Fp8 lora dense kernel (#35242)

Signed-off-by: Yu Gong <yu3.gong@gmail.com>

tests/lora/test_punica_ops_fp8.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""FP8 accuracy tests for LoRA shrink and expand kernels.
+
+Tests the FP8 kernels by:
+1. Quantizing bf16 inputs/weights to FP8
+2. Dequantizing them back to bf16
+3. Running the bf16 reference (sgmv_shrink/sgmv_expand) with dequantized values
+4. Comparing FP8 kernel output against this dequantized reference
+
+This isolates kernel correctness from quantization precision loss,
+allowing much tighter tolerances than comparing against the original bf16.
+"""
+
+import math
+from threading import Lock
+
+import pytest
+import torch
+
+import vllm.lora.ops.torch_ops as torch_ops
+import vllm.lora.ops.triton_ops as triton_ops
+from vllm.lora.ops.triton_ops import LoRAKernelMeta
+from vllm.lora.ops.triton_ops.lora_expand_fp8_op import (
+    _EXPAND_LORA_SCALE_PTR_DICT,
+)
+from vllm.lora.ops.triton_ops.lora_shrink_fp8_op import (
+    _SHRINK_LORA_SCALE_PTR_DICT,
+)
+from vllm.lora.ops.triton_ops.utils import _LORA_A_PTR_DICT, _LORA_B_PTR_DICT
+from vllm.utils.torch_utils import set_random_seed
+
+DEVICES = [f"cuda:{0}"]
+SEED = [0]
+
+_dict_lock = Lock()
+
+
+@pytest.fixture(autouse=True)
+def reset_device(reset_default_device):
+    pass
+
+
+# ============================================================================
+# Reference implementations (bf16 baseline)
+# ============================================================================
+
+
+def sgmv_shrink_for_nslices(
+    nslices,
+    inputs_tensor,
+    lora_weights_lst,
+    out_tensor,
+    b_seq_start_loc,
+    seq_len_tensor,
+    prompt_lora_mapping,
+    batches,
+    max_seq_length,
+    num_tokens,
+    scaling,
+):
+    """Wrapper around torch_ops.sgmv_shrink that handles any nslices."""
+    for index in range(nslices):
+        torch_ops.sgmv_shrink(
+            inputs_tensor,
+            lora_weights_lst[index],
+            out_tensor[index],
+            b_seq_start_loc,
+            seq_len_tensor,
+            prompt_lora_mapping,
+            batches,
+            max_seq_length,
+            num_tokens,
+            scaling,
+        )
+
+
+def sgmv_expand_for_nslices(
+    nslices,
+    hidden_size,
+    inputs_tensor,
+    lora_weights_lst,
+    out_tensor,
+    b_seq_start_loc,
+    seq_len_tensor,
+    prompt_lora_mapping,
+    batches,
+    max_seq_length,
+    num_tokens,
+    add_inputs,
+):
+    """Wrapper around torch_ops.sgmv_expand that handles any nslices."""
+    if nslices == 1:
+        torch_ops.sgmv_expand(
+            inputs_tensor[0],
+            lora_weights_lst[0],
+            out_tensor,
+            b_seq_start_loc,
+            seq_len_tensor,
+            prompt_lora_mapping,
+            batches,
+            max_seq_length,
+            num_tokens,
+            add_inputs=add_inputs,
+        )
+    else:
+        slice_offset = 0
+        for index in range(nslices):
+            torch_ops.sgmv_expand_slice(
+                inputs_tensor[index],
+                lora_weights_lst[index],
+                out_tensor,
+                b_seq_start_loc,
+                seq_len_tensor,
+                prompt_lora_mapping,
+                batches,
+                max_seq_length,
+                num_tokens,
+                slice_offset,
+                hidden_size,
+                add_inputs=add_inputs,
+            )
+            slice_offset += hidden_size
+
+
+# ============================================================================
+# FP8 Quantization Helpers
+# ============================================================================
+
+FP8_DTYPE = torch.float8_e4m3fn
+FP8_MAX = torch.finfo(FP8_DTYPE).max
+FP8_MIN = torch.finfo(FP8_DTYPE).min
+
+
+def quantize_to_fp8_per_tensor(
+    tensor: torch.Tensor,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    """Quantize a tensor to FP8 with per-tensor scaling."""
