[Core] FlashInfer CUTLASS fused MoE backend (NVFP4) (#20037)

Signed-off-by: shuw <shuw@nvidia.com>
Signed-off-by: mgoin <mgoin64@gmail.com>
Co-authored-by: mgoin <mgoin64@gmail.com>

vllm/_custom_ops.py

@@ -956,11 +956,11 @@ def cutlass_moe_mm(out_tensors: torch.Tensor, a_tensors: torch.Tensor,
                                        c_strides, per_act_token, per_out_ch)
 
 
-def cutlass_fp4_moe_mm(a_tensors: torch.Tensor, b_tensors: torch.Tensor,
-                       a_scales: torch.Tensor, b_scales: torch.Tensor,
-                       alphas: torch.Tensor, problem_sizes: torch.Tensor,
-                       expert_offsets: torch.Tensor, sf_offsets: torch.Tensor,
-                       out_dtype: torch.dtype, device: torch.device):
+def cutlass_fp4_moe_mm(out_tensors: torch.Tensor, a_tensors: torch.Tensor,
+                       b_tensors: torch.Tensor, a_scales: torch.Tensor,
+                       b_scales: torch.Tensor, alphas: torch.Tensor,
+                       problem_sizes: torch.Tensor,
+                       expert_offsets: torch.Tensor, sf_offsets: torch.Tensor):
     """
     An FP4 Blockscaled Group Gemm that takes in  a_tensors, b_tensors and runs
     the gemms for each combination based on the specified problem sizes.
@@ -977,14 +977,10 @@ def cutlass_fp4_moe_mm(a_tensors: torch.Tensor, b_tensors: torch.Tensor,
     - problem_sizes: MxNxK sizes of each expert's multiplication in two grouped
                      MMs used in the fused MoE operation.
     """
-    m_topk = a_tensors.shape[0]
-    n = b_tensors.shape[1]
-    c_shape = (m_topk, n)
-    c = torch.empty(c_shape, device=device, dtype=out_dtype)
-    torch.ops._C.cutlass_fp4_group_mm(c, a_tensors, b_tensors, a_scales,
-                                      b_scales, alphas, problem_sizes,
-                                      expert_offsets, sf_offsets)
-    return c.to(out_dtype)
+    return torch.ops._C.cutlass_fp4_group_mm(out_tensors, a_tensors, b_tensors,
+                                             a_scales, b_scales, alphas,
+                                             problem_sizes, expert_offsets,
+                                             sf_offsets)
 
 
 # aqlm

vllm/envs.py

@@ -119,6 +119,7 @@ if TYPE_CHECKING:
     VLLM_TPU_BUCKET_PADDING_GAP: int = 0
     VLLM_TPU_MOST_MODEL_LEN: Optional[int] = None
     VLLM_USE_DEEP_GEMM: bool = False
+    VLLM_USE_FLASHINFER_MOE: bool = False
     VLLM_XGRAMMAR_CACHE_MB: int = 0
     VLLM_MSGPACK_ZERO_COPY_THRESHOLD: int = 256
     VLLM_ALLOW_INSECURE_SERIALIZATION: bool = False
@@ -853,6 +854,10 @@ environment_variables: dict[str, Callable[[], Any]] = {
     "VLLM_USE_DEEP_GEMM":
     lambda: bool(int(os.getenv("VLLM_USE_DEEP_GEMM", "0"))),
 
+    # Allow use of FlashInfer CUTLASS kernels for fused moe ops.
+    "VLLM_USE_FLASHINFER_MOE":
+    lambda: bool(int(os.getenv("VLLM_USE_FLASHINFER_MOE", "0"))),
+
     # Control the cache sized used by the xgrammar compiler. The default
     # of 512 MB should be enough for roughly 1000 JSON schemas.
     # It can be changed with this variable if needed for some reason.

vllm/model_executor/layers/fused_moe/batched_deep_gemm_moe.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -255,28 +255,18 @@ class BatchedDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
         output = (num_experts, max_num_tokens * num_dispatchers, K)
         return (workspace13, workspace2, output, a.dtype)
 
-    def apply(
-        self,
-        output: torch.Tensor,
-        hidden_states: torch.Tensor,
-        w1: torch.Tensor,
-        w2: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        activation: str,
-        global_num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        w1_scale: Optional[torch.Tensor],
-        w2_scale: Optional[torch.Tensor],
-        w1_zp: Optional[torch.Tensor],
-        w2_zp: Optional[torch.Tensor],
-        a1q_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        workspace13: torch.Tensor,
-        workspace2: torch.Tensor,
-        expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-        apply_router_weight_on_input: bool,
-    ):
+    def apply(self, output: torch.Tensor, hidden_states: torch.Tensor,
+              w1: torch.Tensor, w2: torch.Tensor, topk_weights: torch.Tensor,
+              topk_ids: torch.Tensor, activation: str, global_num_experts: int,
+              expert_map: Optional[torch.Tensor],
+              w1_scale: Optional[torch.Tensor],
+              w2_scale: Optional[torch.Tensor], w1_zp: Optional[torch.Tensor],
+              w2_zp: Optional[torch.Tensor], a1q_scale: Optional[torch.Tensor],
+              a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
+              workspace2: torch.Tensor,
+              expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         assert expert_tokens_meta is not None
         expert_num_tokens = expert_tokens_meta.expert_num_tokens
 

vllm/model_executor/layers/fused_moe/batched_triton_or_deep_gemm_moe.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -142,7 +142,8 @@ class BatchedTritonOrDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
               a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
               workspace2: torch.Tensor,
               expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-              apply_router_weight_on_input: bool):
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         experts = (self.batched_deep_gemm_experts
                    if self.allow_deep_gemm else self.batched_triton_experts)
         assert experts is not None
@@ -150,4 +151,4 @@ class BatchedTritonOrDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
                       activation, global_num_experts, expert_map, w1_scale,
                       w2_scale, w1_zp, w2_zp, a1q_scale, a2_scale, workspace13,
                       workspace2, expert_tokens_meta,
-                      apply_router_weight_on_input)
+                      apply_router_weight_on_input, extra_expert_args)

vllm/model_executor/layers/fused_moe/config.py

@@ -15,6 +15,7 @@ from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization.base_config import (
     QuantizationConfig)
 from vllm.utils import cdiv
+from vllm.utils.flashinfer import has_flashinfer_cutlass_fused_moe
 
 logger = init_logger(__name__)
 
@@ -188,6 +189,11 @@ class FusedMoEParallelConfig:
         return (self.use_all2all_kernels
                 and envs.VLLM_ALL2ALL_BACKEND == "deepep_low_latency")
 
+    @property
+    def use_flashinfer_cutlass_kernels(self):
+        return (envs.VLLM_USE_FLASHINFER_MOE
+                and has_flashinfer_cutlass_fused_moe())
+
     @staticmethod
     def make(tp_size_: int, dp_size_: int,
              vllm_parallel_config: ParallelConfig) -> "FusedMoEParallelConfig":
@@ -392,6 +398,10 @@ class FusedMoEConfig:
     def use_deepep_ll_kernels(self):
         return self.moe_parallel_config.use_deepep_ll_kernels
 
+    @property
+    def use_flashinfer_cutlass_kernels(self):
+        return self.moe_parallel_config.use_flashinfer_cutlass_kernels
+
     @staticmethod
     def make(
         num_experts: int,
@@ -435,6 +445,12 @@ class FusedMoEConfig:
             if quant_dtype is None and isinstance(quant_config, Fp8Config):
                 quant_dtype = torch.float8_e4m3fn
 
+            from vllm.model_executor.layers.quantization.modelopt import (
+                ModelOptNvFp4Config)
+            if quant_dtype is None and isinstance(quant_config,
+                                                  ModelOptNvFp4Config):
+                quant_dtype = torch.uint8
+
             if weight_quant is not None:
                 per_out_ch_quant = (
                     weight_quant.strategy == QuantizationStrategy.CHANNEL)

vllm/model_executor/layers/fused_moe/cutlass_moe.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 """ CUTLASS based Fused MoE kernels."""
-from typing import Callable, Optional
+from typing import Any, Callable, Optional
 
 import torch
 
@@ -14,7 +14,8 @@ from vllm.model_executor.layers.fused_moe.prepare_finalize import (
 from vllm.model_executor.layers.fused_moe.topk_weight_and_reduce import (
     TopKWeightAndReduceDelegate)
 from vllm.model_executor.layers.fused_moe.utils import (_fp8_quantize,
-                                                        _resize_cache)
+                                                        _resize_cache,
+                                                        extract_required_args)
 from vllm.scalar_type import scalar_types
 
 logger = init_logger(__name__)
@@ -298,7 +299,8 @@ class CutlassExpertsFp8(mk.FusedMoEPermuteExpertsUnpermute):
               a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
               workspace2: torch.Tensor,
               expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-              apply_router_weight_on_input: bool):
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         assert w1_zp is None, "w1_zp is not supported in CUTLASS MoE"
         assert w2_zp is None, "w2_zp is not supported in CUTLASS MoE"
 
@@ -431,23 +433,28 @@ FLOAT4_E2M1_MAX = scalar_types.float4_e2m1f.max()
 FLOAT8_E4M3_MAX = torch.finfo(torch.float8_e4m3fn).max
 
