chore: import upstream snapshot with attribution

vllm/model_executor/kernels/linear/nvfp4/__init__.py

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from vllm.model_executor.kernels.linear.nvfp4.base import (
+    NvFp4LinearKernel,
+    NvFp4LinearLayerConfig,
+)
+
+__all__ = [
+    "NvFp4LinearKernel",
+    "NvFp4LinearLayerConfig",
+]

vllm/model_executor/kernels/linear/nvfp4/base.py

@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+
+import torch
+
+from vllm.model_executor.layers.quantization.utils.quant_utils import QuantKey
+
+
+@dataclass
+class NvFp4LinearLayerConfig:
+    """Configuration for an NVFP4 linear layer.
+
+    All NVFP4 layers share the same structure: packed uint8 weights (2 FP4 values per
+    byte), FP8-E4M3 per-block weight scales (group size 16), and scalar global
+    scales for both weights and activations.
+    """
+
+    pass
+
+
+class NvFp4LinearKernel(ABC):
+    """Base class for NVFP4 quantized linear kernels.
+
+    Each subclass implements a specific GEMM backend (CUTLASS, Marlin, etc).
+    The kernel selection mechanism iterates over registered subclasses in
+    priority order,calling ``is_supported`` and ``can_implement`` to find the best
+    match for the current hardware.
+    """
+
+    def __init__(self, config: NvFp4LinearLayerConfig) -> None:
+        assert self.can_implement(config)[0]
+        assert self.is_supported()[0]
+        self.config = config
+
+    def input_quant_key(self) -> QuantKey | None:
+        """Return the input quantization key supported by this kernel. If the kernel
+        does not support input quantization outside of the kernel, return None.
+        """
+        return None
+
+    @classmethod
+    @abstractmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        """Return whether this kernel can run on the current platform."""
+        raise NotImplementedError
+
+    @classmethod
+    @abstractmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        """Return whether this kernel can handle *config*."""
+        raise NotImplementedError
+
+    @abstractmethod
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        """Transform weights into the format required by this kernel.
+
+        Called once after checkpoint weights have been loaded onto the
+        device.  Implementations should repack / swizzle / pad weights
+        and scales in-place on *layer*.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        """Run the quantized GEMM."""
+        raise NotImplementedError

vllm/model_executor/kernels/linear/nvfp4/cutlass.py

@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm._custom_ops import (
+    cutlass_scaled_fp4_mm,
+    scaled_fp4_quant,
+)
+from vllm.model_executor.layers.quantization.utils.nvfp4_utils import (
+    cutlass_fp4_supported,
+    pad_nvfp4_weight_for_cutlass,
+    slice_nvfp4_output,
+    swizzle_blockscale,
+)
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+
+class CutlassNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via the vLLM CUTLASS kernel."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if cutlass_fp4_supported():
+            return True, None
+        return False, "CUTLASS FP4 kernels not available"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        layer.weight_scale = torch.nn.Parameter(
+            swizzle_blockscale(layer.weight_scale.data), requires_grad=False
+        )
+        padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
+            layer.weight.data
+        )
+        layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
+        layer.weights_padding_cols = weights_padding_cols
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+        weights_padding_bytes = getattr(layer, "weights_padding_cols", 0)
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="cutlass",
+            padded_n=x.shape[-1] + weights_padding_bytes * 2,
+        )
+
+        out = cutlass_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)

vllm/model_executor/kernels/linear/nvfp4/emulation.py

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm.model_executor.layers.quantization.utils.nvfp4_emulation_utils import (
+    kE2M1ToFloat_handle,
+    run_nvfp4_emulations,
+)
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+
+class EmulationNvFp4LinearKernel(NvFp4LinearKernel):
+    """Software emulation fallback for NVFP4 (dequant → BF16 matmul)."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        # Always available as a last-resort fallback.
+        return True, None
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        # Move the E2M1 lookup table to the device now, because
+        # `.to(device)` is not allowed during CUDA graph capture.
+        kE2M1ToFloat_handle.val = kE2M1ToFloat_handle.val.to(layer.weight.device)
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        out = run_nvfp4_emulations(
+            x=x,
+            input_global_scale=layer.input_global_scale_inv,
+            weight=layer.weight,
+            weight_scale_swizzled=layer.weight_scale,
+            weight_global_scale=layer.weight_global_scale,
+            swizzle=False,
+        )
+        if bias is not None:
+            out = out + bias
+        return out