+    amax = tensor.abs().float().max().clamp(min=1e-12)
+    scale = (amax / FP8_MAX).to(torch.float32)
+    fp8_tensor = (tensor.float() / scale).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+    return fp8_tensor, scale.reshape(1)
+
+
+def quantize_to_fp8_per_channel(
+    tensor: torch.Tensor,
+    channel_dim: int = 0,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    """Quantize a tensor to FP8 with per-channel scaling.
+
+    For shrink lora_a weights of shape (num_loras, rank, hidden_size):
+        channel_dim=1 gives per-rank scaling -> scale shape (num_loras, rank)
+    For expand lora_b weights of shape (num_loras, hidden_size, rank):
+        channel_dim=1 gives per-hidden scaling -> scale shape (num_loras, hidden_size)
+    """
+    # Compute amax along all dims except the leading dims up to channel_dim+1
+    reduce_dims = list(range(channel_dim + 1, tensor.ndim))
+    if reduce_dims:
+        amax = tensor.abs().float().amax(dim=reduce_dims).clamp(min=1e-12)
+    else:
+        amax = tensor.abs().float().clamp(min=1e-12)
+    scale = (amax / FP8_MAX).to(torch.float32)
+
+    # Expand scale for broadcasting
+    for _ in reduce_dims:
+        scale = scale.unsqueeze(-1)
+    fp8_tensor = (tensor.float() / scale).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+    scale = scale.squeeze()
+    if scale.ndim == 0:
+        scale = scale.unsqueeze(0)
+    return fp8_tensor, scale
+
+
+def quantize_to_fp8_per_token(
+    tensor: torch.Tensor,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    """Quantize a 2D tensor to FP8 with per-token (per-row) scaling.
+
+    Input shape: (num_tokens, hidden_size)
+    Returns: (fp8_tensor, scale) where scale shape is (num_tokens, 1)
+    """
+    assert tensor.ndim == 2
+    amax = tensor.abs().float().amax(dim=1, keepdim=True).clamp(min=1e-12)
+    scale = (amax / FP8_MAX).to(torch.float32)
+    fp8_tensor = (tensor.float() / scale).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+    return fp8_tensor, scale
+
+
+def quantize_to_fp8_blockwise(
+    tensor: torch.Tensor,
+    group_n: int,
+    group_k: int,
+) -> tuple[torch.Tensor, torch.Tensor]:
+    """Quantize a 2D or 3D tensor to FP8 with block-wise scaling.
