[Bugfix] Register fp8 cutlass_group_gemm as supported for only SM90+SM100

[mgoin]

Purpose

FIX #32109

We only have implementation for SM90 and SM100, so we should properly restrict for the FP8 oracle to work. Without this change users on SM120 would default to this kernel backend and see an unsupported error when it should be using the Triton kernel.

csrc/quantization/w8a8/cutlass/moe/grouped_mm_c3x_sm90.cu
csrc/quantization/w8a8/cutlass/moe/grouped_mm_c3x_sm100.cu

Test Plan

Test Result

Tested manually by locally changing the condition to disqualify cuda_device_capability == 100, where my resulting kernel selection changed from

(Worker_TP0 pid=1113294) INFO 01-28 17:18:33 [fp8.py:329] Using VLLM_CUTLASS Fp8 MoE backend out of potential backends: ['AITER', 'FLASHINFER_TRTLLM', 'FLASHINFER_CUTLASS', 'DEEPGEMM', 'BATCHED_DEEPGEMM', 'VLLM_CUTLASS', 'BATCHED_VLLM_CUTLASS', 'TRITON', 'BATCHED_TRITON', 'MARLIN'].

to

(Worker_TP0 pid=1118221) INFO 01-28 17:19:55 [fp8.py:329] Using TRITON Fp8 MoE backend out of potential backends: ['AITER', 'FLASHINFER_TRTLLM', 'FLASHINFER_CUTLASS', 'DEEPGEMM', 'BATCHED_DEEPGEMM', 'VLLM_CUTLASS', 'BATCHED_VLLM_CUTLASS', 'TRITON', 'BATCHED_TRITON', 'MARLIN'].

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[gemini-code-assist]

Code Review

This pull request correctly restricts the cutlass_group_gemm to be supported only on architectures with compute capabilities 9.x (Hopper) and 10.x (Blackwell). The added check is straightforward and effectively prevents the kernel from being used on unsupported hardware, which resolves the underlying bug. The implementation is well-placed and looks good.