[CUDA] Fix QMoE int4/int8 weight prepack to always use SM80 layout

docs/contrib_ops/cuda/moe_qmoe.md

@@ -71,6 +71,7 @@
 | `expert_weight_bits` (QMoE only) | int | 4 | 4 (INT4/MXFP4) or 8 (INT8/FP8). |
 | `block_size` (QMoE only) | int | -1 | Group size for INT4/INT8 group-wise quantization. -1 = per-output-channel. |
 | `quant_type` (QMoE only) | string | `"int"` | `"int"`, `"fp4"`, `"fp8"`, `"wfp4afp8"`. See [§3](#3-quantization-modes). |
+| `weights_prepacked` (QMoE only) | int | -1 | Tri-state, only meaningful when `quant_type="int"`. The prepacked layouts selected by `-1` and `1` are **EP-determined**. `-1` (default): the INT4/INT8 `fc1`/`fc2` initializers are already prepacked in the EP's default layout (e.g. from `pack_weights_for_cuda_mixed_gemm` for the CUDA EP). `1`: already prepacked in the EP's SM90 (Hopper) layout. `0`: the initializers are raw `[E, N, K/pack]` tensors (as produced by `quantize_matmul_{4,8}bits`) and the kernel runs the CUTLASS layout transform in `PrePack()` for the runtime arch. **Note:** the CUDA EP INT4/INT8 MoE GEMM always runs the Ampere (SM80) kernel — even on SM90 — so it consumes the SM80 `fpA_intB` layout on all architectures; `-1` and `1` are therefore equivalent for the CUDA EP today, and `1` is reserved for a possible future Hopper-specific layout. See [§5.1](#51-weights-input-2--5--8). |
 
 ### 2.2 Type Constraints
 
@@ -228,10 +229,53 @@
 
 ### 5.1 Weights (input 2 / 5 / 8)
 
-Not transformed at runtime. INT4/INT8 weights must already be packed offline by
-`pack_weights_for_cuda_mixed_gemm` (see [§6](#6-weight-formats)). MXFP4 weights
-must be packed by `pack_fp4_weights_for_cuda_moe_gemm`. FP8 weights are stored
-as raw e4m3 bytes (no packing).
+**INT4/INT8** weight layout is controlled by the `weights_prepacked` attribute
+([§2.1](#21-attributes)). The prepacked layouts selected by `-1` and `1` are
+determined by the execution provider:
+
+- **`weights_prepacked=-1` (default)** — the `fc1`/`fc2` weights are already in
+  the EP's default prepacked layout (e.g. packed offline by
+  `pack_weights_for_cuda_mixed_gemm` for the CUDA EP). They are copied to GPU
+  and consumed as-is.
+- **`weights_prepacked=1`** — the `fc1`/`fc2` weights are already in the EP's
+  **SM90** (Hopper) prepacked layout (reserved; see the note below).
+- **`weights_prepacked=0`** — the `fc1`/`fc2` weights are raw, schema-conformant
+  `[E, N, K/pack]` tensors as produced by `quantize_matmul_{4,8}bits`. `PrePack`
+  runs the CUTLASS layout transform itself via `PrePackIntExpertWeights`,
+  removing the offline pre-pack dependency. This makes integer QMoE symmetric
+  with `MatMulNBits::PrePack_B`.
+
+> **Single layout on the CUDA EP.** The CUDA EP INT4/INT8 MoE GEMM always
+> dispatches to the Ampere (**SM80**) grouped-GEMM kernel — even on SM90 —
+> because mixed int-weight + fp16/bf16 activation is not a valid Hopper TMA
+> warp-specialized specialisation (`isValidHopperMOESpecialisation` is `false`).
+> This matches **TensorRT-LLM**, which likewise routes `W4A16`/`W8A16` MoE to the
+> SM80 kernel on Hopper; its Hopper TMA-WS mixed-dtype MoE kernel is reserved for
+> `W4A8` (FP8 activation) and `WFP4A16` (FP4 weight). Consequently the CUDA EP
+> consumes the **SM80 `fpA_intB` layout on every GPU**, `PrePack` always packs
+> for SM80, and `weights_prepacked=-1` and `=1` are equivalent today. `1` is
+> accepted and reserved for a possible future Hopper-specific layout (e.g.
+> `W4A8`). There is therefore no architecture-match constraint: SM80-format
+> weights run correctly on SM90 via the SM80 kernel.
+
+`PrePackIntExpertWeights` loops over the `E` experts and, per expert, applies the
+same transpose + row-permutation / column-interleave / bias / pair-interleave
+transform as `pack_weights_for_cuda_mixed_gemm` (see [§6.1](#61-int4-group-wise-quant_typeint-expert_weight_bits4)),
+always targeting the SM80 layout. SM75+ is required. The source
+`[E, N, K/pack]` initializers are released after their shapes are cached
+(`fc1_weights_shape_` / `fc2_weights_shape_`), so peak weight memory stays ~1×.
+The prepacked GPU buffers (`packed_fc1_weights_` / `packed_fc2_weights_`) are then
+preferred by `ComputeInternal`. If prepacking is disabled at the session level
+(`session.disable_prepacking`), the buffers stay null and the raw initializer
+pointers are read at compute time instead.
+
+> **Note**: `weights_prepacked=0` is the only path that triggers an in-`PrePack`
+> layout transform for INT weights. FP4 / FP8 / WFP4AFP8 weight handling is
+> unaffected.
+
+MXFP4 weights must be packed by `pack_fp4_weights_for_cuda_moe_gemm`. FP8 weights
+are stored as raw e4m3 bytes (no packing).
+
 
