[MoE Refactor] Centralize FlashInfer CUTLASS MoE runner (#28211)

python/sglang/srt/layers/moe/moe_runner/flashinfer_cutlass.py

@@ -0,0 +1,372 @@
+"""FlashInfer CUTLASS MoE fused funcs.
+
+This module owns the FlashInfer ``cutlass_fused_moe`` calls used by the
+unquantized, ModelOpt FP8, ModelOpt NVFP4, and SM90 MXFP4 MoE paths.
+Quantization methods prepare a small quant_info payload and route through
+``MoeRunner``.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Optional
+
+import torch
+
+from sglang.srt.distributed import get_tp_group
+from sglang.srt.distributed.device_communicators.pynccl_allocator import (
+    use_symmetric_memory,
+)
+from sglang.srt.layers.dp_attention import is_allocation_symmetric
+from sglang.srt.layers.moe.moe_runner.base import (
+    MoeQuantInfo,
+    MoeRunnerConfig,
+    register_fused_func,
+)
+from sglang.srt.layers.quantization.fp8_kernel import scaled_fp8_quant
+from sglang.srt.utils import is_flashinfer_available
+from sglang.srt.utils.common import next_power_of_2
+
+if TYPE_CHECKING:
+    from sglang.srt.layers.moe.token_dispatcher.flashinfer import (
+        FlashinferCombineInput,
+        FlashinferDispatchOutput,
+    )
+    from sglang.srt.layers.moe.token_dispatcher.standard import (
+        StandardCombineInput,
+        StandardDispatchOutput,
+    )
+
+
+@dataclass
+class FlashInferCutlassMoeQuantInfo(MoeQuantInfo):
+    """Payload for FlashInfer CUTLASS fused MoE.
+
+    ``quant_type`` selects the input/weight conventions:
+      - ``"bf16"``: unquantized weights, BF16/FP16 input, no quant scales.
+      - ``"fp8"``: FP8 weights, FP8-quantized input, per-tensor scales.
+      - ``"fp4"``: NVFP4 packed weights and optional NVFP4 packed input.
+    """
+
+    quant_type: str
+    w13_weight: torch.Tensor
+    w2_weight: torch.Tensor
+    quant_scales: Optional[list[torch.Tensor]] = None
+    output_dtype: Optional[torch.dtype] = None
+    moe_tp_size: int = 1
+    moe_tp_rank: int = 0
+    moe_ep_size: int = 1
+    moe_ep_rank: int = 0
+    apply_routed_scaling_factor: bool = True
+
+
+@dataclass
+class FlashInferCutlassMxfp4MoeQuantInfo(MoeQuantInfo):
+    """Quantization payload for the SM90 CUTLASS W4A16 MXFP4 MoE path.
+
+    Weights and scales are pre-interleaved at load time via
+    ``interleave_moe_{weights,scales}_for_sm90_mixed_gemm``; this dataclass
+    only carries references plus the per-call routing/topology fields.
+    """
+
+    # Pre-interleaved weights (uint8, packed FP4)
+    w13_weight: torch.Tensor  # [E, 2*N, K/2]
+    w2_weight: torch.Tensor  # [E, K, N/2]
+
+    # Pre-interleaved E8M0 block scales (uint8; viewed as int32 at call time)
+    w13_weight_scale: torch.Tensor  # [E, 2*N, K/32]
+    w2_weight_scale: torch.Tensor  # [E, K, N/32]
+
+    # Per-expert bias. GPT-OSS has both; DSv4 leaves both None.
+    w13_bias: Optional[torch.Tensor] = None  # bf16 [E, 2*N]
+    w2_bias: Optional[torch.Tensor] = None  # bf16 [E, K]
+
+    # Per-expert SwiGLU scalars (fp32 [E]). Either all three are present
+    # (clamped SwiGLU) or all three are None (kernel default SwiGLU).
+    swiglu_alpha: Optional[torch.Tensor] = None
+    swiglu_beta: Optional[torch.Tensor] = None
+    swiglu_limit: Optional[torch.Tensor] = None
+
+    # TP/EP topology (forwarded to the FlashInfer kernel)
+    moe_tp_size: int = 1
+    moe_tp_rank: int = 0
+    moe_ep_size: int = 1
+    moe_ep_rank: int = 0
+
+    # GPT-OSS pads its input hidden dim up to the (pre-padded) loaded weight
+    # width and trims the output back. DSv4 leaves this as ``None`` (no pad).
+    padded_hidden: Optional[int] = None
+
+
+def _flashinfer_cutlass_fused_moe():
+    if not is_flashinfer_available():
+        raise RuntimeError(
+            "flashinfer_cutlass MoE runner backend requires flashinfer to be installed."
+        )
+    from flashinfer.fused_moe import cutlass_fused_moe
+    from flashinfer.fused_moe.core import ActivationType
+
+    return cutlass_fused_moe, ActivationType
+
+
+def _activation_type(runner_config: MoeRunnerConfig):
+    from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import get_activation_type
+
+    _, ActivationType = _flashinfer_cutlass_fused_moe()
+    activation = ActivationType(
+        get_activation_type(
+            runner_config.activation,
+            is_gated=runner_config.is_gated,
+        )
+    )
+    supported = {
+        ActivationType.Swiglu,
+        ActivationType.Geglu,
+        ActivationType.Relu2,
+        ActivationType.Identity,
+    }
+    assert activation in supported, (