 
-def cutlass_moe_fp4(a: torch.Tensor,
-                    a1_gscale: torch.Tensor,
-                    w1_fp4: torch.Tensor,
-                    w1_blockscale: torch.Tensor,
-                    w1_alphas: torch.Tensor,
-                    a2_gscale: torch.Tensor,
-                    w2_fp4: torch.Tensor,
-                    w2_blockscale: torch.Tensor,
-                    w2_alphas: torch.Tensor,
-                    topk_weights: torch.Tensor,
-                    topk_ids: torch.Tensor,
-                    m: int,
-                    n: int,
-                    k: int,
-                    e: int,
-                    device: torch.device,
-                    apply_router_weight_on_input: bool = False):
+def run_cutlass_moe_fp4(
+    output: torch.Tensor,
+    a: torch.Tensor,
+    a1_gscale: torch.Tensor,
+    w1_fp4: torch.Tensor,
+    w1_blockscale: torch.Tensor,
+    w1_alphas: torch.Tensor,
+    a2_gscale: torch.Tensor,
+    w2_fp4: torch.Tensor,
+    w2_blockscale: torch.Tensor,
+    w2_alphas: torch.Tensor,
+    topk_weights: torch.Tensor,
+    topk_ids: torch.Tensor,
+    workspace13: torch.Tensor,
+    workspace2: torch.Tensor,
+    m: int,
+    n: int,
+    k: int,
+    e: int,
+    device: torch.device,
+    apply_router_weight_on_input: bool = False,
+) -> None:
     """
     MoE implementation for FP4 Inputs
     
@@ -487,16 +494,16 @@ def cutlass_moe_fp4(a: torch.Tensor,
 
     assert (e_w1 == e_w2 and e_w1 == e), ("Number of experts must match",
                                           " between weights.")
-    assert (k_a // 2 == half_k_w1
+    assert (k_a == half_k_w1 * 2
             and k == k_w2), ("Hidden size mismatch between a, w1 and w2")
-    assert (nx2_w1 == n * 2 and half_n_w2 == n // 2), ("mismatch in "
-                                                       "expected `n`")
+    assert (nx2_w1 == n * 2 and half_n_w2 * 2 == n), ("mismatch in "
+                                                      "expected `n`")
     assert (m == m_a), "input shape mismatch"
     assert 2 * half_k_w1 == k_w2, "Hidden size mismatch w2 and w1"
     assert a.dtype in [torch.half, torch.bfloat16], "Invalid input dtype"
     assert (topk_weights.size(0) == m and topk_ids.size(0)
             == m), ("topk must be provided for each row of a")
-
+    topk = topk_ids.size(1)
     out_dtype = a.dtype
     num_topk = topk_ids.size(1)
 
@@ -523,7 +530,6 @@ def cutlass_moe_fp4(a: torch.Tensor,
                                 blockscale_offsets)
 
     a = ops.shuffle_rows(a, a_map)
-
     rep_a_fp4, rep_a_blockscale = ops.scaled_fp4_experts_quant(
         a,
         a1_gscale,
@@ -531,34 +537,220 @@ def cutlass_moe_fp4(a: torch.Tensor,
         blockscale_offsets,
         num_topk,
     )
-
-    c1 = ops.cutlass_fp4_moe_mm(rep_a_fp4, w1_fp4, rep_a_blockscale,
-                                w1_blockscale, w1_alphas, problem_sizes1,
-                                expert_offsets[:-1], blockscale_offsets[:-1],
-                                out_dtype, device)
+    c1 = _resize_cache(workspace13, (m * topk, n * 2))
+    c2 = _resize_cache(workspace2, (m * topk, n))
+    c3 = _resize_cache(workspace13, (m * topk, k))
+    ops.cutlass_fp4_moe_mm(c1, rep_a_fp4, w1_fp4, rep_a_blockscale,
+                           w1_blockscale, w1_alphas, problem_sizes1,
+                           expert_offsets[:-1], blockscale_offsets[:-1])
     del rep_a_fp4, rep_a_blockscale
-    # hidden size dimension is split to one halfpytho sized tensor.
-    intermediate = torch.empty((m * num_topk, w1_fp4.size(1) // 2),
-                               device=device,
-                               dtype=out_dtype)
-
-    torch.ops._C.silu_and_mul(intermediate, c1)
-
+    torch.ops._C.silu_and_mul(c2, c1)
     int_fp4, int_blockscale = ops.scaled_fp4_experts_quant(
-        intermediate, a2_gscale, expert_offsets, blockscale_offsets, num_topk)
+        c2, a2_gscale, expert_offsets, blockscale_offsets, num_topk)
 
-    c2 = ops.cutlass_fp4_moe_mm(int_fp4, w2_fp4, int_blockscale, w2_blockscale,
-                                w2_alphas, problem_sizes2, expert_offsets[:-1],
-                                blockscale_offsets[:-1], out_dtype, device)
+    ops.cutlass_fp4_moe_mm(c3, int_fp4, w2_fp4, int_blockscale, w2_blockscale,
+                           w2_alphas, problem_sizes2, expert_offsets[:-1],
+                           blockscale_offsets[:-1])
     del int_fp4, int_blockscale
 
-    c2 = ops.shuffle_rows(c2, c_map)
+    c3 = ops.shuffle_rows(c3, c_map)
+
+    assert output.dtype == out_dtype
     if not apply_router_weight_on_input:
-        out = (c2.view(m, num_topk, k) *
-               topk_weights.view(m, num_topk, 1).to(out_dtype)).sum(dim=1)
+        output.copy_(
+            (c3.view(m, num_topk, k) *
+             topk_weights.view(m, num_topk, 1).to(out_dtype)).sum(dim=1),
+            non_blocking=True)
     else:
-        out = c2.view(m, num_topk, k).sum(dim=1)
-    return out.to(dtype=out_dtype)
+        output.copy_(c3.view(m, num_topk, k).sum(dim=1), non_blocking=True)
+    return
+
+
+class CutlassExpertsFp4(mk.FusedMoEPermuteExpertsUnpermute):
+
+    def __init__(
+        self,
+        max_experts_per_worker: int,
+        out_dtype: torch.dtype,
+        per_act_token_quant: bool,
+        per_out_ch_quant: bool,
+        block_shape: Optional[list[int]] = None,
+        use_batched_format: bool = False,
+    ):
+        super().__init__(
+            FusedMoEQuantConfig(
+                quant_dtype=torch.uint8,
+                per_act_token_quant=per_act_token_quant,
+                per_out_ch_quant=per_out_ch_quant,
+                block_shape=block_shape,
+            ))
+        self.max_experts_per_worker = max_experts_per_worker
+        self.out_dtype = out_dtype
+        self.use_batched_format = use_batched_format
+
+    @property
+    def activation_formats(
+        self
+    ) -> tuple[mk.FusedMoEActivationFormat, mk.FusedMoEActivationFormat]:
+        if self.use_batched_format:
+            return (mk.FusedMoEActivationFormat.BatchedExperts,
+                    mk.FusedMoEActivationFormat.BatchedExperts)
+        else:
+            return (mk.FusedMoEActivationFormat.Standard,
+                    mk.FusedMoEActivationFormat.Standard)
+
+    def supports_expert_map(self) -> bool:
+        return False
+
+    def supports_chunking(self) -> bool:
+        return True
+
+    def finalize_weight_and_reduce_impl(self) -> mk.TopKWeightAndReduce:
+        # Let PrepareAndFinalize::finalize() decide the impl.
+        return TopKWeightAndReduceDelegate()
+
+    def workspace_shapes(
+        self,
+        a: torch.Tensor,
+        aq: torch.Tensor,
+        M: int,
+        N: int,
+        K: int,
+        topk: int,
+        global_num_experts: int,
+        local_num_experts: int,
+        expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+    ) -> tuple[tuple[int, ...], tuple[int, ...], tuple[int, ...], torch.dtype]:
+        workspace1: tuple[int, ...] = ()
+        workspace2: tuple[int, ...] = ()
+        output: tuple[int, ...] = ()
+        if self.use_batched_format:
+            padded_M = aq.size(1)
+            workspace1 = (self.max_experts_per_worker, padded_M, max(N, K))
+            workspace2 = (self.max_experts_per_worker, padded_M, (N // 2))
+            output = (self.max_experts_per_worker, padded_M, K)
+        else:
+            workspace1 = (M * topk, max(2 * N, K))
+            workspace2 = (M * topk, N)
+            output = (M, K)
+        return (workspace1, workspace2, output,
+                self.out_dtype if self.out_dtype is not None else a.dtype)
+
+    def apply(self, output: torch.Tensor, hidden_states: torch.Tensor,
+              w1: torch.Tensor, w2: torch.Tensor, topk_weights: torch.Tensor,
+              topk_ids: torch.Tensor, activation: str, global_num_experts: int,
+              expert_map: Optional[torch.Tensor], w1_scale: torch.Tensor,
+              w2_scale: torch.Tensor, w1_zp: Optional[torch.Tensor],
+              w2_zp: Optional[torch.Tensor], a1q_scale: Optional[torch.Tensor],
+              a2_scale: torch.Tensor, workspace13: Optional[torch.Tensor],
+              workspace2: Optional[torch.Tensor],
+              expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
+        required_keys = [
+            "g1_alphas", "g2_alphas", "a1_gscale", "a2_gscale", "m", "n", "k",
+            "e", "device"
+        ]
+        (g1_alphas, g2_alphas, a1_gscale, a2_gscale, m, n, k, e,
+         device) = extract_required_args(extra_expert_args, required_keys)
+        run_cutlass_moe_fp4(
+            output=output,
+            a=hidden_states,
+            a1_gscale=a1_gscale,
+            w1_fp4=w1,
+            w1_blockscale=w1_scale,
+            w1_alphas=g1_alphas,
+            a2_gscale=a2_gscale,
+            w2_fp4=w2,
+            w2_blockscale=w2_scale,
+            w2_alphas=g2_alphas,
+            topk_weights=topk_weights,
+            topk_ids=topk_ids,
+            workspace13=workspace13,
+            workspace2=workspace2,
+            m=m,
+            n=n,
+            k=k,
+            e=e,
+            device=device,
+            apply_router_weight_on_input=apply_router_weight_on_input,
+        )
+
+
+def cutlass_moe_fp4(
+        a: torch.Tensor,
+        w1_fp4: torch.Tensor,
+        w2_fp4: torch.Tensor,
+        w1_blockscale: torch.Tensor,
+        w2_blockscale: torch.Tensor,
+        g1_alphas: torch.Tensor,
+        g2_alphas: torch.Tensor,
+        a1_gscale: torch.Tensor,
+        a2_gscale: torch.Tensor,
+        topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor,
+        m: int,
+        n: int,
+        k: int,
+        e: int,
+        device: torch.device,
+        expert_map: Optional[torch.Tensor] = None,
+        apply_router_weight_on_input: bool = False) -> torch.Tensor:
+    assert expert_map is None, ("Expert Parallelism / expert_map "
+                                "is currently not supported for "
+                                "ModelOptNvFp4FusedMoE's cutlass_moe_fp4.")
+    fn = mk.FusedMoEModularKernel(
+        MoEPrepareAndFinalizeNoEP(),
+        CutlassExpertsFp4(
+            max_experts_per_worker=e,
+            out_dtype=a.dtype,
+            per_act_token_quant=False,
+            per_out_ch_quant=False,
+            use_batched_format=False,
+        ),
+    )
+    extra_expert_args = {
+        'g1_alphas': g1_alphas,
+        'g2_alphas': g2_alphas,
+        'a1_gscale': a1_gscale,
+        'a2_gscale': a2_gscale,
+        'm': m,
+        'n': n,
+        'k': k,
+        'e': e,
+        'device': device,
+    }
+
+    # NVFP4 requires two levels of quantization, which involves computing some
+    # scaling factors dynamically. This makes it incompatible with the typical
+    # prepare -> MoE -> finalize pipeline. Move the quantization logic into the
+    # MoE body.
+    extra_prepare_args = {
+        'skip_quant': True,
+    }
+    # Similar reason as above.
+    extra_finalize_args = {
+        'skip_weight_reduce': True,
+    }
+    return fn(
+        hidden_states=a,
+        w1=w1_fp4,
+        w2=w2_fp4,
+        topk_weights=topk_weights,
+        topk_ids=topk_ids,
+        inplace=False,
+        activation="silu",
+        global_num_experts=e,
+        expert_map=None,
+        w1_scale=w1_blockscale,
+        w2_scale=w2_blockscale,
+        a1_scale=None,
+        a2_scale=None,
+        apply_router_weight_on_input=apply_router_weight_on_input,
+        extra_expert_args=extra_expert_args,
+        extra_prepare_args=extra_prepare_args,
+        extra_finalize_args=extra_finalize_args,
+    )
 