 ### 5.2 INT4/INT8 scales + zero-point → bias
 
@@ -287,7 +331,12 @@
 INT4 packing layout within a byte: `[high_nibble | low_nibble] = [elt_1 | elt_0]`.
 Each INT4 element is in `[-8, 7]` (signed) before bias, `[0, 15]` after the +8 bias.
 
-#### Preprocessing pipeline (offline, `pack_weights_for_cuda_mixed_gemm`)
+#### Preprocessing pipeline (offline `pack_weights_for_cuda_mixed_gemm`, or in-`PrePack` via `PrePackIntExpertWeights`)
+
+This is the layout transform applied either offline by
+`pack_weights_for_cuda_mixed_gemm`, or per-expert inside `PrePack` when
+`weights_prepacked=0` (see [§5.1](#51-weights-input-2--5--8)).
+
 
 1. **Input layout**: `[N, K]` per expert (Out × In), 2 elements per byte for INT4.
 2. **Transpose & signed conversion**:
@@ -405,6 +454,17 @@
   — does not use `pack_weights_for_cuda_mixed_gemm`.
 - **FP8**: no packing.
 
+> **QMoE uses Group A on every GPU.** The table above describes the layouts the
+> `pack_weights_for_cuda_mixed_gemm` *preprocessor* can emit. The QMoE INT4/INT8
+> MoE GEMM, however, always dispatches to the Ampere (SM80) grouped-GEMM kernel —
+> even on SM90 — because mixed int-weight + fp16/bf16 activation is not a valid
+> Hopper TMA warp-specialized specialisation (the same is true in TensorRT-LLM).
+> It therefore consumes the **Group A (SM80) layout on all architectures,
+> including Hopper**. For QMoE, always pack INT4/INT8 weights for SM80 (`arch=80`),
+> and `PrePackIntExpertWeights` (`weights_prepacked=0`) does exactly that
+> regardless of the runtime device SM. Group B (SM90) layout is currently unused
+> by QMoE.
+
 ---
 