+        f"Activation {runner_config.activation!r} "
+        f"(is_gated={runner_config.is_gated}) maps to {activation.name}, "
+        "which is not supported by flashinfer cutlass moe."
+    )
+    return activation
+
+
+def _maybe_apply_routed_scaling_factor(
+    output: torch.Tensor,
+    quant_info: FlashInferCutlassMoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+) -> torch.Tensor:
+    if (
+        quant_info.apply_routed_scaling_factor
+        and runner_config.routed_scaling_factor is not None
+    ):
+        output.mul_(runner_config.routed_scaling_factor)
+    return output
+
+
+def _prepare_input(
+    dispatch_output,
+    quant_info: FlashInferCutlassMoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+) -> tuple[torch.Tensor, Optional[torch.Tensor], torch.dtype, int]:
+    x = dispatch_output.hidden_states
+    x_sf = dispatch_output.hidden_states_scale
+
+    if quant_info.quant_type == "fp8":
+        assert quant_info.quant_scales is not None and len(quant_info.quant_scales) == 4
+        x, _ = scaled_fp8_quant(x, quant_info.quant_scales[3])
+        x_sf = None
+        output_dtype = quant_info.output_dtype or dispatch_output.hidden_states.dtype
+        output_col = dispatch_output.hidden_states.shape[1]
+    elif quant_info.quant_type == "fp4":
+        output_dtype = quant_info.output_dtype or torch.bfloat16
+        output_col = x.shape[1]
+        if x_sf is not None and runner_config.is_gated:
+            output_col *= 2
+    else:
+        assert quant_info.quant_type == "bf16"
+        output_dtype = quant_info.output_dtype or x.dtype
+        output_col = x.shape[1]
+
+    return x, x_sf, output_dtype, output_col
+
+
+def _run_flashinfer_cutlass(
+    *,
+    dispatch_output,
+    quant_info: FlashInferCutlassMoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+    output: Optional[torch.Tensor] = None,
+    enable_alltoall: bool = False,
+) -> torch.Tensor:
+    flashinfer_cutlass_fused_moe, _ = _flashinfer_cutlass_fused_moe()
+
+    topk_output = dispatch_output.topk_output
+    topk_weights = topk_output.topk_weights
+    topk_ids = topk_output.topk_ids
+    x, x_sf, output_dtype, output_col = _prepare_input(
+        dispatch_output, quant_info, runner_config
+    )
+
+    if output is None:
+        with use_symmetric_memory(
+            get_tp_group(), disabled=not is_allocation_symmetric()
+        ):
+            output = torch.empty(
+                x.shape[0],
+                output_col,
+                dtype=output_dtype,
+                device=x.device,
+            )
+
+    w13_weight = quant_info.w13_weight
+    w2_weight = quant_info.w2_weight
+    quant_scales = quant_info.quant_scales
+    if quant_info.quant_type == "fp4":
+        w13_weight = w13_weight.view(torch.long)
+        w2_weight = w2_weight.view(torch.long)
+        assert quant_scales is not None and len(quant_scales) == 6
+        quant_scales = [
+            quant_scales[0],
+            quant_scales[1].view(torch.int32),
+            quant_scales[2],
+            quant_scales[3],
+            quant_scales[4].view(torch.int32),
+            quant_scales[5],
+        ]
+
+    output = flashinfer_cutlass_fused_moe(
+        output=output,
+        input=x,
+        token_selected_experts=topk_ids.to(torch.int),
+        token_final_scales=topk_weights,
+        fc1_expert_weights=w13_weight,
+        fc2_expert_weights=w2_weight,
+        output_dtype=output_dtype,
+        input_sf=x_sf,
+        quant_scales=quant_scales,
+        ep_size=quant_info.moe_ep_size,
+        ep_rank=quant_info.moe_ep_rank,
+        tp_size=quant_info.moe_tp_size,
+        tp_rank=quant_info.moe_tp_rank,
+        tune_max_num_tokens=next_power_of_2(x.shape[0]),
+        activation_type=_activation_type(runner_config),
+        enable_alltoall=enable_alltoall,
+    )[0]
+
+    if quant_info.quant_type in ("bf16", "fp8"):
+        _maybe_apply_routed_scaling_factor(output, quant_info, runner_config)
+    return output
+
+
+@register_fused_func("none", "flashinfer_cutlass")
+def fused_experts_none_to_flashinfer_cutlass(
+    dispatch_output: StandardDispatchOutput,
+    quant_info: MoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+) -> StandardCombineInput:
+    from sglang.srt.layers.moe.token_dispatcher.standard import StandardCombineInput
+
+    assert isinstance(
+        quant_info, FlashInferCutlassMoeQuantInfo
+    ), f"Unexpected quant_info type for flashinfer_cutlass: {type(quant_info)}"
+    assert (