 
 def _valid_cutlass_block_scaled_grouped_gemm(

vllm/model_executor/layers/fused_moe/deep_gemm_moe.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 import functools
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -152,6 +152,7 @@ class DeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
         workspace2: torch.Tensor,
         expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
         apply_router_weight_on_input: bool,
+        extra_expert_args: Optional[dict[str, Any]],
     ):
         assert self.block_shape is not None
         assert a1q_scale is not None

vllm/model_executor/layers/fused_moe/deepep_ht_prepare_finalize.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import deep_ep
 import torch
@@ -127,16 +127,12 @@ class DeepEPHTPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
                 expert_topk_weights)
 
     def prepare(
-        self,
-        a1: torch.Tensor,
-        a1_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        apply_router_weight_on_input: bool,
+        self, a1: torch.Tensor, a1_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor], topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor, num_experts: int,
+        expert_map: Optional[torch.Tensor], apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[mk.ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -191,7 +187,8 @@ class DeepEPHTPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
     def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
                  topk_weights: torch.Tensor, topk_ids: torch.Tensor,
                  apply_router_weight_on_input: bool,
-                 weight_and_reduce_impl: mk.TopKWeightAndReduce) -> None:
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
 
         assert self.handle is not None
 

vllm/model_executor/layers/fused_moe/deepep_ll_prepare_finalize.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional, Union
+from typing import Any, Optional, Union
 
 import deep_ep
 import torch
@@ -111,16 +111,12 @@ class DeepEPLLPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
         return x, x_scales
 
     def prepare(
-        self,
-        a1: torch.Tensor,
-        a1_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        apply_router_weight_on_input: bool,
+        self, a1: torch.Tensor, a1_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor], topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor, num_experts: int,
+        expert_map: Optional[torch.Tensor], apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[mk.ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -169,7 +165,8 @@ class DeepEPLLPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
     def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
                  topk_weights: torch.Tensor, topk_ids: torch.Tensor,
                  apply_router_weight_on_input: bool,
-                 weight_and_reduce_impl: mk.TopKWeightAndReduce) -> None:
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
         assert isinstance(
             weight_and_reduce_impl, TopKWeightAndReduceDelegate
         ), ("Weight application and reduction happens in the combine kernel.")

vllm/model_executor/layers/fused_moe/flashinfer_cutlass_moe.py

@@ -0,0 +1,198 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from typing import Any, Optional
+
+import torch
+
+import vllm.model_executor.layers.fused_moe.modular_kernel as mk
+from vllm.logger import init_logger
+from vllm.model_executor.layers.fused_moe.config import FusedMoEQuantConfig
+from vllm.model_executor.layers.fused_moe.topk_weight_and_reduce import (
+    TopKWeightAndReduceDelegate)
+from vllm.model_executor.layers.fused_moe.utils import extract_required_args
+from vllm.utils.flashinfer import (flashinfer_cutlass_fused_moe,
+                                   has_flashinfer_cutlass_fused_moe)
+
+logger = init_logger(__name__)
+
+
+def is_valid_flashinfer_cutlass_fused_moe(hidden_states: torch.Tensor,
+                                          w1: torch.Tensor,
+                                          w2: torch.Tensor) -> bool:
+    """
+    Check if the given problem size is supported by the FlashInfer CUTLASS MoE 
+    kernel.
+    """
+    if not has_flashinfer_cutlass_fused_moe():
+        logger.debug_once("FlashInferExperts disabled: "
+                          "flashinfer_cutlass_fused_moe not available.")
+        return False
+    # Data type checks
+    if (w1.dtype != torch.uint8 or w2.dtype != torch.uint8
+            or hidden_states.dtype
+            not in [torch.float32, torch.float16, torch.bfloat16]):
+        logger.debug_once(
+            "FlashInferExperts disabled: w1/w2 must be torch.uint8 "
+            f"(got w1={w1.dtype}, w2={w2.dtype}), hidden_states must be "
+            f"float32, float16, or bfloat16 (got {hidden_states.dtype}).")
+        return False
+    return True
+
+
+class FlashInferExperts(mk.FusedMoEPermuteExpertsUnpermute):
+
+    def __init__(
+        self,
+        use_nvfp4_w4a4: bool = False,
+        use_fp8_w8a8: bool = False,
+        use_dp: bool = False,
+        ep_rank: int = 0,
+        ep_size: int = 1,
+        tp_rank: int = 0,
+        tp_size: int = 1,
+        num_dispatchers: Optional[int] = None,
+        use_batched_format: bool = False,
+    ):
+        super().__init__(
+            FusedMoEQuantConfig(
+                quant_dtype=torch.uint8,
+                per_act_token_quant=False,
+                block_shape=None,
+            ))
+        self.use_nvfp4_w4a4 = use_nvfp4_w4a4
+        self.use_fp8_w8a8 = use_fp8_w8a8
+        self.ep_rank = ep_rank
+        self.ep_size = ep_size
+        self.tp_rank = tp_rank
+        self.tp_size = tp_size
+        self.use_dp = use_dp
+        assert not use_batched_format or num_dispatchers is not None
+        self.num_dispatchers = num_dispatchers
+
+    @property
+    def activation_formats(
+        self
+    ) -> tuple[mk.FusedMoEActivationFormat, mk.FusedMoEActivationFormat]:
+        return (mk.FusedMoEActivationFormat.Standard,
+                mk.FusedMoEActivationFormat.Standard)
+
+    def supports_expert_map(self) -> bool:
+        return False
+
+    def supports_chunking(self) -> bool:
+        # This refers to TP chunking; DP chunking is handled separately.
+        return True
+
+    def finalize_weight_and_reduce_impl(self) -> mk.TopKWeightAndReduce:
+        # Let PrepareAndFinalize::finalize() decide the impl.
+        return TopKWeightAndReduceDelegate()
+
+    def workspace_shapes(
+        self,
+        a: torch.Tensor,
+        aq: torch.Tensor,
+        M: int,
+        N: int,
+        K: int,
+        topk: int,
+        global_num_experts: int,
+        local_num_experts: int,
+        expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+    ) -> tuple[tuple[int, ...], tuple[int, ...], tuple[int, ...], torch.dtype]:
+        # We use global_num_experts due to how moe_align_block_size handles
+        # expert_maps.
+        """
+        Compute the shapes for the temporary and final outputs of the two gemms
+        and activation in the fused expert function.  Since the gemms are
+        independent, the workspace for the first gemm can be shared with the
+        workspace for the last gemm.
+
+        Returns a tuple of:
+        - workspace13 shape tuple: must be large enough to hold the
+          result of either expert gemm.
+        - workspace2 shape tuple: must be large enough to hold the
+          result of the activation function.
+        - output shape tuple: must be exact size of the final gemm output.
+        - Workspace type: The dtype to use for the workspace tensors.
+        - Note: in order for activation chunking to work, the first dimension
+          of each tuple must be the number of tokens.
+        """
+        assert self.use_nvfp4_w4a4 is True, ("Only nvfp4 quantization is "
+                                             "currently supported.")
+        aq_m, aq_n = aq.shape
+        workspace2 = ()
+        output_shape = (aq_m, aq_n * 2)
+        workspace_dtype = a.dtype
+        workspace1 = output_shape
+        # The workspace is determined by `aq`, since it comes after any
+        # potential communication op and is involved in the expert computation.
+        return (workspace1, workspace2, output_shape, workspace_dtype)
+
+    def apply(
+        self,
+        output: torch.Tensor,
+        hidden_states: torch.Tensor,
+        w1: torch.Tensor,
+        w2: torch.Tensor,
+        topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor,
+        activation: str,
+        global_num_experts: int,
+        expert_map: Optional[torch.Tensor],
+        w1_scale: Optional[torch.Tensor],
+        w2_scale: Optional[torch.Tensor],
+        w1_zp: Optional[torch.Tensor],
+        w2_zp: Optional[torch.Tensor],
+        a1q_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor],  # Not used
+        workspace13: Optional[torch.Tensor],
+        workspace2: Optional[torch.Tensor],
+        expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+        apply_router_weight_on_input: Optional[bool],
+        extra_expert_args: Optional[dict[str, Any]],
+    ):
+        assert extra_expert_args is not None, \
+            "extra_expert_args must be provided"
+        required_keys = [
+            'g1_alphas', 'g2_alphas', 'a1_gscale', 'a2_gscale', 'out_dtype'
+        ]
+
+        g1_alphas, g2_alphas, a1_gscale, a2_gscale, out_dtype = (
+            extract_required_args(extra_expert_args, required_keys))
+
+        # Flashinfer CUTLASS kernel takes scalar global scales,
+        # min because inv_scale.
+        assert self.use_nvfp4_w4a4 is True, ("Only nvfp4 quantization is "
+                                             "currently supported.")
+
+        # Ensure w1_scale and w2_scale are not None before calling view
+        assert w1_scale is not None and w2_scale is not None, (
+            "w1_scale and w2_scale must not "
+            "be None for FlashInferExperts")
+
+        assert not apply_router_weight_on_input
+
+        quant_scales = [
+            a1_gscale,
+            w1_scale.view(torch.int32),
+            g1_alphas,
+            a2_gscale,
+            w2_scale.view(torch.int32),
+            g2_alphas,
+        ]
+        _ = flashinfer_cutlass_fused_moe(
+            hidden_states,
+            topk_ids.to(torch.int),
+            topk_weights,
+            # FlashInfer API requires weight to be long for nvfp4
+            w1.view(torch.long),
+            w2.view(torch.long),
+            output_dtype=out_dtype,
+            quant_scales=quant_scales,
+            input_sf=a1q_scale,
+            tp_size=self.tp_size,
+            tp_rank=self.tp_rank,
+            ep_size=self.ep_size,
+            ep_rank=self.ep_rank,
+            output=output,
+        )