 ## 8. SwiGLU Fusion
@@ -830,7 +890,7 @@
 |-----------|----------|
 | [test_moe_cuda.py](onnxruntime/test/python/transformers/test_moe_cuda.py) | Standard MoE on CUDA: FP16/BF16, SiLU/GeLU/SwiGLU, routing, GEMM parity. SwiGLU coverage includes both GPT-OSS (`TestSwigluMoE`: interleaved, alpha=1.702/beta=1.0/limit=7.0) and Standard/Llama-Gemma (`TestStandardSwigluMoE`: concatenated `swiglu_fusion=2`, alpha=1.0/beta=0.0/no limit → `SiLU(Gate)×Value`). |
 | [test_moe_cpu.py](onnxruntime/test/python/transformers/test_moe_cpu.py) | Standard MoE on CPU (smoke). |
-| [test_qmoe_cuda.py](onnxruntime/test/python/transformers/test_qmoe_cuda.py) | INT4/INT8 QMoE — primary regression signal for the production QMoE path. Exercises `pack_weights_for_cuda_mixed_gemm` and dequant-then-matmul reference. |
+| [test_qmoe_cuda.py](onnxruntime/test/python/transformers/test_qmoe_cuda.py) | INT4/INT8 QMoE — primary regression signal for the production QMoE path. Exercises `pack_weights_for_cuda_mixed_gemm` and dequant-then-matmul reference. `TestQMoEIntPrePackSmoke` covers the raw-weight `weights_prepacked=0` in-`PrePack` layout transform (smoke test: asserts finite output, not bit-parity). |
 | [test_qmoe_cpu.py](onnxruntime/test/python/transformers/test_qmoe_cpu.py) | INT4/INT8 QMoE on CPU (smoke). |
 | [test_qmoe_fp4_cuda.py](onnxruntime/test/python/transformers/test_qmoe_fp4_cuda.py) | MXFP4 QMoE: quantization utilities, packing, FP16/BF16, SiLU/SwiGLU, top-k and expert-count variants. End-to-end runs on SM120; on SM<120 the dequant fallback is exercised. |
 | [test_qmoe_fp8_cuda.py](onnxruntime/test/python/transformers/test_qmoe_fp8_cuda.py) | FP8 W8A16 QMoE on SM90+ native path and SM<90 dequant fallback. |
@@ -954,6 +1014,11 @@
   cannot. See [§14.1](#141-msvc-and-tma-grouped-moe-gemm).
 - **WFP4AFP8 native** requires SM100+ hardware; only the dequant fallback path
   is validated end-to-end so far.
+- **In-`PrePack` INT weight layout transform** (`weights_prepacked=0`) is
+  currently covered only by a smoke test (`TestQMoEIntPrePackSmoke`), not a
+  bit-parity check: the existing offline pre-pack harness hardcodes
+  `force_arch=80` and produces incorrect output on SM≥90, so a parity
+  comparison against it is omitted until that harness honours the runtime SM.
 - **Hopper W4A8** (INT4 weight + FP8 activation) is not supported — TRT-LLM gates
   its fast path to SM89 only.
 

onnxruntime/contrib_ops/cuda/llm/fpA_intB_gemm_preprocessors.h

@@ -31,6 +31,8 @@ enum class QuantType {
   W4_AFP8
 };
 
+int get_arch_for_mixed_gemm_weight_preprocess(int arch);
+
 void preprocess_weights_for_mixed_gemm_cuda(cudaStream_t stream,
                                             int arch,
                                             int8_t* preprocessed_quantized_weight,

onnxruntime/contrib_ops/cuda/llm/fpA_intB_gemm_preprocessors_impl.cu

@@ -521,6 +521,19 @@ void add_bias_and_interleave_quantized_tensor_inplace_cuda(
   }
 }
 
+int get_arch_for_mixed_gemm_weight_preprocess(int arch) {
+  ORT_ENFORCE(arch >= 75, "Unsupported CUDA architecture: ", arch);
+  if (arch < 80) {
+    return 75;
+  }
+#ifndef EXCLUDE_SM_90
+  if (arch >= 90 && arch < 100) {
+    return 90;
+  }
+#endif
+  return 80;
+}
+
 void preprocess_weights_for_mixed_gemm_cuda(cudaStream_t stream,
                                             int arch,
                                             int8_t* preprocessed_quantized_weight,

onnxruntime/contrib_ops/cuda/llm/fpA_intB_gemm_preprocessors_impl.h

@@ -120,11 +120,11 @@ LayoutDetails getLayoutDetailsForArch(QuantType quant_type) {
 }
 