vllm/model_executor/kernels/linear/nvfp4/fbgemm.py

@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm._custom_ops import scaled_fp4_quant
+from vllm.model_executor.layers.quantization.utils.nvfp4_utils import (
+    slice_nvfp4_output,
+    swizzle_blockscale,
+)
+from vllm.utils.import_utils import has_fbgemm_gpu
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+
+class FbgemmNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FBGEMM."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if has_fbgemm_gpu():
+            return True, None
+        return False, "fbgemm_gpu required"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        swizzled = swizzle_blockscale(layer.weight_scale.data)
+        layer.weight_scale = torch.nn.Parameter(
+            swizzled.view(-1).view(torch.uint8), requires_grad=False
+        )
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        import fbgemm_gpu  # noqa: F401 - registers torch.ops.fbgemm.*
+
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="fbgemm",
+        )
+
+        out = torch.ops.fbgemm.f4f4bf16(
+            x_fp4,
+            layer.weight,
+            x_blockscale.view(-1).view(torch.uint8),
+            layer.weight_scale,
+            layer.alpha,
+            use_mx=False,
+        ).to(output_dtype)
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)

vllm/model_executor/kernels/linear/nvfp4/flashinfer.py

@@ -0,0 +1,372 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm._custom_ops import scaled_fp4_quant
+from vllm.model_executor.layers.fusion.quant_activation import (
+    QuantizedActivation,
+    as_quantized_activation,
+)
+from vllm.model_executor.layers.quantization.utils.nvfp4_utils import (
+    pad_nvfp4_activation_for_cutlass,
+    pad_nvfp4_weight_for_cutlass,
+    slice_nvfp4_output,
+    swizzle_blockscale,
+)
+from vllm.model_executor.layers.quantization.utils.quant_utils import (
+    QuantKey,
+    kNvfp4Dynamic,
+)
+from vllm.platforms import current_platform
+from vllm.utils.flashinfer import (
+    flashinfer_scaled_fp4_mm,
+    has_flashinfer,
+    has_flashinfer_b12x_gemm,
+)
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+
+class FlashInferCuteDslNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FlashInfer's cutedsl backend."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if not current_platform.is_device_capability_family(100):
+            return False, "FlashInfer cutedsl requires sm_10x"
+        if not has_flashinfer():
+            return False, "FlashInfer required"
+        return True, None
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        # cutedsl uses the same swizzled + padded layout as cutlass.
+        layer.weight_scale = torch.nn.Parameter(
+            swizzle_blockscale(layer.weight_scale.data), requires_grad=False
+        )
+        padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
+            layer.weight.data
+        )
+        layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
+        layer.weights_padding_cols = weights_padding_cols
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="flashinfer-cutedsl",
+        )
+
+        x_fp4 = pad_nvfp4_activation_for_cutlass(
+            x_fp4, getattr(layer, "weights_padding_cols", 0)
+        )
+
+        out = flashinfer_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+            backend="cute-dsl",
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)
+
+
+class FlashInferCutlassNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FlashInfer's CUTLASS wrapper."""
+
+    def input_quant_key(self) -> QuantKey | None:
+        """This kernel supports dynamic quantization of the input. By
+        convention, pre-quantized blockscales must use the swizzled layout."""
+        return kNvfp4Dynamic
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        from vllm.model_executor.layers.quantization.utils.nvfp4_utils import (
+            cutlass_fp4_supported,
+        )
+
+        if (
+            cutlass_fp4_supported()
+            and current_platform.has_device_capability(100)
+            and has_flashinfer()
+        ):
+            return True, None
+        return False, "FlashInfer + >=sm_100 required"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        layer.weight_scale = torch.nn.Parameter(
+            swizzle_blockscale(layer.weight_scale.data), requires_grad=False
+        )
+        padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
+            layer.weight.data
+        )
+        layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
+        layer.weights_padding_cols = weights_padding_cols
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor | QuantizedActivation,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        weights_padding_bytes = getattr(layer, "weights_padding_cols", 0)
+
+        qa = as_quantized_activation(x, self.input_quant_key())
+        if qa is not None:
+            x_fp4, x_blockscale = qa.data, qa.scale