vllm/model_executor/layers/fused_moe/flashinfer_cutlass_prepare_finalize.py

@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from typing import Any, Optional
+
+import torch
+
+import vllm.envs as envs
+import vllm.model_executor.layers.fused_moe.modular_kernel as mk
+from vllm.distributed import get_dp_group
+from vllm.forward_context import get_forward_context
+from vllm.model_executor.layers.fused_moe.config import FusedMoEQuantConfig
+from vllm.model_executor.layers.fused_moe.utils import (
+    extract_required_args, moe_kernel_quantize_input)
+from vllm.utils.flashinfer import fp4_swizzle_blockscale
+
+
+def get_local_sizes(local_tokens):
+    cu_sizes = get_forward_context().dp_metadata.cu_tokens_across_dp_cpu
+    sizes = [cu_sizes[0].item()]
+    for i in range(1, len(cu_sizes)):
+        sizes.append((cu_sizes[i] - cu_sizes[i - 1]).item())
+    max_num_tokens = envs.VLLM_MOE_DP_CHUNK_SIZE
+    sizes_chunked = [max_num_tokens] * len(sizes)
+    if local_tokens < max_num_tokens:
+        # When the number of local tokens is less than max_num_tokens, all other
+        # ranks will also have fewer than max_num_tokens. The remaining tokens
+        # are accounted for as residual.
+        sizes_chunked = [x % max_num_tokens for x in sizes]
+
+    return sizes_chunked
+
+
+class FlashInferCutlassMoEPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
+
+    def __init__(
+        self,
+        quant_dtype: Optional[torch.dtype] = None,
+        per_channel_quant: bool = False,
+        block_shape: Optional[list[int]] = None,
+        num_dispatchers: int = 1,
+    ):
+        super().__init__()
+        self.per_channel_quant = per_channel_quant
+        self.block_shape = block_shape
+        self.quant_dtype = quant_dtype
+        self.num_dispatchers_ = num_dispatchers
+
+    @property
+    def activation_format(self) -> mk.FusedMoEActivationFormat:
+        return mk.FusedMoEActivationFormat.Standard
+
+    def max_num_tokens_per_rank(self) -> Optional[int]:
+        return None
+
+    def topk_indices_dtype(self) -> Optional[torch.dtype]:
+        return None
+
+    def num_dispatchers(self) -> int:
+        return self.num_dispatchers_
+
+    def prepare(
+        self,
+        a1: torch.Tensor,
+        a1_scale: Optional[torch.Tensor],  # Not used
+        a2_scale: Optional[torch.Tensor],  # Not used
+        topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor,
+        num_experts: int,
+        expert_map: Optional[torch.Tensor],
+        apply_router_weight_on_input: bool,
+        quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
+    ) -> tuple[torch.Tensor, Optional[torch.Tensor], Optional[torch.Tensor],
+               Optional[torch.Tensor], Optional[torch.Tensor]]:
+
+        assert not apply_router_weight_on_input
+
+        (a1_gscale, use_dp, local_tokens) = extract_required_args(
+            extra_prepare_args, ['a1_gscale', 'use_dp', 'local_tokens'])
+
+        a1q, a1q_scale = moe_kernel_quantize_input(
+            a1,
+            a1_gscale,
+            quant_config.quant_dtype,
+            self.per_channel_quant,
+            self.block_shape,
+            is_fp4_scale_swizzled=not use_dp,  # Swizzling after communication
+        )
+        if use_dp:
+            topk_weights, topk_ids, a1q, a1q_scale = \
+                get_dp_group().all_gatherv([topk_weights, topk_ids, a1q, a1q_scale], # noqa: E501
+                                           dim=0,
+                                           sizes=get_local_sizes(local_tokens))
+            a1_m, a1_n = a1q.shape
+            a1q_scale = fp4_swizzle_blockscale(a1q_scale, a1_m, a1_n * 2)
+
+        return a1q, a1q_scale, None, topk_ids, topk_weights
+
+    def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
+                 topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+                 apply_router_weight_on_input: bool,
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
+
+        (use_dp,
+         local_tokens) = extract_required_args(extra_finalize_args,
+                                               ['use_dp', 'local_tokens'])
+        if use_dp:
+            fused_expert_output = get_dp_group().reduce_scatterv(
+                fused_expert_output,
+                dim=0,
+                sizes=get_local_sizes(local_tokens),
+            )
+        output.copy_(fused_expert_output)

vllm/model_executor/layers/fused_moe/fused_batched_moe.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 """Fused batched MoE kernel."""
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -496,16 +496,12 @@ class BatchedPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
         return self.num_dispatchers_
 
     def prepare(
-        self,
-        a1: torch.Tensor,
-        a1_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        apply_router_weight_on_input: bool,
+        self, a1: torch.Tensor, a1_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor], topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor, num_experts: int,
+        expert_map: Optional[torch.Tensor], apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[mk.ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -594,15 +590,11 @@ class BatchedPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
 
         return b_a1, b_a1_scale, expert_tokens_meta, None, None
 
-    def finalize(
-        self,
-        output: torch.Tensor,
-        fused_expert_output: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        apply_router_weight_on_input: bool,
-        weight_and_reduce_impl: mk.TopKWeightAndReduce,
-    ) -> None:
+    def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
+                 topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+                 apply_router_weight_on_input: bool,
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
         if isinstance(weight_and_reduce_impl, TopKWeightAndReduceDelegate):
             weight_and_reduce_impl = TopKWeightAndReduceNaiveBatched(self.rank)
         weight_and_reduce_impl.apply(
@@ -706,7 +698,8 @@ class NaiveBatchedExperts(mk.FusedMoEPermuteExpertsUnpermute):
               a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
               workspace2: torch.Tensor,
               expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-              apply_router_weight_on_input: bool):
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         assert hidden_states.dim() == 3
         assert expert_tokens_meta is not None
         expert_num_tokens = expert_tokens_meta.expert_num_tokens
@@ -911,7 +904,8 @@ class BatchedTritonExperts(mk.FusedMoEPermuteExpertsUnpermute):
               a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
               workspace2: torch.Tensor,
               expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-              apply_router_weight_on_input: bool):
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         # Check constraints.
         if self.use_int4_w4a16:
             assert hidden_states.size(-1) // 2 == w1.size(2), (

vllm/model_executor/layers/fused_moe/fused_moe.py

@@ -1646,6 +1646,7 @@ class TritonExperts(mk.FusedMoEPermuteExpertsUnpermute):
         workspace2: torch.Tensor,
         expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
         apply_router_weight_on_input: bool,
+        extra_expert_args: Optional[dict[str, Any]],
     ):
         # Check constraints.
         if self.use_int4_w4a16:

vllm/model_executor/layers/fused_moe/layer.py

@@ -34,6 +34,7 @@ from vllm.model_executor.utils import set_weight_attrs
 from vllm.platforms import current_platform
 from vllm.platforms.interface import CpuArchEnum
 from vllm.utils import direct_register_custom_op, has_deep_ep, has_pplx
+from vllm.utils.flashinfer import has_flashinfer
 
 if current_platform.is_cuda_alike():
     from .fused_batched_moe import BatchedTritonExperts
@@ -45,6 +46,9 @@ if current_platform.is_cuda_alike():
         from .deepep_ht_prepare_finalize import DeepEPHTPrepareAndFinalize
         from .deepep_ll_prepare_finalize import (DEEPEP_QUANT_BLOCK_SHAPE,
                                                  DeepEPLLPrepareAndFinalize)
+    if has_flashinfer():
+        from .flashinfer_cutlass_prepare_finalize import (
+            FlashInferCutlassMoEPrepareAndFinalize)
 else:
     fused_experts = None  # type: ignore
     FusedMoEPermuteExpertsUnpermute = None  # type: ignore
@@ -99,6 +103,9 @@ class FusedMoEMethodBase(QuantizeMethodBase):
 
         prepare_finalize: Optional[FusedMoEPrepareAndFinalize] = None
 
+        if moe.use_flashinfer_cutlass_kernels:
+            prepare_finalize = FlashInferCutlassMoEPrepareAndFinalize(
+                quant_dtype=moe.quant_dtype, )
         if moe.use_pplx_kernels:
             hidden_dim_bytes, hidden_scale_bytes = pplx_hidden_dim_scale_bytes(
                 moe.max_num_tokens,
@@ -204,6 +211,12 @@ class FusedMoEMethodBase(QuantizeMethodBase):
             f"{self.__class__.__name__} must select appropriate gemm "
             "implementation based on the prepare_finalize")
 