+        not runner_config.apply_router_weight_on_input
+    ), "apply_router_weight_on_input is not supported for FlashInfer CUTLASS"
+
+    output = _run_flashinfer_cutlass(
+        dispatch_output=dispatch_output,
+        quant_info=quant_info,
+        runner_config=runner_config,
+    )
+    return StandardCombineInput(hidden_states=output)
+
+
+@register_fused_func("flashinfer", "flashinfer_cutlass")
+def fused_experts_flashinfer_to_flashinfer_cutlass(
+    dispatch_output: FlashinferDispatchOutput,
+    quant_info: MoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+) -> FlashinferCombineInput:
+    from sglang.srt.layers.moe.token_dispatcher.flashinfer import (
+        FlashinferCombineInput,
+    )
+
+    assert isinstance(
+        quant_info, FlashInferCutlassMoeQuantInfo
+    ), f"Unexpected quant_info type for flashinfer_cutlass: {type(quant_info)}"
+    assert (
+        not runner_config.apply_router_weight_on_input
+    ), "apply_router_weight_on_input is not supported for FlashInfer CUTLASS"
+
+    output = _run_flashinfer_cutlass(
+        dispatch_output=dispatch_output,
+        quant_info=quant_info,
+        runner_config=runner_config,
+        output=dispatch_output.moe_output,
+        enable_alltoall=True,
+    )
+    return FlashinferCombineInput(hidden_states=output)
+
+
+@register_fused_func("none", "flashinfer_mxfp4")
+def fused_experts_none_to_flashinfer_mxfp4(
+    dispatch_output: StandardDispatchOutput,
+    quant_info: MoeQuantInfo,
+    runner_config: MoeRunnerConfig,
+) -> StandardCombineInput:
+    """SM90 W4A16 MXFP4 fused expert forward pass.
+
+    This preserves the ``flashinfer_mxfp4`` runner backend registration while
+    centralizing the CUTLASS execution in this module.
+    """
+    from sglang.srt.layers.moe.token_dispatcher.standard import StandardCombineInput
+    from sglang.srt.layers.moe.topk import TopKOutputChecker
+
+    assert isinstance(
+        quant_info, FlashInferCutlassMxfp4MoeQuantInfo
+    ), f"Unexpected quant_info type for flashinfer_mxfp4: {type(quant_info)}"
+
+    flashinfer_cutlass_fused_moe, ActivationType = _flashinfer_cutlass_fused_moe()
+
+    x = dispatch_output.hidden_states
+    topk_output = dispatch_output.topk_output
+
+    # Under ``--moe-runner-backend flashinfer_mxfp4`` topk may be in bypassed
+    # form (the SM100 trtllm-gen path does routing internally). The CUTLASS
+    # SM90 path needs explicit topk_ids / topk_weights; materialize here.
+    if TopKOutputChecker.format_is_bypassed(topk_output):
+        topk_output = topk_output.to_standard()
+    topk_ids = topk_output.topk_ids
+    topk_weights = topk_output.topk_weights
+
+    # GPT-OSS: pad input hidden dim up to the loaded weight width. DSv4
+    # leaves padded_hidden as None (or equal to origin_hidden), no pad.
+    origin_hidden = x.shape[-1]
+    padded_hidden = quant_info.padded_hidden
+    do_pad = padded_hidden is not None and padded_hidden != origin_hidden
+    if do_pad:
+        x = torch.nn.functional.pad(
+            x,
+            (0, padded_hidden - origin_hidden),
+            mode="constant",
+            value=0.0,
+        )
+
+    out_hidden = padded_hidden if do_pad else origin_hidden
+    output_dtype = torch.bfloat16
+    with use_symmetric_memory(get_tp_group(), disabled=not is_allocation_symmetric()):
+        out = torch.empty(x.shape[0], out_hidden, dtype=output_dtype, device=x.device)
+
+    flashinfer_cutlass_fused_moe(
+        input=x,
+        token_selected_experts=topk_ids.to(torch.int),
+        token_final_scales=topk_weights,
+        fc1_expert_weights=quant_info.w13_weight,
+        fc2_expert_weights=quant_info.w2_weight,
+        output_dtype=output_dtype,
+        quant_scales=[
+            quant_info.w13_weight_scale.view(torch.int32),
+            quant_info.w2_weight_scale.view(torch.int32),
+        ],
+        fc1_expert_biases=quant_info.w13_bias,
+        fc2_expert_biases=quant_info.w2_bias,
+        swiglu_alpha=quant_info.swiglu_alpha,
+        swiglu_beta=quant_info.swiglu_beta,
+        swiglu_limit=quant_info.swiglu_limit,
+        tp_size=quant_info.moe_tp_size,
+        tp_rank=quant_info.moe_tp_rank,
+        ep_size=quant_info.moe_ep_size,
+        ep_rank=quant_info.moe_ep_rank,
+        use_w4_group_scaling=True,
+        activation_type=ActivationType.Swiglu,
+        tune_max_num_tokens=next_power_of_2(x.shape[0]),
+        output=out,
+    )
+
+    if do_pad:
+        out = out[:, :origin_hidden].contiguous()
+
+    return StandardCombineInput(hidden_states=out)