 LayoutDetails getLayoutDetailsForTransform(QuantType quant_type, int arch) {
-  ORT_ENFORCE(arch >= 75, "Unsupported CUDA architecture: ", arch);
-  if (arch < 80) {
+  arch = get_arch_for_mixed_gemm_weight_preprocess(arch);
+  if (arch == 75) {
     return getLayoutDetailsForArch<cutlass::arch::Sm75>(quant_type);
 #ifndef EXCLUDE_SM_90
-  } else if (arch >= 90 && arch < 100) {
+  } else if (arch == 90) {
     return getLayoutDetailsForArch<cutlass::arch::Sm90>(quant_type);
 #endif
   } else {

onnxruntime/contrib_ops/cuda/moe/moe_quantization.cc

@@ -62,18 +62,26 @@ QMoE::QMoE(const OpKernelInfo& op_kernel_info) : CudaKernel(op_kernel_info), MoE
   this->quant_type_ = op_kernel_info.GetAttrOrDefault<std::string>("quant_type", "int");
   ORT_ENFORCE(quant_type_ == "int" || quant_type_ == "fp4" || quant_type_ == "fp8" || quant_type_ == "wfp4afp8",
               "quant_type must be 'int', 'fp4', 'fp8', or 'wfp4afp8', but got '", quant_type_, "'");
-  // ``weights_prepacked`` is an optional tri-state attribute that defaults to
-  // -1 (auto) in the schema, so each EP picks its own backward-compatible
-  // default rather than the schema imposing one:
-  //   -1 (auto, also the schema default): the EP decides. The CUDA EP's
-  //      backward-compatible default is "prepacked" because all pre-existing
-  //      tooling ships CUTLASS-prepacked weights.
-  //    1: initializers are already prepacked; the compute path reads them as-is.
-  //    0: initializers are raw [E, N, K/pack]; the PrePack hook lays them out.
+  // ``weights_prepacked`` is an optional tri-state attribute (default -1) that
+  // declares the layout of the int4/int8 fc1/fc2 weight initializers. The
+  // concrete prepacked layouts selected by -1 and 1 are determined by the
+  // execution provider. The CUDA EP maps the tri-state as:
+  //   -1 (default): already prepacked in the EP's default int weight layout.
+  //    1: already prepacked in the EP's SM90 (Hopper) int weight layout.
+  //    0: raw [E, N, K/pack] initializers; the PrePack hook lays them out.
+  //
+  // Important: the CUDA QMoE int4/int8 MoE GEMM always dispatches to the
+  // Ampere (SM80) grouped-GEMM kernel -- even on SM90 -- because mixed
+  // int-weight + fp16/bf16 activation is not a valid Hopper TMA warp-specialized
+  // specialisation (see isValidHopperMOESpecialisation). The kernel therefore
+  // consumes the SM80/Ampere CUTLASS fpA_intB layout on every GPU. As a result
+  // the EP default (-1) is the SM80 layout regardless of the runtime device SM,
+  // and SM80-format weights are valid on SM90 (they run via the SM80 kernel).
+  // PrePack (weights_prepacked=0) packs for the SM80 layout accordingly.
   const int64_t weights_prepacked_mode =
       op_kernel_info.GetAttrOrDefault<int64_t>("weights_prepacked", static_cast<int64_t>(-1));
   ORT_ENFORCE(weights_prepacked_mode == -1 || weights_prepacked_mode == 0 || weights_prepacked_mode == 1,
-              "weights_prepacked must be -1 (auto), 0, or 1, but got ", weights_prepacked_mode);
+              "weights_prepacked must be -1 (default), 0, or 1, but got ", weights_prepacked_mode);
   weights_prepacked_ = (weights_prepacked_mode != 0);
 #if !defined(ENABLE_FP4) || !defined(USE_FP4_QMOE)
   ORT_ENFORCE(quant_type_ != "fp4", "QMoE quant_type='fp4' requires USE_FP4_QMOE with CUDA 12.8 or newer.");
@@ -850,7 +858,7 @@ Status QMoE::ComputeInternal(OpKernelContext* context) const {
     // PrePack converted the raw int4/int8 weights to the CUTLASS fpA_intB
     // layout that the runner consumes and freed the source initializer
     // (``is_packed = true``). Gate on ``int_weights_consumed_by_prepack``
-    // (which already requires ``packed_fc1_weights_ != nullptr``) rather than
+    // (which already requires both packed weight buffers) rather than
     // just ``is_int && !weights_prepacked_``: when prepacking is disabled at
     // the session level (``session.disable_prepacking``) PrePack never runs,
     // the prepack buffers stay null, and the raw initializer pointers read
@@ -1158,22 +1166,15 @@ void QMoE::PrePackIntExpertWeights(const Tensor& tensor, cudaStream_t stream, Al
   const int64_t k_packed = shape[2];
   const int64_t k = k_packed * pack_factor;
 