+    def maybe_swap_experts_impl(
+        self,
+        moe_parallel_config: FusedMoEParallelConfig,
+    ):
+        pass
+
     @abstractmethod
     def apply(
         self,
@@ -744,12 +757,15 @@ class FusedMoE(torch.nn.Module):
             moe_quant_params["intermediate_size_full"] = intermediate_size
 
         self.quant_method.create_weights(layer=self, **moe_quant_params)
+        if isinstance(self.quant_method, FusedMoEMethodBase):
+            self.quant_method.maybe_swap_experts_impl(self.moe_parallel_config)
 
         # Chunked all2all staging tensor
         self.batched_hidden_states: Optional[torch.Tensor] = None
         self.batched_router_logits: Optional[torch.Tensor] = None
         if (self.moe_parallel_config.use_pplx_kernels
-                or self.moe_parallel_config.use_deepep_ll_kernels):
+                or self.moe_parallel_config.use_deepep_ll_kernels
+                or self.moe_parallel_config.use_flashinfer_cutlass_kernels):
             self.batched_hidden_states = torch.zeros(
                 (moe.max_num_tokens, self.hidden_size),
                 dtype=moe.in_dtype,
@@ -801,6 +817,10 @@ class FusedMoE(torch.nn.Module):
     def use_deepep_ll_kernels(self):
         return self.moe_parallel_config.use_deepep_ll_kernels
 
+    @property
+    def use_flashinfer_cutlass_kernels(self):
+        return self.moe_parallel_config.use_flashinfer_cutlass_kernels
+
     def _load_per_tensor_weight_scale(self, shard_id: str,
                                       param: torch.nn.Parameter,
                                       loaded_weight: torch.Tensor,
@@ -1402,9 +1422,9 @@ class FusedMoE(torch.nn.Module):
                     final_hidden_states, non_blocking=True)
 
         ctx = get_forward_context()
+        # flashinfer_cutlass_kernels can handle: optional DP + TP/EP
         max_tokens_across_dp = ctx.dp_metadata.max_tokens_across_dp_cpu
         moe_dp_chunk_size_per_rank = self.moe_config.max_num_tokens
-
         num_tokens = full_hidden_states.size(0)
         for chunk_start_ in range(0, max_tokens_across_dp,
                                   moe_dp_chunk_size_per_rank):
@@ -1424,13 +1444,20 @@ class FusedMoE(torch.nn.Module):
     def forward_impl(self, hidden_states: torch.Tensor,
                      router_logits: torch.Tensor):
         assert self.quant_method is not None
+        # Route to the chunked forward path using the FlashInfer Cutlass kernel
+        # only when data parallelism (DP) is enabled.
+        use_flashinfer_cutlass_kernels = (
+            self.dp_size > 1
+            and self.moe_parallel_config.use_flashinfer_cutlass_kernels)
         if (self.moe_parallel_config.use_pplx_kernels
-                or self.moe_parallel_config.use_deepep_ll_kernels):
+                or self.moe_parallel_config.use_deepep_ll_kernels
+                or use_flashinfer_cutlass_kernels):
             return self.forward_impl_chunked(hidden_states, router_logits)
 
         do_naive_dispatch_combine: bool = (
             self.dp_size > 1
-            and not self.moe_parallel_config.use_deepep_ht_kernels)
+            and not self.moe_parallel_config.use_deepep_ht_kernels
+            and not self.moe_parallel_config.use_flashinfer_cutlass_kernels)
         if do_naive_dispatch_combine:
             hidden_states, router_logits = get_ep_group().dispatch(
                 hidden_states, router_logits)
@@ -1460,7 +1487,6 @@ class FusedMoE(torch.nn.Module):
 
         if do_naive_dispatch_combine:
             final_hidden_states = get_ep_group().combine(final_hidden_states)
-
         if self.reduce_results and (self.tp_size > 1 or self.ep_size > 1):
             # Default set to False. (May have to add shared expert outputs.
             final_hidden_states = self.maybe_all_reduce_tensor_model_parallel(

vllm/model_executor/layers/fused_moe/modular_kernel.py

@@ -4,7 +4,7 @@ from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from enum import Enum
 from math import prod
-from typing import Optional, final
+from typing import Any, Optional, final
 
 import torch
 
@@ -150,16 +150,12 @@ class FusedMoEPrepareAndFinalize(ABC):
 
     @abstractmethod
     def prepare(
-        self,
-        a1: torch.Tensor,
-        a1_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        apply_router_weight_on_input: bool,
+        self, a1: torch.Tensor, a1_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor], topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor, num_experts: int,
+        expert_map: Optional[torch.Tensor], apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -190,15 +186,11 @@ class FusedMoEPrepareAndFinalize(ABC):
         raise NotImplementedError
 
     @abstractmethod
-    def finalize(
-        self,
-        output: torch.Tensor,
-        fused_expert_output: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        apply_router_weight_on_input: bool,
-        weight_and_reduce_impl: TopKWeightAndReduce,
-    ) -> None:
+    def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
+                 topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+                 apply_router_weight_on_input: bool,
+                 weight_and_reduce_impl: TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
         """
         Perform any combine plus apply weights and perform a reduction on the
         fused experts output.
@@ -376,6 +368,7 @@ class FusedMoEPermuteExpertsUnpermute(ABC):
         workspace2: torch.Tensor,
         expert_tokens_meta: Optional[ExpertTokensMetadata],
         apply_router_weight_on_input: bool,
+        extra_expert_args: Optional[dict[str, Any]],
     ):
         """
         This function computes the intermediate result of a Mixture of Experts
@@ -460,21 +453,19 @@ class FusedMoEModularKernel(torch.nn.Module):
                 f"{fused_experts.__class__.__name__}."
                 f"{fused_experts.activation_formats[0]}")
 
-    def _do_fused_experts(self, fused_out: Optional[torch.Tensor],
-                          a1: torch.Tensor, a1q: torch.Tensor,
-                          w1: torch.Tensor, w2: torch.Tensor,
-                          topk_weights: torch.Tensor, topk_ids: torch.Tensor,
-                          activation: str, global_num_experts: int,
-                          local_num_experts: int,
-                          expert_map: Optional[torch.Tensor],
-                          w1_scale: Optional[torch.Tensor],
-                          w2_scale: Optional[torch.Tensor],
-                          w1_zp: Optional[torch.Tensor],
-                          w2_zp: Optional[torch.Tensor],
-                          a1q_scale: Optional[torch.Tensor],
-                          a2_scale: Optional[torch.Tensor],
-                          expert_tokens_meta: Optional[ExpertTokensMetadata],
-                          apply_router_weight_on_input: bool) -> torch.Tensor:
+    def _do_fused_experts(
+            self, fused_out: Optional[torch.Tensor], a1: torch.Tensor,
+            a1q: torch.Tensor, w1: torch.Tensor, w2: torch.Tensor,
+            topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+            activation: str, global_num_experts: int, local_num_experts: int,
+            expert_map: Optional[torch.Tensor],
+            w1_scale: Optional[torch.Tensor], w2_scale: Optional[torch.Tensor],
+            w1_zp: Optional[torch.Tensor], w2_zp: Optional[torch.Tensor],
+            a1q_scale: Optional[torch.Tensor],
+            a2_scale: Optional[torch.Tensor],
+            expert_tokens_meta: Optional[ExpertTokensMetadata],
+            apply_router_weight_on_input: bool,
+            extra_expert_args: Optional[dict[str, Any]]) -> torch.Tensor:
 
         _, M, N, K, top_k = _moe_problem_size(a1q, w1, w2, topk_ids)
 
@@ -517,7 +508,8 @@ class FusedMoEModularKernel(torch.nn.Module):
             workspace13=workspace13,
             workspace2=workspace2,
             expert_tokens_meta=expert_tokens_meta,
-            apply_router_weight_on_input=apply_router_weight_on_input)
+            apply_router_weight_on_input=apply_router_weight_on_input,
+            extra_expert_args=extra_expert_args)
 
         return fused_out
 
@@ -541,6 +533,7 @@ class FusedMoEModularKernel(torch.nn.Module):
         a2_scale: Optional[torch.Tensor],
         expert_tokens_meta: Optional[ExpertTokensMetadata],
         apply_router_weight_on_input: bool,
+        extra_expert_args: Optional[dict[str, Any]],
     ) -> torch.Tensor:
 
         _, M, N, K, top_k = _moe_problem_size(a1q, w1, w2, topk_ids)
@@ -568,7 +561,8 @@ class FusedMoEModularKernel(torch.nn.Module):
                 a1q_scale=a1q_scale,
                 a2_scale=a2_scale,
                 expert_tokens_meta=expert_tokens_meta,
-                apply_router_weight_on_input=apply_router_weight_on_input)
+                apply_router_weight_on_input=apply_router_weight_on_input,
+                extra_expert_args=extra_expert_args)
 