python/sglang/srt/layers/moe/moe_runner/flashinfer_mxfp4.py

@@ -1,174 +0,0 @@
-"""FlashInfer SM90 cutlass mixed-input W4A16 MXFP4 MoE fused func.
-
-Registered for ``("none", "flashinfer_mxfp4")``. Drives FlashInfer's
-``cutlass_fused_moe(use_w4_group_scaling=True)`` (PR #3084 in flashinfer,
-SM90 only). Quant methods build the quant_info each forward and call
-``MoeRunner.run(dispatch_output, quant_info)``.
-
-Two production call sites share this fused func:
-  - GPT-OSS via :class:`Mxfp4MoEMethod` (input pad/output trim + per-expert
-    SwiGLU scalars + per-expert bias)
-  - DSv4 via :class:`Mxfp4FlashinferCutlassMoEMethod` (no bias, optional
-    SwiGLU scalars, no padding)
-
-The SM100 trtllm-gen path also lives under ``MoeRunnerBackend.FLASHINFER_MXFP4``
-but is intentionally left in the legacy bypass path for now; migrating it is a
-follow-up.
-"""
-
-from __future__ import annotations
-
-from dataclasses import dataclass
-from typing import TYPE_CHECKING, Optional
-
-import torch
-
-from sglang.srt.distributed import get_tp_group
-from sglang.srt.distributed.device_communicators.pynccl_allocator import (
-    use_symmetric_memory,
-)
-from sglang.srt.layers.dp_attention import is_allocation_symmetric
-from sglang.srt.layers.moe.moe_runner.base import (
-    MoeQuantInfo,
-    MoeRunnerConfig,
-    register_fused_func,
-)
-from sglang.srt.utils import is_flashinfer_available
-from sglang.srt.utils.common import next_power_of_2
-
-if TYPE_CHECKING:
-    from sglang.srt.layers.moe.token_dispatcher import StandardDispatchOutput
-    from sglang.srt.layers.moe.token_dispatcher.standard import StandardCombineInput
-
-
-@dataclass
-class FlashInferMxfp4CutlassMoeQuantInfo(MoeQuantInfo):
-    """Quantization payload for the SM90 cutlass W4A16 MXFP4 MoE path.
-
-    Weights and scales are pre-interleaved at load time via
-    ``interleave_moe_{weights,scales}_for_sm90_mixed_gemm``; this dataclass
-    only carries references plus the per-call routing/topology fields.
-    """
-
-    # Pre-interleaved weights (uint8, packed FP4)
-    w13_weight: torch.Tensor  # [E, 2*N, K/2]
-    w2_weight: torch.Tensor  # [E, K, N/2]
-
-    # Pre-interleaved E8M0 block scales (uint8; viewed as int32 at call time)
-    w13_weight_scale: torch.Tensor  # [E, 2*N, K/32]
-    w2_weight_scale: torch.Tensor  # [E, K, N/32]
-
-    # Per-expert bias. GPT-OSS has both; DSv4 leaves both None.
-    w13_bias: Optional[torch.Tensor] = None  # bf16 [E, 2*N]
-    w2_bias: Optional[torch.Tensor] = None  # bf16 [E, K]
-
-    # Per-expert SwiGLU scalars (fp32 [E]). Either all three are present
-    # (clamped SwiGLU) or all three are None (kernel default SwiGLU).
-    swiglu_alpha: Optional[torch.Tensor] = None
-    swiglu_beta: Optional[torch.Tensor] = None
-    swiglu_limit: Optional[torch.Tensor] = None
-
-    # TP/EP topology (forwarded to the FlashInfer kernel)
-    moe_tp_size: int = 1
-    moe_tp_rank: int = 0
-    moe_ep_size: int = 1
-    moe_ep_rank: int = 0
-
-    # GPT-OSS pads its input hidden dim up to the (pre-padded) loaded weight
-    # width and trims the output back. DSv4 leaves this as ``None`` (no pad).
-    padded_hidden: Optional[int] = None
-
-
-def _flashinfer_cutlass_fused_moe():
-    """Lazy import — keeps non-flashinfer wheels importable."""
-    if not is_flashinfer_available():
-        raise RuntimeError(
-            "flashinfer_mxfp4 runner backend requires flashinfer to be installed."
-        )
-    from flashinfer.fused_moe import cutlass_fused_moe
-    from flashinfer.fused_moe.core import ActivationType
-
-    return cutlass_fused_moe, ActivationType
-
-
-@register_fused_func("none", "flashinfer_mxfp4")
-def fused_experts_none_to_flashinfer_mxfp4(
-    dispatch_output: StandardDispatchOutput,
-    quant_info: MoeQuantInfo,
-    runner_config: MoeRunnerConfig,
-) -> StandardCombineInput:
-    """SM90 W4A16 MXFP4 fused expert forward pass.
-
-    Mirrors the legacy ``Mxfp4MoEMethod._apply_sm90_cutlass`` and DSv4's
-    ``Mxfp4FlashinferCutlassMoEMethod.apply`` exactly; difference vs those is
-    that all per-layer state arrives via ``quant_info`` rather than via the
-    layer module, so this function is layer-agnostic.
-    """
-    from sglang.srt.layers.moe.token_dispatcher.standard import StandardCombineInput
-    from sglang.srt.layers.moe.topk import TopKOutputChecker
-
-    assert isinstance(
-        quant_info, FlashInferMxfp4CutlassMoeQuantInfo
-    ), f"Unexpected quant_info type for flashinfer_mxfp4: {type(quant_info)}"
-
-    flashinfer_cutlass_fused_moe, ActivationType = _flashinfer_cutlass_fused_moe()
-
-    x = dispatch_output.hidden_states
-    topk_output = dispatch_output.topk_output
-
-    # Under ``--moe-runner-backend flashinfer_mxfp4`` topk may be in bypassed
-    # form (the SM100 trtllm-gen path does routing internally). The cutlass
-    # SM90 path needs explicit topk_ids / topk_weights; materialize here.
-    if TopKOutputChecker.format_is_bypassed(topk_output):
-        topk_output = topk_output.to_standard()
-    topk_ids = topk_output.topk_ids
-    topk_weights = topk_output.topk_weights
-
-    # GPT-OSS: pad input hidden dim up to the loaded weight width. DSv4
-    # leaves padded_hidden as None (or equal to origin_hidden), no pad.
-    origin_hidden = x.shape[-1]
-    padded_hidden = quant_info.padded_hidden
-    do_pad = padded_hidden is not None and padded_hidden != origin_hidden
-    if do_pad:
-        x = torch.nn.functional.pad(
-            x,
-            (0, padded_hidden - origin_hidden),
-            mode="constant",
-            value=0.0,
-        )
-
-    out_hidden = padded_hidden if do_pad else origin_hidden
-    output_dtype = torch.bfloat16
-    with use_symmetric_memory(get_tp_group(), disabled=not is_allocation_symmetric()):
-        out = torch.empty(x.shape[0], out_hidden, dtype=output_dtype, device=x.device)
-
-    flashinfer_cutlass_fused_moe(
-        input=x,
-        token_selected_experts=topk_ids.to(torch.int),
-        token_final_scales=topk_weights,
-        fc1_expert_weights=quant_info.w13_weight,
-        fc2_expert_weights=quant_info.w2_weight,
-        output_dtype=output_dtype,
-        quant_scales=[
-            quant_info.w13_weight_scale.view(torch.int32),
-            quant_info.w2_weight_scale.view(torch.int32),
-        ],
-        fc1_expert_biases=quant_info.w13_bias,
-        fc2_expert_biases=quant_info.w2_bias,
-        swiglu_alpha=quant_info.swiglu_alpha,
-        swiglu_beta=quant_info.swiglu_beta,
-        swiglu_limit=quant_info.swiglu_limit,
-        tp_size=quant_info.moe_tp_size,
-        tp_rank=quant_info.moe_tp_rank,
-        ep_size=quant_info.moe_ep_size,
-        ep_rank=quant_info.moe_ep_rank,
-        use_w4_group_scaling=True,
-        activation_type=ActivationType.Swiglu,
-        tune_max_num_tokens=next_power_of_2(x.shape[0]),
-        output=out,
-    )
-
-    if do_pad:
-        out = out[:, :origin_hidden].contiguous()
-
-    return StandardCombineInput(hidden_states=out)