-  // Weight packing is architecture-aware (see
-  // docs/contrib_ops/cuda/moe_qmoe.md §7 "Cross-Architecture Packing
-  // Compatibility"). SM90 (Hopper) uses its own Permuted-Linear layout that
-  // skips column interleaving, so it is its own compatibility group. Every
-  // other supported arch — SM75/80/86/89 and SM100/120 (Blackwell) — shares
-  // the SM80 fpA_intB layout, so they all pack as SM80. SM70 and older lack
-  // INT8 LDSM and are unsupported. The compute-side runner selects the same
-  // layout from this clamped arch, so the two cannot drift.
-  //
-  // SM75 is passed through unchanged (rather than clamped to 80) even though it
-  // shares SM80's layout: the compute-side dispatch (getLayoutDetailsForTransform)
-  // still has a distinct SM75 branch, so mirroring it here avoids confusing a
-  // reader into thinking prepack and dispatch disagree.
-  ORT_ENFORCE(sm_ >= 75,
-              "QMoE int4/int8 weight prepack requires SM75 or newer, got sm=", sm_);
-  const int packing_sm = (sm_ == 90 || sm_ == 75) ? sm_ : 80;
+  // The CUDA QMoE int4/int8 MoE GEMM always dispatches to the Ampere (SM80)
+  // grouped-GEMM kernel -- even on SM90 -- because mixed int-weight + fp16/bf16
+  // is not a valid Hopper TMA warp-specialized specialisation. The kernel thus
+  // consumes the SM80 CUTLASS fpA_intB layout on every GPU, so the weights must
+  // always be preprocessed for SM80 regardless of the runtime device SM.
+  // (Using get_arch_for_mixed_gemm_weight_preprocess(sm_) here would emit the
+  // SM90 layout on Hopper, which the SM80 kernel cannot consume -> wrong output.)
+  const int packing_sm =
+      onnxruntime::llm::kernels::weight_only::get_arch_for_mixed_gemm_weight_preprocess(80);
 
   // Per-expert sizes.
   const size_t per_expert_bytes = static_cast<size_t>(n) * static_cast<size_t>(k) / pack_factor;