+
+    For a 2D tensor (num_tokens, hidden_size):
+        Blocks of size (1, group_k) ->
+            scale shape (num_tokens, ceil(hidden_size/group_k))
+
+    For a 3D tensor (num_loras, N, K):
+        Blocks of size (group_n, group_k) ->
+            scale shape (num_loras, ceil(N/group_n), ceil(K/group_k))
+    """
+    if tensor.ndim == 2:
+        M, K = tensor.shape
+        n_blocks_k = math.ceil(K / group_k)
+        scale = torch.zeros(M, n_blocks_k, dtype=torch.float32, device=tensor.device)
+        fp8_tensor = torch.zeros_like(tensor, dtype=FP8_DTYPE)
+        for m in range(M):
+            for bk in range(n_blocks_k):
+                k_start = bk * group_k
+                k_end = min(k_start + group_k, K)
+                block = tensor[m, k_start:k_end].float()
+                amax = block.abs().max().clamp(min=1e-12)
+                s = (amax / FP8_MAX).to(torch.float32)
+                scale[m, bk] = s
+                fp8_tensor[m, k_start:k_end] = (
+                    (block / s).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+                )
+        return fp8_tensor, scale
+    elif tensor.ndim == 3:
+        L, N, K = tensor.shape
+        n_blocks_n = math.ceil(N / group_n)
+        n_blocks_k = math.ceil(K / group_k)
+        scale = torch.zeros(
+            L, n_blocks_n, n_blocks_k, dtype=torch.float32, device=tensor.device
+        )
+        fp8_tensor = torch.zeros_like(tensor, dtype=FP8_DTYPE)
+        for li in range(L):
+            for bn in range(n_blocks_n):
+                for bk in range(n_blocks_k):
+                    n_start = bn * group_n
+                    n_end = min(n_start + group_n, N)
+                    k_start = bk * group_k
+                    k_end = min(k_start + group_k, K)
+                    block = tensor[li, n_start:n_end, k_start:k_end].float()
+                    amax = block.abs().max().clamp(min=1e-12)
+                    s = (amax / FP8_MAX).to(torch.float32)
+                    scale[li, bn, bk] = s
+                    fp8_tensor[li, n_start:n_end, k_start:k_end] = (
+                        (block / s).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+                    )
+        return fp8_tensor, scale
+    else:
+        raise ValueError(f"Unsupported tensor ndim: {tensor.ndim}")
+
+
+# ============================================================================
+# FP8 Dequantization Helpers
+# ============================================================================
+
+
+def dequantize_fp8_per_tensor(
+    fp8_tensor: torch.Tensor,
+    scale: torch.Tensor,
+    output_dtype: torch.dtype = torch.bfloat16,
+) -> torch.Tensor:
+    """Dequantize FP8 tensor with per-tensor scale back to output_dtype."""
+    return (fp8_tensor.float() * scale.float()).to(output_dtype)
+
+
+def dequantize_fp8_per_channel(
+    fp8_tensor: torch.Tensor,
+    scale: torch.Tensor,
+    channel_dim: int,
+    output_dtype: torch.dtype = torch.bfloat16,
+) -> torch.Tensor:
+    """Dequantize FP8 tensor with per-channel scale back to output_dtype.
+
+    For 3D tensor (num_loras, N, K) with channel_dim=1:
+        scale shape is (num_loras, N), broadcast over K.
+    """
+    expand_scale = scale.float()
+    # Add trailing dims for broadcasting
+    for _ in range(channel_dim + 1, fp8_tensor.ndim):
+        expand_scale = expand_scale.unsqueeze(-1)
+    return (fp8_tensor.float() * expand_scale).to(output_dtype)
+
+
+def dequantize_fp8_per_token(
+    fp8_tensor: torch.Tensor,
+    scale: torch.Tensor,
+    output_dtype: torch.dtype = torch.bfloat16,
+) -> torch.Tensor:
+    """Dequantize FP8 2D tensor with per-token scale back to output_dtype.
+
+    fp8_tensor: (num_tokens, hidden_size), scale: (num_tokens, 1)
+    """
+    return (fp8_tensor.float() * scale.float()).to(output_dtype)
+
+
+def dequantize_fp8_blockwise(
+    fp8_tensor: torch.Tensor,
+    scale: torch.Tensor,
+    group_n: int,
+    group_k: int,
+    output_dtype: torch.dtype = torch.bfloat16,
+) -> torch.Tensor:
+    """Dequantize FP8 tensor with block-wise scale back to output_dtype."""