python/sglang/srt/layers/moe/moe_runner/runner.py

@@ -61,6 +61,8 @@ class MoeRunner:
             self.runner_core = None  # FlashInfer TRT-LLM only supports fused path
         elif runner_backend.is_flashinfer_cutedsl():
             self.runner_core = None  # FlashInfer CuteDSL only supports fused path
+        elif runner_backend.is_flashinfer_cutlass():
+            self.runner_core = None  # FlashInfer CUTLASS only supports fused path
         elif runner_backend.is_flashinfer_mxfp4():
             self.runner_core = None  # FlashInfer MXFP4 only supports fused path
         else:

python/sglang/srt/layers/quantization/modelopt_quant.py

@@ -4,24 +4,17 @@
 from __future__ import annotations
 
 import logging
-from enum import IntEnum
 from typing import TYPE_CHECKING, Any, Dict, List, Optional
 
 import regex as re
 import torch
 from torch.nn.parameter import Parameter
 
-from sglang.srt.distributed import get_tp_group
-from sglang.srt.distributed.device_communicators.pynccl_allocator import (
-    use_symmetric_memory,
-)
 from sglang.srt.environ import envs
-from sglang.srt.layers.dp_attention import is_allocation_symmetric
 from sglang.srt.layers.moe import (
     MoeRunner,
     MoeRunnerBackend,
     MoeRunnerConfig,
-    get_moe_a2a_backend,
     get_moe_runner_backend,
 )
 from sglang.srt.layers.moe.cutlass_moe_params import CutlassMoEParams, CutlassMoEType
@@ -71,7 +64,6 @@ from sglang.srt.utils.common import (
     is_flashinfer_available,
     is_sm100_supported,
     is_sm120_supported,
-    next_power_of_2,
     round_up,
 )
 from sglang.srt.utils.custom_op import register_custom_op
@@ -104,20 +96,6 @@ if is_cuda():
 else:
     cutlass_fp4_gemm = None
 
-try:
-    from flashinfer.fused_moe import cutlass_fused_moe as flashinfer_cutlass_fused_moe
-    from flashinfer.fused_moe.core import ActivationType
-except ImportError:
-    flashinfer_cutlass_fused_moe = None
-
-    # Define a minimal ActivationType enum if flashinfer is not available
-    class ActivationType(IntEnum):
-        Swiglu = 3
-        Geglu = 4
-        Relu2 = 6
-        Identity = 7
-
-
 # Initialize logger for the module
 logger = logging.getLogger(__name__)
 
@@ -1031,7 +1009,15 @@ class ModelOptFp8MoEMethod(FusedMoEMethodBase):
         self, layer: torch.nn.Module, moe_runner_config: MoeRunnerConfig
     ):
         self.moe_runner_config = moe_runner_config
-        self.runner = MoeRunner(MoeRunnerBackend.TRITON, moe_runner_config)
+        moe_runner_backend = get_moe_runner_backend()
+        if moe_runner_backend.is_flashinfer_cutlass():
+            import sglang.srt.layers.moe.moe_runner.flashinfer_cutlass  # noqa: F401
+
+            self.runner = MoeRunner(
+                MoeRunnerBackend.FLASHINFER_CUTLASS, moe_runner_config
+            )
+        else:
+            self.runner = MoeRunner(MoeRunnerBackend.TRITON, moe_runner_config)
 
     def apply(
         self,
@@ -1040,7 +1026,6 @@ class ModelOptFp8MoEMethod(FusedMoEMethodBase):
     ) -> CombineInput:
         x = dispatch_output.hidden_states
         topk_output = dispatch_output.topk_output
-        from sglang.srt.layers.moe.token_dispatcher import StandardCombineInput
         from sglang.srt.layers.moe.topk import TopKOutputChecker
 
         # Fast path: TRT-LLM FP8 per-tensor MoE using BYPASSED TopK routing
@@ -1052,14 +1037,9 @@ class ModelOptFp8MoEMethod(FusedMoEMethodBase):
             from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import (
                 FlashInferTrtllmFp8MoeQuantInfo,
                 fused_experts_none_to_flashinfer_trtllm_fp8,
-            )
-            from sglang.srt.layers.moe.utils import RoutingMethodType
-
-            topk_config = topk_output.topk_config
-
-            from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import (
                 get_activation_type,
             )
+            from sglang.srt.layers.moe.utils import RoutingMethodType
 
