vllm/csrc/quantization/fp4/nvfp4_scaled_mm_sm120_kernels.cu
Roberto L. Castro 789562c28c
Support CUTLASS NVFP4 (w4a4) for Blackwell Geforce GPUs (SM120) (#21309)
Signed-off-by: LopezCastroRoberto <roberto.lopez.castro@udc.es>
2025-08-03 00:54:22 -07:00

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/*
* Copyright (c) 2025, NVIDIA CORPORATION. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <torch/all.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "cutlass_extensions/common.hpp"
#include "cutlass/cutlass.h"
#include "cutlass/gemm/collective/collective_builder.hpp"
#include "cutlass/epilogue/collective/collective_builder.hpp"
#include "cutlass/gemm/device/gemm_universal_adapter.h"
#include "cutlass/gemm/kernel/gemm_universal.hpp"
#include "cutlass/util/packed_stride.hpp"
#include "core/math.hpp"
using namespace cute;
#define CHECK_TYPE(x, st, m) \
TORCH_CHECK(x.scalar_type() == st, ": Inconsistency of Tensor type:", m)
#define CHECK_TH_CUDA(x, m) \
TORCH_CHECK(x.is_cuda(), m, ": must be a CUDA tensor")
#define CHECK_CONTIGUOUS(x, m) \
TORCH_CHECK(x.is_contiguous(), m, ": must be contiguous")
#define CHECK_INPUT(x, st, m) \
CHECK_TH_CUDA(x, m); \
CHECK_CONTIGUOUS(x, m); \
CHECK_TYPE(x, st, m)
constexpr auto FLOAT4_E2M1X2 = at::ScalarType::Byte;
constexpr auto SF_DTYPE = at::ScalarType::Float8_e4m3fn;
struct sm120_fp4_config_M256 {
using ClusterShape = Shape<_1, _1, _1>;
using MmaTileShape = Shape<_128, _128, _128>;
using PerSmTileShape_MNK = Shape<_128, _128, _128>;
};
struct sm120_fp4_config_default {
using ClusterShape = Shape<_1, _1, _1>;
using MmaTileShape = Shape<_256, _128, _128>;
using PerSmTileShape_MNK = Shape<_256, _128, _128>;
};
template <typename Config, typename OutType>
struct Fp4GemmSm120 {
using ElementA = cutlass::nv_float4_t<cutlass::float_e2m1_t>;
using LayoutATag = cutlass::layout::RowMajor;
static constexpr int AlignmentA = 32;
using ElementB = cutlass::nv_float4_t<cutlass::float_e2m1_t>;
using LayoutBTag = cutlass::layout::ColumnMajor;
static constexpr int AlignmentB = 32;
using ElementD = OutType;
using ElementC = OutType;
using LayoutCTag = cutlass::layout::RowMajor;
using LayoutDTag = cutlass::layout::RowMajor;
static constexpr int AlignmentD = 128 / cutlass::sizeof_bits<ElementD>::value;
static constexpr int AlignmentC = 128 / cutlass::sizeof_bits<ElementC>::value;
using ElementAccumulator = float;
using ArchTag = cutlass::arch::Sm120;
using OperatorClass = cutlass::arch::OpClassBlockScaledTensorOp;
using MmaTileShape = typename Config::MmaTileShape;
using ClusterShape = typename Config::ClusterShape;
using PerSmTileShape_MNK = typename Config::PerSmTileShape_MNK;
using CollectiveEpilogue =
typename cutlass::epilogue::collective::CollectiveBuilder<
ArchTag, OperatorClass, PerSmTileShape_MNK, ClusterShape,
cutlass::epilogue::collective::EpilogueTileAuto, ElementAccumulator,
ElementAccumulator, ElementC, LayoutCTag, AlignmentC, ElementD,
LayoutDTag, AlignmentD,
cutlass::epilogue::collective::EpilogueScheduleAuto>::CollectiveOp;
using CollectiveMainloop =
typename cutlass::gemm::collective::CollectiveBuilder<
ArchTag, OperatorClass, ElementA, LayoutATag, AlignmentA, ElementB,
LayoutBTag, AlignmentB, ElementAccumulator, MmaTileShape,
ClusterShape,
cutlass::gemm::collective::StageCountAutoCarveout<static_cast<int>(
sizeof(typename CollectiveEpilogue::SharedStorage))>,