+            x_fp4 = pad_nvfp4_activation_for_cutlass(x_fp4, weights_padding_bytes)
+            output_dtype = qa.orig_dtype
+            output_shape = [*qa.orig_shape[:-1], output_size]
+        else:
+            assert isinstance(x, torch.Tensor)
+            output_dtype = x.dtype
+            output_shape = [*x.shape[:-1], output_size]
+            x_fp4, x_blockscale = scaled_fp4_quant(
+                x,
+                layer.input_global_scale_inv,
+                is_sf_swizzled_layout=True,
+                backend="flashinfer-cutlass",
+                padded_n=x.shape[-1] + weights_padding_bytes * 2,
+            )
+
+        out = flashinfer_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+            backend="cutlass",
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)
+
+
+class FlashInferTrtllmNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FlashInfer's TensorRT-LLM wrapper."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if has_flashinfer():
+            return True, None
+        return False, "FlashInfer required"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        from flashinfer import shuffle_matrix_a, shuffle_matrix_sf_a
+
+        weight = layer.weight.data
+        weight_scale = layer.weight_scale.data
+        epilogue_tile_m = 128
+
+        layer.weight = torch.nn.Parameter(
+            shuffle_matrix_a(weight.view(torch.uint8), epilogue_tile_m),
+            requires_grad=False,
+        )
+        layer.weight_scale = torch.nn.Parameter(
+            shuffle_matrix_sf_a(weight_scale.view(torch.uint8), epilogue_tile_m)
+            .reshape(weight_scale.shape)
+            .view(torch.float8_e4m3fn),
+            requires_grad=False,
+        )
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="flashinfer-trtllm",
+        )
+
+        out = flashinfer_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+            backend="trtllm",
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)
+
+
+class FlashInferCudnnNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FlashInfer's cuDNN wrapper."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if has_flashinfer():
+            return True, None
+        return False, "FlashInfer required"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        # cuDNN uses the same swizzled + padded layout as CUTLASS
+        layer.weight_scale = torch.nn.Parameter(
+            swizzle_blockscale(layer.weight_scale.data), requires_grad=False
+        )
+        padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
+            layer.weight.data
+        )
+        layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
+        layer.weights_padding_cols = weights_padding_cols
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+        weights_padding_bytes = getattr(layer, "weights_padding_cols", 0)
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="flashinfer-cudnn",
+            padded_n=x.shape[-1] + weights_padding_bytes * 2,
+        )
+
+        out = flashinfer_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+            backend="cudnn",
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)
+
+
+class FlashInferB12xNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 GEMM via FlashInfer's b12x CuTe DSL warp-level MMA kernel (SM120+)."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if current_platform.has_device_capability(120) and has_flashinfer_b12x_gemm():
+            return True, None
+        return (
+            False,
+            "FlashInfer b12x requires SM120+ and FlashInfer "
+            "with Sm120BlockScaledDenseGemmKernel",
+        )
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        layer.weight_scale = torch.nn.Parameter(
+            swizzle_blockscale(layer.weight_scale.data), requires_grad=False
+        )
+        padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
+            layer.weight.data
+        )
+        layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
+        layer.weights_padding_cols = weights_padding_cols
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        output_size = layer.output_size_per_partition
+        output_dtype = x.dtype
+        output_shape = [*x.shape[:-1], output_size]
+
+        x_fp4, x_blockscale = scaled_fp4_quant(
+            x,
+            layer.input_global_scale_inv,
+            is_sf_swizzled_layout=True,
+            backend="b12x",
+        )
+
+        x_fp4 = pad_nvfp4_activation_for_cutlass(
+            x_fp4, getattr(layer, "weights_padding_cols", 0)
+        )
+
+        out = flashinfer_scaled_fp4_mm(
+            x_fp4,
+            layer.weight,
+            x_blockscale,
+            layer.weight_scale,
+            layer.alpha,
+            output_dtype,
+            backend="b12x",
+        )
+
+        out = slice_nvfp4_output(out, output_size)
+
+        if bias is not None:
+            out = out + bias
+        return out.view(*output_shape)

