglang/srt/models/deepseek_common/utils.py
index 514cc025c..9d6056b91 100644
--- a/python/sglang/srt/models/deepseek_common/utils.py
+++ b/python/sglang/srt/models/deepseek_common/utils.py
@@ -11,9 +11,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 # ==============================================================================
+import logging
+import math
+from typing import Optional
+
+import torch
 
 from sglang.srt.environ import envs
 from sglang.srt.layers.moe.fused_moe_triton.layer import get_moe_runner_backend
+from sglang.srt.layers.quantization.base_config import QuantizationConfig
 from sglang.srt.layers.quantization.fp8_kernel import is_fp8_fnuz
 from sglang.srt.utils import (
     cpu_has_amx_support,
@@ -24,6 +30,7 @@ from sglang.srt.utils import (
     is_gfx95_supported,
     is_hip,
     is_npu,
+    is_nvidia_cublas_cu12_version_ge_12_9,
 )
 
 _is_hip = is_hip()
@@ -38,6 +45,22 @@ _is_gfx95_supported = is_gfx95_supported()
 _use_aiter_gfx95 = _use_aiter and _is_gfx95_supported
 
 
+_is_cublas_ge_129 = is_nvidia_cublas_cu12_version_ge_12_9()
+
+logger = logging.getLogger(__name__)
+
+NVFP4_CKPT_FP8_ATTN_QUANT_MODULES = ["q_b_proj"]
+
+FORWARD_ABSORB_CORE_ATTENTION_BACKENDS = [
+    "fa3",
+    "nsa",
+    "flashinfer",
+    "cutlass_mla",
+    "trtllm_mla",
+    "ascend",
+]
+
+
 def awq_dequantize_func():
     """
     Get the AWQ dequantize function for the current device
@@ -66,10 +89,27 @@ def awq_dequantize_func():
         return None
 
 
-def enable_nextn_moe_bf16_cast_to_fp8(quant_config):
+def enable_nextn_moe_bf16_cast_to_fp8(
+    quant_config: Optional[QuantizationConfig],
+) -> bool:
     return (
         envs.SGLANG_NVFP4_CKPT_FP8_NEXTN_MOE.get()
         and quant_config is not None
         and quant_config.get_name() == "modelopt_fp4"
         and get_moe_runner_backend().is_deep_gemm()
     )
+
+
+def yarn_get_mscale(scale: float = 1, mscale: float = 1) -> float:
+    if scale <= 1:
+        return 1.0
+    return 0.1 * mscale * math.log(scale) + 1.0
+
+
+def _get_llama_4_scaling(
+    original_max_position_embeddings: int, scaling_beta: float, positions: torch.Tensor
+) -> torch.Tensor:
+    scaling = 1 + scaling_beta * torch.log(
+        1 + torch.floor(positions / original_max_position_embeddings)
+    )
+    return scaling[..., None, None]
diff --git a/python/sglang/srt/models/deepseek_v2.py b/python/sglang/srt/models/deepseek_v2.py
index 365fd6690..97e07da27 100644
--- a/python/sglang/srt/models/deepseek_v2.py
+++ b/python/sglang/srt/models/deepseek_v2.py
@@ -128,15 +128,19 @@ from sglang.srt.models.deepseek_common.deepseek_weight_loader import (
     DeepseekV2WeightLoaderMixin,
 )
 from sglang.srt.models.deepseek_common.utils import (
+    FORWARD_ABSORB_CORE_ATTENTION_BACKENDS,
     _device_sm,
+    _get_llama_4_scaling,
     _is_cpu,
     _is_cpu_amx_available,
+    _is_cublas_ge_129,
     _is_cuda,
     _is_gfx95_supported,
     _is_hip,
     _is_npu,
     _use_aiter,
     _use_aiter_gfx95,
+    yarn_get_mscale,
 )
 from sglang.srt.server_args import get_global_server_args
 from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
@@ -146,7 +150,6 @@ from sglang.srt.utils import (
     add_prefix,
     get_bool_env_var,
     is_non_idle_and_non_empty,
-    is_nvidia_cublas_cu12_version_ge_12_9,
     log_info_on_rank0,
     make_layers,
     use_intel_amx_backend,
@@ -193,8 +196,6 @@ elif _is_npu:
 else:
     pass
 
-_is_cublas_ge_129 = is_nvidia_cublas_cu12_version_ge_12_9()
-
 logger = logging.getLogger(__name__)
 
 
@@ -1049,24 +1050,6 @@ class DeepseekV2MoE(nn.Module):
         state.hidden_states_mlp_output = final_hidden_states
 
 
-def yarn_get_mscale(scale: float = 1, mscale: float = 1) -> float:
-    import math
-
-    if scale <= 1:
-        return 1.0
-    return 0.1 * mscale * math.log(scale) + 1.0
-
-
-def _get_llama_4_scaling(
-    original_max_position_embeddings: int, scaling_beta: float, positions: torch.Tensor
-) -> torch.Tensor:
-    scaling = 1 + scaling_beta * torch.log(
-        1 + torch.floor(positions / original_max_position_embeddings)
-    )
-    # Broadcast over num_heads and head_dim
-    return scaling[..., None, None]
-
-
 class DeepseekV2AttentionMLA(nn.Module, DeepseekMHAForwardMixin):
 
     def __init__(