cutlass::gemm::collective::KernelScheduleAuto>::CollectiveOp;
using GemmKernel = cutlass::gemm::kernel::GemmUniversal<
Shape<int, int, int, int>, CollectiveMainloop, CollectiveEpilogue, void>;
using Gemm = cutlass::gemm::device::GemmUniversalAdapter<GemmKernel>;
};
template <typename Gemm>
typename Gemm::Arguments args_from_options(at::Tensor& D, at::Tensor const& A,
at::Tensor const& B,
at::Tensor const& A_sf,
at::Tensor const& B_sf,
torch::Tensor const& alpha, int M,
int N, int K) {
using ElementA = typename Gemm::ElementA;
using ElementB = typename Gemm::ElementB;
using ElementD = typename Gemm::ElementD;
using ElementSFA = cutlass::float_ue4m3_t;
using ElementSFB = cutlass::float_ue4m3_t;
using ElementCompute = float;
using StrideA = typename Gemm::GemmKernel::StrideA;
using StrideB = typename Gemm::GemmKernel::StrideB;
using StrideC = typename Gemm::GemmKernel::StrideC;
using StrideD = typename Gemm::GemmKernel::StrideD;
using Sm1xxBlkScaledConfig =
typename Gemm::GemmKernel::CollectiveMainloop::Sm1xxBlkScaledConfig;
auto stride_A = cutlass::make_cute_packed_stride(StrideA{}, {M, K, 1});
auto stride_B = cutlass::make_cute_packed_stride(StrideB{}, {N, K, 1});
auto stride_D = cutlass::make_cute_packed_stride(StrideD{}, {M, N, 1});
auto layout_SFA = Sm1xxBlkScaledConfig::tile_atom_to_shape_SFA(
cute::make_shape(M, N, K, 1));
auto layout_SFB = Sm1xxBlkScaledConfig::tile_atom_to_shape_SFB(
cute::make_shape(M, N, K, 1));
typename Gemm::Arguments arguments{
cutlass::gemm::GemmUniversalMode::kGemm,
{M, N, K, 1},
{static_cast<ElementA const*>(A.data_ptr()), stride_A,
static_cast<ElementB const*>(B.data_ptr()), stride_B,
static_cast<ElementSFA const*>(A_sf.data_ptr()), layout_SFA,
static_cast<ElementSFB const*>(B_sf.data_ptr()), layout_SFB},
{{},
static_cast<ElementD const*>(D.data_ptr()),
stride_D,
static_cast<ElementD*>(D.data_ptr()),
stride_D}};
auto& fusion_args = arguments.epilogue.thread;
fusion_args.alpha_ptr = static_cast<ElementCompute const*>(alpha.data_ptr());
return arguments;
}
template <typename Gemm>
void runGemm(at::Tensor& D, at::Tensor const& A, at::Tensor const& B,
at::Tensor const& A_sf, at::Tensor const& B_sf,
torch::Tensor const& alpha, int M, int N, int K,
cudaStream_t stream) {
Gemm gemm;
auto arguments = args_from_options<Gemm>(D, A, B, A_sf, B_sf, alpha, M, N, K);
size_t workspace_size = Gemm::get_workspace_size(arguments);
auto const workspace_options =
torch::TensorOptions().dtype(torch::kUInt8).device(A.device());
auto workspace = torch::empty(workspace_size, workspace_options);
CUTLASS_CHECK(gemm.can_implement(arguments));
CUTLASS_CHECK(gemm.initialize(arguments, workspace.data_ptr(), stream));
CUTLASS_CHECK(gemm.run(arguments, workspace.data_ptr(), stream));
}
void cutlass_fp4_bf16_gemm_dispatch(torch::Tensor& D, torch::Tensor const& A,
torch::Tensor const& B,
torch::Tensor const& A_sf,
torch::Tensor const& B_sf,
torch::Tensor const& alpha, int m, int n,
int k, cudaStream_t stream) {
uint32_t const mp2 = std::max(static_cast<uint32_t>(16), next_pow_2(m));
if (mp2 <= 256) {
runGemm<Fp4GemmSm120<sm120_fp4_config_M256, cutlass::bfloat16_t>::Gemm>(
D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
} else {
runGemm<Fp4GemmSm120<sm120_fp4_config_default, cutlass::bfloat16_t>::Gemm>(
D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
}
}
void cutlass_fp4_f16_gemm_dispatch(torch::Tensor& D, torch::Tensor const& A,