vllm/model_executor/kernels/linear/nvfp4/humming.py

@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm.logger import init_logger
+from vllm.model_executor.layers.quantization.utils.humming_utils import (
+    prepare_humming_layer,
+)
+from vllm.platforms import current_platform
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+logger = init_logger(__name__)
+
+
+class HummingNvFp4LinearKernel(NvFp4LinearKernel):
+    """Humming GEMM Kernel for NVFP4."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if not current_platform.is_cuda():
+            return False, "Humming only supported on CUDA"
+
+        if not current_platform.has_device_capability(75):
+            return False, "Humming only supported on SM75+"
+
+        return True, None
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        # Route through humming's compressed-tensors nvfp4 loader (same path as
+        # the MoE oracle); the native group_tensor schema mishandles a scalar
+        # global scale.
+        quant_config = {
+            "quant_method": "compressed-tensors",
+            "format": "nvfp4-pack-quantized",
+            "type": "float",
+            "num_bits": 4,
+            "strategy": "group",
+            "group_size": 16,
+        }
+        # CT pack-quantized reads `weight_packed`; the scheme renamed it to `weight`.
+        if not hasattr(layer, "weight_packed"):
+            layer.weight_packed = layer.weight
+            del layer.weight
+        # The CT linear scheme inverts the global scale (1/scale) for
+        # marlin/cutlass; humming wants the original.
+        layer.weight_global_scale = torch.nn.Parameter(
+            1.0 / layer.weight_global_scale, requires_grad=False
+        )
+        prepare_humming_layer(layer, quant_config)
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        from vllm.utils.humming import HummingMethod
+
+        flatten_inputs = x.view(-1, x.size(-1))
+        output = HummingMethod.forward_layer(
+            layer=layer,
+            inputs=flatten_inputs,
+            compute_config=layer.compute_config,
+        )
+        return output.view(*x.shape[:-1], output.size(-1))

vllm/model_executor/kernels/linear/nvfp4/marlin.py

@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import torch
+
+from vllm.logger import init_logger
+from vllm.model_executor.layers.quantization.utils.marlin_utils_fp4 import (
+    apply_fp4_marlin_linear,
+    is_fp4_marlin_supported,
+    prepare_fp4_layer_for_marlin,
+)
+
+from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
+
+logger = init_logger(__name__)
+
+
+class MarlinNvFp4LinearKernel(NvFp4LinearKernel):
+    """NVFP4 weight-only GEMM via Marlin (W4A16)."""
+
+    @classmethod
+    def is_supported(
+        cls, compute_capability: int | None = None
+    ) -> tuple[bool, str | None]:
+        if is_fp4_marlin_supported():
+            return True, None
+        return False, "Marlin FP4 not available"
+
+    @classmethod
+    def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
+        return True, None
+
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        logger.warning_once(
+            "Your GPU does not have native support for FP4 computation but "
+            "FP4 quantization is being used. Weight-only FP4 compression "
+            "will be used leveraging the Marlin kernel. This may degrade "
+            "performance for compute-heavy workloads."
+        )
+        prepare_fp4_layer_for_marlin(layer)
+
+    def apply_weights(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        bias: torch.Tensor | None = None,
+    ) -> torch.Tensor:
+        return apply_fp4_marlin_linear(
+            input=x,
+            weight=layer.weight,
+            weight_scale=layer.weight_scale,
+            weight_global_scale=layer.weight_global_scale,
+            workspace=layer.workspace,
+            size_n=layer.output_size_per_partition,
+            size_k=layer.input_size_per_partition,
+            bias=bias,
+        )