+    if fp8_tensor.ndim == 2:
+        M, K = fp8_tensor.shape
+        out = torch.zeros(M, K, dtype=output_dtype, device=fp8_tensor.device)
+        n_blocks_k = math.ceil(K / group_k)
+        for m in range(M):
+            for bk in range(n_blocks_k):
+                k_start = bk * group_k
+                k_end = min(k_start + group_k, K)
+                out[m, k_start:k_end] = (
+                    fp8_tensor[m, k_start:k_end].float() * scale[m, bk].float()
+                ).to(output_dtype)
+        return out
+    elif fp8_tensor.ndim == 3:
+        L, N, K = fp8_tensor.shape
+        out = torch.zeros(L, N, K, dtype=output_dtype, device=fp8_tensor.device)
+        n_blocks_n = math.ceil(N / group_n)
+        n_blocks_k = math.ceil(K / group_k)
+        for l_idx in range(L):
+            for bn in range(n_blocks_n):
+                for bk in range(n_blocks_k):
+                    n_start = bn * group_n
+                    n_end = min(n_start + group_n, N)
+                    k_start = bk * group_k
+                    k_end = min(k_start + group_k, K)
+                    out[l_idx, n_start:n_end, k_start:k_end] = (
+                        fp8_tensor[l_idx, n_start:n_end, k_start:k_end].float()
+                        * scale[l_idx, bn, bk].float()
+                    ).to(output_dtype)
+        return out
+    else:
+        raise ValueError(f"Unsupported tensor ndim: {fp8_tensor.ndim}")
+
+
+# ============================================================================
+# FP8 Data Generation
+# ============================================================================
+
+
+def generate_fp8_shrink_data(
+    batches: int,
+    hidden_size: int,
+    num_loras: int,
+    rank: int,
+    seq_length: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    quant_mode: str,  # "per_tensor", "per_channel", "blockwise"
+    group_k: int = 128,
+    group_n: int = 128,
+):
+    """Generate test data for FP8 shrink kernel.
+
+    Shrink: output = input @ lora_a^T * scaling
+    input: (num_tokens, hidden_size) -> quantized to FP8
+    lora_a: (num_loras, rank, hidden_size) -> quantized to FP8
+
+    Returns bf16 reference tensors, FP8 quantized tensors with scales,
+    and dequantized bf16 tensors for accurate reference computation.
+    """
+    seq_len_tensor = torch.randint(seq_length, seq_length + 1, (batches,)).to(device)
+    b_seq_start_loc = torch.cumsum(
+        torch.tensor([0] + seq_len_tensor[:-1].tolist(), dtype=torch.long),
+        dim=0,
+    ).to(device)
+    total_tokens = seq_len_tensor.sum().item()
+
+    # Generate bf16 reference data
+    inputs_bf16 = torch.randn(total_tokens, hidden_size, dtype=dtype, device=device)
+
+    lora_a_weights_bf16 = []
+    for _ in range(nslices):
+        lora_a_weights_bf16.append(
+            torch.randn(num_loras, rank, hidden_size, dtype=dtype, device=device)
+        )
+
+    # Quantize inputs to FP8 and dequantize back for reference
+    if quant_mode == "blockwise":
+        inputs_fp8, a_scale = quantize_to_fp8_blockwise(
+            inputs_bf16, group_n=1, group_k=group_k
+        )
+        inputs_dequant = dequantize_fp8_blockwise(
+            inputs_fp8,
+            a_scale,
+            group_n=1,
+            group_k=group_k,
+            output_dtype=dtype,
+        )
+    elif quant_mode == "per_tensor":
+        # Per-tensor: kernel loads a single scalar from a_scale_ptr
+        inputs_fp8, a_scale = quantize_to_fp8_per_tensor(inputs_bf16)
+        inputs_dequant = dequantize_fp8_per_tensor(
+            inputs_fp8,
+            a_scale,
+            output_dtype=dtype,
+        )
+    else:
+        # per_channel: kernel loads per-token a_scale via ram indexing
+        inputs_fp8, a_scale = quantize_to_fp8_per_token(inputs_bf16)