             _SUPPORTED_FP8_ACTIVATIONS = {"silu", "relu2"}
             assert self.moe_runner_config.activation in _SUPPORTED_FP8_ACTIVATIONS, (
@@ -1096,75 +1076,33 @@ class ModelOptFp8MoEMethod(FusedMoEMethodBase):
             )
 
         if get_moe_runner_backend().is_flashinfer_cutlass():
-            from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import (
-                get_activation_type,
-            )
-
             activation_str = self.moe_runner_config.activation
             assert activation_str in _SUPPORTED_ACT_STRS, (
                 f"Activation {activation_str!r} is not supported for "
                 f"flashinfer cutlass fp8 moe (supported: {_SUPPORTED_ACT_STRS})."
             )
-            activation = ActivationType(
-                get_activation_type(
-                    activation_str, is_gated=self.moe_runner_config.is_gated
-                )
+            from sglang.srt.layers.moe.moe_runner.flashinfer_cutlass import (
+                FlashInferCutlassMoeQuantInfo,
             )
-            # FlashInfer CUTLASS MoE supports gated Swiglu/Geglu and non-gated
-            # Relu2/Identity. Non-gated Silu/Gelu are not implemented.
-            _CUTLASS_SUPPORTED = {
-                ActivationType.Swiglu,
-                ActivationType.Geglu,
-                ActivationType.Relu2,
-                ActivationType.Identity,
-            }
-            assert activation in _CUTLASS_SUPPORTED, (
-                f"Activation {activation_str!r} (is_gated="
-                f"{self.moe_runner_config.is_gated}) maps to {activation.name}, "
-                "which is not supported by flashinfer cutlass fp8 moe."
-            )
-            topk_weights, topk_ids = topk_output.topk_weights, topk_output.topk_ids
-            x_fp8, _ = scaled_fp8_quant(x, layer.w13_input_scale)
-            output_dtype = x.dtype
-            original_col = x.shape[1]
-            x_sf = None
 
-            with use_symmetric_memory(
-                get_tp_group(), disabled=not is_allocation_symmetric()
-            ):
-                symm_output = torch.empty(
-                    x.shape[0], original_col, dtype=output_dtype, device=x.device
-                )
-            output = flashinfer_cutlass_fused_moe(
-                output=symm_output,
-                input=x_fp8,
-                token_selected_experts=topk_ids.to(torch.int),
-                token_final_scales=topk_weights,
-                fc1_expert_weights=layer.w13_weight,
-                fc2_expert_weights=layer.w2_weight,
-                output_dtype=output_dtype,
-                input_sf=x_sf,
+            quant_info = FlashInferCutlassMoeQuantInfo(
+                quant_type="fp8",
+                w13_weight=layer.w13_weight,
+                w2_weight=layer.w2_weight,
                 quant_scales=[
                     layer.fc1_dequant,
                     layer.fc2_quant,
                     layer.fc2_dequant,
                     layer.fc1_input_dequant,
                 ],
-                ep_size=layer.moe_ep_size,
-                ep_rank=layer.moe_ep_rank,
-                tp_size=layer.moe_tp_size,
-                tp_rank=layer.moe_tp_rank,
-                tune_max_num_tokens=next_power_of_2(x.shape[0]),
-                activation_type=activation,
-            )[0]
-
-            if (
-                not layer.should_fuse_routed_scaling_factor_in_topk
-                and self.moe_runner_config.routed_scaling_factor is not None
-            ):
-                output.mul_(self.moe_runner_config.routed_scaling_factor)
-
-            return StandardCombineInput(hidden_states=output)
+                output_dtype=x.dtype,
+                moe_ep_size=layer.moe_ep_size,
+                moe_ep_rank=layer.moe_ep_rank,
+                moe_tp_size=layer.moe_tp_size,
+                moe_tp_rank=layer.moe_tp_rank,
+                apply_routed_scaling_factor=not layer.should_fuse_routed_scaling_factor_in_topk,
+            )
+            return self.runner.run(dispatch_output, quant_info)
 
         quant_info = TritonMoeQuantInfo(
             w13_weight=layer.w13_weight,
@@ -1320,9 +1258,9 @@ class ModelOptFp4Config(ModelOptQuantConfig):
                     "Expected either flat format (config.json) or nested format (hf_quant_config.json)."
                 )
 
-        if not quant_method in ["FP8", "NVFP4"]:
+        if quant_method not in ["FP8", "NVFP4"]:
             raise ValueError(
-                f"ModelOpt currently only supports: FP8, NVFP4"
+                "ModelOpt currently only supports: FP8, NVFP4"
                 " quantizations in sglang. Please check the "
                 "quantization config for your model's configuration."
             )
@@ -2327,8 +2265,10 @@ class ModelOptNvFp4FusedMoEMethod(FusedMoEMethodBase):
         if moe_runner_backend.is_flashinfer_cutedsl():
             import sglang.srt.layers.moe.moe_runner.flashinfer_cutedsl  # noqa: F401 – triggers @register_fused_func
 
-        if not moe_runner_backend.is_flashinfer_cutlass():
-            self.runner = MoeRunner(moe_runner_backend, moe_runner_config)
+        if moe_runner_backend.is_flashinfer_cutlass():
+            import sglang.srt.layers.moe.moe_runner.flashinfer_cutlass  # noqa: F401
+
+        self.runner = MoeRunner(moe_runner_backend, moe_runner_config)
 
     def apply(
         self,
@@ -2458,85 +2398,33 @@ class ModelOptNvFp4FusedMoEMethod(FusedMoEMethodBase):
             return self.runner.run(dispatch_output, quant_info)
 
         if self.enable_flashinfer_cutlass_moe:
-            from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import (
-                get_activation_type,
+            from sglang.srt.layers.moe.moe_runner.flashinfer_cutlass import (
+                FlashInferCutlassMoeQuantInfo,
             )
-            from sglang.srt.layers.moe.token_dispatcher import DispatchOutputChecker
 
