[Kernel] Add support for block FP8 on SM120 (NVIDIA 5090 and RTX PRO 6000) (#22131)

Signed-off-by: Junhao Li <junhao@ubicloud.com>

CMakeLists.txt

@@ -427,6 +427,7 @@ if(VLLM_GPU_LANG STREQUAL "CUDA")
     set(SRCS
       "csrc/quantization/cutlass_w8a8/scaled_mm_c3x_sm120.cu"
       "csrc/quantization/cutlass_w8a8/c3x/scaled_mm_sm120_fp8.cu"
+      "csrc/quantization/cutlass_w8a8/c3x/scaled_mm_blockwise_sm120_fp8.cu"
     )
     set_gencode_flags_for_srcs(
       SRCS "${SRCS}"

csrc/cutlass_extensions/common.hpp

@@ -60,3 +60,13 @@ struct enable_sm100_only : Kernel {
 #endif
   }
 };
+
+template <typename Kernel>
+struct enable_sm120_only : Kernel {
+  template <typename... Args>
+  CUTLASS_DEVICE void operator()(Args&&... args) {
+#if defined __CUDA_ARCH__ && __CUDA_ARCH__ == 1200
+    Kernel::operator()(std::forward<Args>(args)...);
+#endif
+  }
+};

csrc/quantization/cutlass_w8a8/c3x/scaled_mm_blockwise_sm120_fp8.cu

@@ -0,0 +1,23 @@
+#include "scaled_mm_kernels.hpp"
+#include "scaled_mm_blockwise_sm120_fp8_dispatch.cuh"
+#include "cutlass_extensions/epilogue/scaled_mm_epilogues_c3x.hpp"
+
+namespace vllm {
+
+void cutlass_scaled_mm_blockwise_sm120_fp8(torch::Tensor& out,
+                                           torch::Tensor const& a,
+                                           torch::Tensor const& b,
+                                           torch::Tensor const& a_scales,
+                                           torch::Tensor const& b_scales) {
+  if (out.dtype() == torch::kBFloat16) {
+    cutlass_gemm_blockwise_sm120_fp8_dispatch<cutlass::bfloat16_t>(
+        out, a, b, a_scales, b_scales);
+
+  } else {
+    TORCH_CHECK(out.dtype() == torch::kFloat16);
+    cutlass_gemm_blockwise_sm120_fp8_dispatch<cutlass::half_t>(
+        out, a, b, a_scales, b_scales);
+  }
+}
+
+}  // namespace vllm