         # Chunking required case
         assert num_chunks > 1
@@ -624,6 +618,15 @@ class FusedMoEModularKernel(torch.nn.Module):
                 expert_num_tokens=c_expert_num_tokens,
                 expert_num_tokens_cpu=c_expert_num_tokens_cpu)
 
+        m = None
+        if extra_expert_args is not None and 'm' in extra_expert_args:
+            m = extra_expert_args.get('m')
+
+        if extra_expert_args is not None:
+            chunked_extra_expert_args = extra_expert_args
+        else:
+            chunked_extra_expert_args = {}
+
         for chunk_idx in range(num_chunks):
             c_a1q, c_a1q_scale, c_a2_scale, c_topk_ids, c_topk_weights = (
                 slice_input_tensors(chunk_idx))
@@ -634,6 +637,11 @@ class FusedMoEModularKernel(torch.nn.Module):
                     expert_tokens_meta, c_topk_ids, local_num_experts,
                     expert_map)
 
+            s = chunk_idx * CHUNK_SIZE
+            e = min(s + CHUNK_SIZE, M)
+
+            if m is not None:
+                chunked_extra_expert_args['m'] = e - s
             self._do_fused_experts(
                 fused_out=slice_output_tensor(chunk_idx),
                 a1=a1,
@@ -653,7 +661,8 @@ class FusedMoEModularKernel(torch.nn.Module):
                 a1q_scale=c_a1q_scale,
                 a2_scale=c_a2_scale,
                 expert_tokens_meta=c_expert_tokens_meta,
-                apply_router_weight_on_input=apply_router_weight_on_input)
+                apply_router_weight_on_input=apply_router_weight_on_input,
+                extra_expert_args=chunked_extra_expert_args)
 
         return fused_out
 
@@ -675,6 +684,9 @@ class FusedMoEModularKernel(torch.nn.Module):
         a1_scale: Optional[torch.Tensor] = None,
         a2_scale: Optional[torch.Tensor] = None,
         apply_router_weight_on_input: bool = False,
+        extra_expert_args: Optional[dict] = None,
+        extra_prepare_args: Optional[dict] = None,
+        extra_finalize_args: Optional[dict] = None,
     ) -> torch.Tensor:
         """
         This function computes a Mixture of Experts (MoE) layer using two sets
@@ -707,6 +719,12 @@ class FusedMoEModularKernel(torch.nn.Module):
         - apply_router_weight_on_input (bool): When true, the topk weights are
           applied directly on the inputs. This is only applicable when topk is
           1.
+        - extra_expert_args (Optional[dict]): Extra keyword arguments to pass to
+          fused_experts.apply.
+        - extra_prepare_args (Optional[dict]): Extra keyword arguments to pass
+          to prepare.
+        - extra_finalize_args (Optional[dict]): Extra keyword arguments to pass 
+          to finalize.
 
         Returns:
         - torch.Tensor: The output tensor after applying the MoE layer.
@@ -730,6 +748,7 @@ class FusedMoEModularKernel(torch.nn.Module):
              expert_map,
              apply_router_weight_on_input,
              self.fused_experts.quant_config,
+             extra_prepare_args,
          )
 
         # Maybe prepare gathered topk_ids and topk_weights from other EP ranks.
@@ -766,11 +785,13 @@ class FusedMoEModularKernel(torch.nn.Module):
                 a1q_scale=a1q_scale,
                 a2_scale=a2_scale,
                 expert_tokens_meta=expert_tokens_meta,
-                apply_router_weight_on_input=apply_router_weight_on_input)
+                apply_router_weight_on_input=apply_router_weight_on_input,
+                extra_expert_args=extra_expert_args)
 
         self.prepare_finalize.finalize(
             output, fused_out, topk_weights, topk_ids,
             apply_router_weight_on_input,
-            self.fused_experts.finalize_weight_and_reduce_impl())
+            self.fused_experts.finalize_weight_and_reduce_impl(),
+            extra_finalize_args)
 
         return output

vllm/model_executor/layers/fused_moe/pplx_prepare_finalize.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import pplx_kernels as pplx
 import torch
@@ -89,16 +89,12 @@ class PplxPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
         return self.num_dispatchers_
 
     def prepare(
-        self,
-        a1: torch.Tensor,
-        a1_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        apply_router_weight_on_input: bool,
+        self, a1: torch.Tensor, a1_scale: Optional[torch.Tensor],
+        a2_scale: Optional[torch.Tensor], topk_weights: torch.Tensor,
+        topk_ids: torch.Tensor, num_experts: int,
+        expert_map: Optional[torch.Tensor], apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]]
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[mk.ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -217,15 +213,11 @@ class PplxPrepareAndFinalize(mk.FusedMoEPrepareAndFinalize):
 
         return expert_x, expert_x_scale, expert_tokens_meta, None, None
 
-    def finalize(
-        self,
-        output: torch.Tensor,
-        fused_expert_output: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        apply_router_weight_on_input: bool,
-        weight_and_reduce_impl: mk.TopKWeightAndReduce,
-    ) -> None:
+    def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
+                 topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+                 apply_router_weight_on_input: bool,
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
         assert isinstance(
             weight_and_reduce_impl, TopKWeightAndReduceDelegate
         ), ("Weight application and reduction happens in the combine kernel.")

vllm/model_executor/layers/fused_moe/prepare_finalize.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -38,6 +38,7 @@ class MoEPrepareAndFinalizeNoEP(mk.FusedMoEPrepareAndFinalize):
         expert_map: Optional[torch.Tensor],
         apply_router_weight_on_input: bool,
         quant_config: FusedMoEQuantConfig,
+        extra_prepare_args: Optional[dict[str, Any]],
     ) -> tuple[torch.Tensor, Optional[torch.Tensor],
                Optional[mk.ExpertTokensMetadata], Optional[torch.Tensor],
                Optional[torch.Tensor]]:
@@ -48,26 +49,33 @@ class MoEPrepareAndFinalizeNoEP(mk.FusedMoEPrepareAndFinalize):
             assert topk == 1, \
                 "apply_router_weight_on_input is only implemented for topk=1"
             a1.mul_(topk_weights.to(a1.dtype))
+
+        if (extra_prepare_args is not None
+                and extra_prepare_args.get("skip_quant", True)):
+            # Skip quantization if explicitly requested
+            return a1, None, None, None, None
+
         a1q, a1q_scale = moe_kernel_quantize_input(
             a1, a1_scale, quant_config.quant_dtype,
             quant_config.per_act_token_quant, quant_config.block_shape)
 
         return a1q, a1q_scale, None, None, None
 
-    def finalize(
-        self,
-        output: torch.Tensor,
-        fused_expert_output: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        apply_router_weight_on_input: bool,
-        weight_and_reduce_impl: mk.TopKWeightAndReduce,
-    ) -> None:
-        if isinstance(weight_and_reduce_impl, TopKWeightAndReduceDelegate):
-            weight_and_reduce_impl = TopKWeightAndReduceContiguous()
-        weight_and_reduce_impl.apply(
-            output=output,
-            fused_expert_output=fused_expert_output,
-            topk_weights=topk_weights,
-            topk_ids=topk_ids,
-            apply_router_weight_on_input=apply_router_weight_on_input)
+    def finalize(self, output: torch.Tensor, fused_expert_output: torch.Tensor,
+                 topk_weights: torch.Tensor, topk_ids: torch.Tensor,
+                 apply_router_weight_on_input: bool,
+                 weight_and_reduce_impl: mk.TopKWeightAndReduce,
+                 extra_finalize_args: Optional[dict[str, Any]]) -> None:
+        if (extra_finalize_args is not None
+                and extra_finalize_args.get("skip_weight_reduce", True)):
+            assert output.shape == fused_expert_output.shape
+            output.copy_(fused_expert_output)
+        else:
+            if isinstance(weight_and_reduce_impl, TopKWeightAndReduceDelegate):
+                weight_and_reduce_impl = TopKWeightAndReduceContiguous()
+            weight_and_reduce_impl.apply(
+                output=output,
+                fused_expert_output=fused_expert_output,
+                topk_weights=topk_weights,
+                topk_ids=topk_ids,
+                apply_router_weight_on_input=apply_router_weight_on_input)

vllm/model_executor/layers/fused_moe/triton_deep_gemm_moe.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-from typing import Optional
+from typing import Any, Optional
 
 import torch
 
@@ -119,28 +119,18 @@ class TritonOrDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
                                                        local_num_experts,
                                                        expert_tokens_meta)
 
-    def apply(
-        self,
-        output: torch.Tensor,
-        hidden_states: torch.Tensor,
-        w1: torch.Tensor,
-        w2: torch.Tensor,
-        topk_weights: torch.Tensor,
-        topk_ids: torch.Tensor,
-        activation: str,
-        global_num_experts: int,
-        expert_map: Optional[torch.Tensor],
-        w1_scale: Optional[torch.Tensor],
-        w2_scale: Optional[torch.Tensor],
-        w1_zp: Optional[torch.Tensor],
-        w2_zp: Optional[torch.Tensor],
-        a1q_scale: Optional[torch.Tensor],
-        a2_scale: Optional[torch.Tensor],
-        workspace13: torch.Tensor,
-        workspace2: torch.Tensor,
-        expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
-        apply_router_weight_on_input: bool,
-    ):
+    def apply(self, output: torch.Tensor, hidden_states: torch.Tensor,
+              w1: torch.Tensor, w2: torch.Tensor, topk_weights: torch.Tensor,
+              topk_ids: torch.Tensor, activation: str, global_num_experts: int,
+              expert_map: Optional[torch.Tensor],
+              w1_scale: Optional[torch.Tensor],
+              w2_scale: Optional[torch.Tensor], w1_zp: Optional[torch.Tensor],
+              w2_zp: Optional[torch.Tensor], a1q_scale: Optional[torch.Tensor],
+              a2_scale: Optional[torch.Tensor], workspace13: torch.Tensor,
+              workspace2: torch.Tensor,
+              expert_tokens_meta: Optional[mk.ExpertTokensMetadata],
+              apply_router_weight_on_input: bool,
+              extra_expert_args: Optional[dict[str, Any]]):
         use_deep_gemm = (self.allow_deep_gemm
                          and (_valid_deep_gemm(hidden_states, w1, w2)
                               or is_blackwell_deep_gemm_used()))
@@ -168,4 +158,5 @@ class TritonOrDeepGemmExperts(mk.FusedMoEPermuteExpertsUnpermute):
             workspace2,
             expert_tokens_meta,
             apply_router_weight_on_input,
+            extra_expert_args,
         )

vllm/model_executor/layers/fused_moe/utils.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 from math import prod
-from typing import Optional, Union
+from typing import Any, Optional, Union
 
 import torch
 
@@ -15,6 +15,7 @@ from vllm.model_executor.layers.quantization.utils.mxfp4_utils import (
 from vllm.platforms import current_platform
 from vllm.triton_utils import tl, triton
 from vllm.utils import cdiv
+from vllm.utils.flashinfer import fp4_quantize
 