             assert (
                 not moe_runner_config.apply_router_weight_on_input
             ), "apply_router_weight_on_input is not supported for Flashinfer"
-            # Resolve the FlashInfer ActivationType honoring the gated flag,
-            # then verify the CUTLASS FP4 kernel supports it.
-            fi_activation = ActivationType(
-                get_activation_type(activation, is_gated=moe_runner_config.is_gated)
-            )
-            _CUTLASS_FP4_SUPPORTED = {
-                ActivationType.Swiglu,
-                ActivationType.Geglu,
-                ActivationType.Relu2,
-                ActivationType.Identity,
-            }
-            assert fi_activation in _CUTLASS_FP4_SUPPORTED, (
-                f"Activation {activation!r} (is_gated={moe_runner_config.is_gated}) "
-                f"maps to {fi_activation.name}, which is not supported by the "
-                "flashinfer cutlass fp4 moe kernel."
-            )
-            # TRTLLM Cutlass moe takes in activations in BF16/Half/nvfp4 precision
-            # and fp4 quantized weights loaded from the checkpoint
-            x = dispatch_output.hidden_states
-            x_sf = dispatch_output.hidden_states_scale
-            topk_output = dispatch_output.topk_output
-            topk_weights, topk_ids = topk_output.topk_weights, topk_output.topk_ids
-
-            output_dtype = torch.bfloat16
-
-            if DispatchOutputChecker.format_is_flashinfer(dispatch_output):
-                symm_output = dispatch_output.moe_output
-            else:
-                # If x_sf is not None, x is FP4 packed (half size), so we need * 2
-                # If x_sf is None, x is not packed, so output_col = x.shape[1]
-                output_col = x.shape[1]
-                if x_sf is not None and layer.moe_runner_config.is_gated:
-                    output_col *= 2
-                with use_symmetric_memory(
-                    get_tp_group(), disabled=not is_allocation_symmetric()
-                ):
-                    symm_output = torch.empty(
-                        x.shape[0],
-                        output_col,
-                        dtype=output_dtype,
-                        device=x.device,
-                    )
-
-            output = flashinfer_cutlass_fused_moe(
-                output=symm_output,
-                input=x,
-                token_selected_experts=topk_ids.to(torch.int),
-                token_final_scales=topk_weights,
-                fc1_expert_weights=layer.w13_weight.view(torch.long),
-                fc2_expert_weights=layer.w2_weight.view(torch.long),
-                output_dtype=output_dtype,
-                input_sf=x_sf,
-                # swizzled_input_sf intentionally omitted; not used for this path.
+            quant_info = FlashInferCutlassMoeQuantInfo(
+                quant_type="fp4",
+                w13_weight=layer.w13_weight,
+                w2_weight=layer.w2_weight,
+                output_dtype=torch.bfloat16,
                 quant_scales=[
                     layer.w13_input_scale_quant,
-                    layer.w13_blockscale_swizzled.view(torch.int32),
+                    layer.w13_blockscale_swizzled,
                     layer.g1_alphas,
                     layer.w2_input_scale_quant,
-                    layer.w2_blockscale_swizzled.view(torch.int32),
+                    layer.w2_blockscale_swizzled,
                     layer.g2_alphas,
                 ],
-                ep_size=layer.moe_ep_size,
-                ep_rank=layer.moe_ep_rank,
-                tp_size=layer.moe_tp_size,
-                tp_rank=layer.moe_tp_rank,
-                tune_max_num_tokens=next_power_of_2(x.shape[0]),
-                activation_type=fi_activation,
-                enable_alltoall=get_moe_a2a_backend().is_flashinfer(),
-            )[0]
-
-            return StandardCombineInput(hidden_states=output)
+                moe_ep_size=layer.moe_ep_size,
+                moe_ep_rank=layer.moe_ep_rank,
+                moe_tp_size=layer.moe_tp_size,
+                moe_tp_rank=layer.moe_tp_rank,
+                apply_routed_scaling_factor=False,
+            )
+            return self.runner.run(dispatch_output, quant_info)
 
         from sglang.srt.layers.moe.cutlass_moe import cutlass_moe_fp4
 

python/sglang/srt/layers/quantization/mxfp4.py

@@ -1039,7 +1039,7 @@ class Mxfp4MoEMethod(FusedMoEMethodBase):
         ):
             # Register the fused func at runner construction so the FusedOpPool
             # lookup at `MoeRunner.__init__` finds it.
-            import sglang.srt.layers.moe.moe_runner.flashinfer_mxfp4  # noqa: F401
+            import sglang.srt.layers.moe.moe_runner.flashinfer_cutlass  # noqa: F401
 
             self.runner = MoeRunner(moe_runner_backend, moe_runner_config)
         else:
@@ -1051,12 +1051,12 @@ class Mxfp4MoEMethod(FusedMoEMethodBase):
         """SM90 (Hopper) MXFP4 x BF16 MoE via FlashInfer's cutlass mixed-input
         path (PR #3084). Routed through the unified ``MoeRunner`` -- this
         helper only builds the quant_info; the actual kernel call lives in
-        :mod:`sglang.srt.layers.moe.moe_runner.flashinfer_mxfp4`."""
-        from sglang.srt.layers.moe.moe_runner.flashinfer_mxfp4 import (
-            FlashInferMxfp4CutlassMoeQuantInfo,
+        :mod:`sglang.srt.layers.moe.moe_runner.flashinfer_cutlass`."""
+        from sglang.srt.layers.moe.moe_runner.flashinfer_cutlass import (
+            FlashInferCutlassMxfp4MoeQuantInfo,
         )
 
-        quant_info = FlashInferMxfp4CutlassMoeQuantInfo(
+        quant_info = FlashInferCutlassMxfp4MoeQuantInfo(
             w13_weight=layer.w13_weight,
             w2_weight=layer.w2_weight,
             w13_weight_scale=layer.w13_weight_scale,

python/sglang/srt/layers/quantization/mxfp4_flashinfer_cutlass_moe.py

@@ -145,7 +145,7 @@ class Mxfp4FlashinferCutlassMoEMethod:
 
         # Register the fused func at runner construction so the FusedOpPool
         # lookup at `MoeRunner.__init__` finds it.
-        import sglang.srt.layers.moe.moe_runner.flashinfer_mxfp4  # noqa: F401
+        import sglang.srt.layers.moe.moe_runner.flashinfer_cutlass  # noqa: F401
 
         self.runner = MoeRunner(MoeRunnerBackend.FLASHINFER_MXFP4, moe_runner_config)
 