csrc/quantization/cutlass_w8a8/c3x/scaled_mm_blockwise_sm120_fp8_dispatch.cuh

@@ -0,0 +1,183 @@
+#pragma once
+
+#include "cuda_utils.h"
+#include "cutlass/cutlass.h"
+#include "cutlass/numeric_types.h"
+
+#include "cute/tensor.hpp"
+#include "cutlass/tensor_ref.h"
+#include "cutlass/gemm/dispatch_policy.hpp"
+#include "cutlass/gemm/collective/collective_builder.hpp"
+#include "cutlass/gemm/device/gemm_universal_adapter.h"
+#include "cutlass/gemm/kernel/gemm_universal.hpp"
+#include "cutlass/gemm/kernel/tile_scheduler_params.h"
+#include "cutlass/epilogue/dispatch_policy.hpp"
+#include "cutlass/epilogue/collective/collective_builder.hpp"
+
+#include "cutlass_extensions/gemm/dispatch_policy.hpp"
+#include "cutlass_extensions/gemm/collective/collective_builder.hpp"
+
+#include "cutlass_gemm_caller.cuh"
+
+namespace vllm {
+
+using namespace cute;
+
+// clang-format off
+template <class OutType, int ScaleGranularityM,
+          int ScaleGranularityN, int ScaleGranularityK,
+          class MmaTileShape, class ClusterShape,
+          class EpilogueScheduler, class MainloopScheduler>
+struct cutlass_3x_gemm_fp8_blockwise {
+  using ElementAB = cutlass::float_e4m3_t;
+
+  using ElementA = ElementAB;
+  using LayoutA = cutlass::layout::RowMajor;
+  using LayoutA_Transpose = typename cutlass::layout::LayoutTranspose<LayoutA>::type;
+  static constexpr int AlignmentA = 128 / cutlass::sizeof_bits<ElementA>::value;
+
+  using ElementB = ElementAB;
+  // ColumnMajor is used for B to match the CUTLASS convention.
+  using LayoutB = cutlass::layout::ColumnMajor;
+  using LayoutB_Transpose = typename cutlass::layout::LayoutTranspose<LayoutB>::type;
+  static constexpr int AlignmentB = 128 / cutlass::sizeof_bits<ElementB>::value;
+
+  using ElementD = OutType;
+  using LayoutD = cutlass::layout::RowMajor;
+  using LayoutD_Transpose = typename cutlass::layout::LayoutTranspose<LayoutD>::type;
+  static constexpr int AlignmentD = 128 / cutlass::sizeof_bits<ElementD>::value;
+
+  using ElementC = void; // TODO: support bias
+  using LayoutC = LayoutD;
+  using LayoutC_Transpose = LayoutD_Transpose;
+  static constexpr int AlignmentC = AlignmentD;
+
+  using ElementAccumulator = float;
+  using ElementCompute = float;
+  using ElementBlockScale = float; 
+
+  using ScaleConfig = cutlass::detail::Sm120BlockwiseScaleConfig<
+        ScaleGranularityM, ScaleGranularityN, ScaleGranularityK,
+        cute::UMMA::Major::MN, cute::UMMA::Major::K>;
+
+  // layout_SFA and layout_SFB cannot be swapped since they are deduced.
+  using LayoutSFA = decltype(ScaleConfig::deduce_layoutSFA());
+  using LayoutSFB = decltype(ScaleConfig::deduce_layoutSFB());
+
+  using ArchTag = cutlass::arch::Sm120;
+  using OperatorClass = cutlass::arch::OpClassTensorOp;
+
+  static constexpr auto RoundStyle = cutlass::FloatRoundStyle::round_to_nearest;
+  using ElementScalar = float;
+  using DefaultOperation = cutlass::epilogue::fusion::LinearCombination<ElementD, ElementCompute, ElementC, ElementScalar, RoundStyle>;
+  using CollectiveEpilogue = typename cutlass::epilogue::collective::CollectiveBuilder<
+      ArchTag,
+      OperatorClass,
+      MmaTileShape,
+      ClusterShape,
+      cutlass::epilogue::collective::EpilogueTileAuto,
+      ElementAccumulator,
+      ElementCompute,
+      ElementC,
+      LayoutC,
+      AlignmentC,
+      ElementD,
+      LayoutD,
+      AlignmentD,
+      EpilogueScheduler,
+      DefaultOperation
+  >::CollectiveOp;
+ 
+  using StageCountType = cutlass::gemm::collective::StageCountAuto; 
+  using CollectiveMainloop = 
+      typename cutlass::gemm::collective::CollectiveBuilder<
+          ArchTag,
+          OperatorClass,
+          ElementA,
+          cute::tuple<LayoutA, LayoutSFA>,
+          AlignmentA,
+          ElementB,
+          cute::tuple<LayoutB, LayoutSFB>,
+          AlignmentB,
+          ElementAccumulator,
+          MmaTileShape,
+          ClusterShape,
+          cutlass::gemm::collective::StageCountAutoCarveout<static_cast<int>(sizeof(typename CollectiveEpilogue::SharedStorage))>,
+          MainloopScheduler
+      >::CollectiveOp;
+
+  using KernelType = enable_sm120_only<cutlass::gemm::kernel::GemmUniversal<
+      Shape<int, int, int, int>, CollectiveMainloop, CollectiveEpilogue>>;
+
+  struct GemmKernel : public KernelType {};
+};
+
+template <typename Gemm>
+void cutlass_gemm_caller_blockwise(torch::Tensor& out, torch::Tensor const& a,
+                                   torch::Tensor const& b,
+                                   torch::Tensor const& a_scales,
+                                   torch::Tensor const& b_scales) {
+  using GemmKernel = typename Gemm::GemmKernel;
+  using StrideA = typename Gemm::GemmKernel::StrideA;
+  using StrideB = typename Gemm::GemmKernel::StrideB;
+  using StrideD = typename Gemm::GemmKernel::StrideD;
+  using StrideC = typename Gemm::GemmKernel::StrideC;
+  using LayoutSFA = typename Gemm::LayoutSFA;
+  using LayoutSFB = typename Gemm::LayoutSFB;
+  using ScaleConfig = typename Gemm::ScaleConfig;
+
+  using ElementAB = typename Gemm::ElementAB;
+  using ElementD = typename Gemm::ElementD;
+
+  int32_t m = a.size(0), n = b.size(1), k = a.size(1);
+
+  StrideA a_stride;
+  StrideB b_stride;
+  StrideC c_stride;
+  a_stride =
+      cutlass::make_cute_packed_stride(StrideA{}, cute::make_shape(m, k, 1));
+  b_stride =
+      cutlass::make_cute_packed_stride(StrideB{}, cute::make_shape(n, k, 1));
+  c_stride =
+      cutlass::make_cute_packed_stride(StrideC{}, cute::make_shape(m, n, 1));
+
+  LayoutSFA layout_SFA = 
+      ScaleConfig::tile_atom_to_shape_SFA(make_shape(m, n, k, 1));
+  LayoutSFB layout_SFB = 
+      ScaleConfig::tile_atom_to_shape_SFB(make_shape(m, n, k, 1));
+
+  auto a_ptr = static_cast<ElementAB*>(a.data_ptr());
+  auto b_ptr = static_cast<ElementAB*>(b.data_ptr());
+  auto a_scales_ptr = static_cast<float*>(a_scales.data_ptr());
+  auto b_scales_ptr = static_cast<float*>(b_scales.data_ptr());
+
+  auto mainloop_args = [&](){
+    return typename GemmKernel::MainloopArguments{
+        a_ptr,        a_stride,   b_ptr,        b_stride,
+        a_scales_ptr, layout_SFA, b_scales_ptr, layout_SFB
+    };
+  }();
+  auto prob_shape = cute::make_shape(m, n, k, 1);
+
+  auto c_ptr = static_cast<ElementD*>(out.data_ptr());
+  typename GemmKernel::EpilogueArguments epilogue_args{
+      {}, c_ptr, c_stride, c_ptr, c_stride};
+  c3x::cutlass_gemm_caller<GemmKernel>(a.device(), prob_shape, mainloop_args,
+                                       epilogue_args);
+}
+
+template <typename OutType>
+void cutlass_gemm_blockwise_sm120_fp8_dispatch(torch::Tensor& out,
+                                               torch::Tensor const& a,
+                                               torch::Tensor const& b,
+                                               torch::Tensor const& a_scales,
+                                               torch::Tensor const& b_scales) {
+  // TODO: better heuristics
+  cutlass_gemm_caller_blockwise<cutlass_3x_gemm_fp8_blockwise<
+      OutType, 1, 128, 128, Shape<_128, _128, _128>,
+      Shape<_1, _1, _1>, cutlass::epilogue::collective::EpilogueScheduleAuto,
+      cutlass::gemm::collective::KernelScheduleAuto>>(
+      out, a, b, a_scales, b_scales);
+}
+
+}  // namespace vllm

