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[Bugfix][Quantization] Guard the MXFP8 FlashInfer path on FlashInfer availability #52648

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Merged
vllm-bot merged 2 commits into from
Aug 18, 2026
Merged

[Bugfix][Quantization] Guard the MXFP8 FlashInfer path on FlashInfer availability #52648

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01d07ee
[Bugfix][Quantization] Check FlashInfer availability for MXFP8 kernels
LH-and-FPGA Aug 17, 2026
652c19b
Delete tests/kernels/quantization/test_mxfp8_kernel_selection.py
mgoin Aug 17, 2026
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12 changes: 8 additions & 4 deletions vllm/model_executor/kernels/linear/mxfp8/flashinfer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
)
from vllm.platforms import current_platform
from vllm.utils import flashinfer as vllm_flashinfer
from vllm.utils.flashinfer import has_flashinfer_cutedsl
from vllm.utils.flashinfer import has_flashinfer, has_flashinfer_cutedsl

from .Mxfp8LinearKernel import Mxfp8LinearKernel, Mxfp8LinearLayerConfig

Expand All @@ -23,9 +23,13 @@ class FlashInferCutlassMxfp8LinearKernel(Mxfp8LinearKernel):
def is_supported(
cls, compute_capability: int | None = None
) -> tuple[bool, str | None]:
if current_platform.has_device_capability(100):
return True, None
return False, "requires >=sm_100 (Blackwell)"
if not (
current_platform.is_cuda() and current_platform.has_device_capability(100)
):
return False, "requires >=sm_100 (Blackwell)"
if not has_flashinfer():
return False, "requires FlashInfer"
return True, None

@classmethod
def can_implement(cls, c: Mxfp8LinearLayerConfig) -> tuple[bool, str | None]:
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3 changes: 2 additions & 1 deletion vllm/model_executor/layers/quantization/utils/mxfp8_utils.py
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Expand Up @@ -177,8 +177,9 @@ def _mxfp8_e4m3_quantize_impl(
alignment: int = 0,
) -> tuple[torch.Tensor, torch.Tensor]:
from vllm.platforms import current_platform
from vllm.utils.flashinfer import has_flashinfer

if current_platform.has_device_capability(100):
if current_platform.has_device_capability(100) and has_flashinfer():
from flashinfer import mxfp8_quantize as flashinfer_mxfp8_quantize

x_q, x_scales = flashinfer_mxfp8_quantize(
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