+        inputs_dequant = dequantize_fp8_per_token(
+            inputs_fp8,
+            a_scale,
+            output_dtype=dtype,
+        )
+
+    # Quantize lora_a weights to FP8 and dequantize back for reference
+    b_scales = []
+    lora_a_weights_fp8 = []
+    lora_a_weights_dequant = []
+    for w in lora_a_weights_bf16:
+        if quant_mode == "per_tensor":
+            w_fp8, w_scale = quantize_to_fp8_per_tensor(w)
+            w_dequant = dequantize_fp8_per_tensor(w_fp8, w_scale, output_dtype=dtype)
+            # Scale shape: (1,) -> need (num_loras,) for the kernel
+            w_scale = w_scale.expand(num_loras).contiguous()
+            lora_a_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_a_weights_dequant.append(w_dequant)
+        elif quant_mode == "per_channel":
+            # Per-channel along rank dim: scale shape (num_loras, rank)
+            w_fp8, w_scale = quantize_to_fp8_per_channel(w, channel_dim=1)
+            w_dequant = dequantize_fp8_per_channel(
+                w_fp8,
+                w_scale,
+                channel_dim=1,
+                output_dtype=dtype,
+            )
+            lora_a_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_a_weights_dequant.append(w_dequant)
+        elif quant_mode == "blockwise":
+            w_fp8, w_scale = quantize_to_fp8_blockwise(
+                w, group_n=group_n, group_k=group_k
+            )
+            w_dequant = dequantize_fp8_blockwise(
+                w_fp8,
+                w_scale,
+                group_n=group_n,
+                group_k=group_k,
+                output_dtype=dtype,
+            )
+            lora_a_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_a_weights_dequant.append(w_dequant)
+
+    # Output tensor (float32 for shrink)
+    out_tensor = torch.zeros(
+        nslices, total_tokens, rank, dtype=torch.float32, device=device
+    )
+    ref_out_tensor = out_tensor.clone()
+
+    # Token-to-lora mapping
+    lora_indices_tensor = torch.randint(0, max(num_loras - 1, 1), (batches,)).to(device)
+    token_lora_mapping = torch.zeros(total_tokens, dtype=torch.long, device=device)
+    current_offset = 0
+    for b_id in range(batches):
+        lora_index = lora_indices_tensor[b_id]
+        sl = seq_len_tensor[b_id].item()
+        token_lora_mapping[current_offset : current_offset + sl] = lora_index
+        current_offset += sl
+
+    return {
+        "inputs_bf16": inputs_bf16,
+        "inputs_fp8": inputs_fp8,
+        "inputs_dequant": inputs_dequant,
+        "lora_a_bf16": lora_a_weights_bf16,
+        "lora_a_fp8": lora_a_weights_fp8,
+        "lora_a_dequant": lora_a_weights_dequant,
+        "a_scale": a_scale,
+        "b_scales": b_scales,
+        "out_tensor": out_tensor,
+        "ref_out_tensor": ref_out_tensor,
+        "token_lora_mapping": token_lora_mapping,
+        "seq_len_tensor": seq_len_tensor,
+        "b_seq_start_loc": b_seq_start_loc,
+        "lora_indices_tensor": lora_indices_tensor,
+        "total_tokens": total_tokens,
+    }
+
+
+def generate_fp8_expand_data(
+    batches: int,
+    hidden_size: int,
+    num_loras: int,
+    rank: int,
+    seq_length: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    quant_mode: str,  # "per_tensor", "per_channel", "blockwise"
+    group_k: int = 128,
+    group_n: int = 128,
+):
+    """Generate test data for FP8 expand kernel (w8a8).
+
+    Expand: output += input @ lora_b^T
+    input: (nslices, num_tokens, rank) -> quantized to FP8 (activations)
+    lora_b: (num_loras, hidden_size, rank) -> quantized to FP8 (weights)
+
+    In w8a8 mode, both activations and weights are FP8.
+    Returns bf16 reference tensors, FP8 quantized tensors with scales,
+    and dequantized bf16 tensors for accurate reference computation.