onnxruntime/contrib_ops/cuda/moe/moe_quantization.h

@@ -46,16 +46,23 @@ class QMoE final : public CudaKernel, public MoEBase {
                                IAllocatorUniquePtr<void>& packed_buf, bool& is_packed);
   int64_t expert_weight_bits_;
   bool is_fp16_;
-  // When true (the schema default), the int4/int8 fc1/fc2 weight
-  // initializers are already in the CUTLASS fpA_intB layout — produced
-  // offline e.g. via ``pack_weights_for_cuda_mixed_gemm`` — and the
-  // compute path reads them as-is. When false, the raw schema-conformant
-  // ``[E, N, K/pack]`` layout (as produced by
-  // ``quantize_matmul_{4,8}bits``) is rewritten inside the PrePack hook
-  // via ``PrePackIntExpertWeights``, removing the offline prepack
-  // dependency. Only meaningful when ``quant_type_ == "int"``. Derived from
-  // the optional tri-state ``weights_prepacked`` attribute: -1/auto (or
-  // absent) maps to true on the CUDA EP, 1 maps to true, 0 maps to false.
+  // When true, the int4/int8 fc1/fc2 weight initializers are already in a
+  // CUTLASS fpA_intB layout — produced offline e.g. via
+  // ``pack_weights_for_cuda_mixed_gemm`` — and the compute path reads them
+  // as-is. When false, the raw schema-conformant ``[E, N, K/pack]`` layout
+  // (as produced by ``quantize_matmul_{4,8}bits``) is rewritten inside the
+  // PrePack hook via ``PrePackIntExpertWeights``, removing the offline
+  // prepack dependency. Only meaningful when ``quant_type_ == "int"``.
+  // Derived from the optional tri-state ``weights_prepacked`` attribute:
+  // -1 (default) and 1 both map to true; 0 maps to false. The concrete
+  // prepacked layouts selected by -1 and 1 are determined by the execution
+  // provider. For the CUDA EP the int4/int8 MoE GEMM always dispatches to the
+  // Ampere (SM80) grouped-GEMM kernel -- even on SM90 -- because mixed
+  // int-weight + fp16/bf16 activation is not a valid Hopper TMA warp-specialized
+  // specialisation (matches TensorRT-LLM, which also routes W4A16/W8A16 MoE to
+  // the SM80 kernel on Hopper). The kernel therefore consumes the SM80 fpA_intB
+  // layout on every GPU, so -1 and 1 are currently equivalent for the CUDA EP;
+  // 1 is reserved for a possible future Hopper-specific layout (e.g. W4A8).
   bool weights_prepacked_ = true;
   // Cached source weight shapes captured at PrePack time. When the
   // PrePack hook consumed and released the original int4/int8 weight

onnxruntime/core/graph/contrib_ops/contrib_defs.cc

@@ -1520,18 +1520,10 @@ ONNX_MS_OPERATOR_SET_SCHEMA(
               AttributeProto::STRING,
               std::string("int"))
         .Attr("weights_prepacked",
-              "Only meaningful when quant_type='int'. Tri-state control over whether the "
-              "int4/int8 fc1/fc2 weight initializers are already laid out in the CUTLASS "
-              "fpA_intB format expected by the runner. -1 (auto): let the execution provider "
-              "choose its own backward-compatible default; the CUDA EP treats auto as "
-              "prepacked. 1: the initializers are already prepacked (e.g. produced offline by "
-              "pack_weights_for_cuda_mixed_gemm) and are consumed as-is. 0: the initializers "
-              "are raw, un-prepacked [E, N, K/pack] tensors as produced by "
-              "quantize_matmul_{4,8}bits; the kernel runs the CUTLASS layout transform itself "
-              "in PrePack(), matching the behaviour of MatMulNBits and removing the offline "
-              "pre-pack requirement from exporters. Defaults to -1 (auto) so each execution "
-              "provider can pick its own backward-compatible default rather than the schema "
-              "imposing one.",
+              "Only meaningful when quant_type='int'. Tri-state control over the layout of the "
+              "int4/int8 fc1/fc2 weight initializers. The concrete prepacked layouts selected by "
+              "-1 and 1 are determined by the execution provider. 0: the initializers are raw, "
+              "un-prepacked [E, N, K/pack] tensors as produced by quantize_matmul_{4,8}bits. Defaults to -1.",
               AttributeProto::INT,
               static_cast<int64_t>(-1))
         .Input(0,