 
 @triton.jit
@@ -98,6 +99,16 @@ def _resize_cache(x: torch.Tensor, v: tuple[int, ...]) -> torch.Tensor:
     return x.flatten()[:prod(v)].view(*v)
 
 
+def _fp4_quantize(
+    A: torch.Tensor,
+    A_scale: Optional[torch.Tensor],
+    is_sf_swizzled_layout: bool,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    return fp4_quantize(A,
+                        A_scale,
+                        is_sf_swizzled_layout=is_sf_swizzled_layout)
+
+
 def _fp8_quantize(
     A: torch.Tensor,
     A_scale: Optional[torch.Tensor],
@@ -172,11 +183,16 @@ def moe_kernel_quantize_input(
     quant_dtype: Union[None, torch.dtype, str],
     per_act_token_quant: bool,
     block_shape: Optional[list[int]] = None,
+    is_fp4_scale_swizzled: bool = True,
 ) -> tuple[torch.Tensor, Optional[torch.Tensor]]:
     if quant_dtype == torch.float8_e4m3fn:
         return _fp8_quantize(A, A_scale, per_act_token_quant, block_shape)
     elif quant_dtype == torch.int8:
         return _int8_quantize(A, A_scale, per_act_token_quant, block_shape)
+    elif quant_dtype == torch.uint8:  # nvfp4
+        return _fp4_quantize(A,
+                             A_scale,
+                             is_sf_swizzled_layout=is_fp4_scale_swizzled)
     elif quant_dtype == "mxfp4":
         return _mxfp4_quantize(A, A_scale, per_act_token_quant, block_shape)
     else:
@@ -236,3 +252,17 @@ def _validate_scale_shape(
         assert block_shape is not None
         expected = (a.shape[0], cdiv(a.shape[1], block_shape[1]))
         assert a_scale.shape == expected, f"{a_scale.shape} == {expected}"
+
+
+def extract_required_args(
+    extra_args: Optional[dict[str, Any]],
+    required_keys: list[str],
+) -> tuple[Any, ...]:
+    if extra_args is None:
+        raise ValueError("`extra_args` must be provided.")
+
+    missing_keys = [k for k in required_keys if k not in extra_args]
+    if missing_keys:
+        raise ValueError(f"Missing keys in `extra_args`: {missing_keys}")
+
+    return tuple(extra_args[k] for k in required_keys)

vllm/model_executor/layers/quantization/compressed_tensors/compressed_tensors_moe.py

@@ -339,19 +339,19 @@ class CompressedTensorsW4A4MoeMethod(CompressedTensorsMoEMethod):
         return cutlass_moe_fp4(
             a=x,
             w1_fp4=layer.w13_weight,
-            w1_blockscale=layer.w13_blockscale_swizzled,
-            w1_alphas=layer.g1_alphas,
             w2_fp4=layer.w2_weight,
+            w1_blockscale=layer.w13_blockscale_swizzled,
             w2_blockscale=layer.w2_blockscale_swizzled,
-            w2_alphas=layer.g2_alphas,
+            g1_alphas=layer.g1_alphas,
+            g2_alphas=layer.g2_alphas,
+            a1_gscale=layer.w13_input_scale_quant,
+            a2_gscale=layer.w2_input_scale_quant,
             topk_weights=topk_weights,
             topk_ids=topk_ids,
             m=x.shape[0],
             n=layer.w2_weight.shape[2] * 2,
             k=x.shape[1],
             e=layer.w13_weight.shape[0],
-            a1_gscale=layer.w13_input_scale_quant,
-            a2_gscale=layer.w2_input_scale_quant,
             device=x.device,
             apply_router_weight_on_input=apply_router_weight_on_input).to(
                 x.dtype)

vllm/model_executor/layers/quantization/modelopt.py

@@ -7,9 +7,15 @@ import torch
 from torch.nn import Module
 from torch.nn.parameter import Parameter
 
+import vllm.envs as envs
+import vllm.model_executor.layers.fused_moe.modular_kernel as mk
 from vllm._custom_ops import (cutlass_scaled_fp4_mm,
                               cutlass_scaled_mm_supports_fp4, scaled_fp4_quant)
+from vllm.distributed import get_ep_group
 from vllm.logger import init_logger
+from vllm.model_executor.layers.fused_moe.config import FusedMoEParallelConfig
+from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_prepare_finalize import (  # noqa: E501
+    FlashInferCutlassMoEPrepareAndFinalize)
 from vllm.model_executor.layers.fused_moe.layer import (
     FusedMoE, FusedMoEMethodBase, FusedMoeWeightScaleSupported)
 from vllm.model_executor.layers.linear import (LinearBase, LinearMethodBase,
@@ -713,6 +719,18 @@ class ModelOptNvFp4FusedMoE(FusedMoEMethodBase):
         self.quant_config = quant_config
         self.cutlass_nvfp4_supported = cutlass_fp4_supported()
         self.use_marlin = False
+        self.allow_flashinfer_cutlass = False
+
+        if envs.VLLM_USE_FLASHINFER_MOE:
+            if self.cutlass_nvfp4_supported and current_platform.is_cuda() \
+               and current_platform.is_device_capability(100):
+                logger.info_once(
+                    "Using FlashInfer kernels for ModelOptNvFp4FusedMoE.")
+                self.allow_flashinfer_cutlass = True
+            else:
+                logger.warning_once(
+                    "Flashinfer CUTLASS Fused MoE not supported "
+                    "or found on the current platform.")
 
         if not self.cutlass_nvfp4_supported:
             if is_fp4_marlin_supported():
@@ -722,6 +740,73 @@ class ModelOptNvFp4FusedMoE(FusedMoEMethodBase):
                                  " quantization. Please use Blackwell and"
                                  " above.")
 
+        self.fused_experts = None  # type: ignore
+
+    def maybe_swap_experts_impl(
+        self,
+        moe_parallel_config: FusedMoEParallelConfig,
+    ):
+        if not self.allow_flashinfer_cutlass:
+            return
+
+        logger.debug_once("FlashInferExperts")
+        # default to TP/EP case only
+
+        experts_kwargs: dict[str, Any] = {
+            "use_nvfp4_w4a4": True,
+            "use_dp": moe_parallel_config.dp_size > 1,
+            "ep_rank": moe_parallel_config.ep_rank,
+            "ep_size": moe_parallel_config.ep_size,
+            "tp_rank": moe_parallel_config.tp_rank,
+            "tp_size": moe_parallel_config.tp_size,
+        }
+
+        from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_moe import (  # noqa: E501
+            FlashInferExperts)
+        experts = FlashInferExperts(**experts_kwargs)
+        self.fused_experts = mk.FusedMoEModularKernel(
+            FlashInferCutlassMoEPrepareAndFinalize(
+                quant_dtype=torch.uint8,
+                #meaning 2x e2m1 packed in one, kernel requirement
+            ),
+            experts,
+        )
+
+    # This method update self.fused_experts
+    # only prepare_finalize is not None call select_gemm_impl
+    # so when native cutlass fp4, fused_expert is in fuse_moe.py fused_expert
+    # when it's not called(TP case), we still have 2 kernels to use.
+    def select_gemm_impl(self, prepare_finalize,
+                         moe) -> mk.FusedMoEPermuteExpertsUnpermute:
+
+        assert moe is not None
+        assert prepare_finalize is not None
+        experts = None
+        all2all_manager = get_ep_group().device_communicator.all2all_manager
+        assert all2all_manager is not None
+        if self.allow_flashinfer_cutlass:
+            from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_moe import (  # noqa: E501
+                FlashInferExperts)
+            logger.debug_once("Using FlashInferExperts")
+            experts = FlashInferExperts(
+                use_nvfp4_w4a4=True,
+                use_dp=moe.moe_parallel_config.dp_size > 1,
+                ep_rank=moe.moe_parallel_config.ep_rank,
+                ep_size=moe.moe_parallel_config.ep_size,
+                tp_rank=moe.moe_parallel_config.tp_rank,
+                tp_size=moe.moe_parallel_config.tp_size,
+            )
+        else:
+            assert moe.dp_size > 1
+            logger.debug_once("Using CutlassExpertsFp4")
+            # Currently CutlassExpertsFp4 doesn't support DP
+            raise ValueError(
+                "CutlassExpertsFp4 doesn't support DP. "
+                "Use flashinfer CUTLASS FusedMoE(VLLM_USE_FLASHINFER_MOE)"
+                " backend instead.")
+
+        return experts
+
     def uses_weight_scale_2_pattern(self) -> bool:
         """
         FP4 variants use 'weight_scale_2' pattern for per-tensor weight scales.
@@ -842,8 +927,30 @@ class ModelOptNvFp4FusedMoE(FusedMoEMethodBase):
                 if scale_ndim == 2 else swizzled_scale.reshape(B, M, K))
 