@@ -217,8 +217,8 @@ class Mxfp4FlashinferCutlassMoEMethod:
         layer: Module,
         dispatch_output: DispatchOutput,
     ) -> CombineInput:
-        from sglang.srt.layers.moe.moe_runner.flashinfer_mxfp4 import (
-            FlashInferMxfp4CutlassMoeQuantInfo,
+        from sglang.srt.layers.moe.moe_runner.flashinfer_cutlass import (
+            FlashInferCutlassMxfp4MoeQuantInfo,
         )
 
         # DSv4 always feeds StandardDispatchOutput; the fused func tolerates
@@ -227,7 +227,7 @@ class Mxfp4FlashinferCutlassMoEMethod:
         if not TopKOutputChecker.format_is_standard(topk_output):
             raise ValueError(f"Unsupported topk output format: {topk_output.format}")
 
-        quant_info = FlashInferMxfp4CutlassMoeQuantInfo(
+        quant_info = FlashInferCutlassMxfp4MoeQuantInfo(
             w13_weight=layer.w13_weight,
             w2_weight=layer.w2_weight,
             w13_weight_scale=layer.w13_weight_scale_inv,

python/sglang/srt/layers/quantization/unquant.py

@@ -35,7 +35,6 @@ from sglang.srt.utils import (
     is_cpu,
     is_hip,
     is_npu,
-    next_power_of_2,
     set_weight_attrs,
     use_intel_amx_backend,
     use_intel_xpu_backend,
@@ -62,12 +61,6 @@ if _use_aiter:
 if _is_npu:
     from sglang.srt.hardware_backend.npu.utils import npu_format_cast
 
-try:
-    from flashinfer.fused_moe import cutlass_fused_moe as flashinfer_cutlass_fused_moe
-    from flashinfer.fused_moe.core import ActivationType
-except ImportError:
-    flashinfer_cutlass_fused_moe = None
-
 
 class UnquantizedEmbeddingMethod(QuantizeMethodBase):
     """Unquantized method for embeddings."""
@@ -412,6 +405,10 @@ class UnquantizedFusedMoEMethod(FusedMoEMethodBase, MultiPlatformOp):
                 if get_moe_runner_backend().is_flashinfer_trtllm_routed()
                 else MoeRunnerBackend.FLASHINFER_TRTLLM
             )
+        elif self.use_flashinfer_cutlass:
+            import sglang.srt.layers.moe.moe_runner.flashinfer_cutlass  # noqa: F401
+
+            backend = MoeRunnerBackend.FLASHINFER_CUTLASS
         elif self.use_deep_gemm:
             backend = MoeRunnerBackend.DEEP_GEMM
         elif self.use_triton_kernels:
@@ -467,12 +464,8 @@ class UnquantizedFusedMoEMethod(FusedMoEMethodBase, MultiPlatformOp):
         layer: torch.nn.Module,
         dispatch_output: StandardDispatchOutput,
     ) -> CombineInput:
-        from sglang.srt.layers.moe.token_dispatcher import StandardCombineInput
-
         x = dispatch_output.hidden_states
 
-        moe_runner_config = self.moe_runner_config
-
         backend = self.runner.runner_backend
         if backend.is_triton_kernels():
             from sglang.srt.layers.moe.moe_runner.triton_kernels import (
@@ -501,34 +494,22 @@ class UnquantizedFusedMoEMethod(FusedMoEMethodBase, MultiPlatformOp):
             )
             return self.runner.run(dispatch_output, quant_info)
         elif self.use_flashinfer_cutlass:
-            topk_output = dispatch_output.topk_output
-            output = flashinfer_cutlass_fused_moe(
-                input=x,
-                token_selected_experts=topk_output.topk_ids,
-                token_final_scales=topk_output.topk_weights,
-                fc1_expert_weights=layer.w13_weight,
-                fc2_expert_weights=layer.w2_weight,
+            from sglang.srt.layers.moe.moe_runner.flashinfer_cutlass import (
+                FlashInferCutlassMoeQuantInfo,
+            )
+
+            quant_info = FlashInferCutlassMoeQuantInfo(
+                quant_type="bf16",
+                w13_weight=layer.w13_weight,
+                w2_weight=layer.w2_weight,
                 output_dtype=x.dtype,
-                quant_scales=None,
-                ep_size=layer.moe_ep_size,
-                ep_rank=layer.moe_ep_rank,
-                tp_size=layer.moe_tp_size,
-                tp_rank=layer.moe_tp_rank,
-                tune_max_num_tokens=next_power_of_2(x.shape[0]),
-                activation_type=(
-                    ActivationType.Relu2
-                    if moe_runner_config.activation == "relu2"
-                    else ActivationType.Swiglu
-                ),
-            )[0]
-
-            if (
-                not layer.should_fuse_routed_scaling_factor_in_topk
-                and moe_runner_config.routed_scaling_factor is not None
-            ):
-                output.mul_(moe_runner_config.routed_scaling_factor)
-
-            return StandardCombineInput(hidden_states=output)
+                moe_ep_size=layer.moe_ep_size,
+                moe_ep_rank=layer.moe_ep_rank,
+                moe_tp_size=layer.moe_tp_size,
+                moe_tp_rank=layer.moe_tp_rank,
+                apply_routed_scaling_factor=not layer.should_fuse_routed_scaling_factor_in_topk,
+            )
+            return self.runner.run(dispatch_output, quant_info)
         elif self.use_flashinfer_trtllm_moe:
             from sglang.srt.layers.moe.moe_runner.flashinfer_trtllm import (
                 FlashInferTrtllmBf16MoeQuantInfo,