torch::Tensor const& B,
torch::Tensor const& A_sf,
torch::Tensor const& B_sf,
torch::Tensor const& alpha, int m, int n,
int k, cudaStream_t stream) {
uint32_t const mp2 = std::max(static_cast<uint32_t>(16), next_pow_2(m));
if (mp2 <= 256) {
runGemm<Fp4GemmSm120<sm120_fp4_config_M256, cutlass::half_t>::Gemm>(
D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
} else {
runGemm<Fp4GemmSm120<sm120_fp4_config_default, cutlass::half_t>::Gemm>(
D, A, B, A_sf, B_sf, alpha, m, n, k, stream);
}
}
void cutlass_scaled_fp4_mm_sm120a(torch::Tensor& D, torch::Tensor const& A,
torch::Tensor const& B,
torch::Tensor const& A_sf,
torch::Tensor const& B_sf,
torch::Tensor const& alpha) {
#if defined(CUTLASS_ARCH_MMA_SM120_SUPPORTED)
CHECK_INPUT(A, FLOAT4_E2M1X2, "a");
CHECK_INPUT(B, FLOAT4_E2M1X2, "b");
CHECK_INPUT(A_sf, SF_DTYPE, "scale_a");
CHECK_INPUT(B_sf, SF_DTYPE, "scale_b");
CHECK_INPUT(alpha, at::ScalarType::Float, "alpha");
TORCH_CHECK(A.dim() == 2, "a must be a matrix");
TORCH_CHECK(B.dim() == 2, "b must be a matrix");
TORCH_CHECK(A.sizes()[1] == B.sizes()[1],
"a and b shapes cannot be multiplied (", A.sizes()[0], "x",
A.sizes()[1], " and ", B.sizes()[0], "x", B.sizes()[1], ")");
auto const m = A.sizes()[0];
auto const n = B.sizes()[0];
auto const k = A.sizes()[1] * 2;
constexpr int alignment = 32;
TORCH_CHECK(k % alignment == 0, "Expected k to be divisible by ", alignment,
", but got a shape: (", A.sizes()[0], "x", A.sizes()[1],
"), k: ", k, ".");
TORCH_CHECK(n % alignment == 0, "Expected n to be divisible by ", alignment,
", but got b shape: (", B.sizes()[0], "x", B.sizes()[1], ").");
auto round_up = [](int x, int y) { return (x + y - 1) / y * y; };
int rounded_m = round_up(m, 128);
int rounded_n = round_up(n, 128);
// Since k is divisible by 32 (alignment), k / 16 is guaranteed to be an
// integer.
int rounded_k = round_up(k / 16, 4);
TORCH_CHECK(A_sf.dim() == 2, "scale_a must be a matrix");
TORCH_CHECK(B_sf.dim() == 2, "scale_b must be a matrix");
TORCH_CHECK(A_sf.sizes()[1] == B_sf.sizes()[1],
"scale_a and scale_b shapes cannot be multiplied (",
A_sf.sizes()[0], "x", A_sf.sizes()[1], " and ", B_sf.sizes()[0],
"x", B_sf.sizes()[1], ")");
TORCH_CHECK(A_sf.sizes()[0] == rounded_m && A_sf.sizes()[1] == rounded_k,
"scale_a must be padded and swizzled to a shape (", rounded_m,
"x", rounded_k, "), but got a shape (", A_sf.sizes()[0], "x",
A_sf.sizes()[1], ")");
TORCH_CHECK(B_sf.sizes()[0] == rounded_n && B_sf.sizes()[1] == rounded_k,
"scale_b must be padded and swizzled to a shape (", rounded_n,
"x", rounded_k, "), but got a shape (", B_sf.sizes()[0], "x",
B_sf.sizes()[1], ")");
auto out_dtype = D.dtype();
const at::cuda::OptionalCUDAGuard device_guard(device_of(A));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream(A.get_device());
if (out_dtype == at::ScalarType::BFloat16) {
return cutlass_fp4_bf16_gemm_dispatch(D, A, B, A_sf, B_sf, alpha, m, n, k,
stream);
} else if (out_dtype == at::ScalarType::Half) {
return cutlass_fp4_f16_gemm_dispatch(D, A, B, A_sf, B_sf, alpha, m, n, k,
stream);
} else {
TORCH_CHECK(false, "Unsupported output data type of nvfp4 mm sm120 (",
out_dtype, ")");
}
#else
TORCH_CHECK(false,
"Unsupported CUTLASS version. Set VLLM_CUTLASS_SRC_DIR to "
"a CUTLASS 3.8 source directory to enable support.");
#endif // defined(CUTLASS_ARCH_MMA_SM120_SUPPORTED)
}