     def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
-
         # GEMM 1
+        # The FlashInfer Cutlass fused MoE kernel expects the combined weights
+        # to be ordered as [w3, w1], unlike the standard [w1, w3] layout.
+        gemm1_weight = layer.w13_weight.data
+        gemm1_weight_scale = layer.w13_weight_scale.data
+
+        if self.allow_flashinfer_cutlass:
+            dim = -2
+            size = gemm1_weight.size(dim)
+            assert size % 2 == 0, f"Expected even size in dim {dim}, got {size}"
+            half = size // 2
+
+            # Reorder weight
+            w1, w3 = gemm1_weight.split(half, dim=dim)
+            gemm1_weight = torch.cat([w3, w1], dim=dim).contiguous()
+
+            # Reorder scale
+            s1, s3 = gemm1_weight_scale.split(half, dim=dim)
+            gemm1_weight_scale = torch.cat([s3, s1], dim=dim).contiguous()
+
+        layer.w13_weight = Parameter(gemm1_weight, requires_grad=False)
+        layer.w13_weight_scale = Parameter(gemm1_weight_scale,
+                                           requires_grad=False)
+
         if not torch.allclose(layer.w13_weight_scale_2[:, 0],
                               layer.w13_weight_scale_2[:, 1]):
             logger.warning_once(
@@ -874,9 +981,6 @@ class ModelOptNvFp4FusedMoE(FusedMoEMethodBase):
         layer.w13_input_scale_quant = Parameter(
             (1 / w13_input_scale).to(torch.float32), requires_grad=False)
 
-        layer.w13_weight = Parameter(layer.w13_weight.data,
-                                     requires_grad=False)
-
         # GEMM 2
         layer.g2_alphas = Parameter(
             (layer.w2_input_scale * layer.w2_weight_scale_2).to(torch.float32),
@@ -961,31 +1065,74 @@ class ModelOptNvFp4FusedMoE(FusedMoEMethodBase):
                 global_num_experts=global_num_experts,
                 expert_map=expert_map)
 
-        assert expert_map is None, ("Expert Parallelism / expert_map "
-                                    "is currently not supported for "
-                                    "ModelOptNvFp4FusedMoE.")
+        if self.fused_experts is None:
+            # If no modular kernel is provided, use cutlass_moe_fp4 for TP case
+            # only (no EP).
+            from vllm.model_executor.layers.fused_moe.cutlass_moe import (
+                cutlass_moe_fp4)
+            out = cutlass_moe_fp4(
+                a=x,
+                w1_fp4=layer.w13_weight,
+                w2_fp4=layer.w2_weight,
+                w1_blockscale=layer.w13_blockscale_swizzled,
+                w2_blockscale=layer.w2_blockscale_swizzled,
+                g1_alphas=layer.g1_alphas,
+                g2_alphas=layer.g2_alphas,
+                a1_gscale=layer.w13_input_scale_quant,
+                a2_gscale=layer.w2_input_scale_quant,
+                topk_weights=topk_weights,
+                topk_ids=topk_ids,
+                m=x.shape[0],
+                n=layer.w2_weight.shape[2] * 2,
+                k=x.shape[1],
+                e=layer.w13_weight.shape[0],
+                device=x.device,
+                expert_map=expert_map,
+                apply_router_weight_on_input=apply_router_weight_on_input)
+        else:
+            # TP or DP case
+            from vllm.model_executor.layers.fused_moe.flashinfer_cutlass_moe import (  # noqa: E501
+                is_valid_flashinfer_cutlass_fused_moe)
+            assert is_valid_flashinfer_cutlass_fused_moe(
+                x, layer.w13_weight, layer.w2_weight), (
+                    "Flashinfer CUTLASS Fused MoE not applicable!")
 
-        from vllm.model_executor.layers.fused_moe.cutlass_moe import (
-            cutlass_moe_fp4)
+            a1_gscale = torch.min(layer.w13_input_scale_quant)
+            a2_gscale = torch.min(layer.w2_input_scale_quant)
+            extra_expert_args = {
+                'g1_alphas': layer.g1_alphas,
+                'g2_alphas': layer.g2_alphas,
+                'out_dtype': x.dtype,
+                # Avoid confusion with a1_scale and a2_scale
+                # where are batch size related.
+                'a1_gscale': a1_gscale,
+                'a2_gscale': a2_gscale,
+            }
+            extra_prepare_args = {
+                'use_dp': layer.dp_size > 1,
+                'local_tokens': x.shape[0],
+                'a1_gscale': a1_gscale,
+            }
+            extra_finalize_args = {
+                'use_dp': layer.dp_size > 1,
+                'local_tokens': x.shape[0],
+            }
 
-        # Cutlass moe takes in activations in BF16/Half precision
-        # and fp4 quantized weights loaded from the checkpoint
-        return cutlass_moe_fp4(
-            a=x,
-            w1_fp4=layer.w13_weight,
-            w1_blockscale=layer.w13_blockscale_swizzled,
-            w1_alphas=layer.g1_alphas,
-            w2_fp4=layer.w2_weight,
-            w2_blockscale=layer.w2_blockscale_swizzled,
-            w2_alphas=layer.g2_alphas,
-            topk_weights=topk_weights,
-            topk_ids=topk_ids,
-            m=x.shape[0],
-            n=layer.w2_weight.shape[2] * 2,
-            k=x.shape[1],
-            e=layer.w13_weight.shape[0],
-            a1_gscale=layer.w13_input_scale_quant,
-            a2_gscale=layer.w2_input_scale_quant,
-            device=x.device,
-            apply_router_weight_on_input=apply_router_weight_on_input).to(
-                x.dtype)
+            out = self.fused_experts(
+                hidden_states=x,
+                w1=layer.w13_weight,
+                w2=layer.w2_weight,
+                topk_weights=topk_weights,
+                topk_ids=topk_ids,
+                inplace=False,  # TODO(shuw): fix later, now output is high prec
+                activation=activation,
+                global_num_experts=global_num_experts,
+                expert_map=expert_map,
+                w1_scale=layer.w13_blockscale_swizzled,
+                w2_scale=layer.w2_blockscale_swizzled,
+                apply_router_weight_on_input=apply_router_weight_on_input,
+                extra_expert_args=extra_expert_args,
+                extra_prepare_args=extra_prepare_args,
+                extra_finalize_args=extra_finalize_args,
+            )
+        return out

vllm/utils/flashinfer.py

@@ -0,0 +1,107 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""Compatibility wrapper for FlashInfer API changes.
+
+Users of vLLM should always import **only** these wrappers.
+"""
+from __future__ import annotations
+
+import contextlib
+import functools
+import importlib
+import importlib.util
+from typing import Any, Callable, NoReturn
+
+from vllm.logger import init_logger
+
+logger = init_logger(__name__)
+
+
+@functools.cache
+def has_flashinfer() -> bool:
+    """Return ``True`` if FlashInfer is available."""
+    # Use find_spec to check if the module exists without importing it
+    # This avoids potential CUDA initialization side effects
+    return importlib.util.find_spec("flashinfer") is not None
+
+
+def _missing(*_: Any, **__: Any) -> NoReturn:
+    """Placeholder for unavailable FlashInfer backend."""
+    raise RuntimeError(
+        "FlashInfer backend is not available. Please install the package "
+        "to enable FlashInfer kernels: "
+        "https://github.com/flashinfer-ai/flashinfer")
+
+
+def _get_submodule(module_name: str) -> Any | None:
+    """Safely import a submodule and return it, or None if not available."""
+    try:
+        return importlib.import_module(module_name)
+    except (ImportError, ModuleNotFoundError):
+        return None
+
+
+# General lazy import wrapper
+def _lazy_import_wrapper(module_name: str,
+                         attr_name: str,
+                         fallback_fn: Callable[..., Any] = _missing):
+    """Create a lazy import wrapper for a specific function."""
+
+    @functools.cache
+    def _get_impl():
+        if not has_flashinfer():
+            return None
+        mod = _get_submodule(module_name)
+        return getattr(mod, attr_name, None) if mod else None
+
+    def wrapper(*args, **kwargs):
+        impl = _get_impl()
+        if impl is None:
+            return fallback_fn(*args, **kwargs)
+        return impl(*args, **kwargs)
+
+    return wrapper
+
+
+# Create lazy wrappers for each function
+flashinfer_cutlass_fused_moe = _lazy_import_wrapper("flashinfer.fused_moe",
+                                                    "cutlass_fused_moe")
+fp4_quantize = _lazy_import_wrapper("flashinfer", "fp4_quantize")
+fp4_swizzle_blockscale = _lazy_import_wrapper("flashinfer",
+                                              "fp4_swizzle_blockscale")
+
+# Special case for autotune since it returns a context manager
+autotune = _lazy_import_wrapper(
+    "flashinfer.autotuner",
+    "autotune",
+    fallback_fn=lambda *args, **kwargs: contextlib.nullcontext())
+
+
+@functools.cache
+def has_flashinfer_cutlass_fused_moe() -> bool:
+    """Return ``True`` if FlashInfer CUTLASS fused MoE is available."""
+    if not has_flashinfer():
+        return False
+
+    # Check if all required functions are available
+    required_functions = [
+        ("flashinfer.fused_moe", "cutlass_fused_moe"),
+        ("flashinfer", "fp4_quantize"),
+        ("flashinfer", "fp4_swizzle_blockscale"),
+    ]
+
+    for module_name, attr_name in required_functions:
+        mod = _get_submodule(module_name)
+        if not mod or not hasattr(mod, attr_name):
+            return False
+    return True
+
+
+__all__ = [
+    "has_flashinfer",
+    "has_flashinfer_cutlass_fused_moe",
+    "flashinfer_cutlass_fused_moe",
+    "fp4_quantize",
+    "fp4_swizzle_blockscale",
+    "autotune",
+]