csrc/quantization/cutlass_w8a8/c3x/scaled_mm_kernels.hpp

@@ -47,4 +47,10 @@ void cutlass_scaled_mm_blockwise_sm100_fp8(torch::Tensor& out,
                                            torch::Tensor const& b,
                                            torch::Tensor const& a_scales,
                                            torch::Tensor const& b_scales);
+
+void cutlass_scaled_mm_blockwise_sm120_fp8(torch::Tensor& out,
+                                           torch::Tensor const& a,
+                                           torch::Tensor const& b,
+                                           torch::Tensor const& a_scales,
+                                           torch::Tensor const& b_scales);
 }  // namespace vllm

csrc/quantization/cutlass_w8a8/scaled_mm_c3x_sm120.cu

@@ -1,11 +1,9 @@
-#include <cudaTypedefs.h>
+#include "c3x/scaled_mm_helper.hpp"
 #include "c3x/scaled_mm_kernels.hpp"
 
-#include "cuda_utils.h"
-
 /*
    This file defines quantized GEMM operations using the CUTLASS 3.x API, for
-   NVIDIA GPUs with sm120 (Blackwell Geforce).
+   NVIDIA GPUs with sm120 (Blackwell).
 */
 
 #if defined ENABLE_SCALED_MM_SM120 && ENABLE_SCALED_MM_SM120
@@ -15,20 +13,10 @@ void cutlass_scaled_mm_sm120(torch::Tensor& c, torch::Tensor const& a,
                              torch::Tensor const& a_scales,
                              torch::Tensor const& b_scales,
                              std::optional<torch::Tensor> const& bias) {
-  TORCH_CHECK(a_scales.dtype() == torch::kFloat32);
+  dispatch_scaled_mm(c, a, b, a_scales, b_scales, bias,
-  TORCH_CHECK(b_scales.dtype() == torch::kFloat32);
+                     vllm::cutlass_scaled_mm_sm120_fp8,
-
+                     nullptr,  // int8 not supported on SM120
-  int M = a.size(0), N = b.size(1), K = a.size(1);
+                     vllm::cutlass_scaled_mm_blockwise_sm120_fp8);
-  TORCH_CHECK(
-      (a_scales.numel() == 1 || a_scales.numel() == a.size(0)) &&
-          (b_scales.numel() == 1 || b_scales.numel() == b.size(1)),
-      "Currently, block scaled fp8 gemm is not implemented for Blackwell");
-
-  // Standard per-tensor/per-token/per-channel scaling
-  TORCH_CHECK(a_scales.is_contiguous() && b_scales.is_contiguous());
-  TORCH_CHECK(a.dtype() == torch::kFloat8_e4m3fn,
-              "Currently, only fp8 gemm is implemented for Blackwell");
-  vllm::cutlass_scaled_mm_sm120_fp8(c, a, b, a_scales, b_scales, bias);
 }
 
 #endif