+    """
+    seq_len_tensor = torch.randint(seq_length, seq_length + 1, (batches,)).to(device)
+    b_seq_start_loc = torch.cumsum(
+        torch.tensor([0] + seq_len_tensor[:-1].tolist(), dtype=torch.long),
+        dim=0,
+    ).to(device)
+    total_tokens = seq_len_tensor.sum().item()
+
+    # Generate bf16 input (shrink output) and quantize to FP8
+    inputs_bf16 = torch.randn(nslices, total_tokens, rank, dtype=dtype, device=device)
+
+    # Quantize input to FP8 and dequantize back for reference
+    inputs_2d_all = inputs_bf16.reshape(-1, rank)
+    if quant_mode == "blockwise":
+        # For blockwise, the kernel indexes a_scale by token id (0..total_tokens-1)
+        # shared across slices. Compute shared scale across slices, then quantize.
+        # First compute per-token-per-block scale across all slices
+        n_blocks_k = math.ceil(rank / group_k)
+        a_scale = torch.zeros(
+            total_tokens, n_blocks_k, dtype=torch.float32, device=device
+        )
+        for m in range(total_tokens):
+            for bk in range(n_blocks_k):
+                k_start = bk * group_k
+                k_end = min(k_start + group_k, rank)
+                # Max across all slices for this token and block
+                block_amax = torch.tensor(0.0, device=device)
+                for s in range(nslices):
+                    block = inputs_bf16[s, m, k_start:k_end].float()
+                    block_amax = torch.max(
+                        block_amax, block.abs().max().clamp(min=1e-12)
+                    )
+                a_scale[m, bk] = (block_amax / FP8_MAX).to(torch.float32)
+
+        # Quantize all slices with the shared scale
+        inputs_fp8_list = []
+        inputs_dequant_list = []
+        for s in range(nslices):
+            slice_2d = inputs_bf16[s]  # (total_tokens, rank)
+            fp8_slice = torch.zeros_like(slice_2d, dtype=FP8_DTYPE)
+            dequant_slice = torch.zeros_like(slice_2d)
+            for m in range(total_tokens):
+                for bk in range(n_blocks_k):
+                    k_start = bk * group_k
+                    k_end = min(k_start + group_k, rank)
+                    block = slice_2d[m, k_start:k_end].float()
+                    s_val = a_scale[m, bk]
+                    fp8_slice[m, k_start:k_end] = (
+                        (block / s_val).clamp(FP8_MIN, FP8_MAX).to(FP8_DTYPE)
+                    )
+                    dequant_slice[m, k_start:k_end] = (
+                        fp8_slice[m, k_start:k_end].float() * s_val.float()
+                    ).to(dtype)
+            inputs_fp8_list.append(fp8_slice)
+            inputs_dequant_list.append(dequant_slice)
+        inputs_fp8 = torch.stack(inputs_fp8_list, dim=0)
+        inputs_dequant = torch.stack(inputs_dequant_list, dim=0)
+    elif quant_mode == "per_tensor":
+        # Per-tensor: kernel loads a single scalar from a_scale_ptr
+        inputs_fp8_2d, a_scale = quantize_to_fp8_per_tensor(inputs_2d_all)
+        inputs_dequant_2d = dequantize_fp8_per_tensor(
+            inputs_fp8_2d,
+            a_scale,
+            output_dtype=dtype,
+        )
+        inputs_fp8 = inputs_fp8_2d.reshape(nslices, total_tokens, rank)
+        inputs_dequant = inputs_dequant_2d.reshape(nslices, total_tokens, rank)
+    else:
+        # per_channel: kernel loads per-token a_scale via ram indexing.
+        # The kernel uses the same a_scale for all slices (indexed by token
+        # id 0..total_tokens-1), so we compute a shared per-token scale
+        # across all slices, then quantize each slice with that shared scale.
+        per_slice_views = [inputs_bf16[s] for s in range(nslices)]
+        # (nslices, total_tokens, rank) -> max across slices per token
+        stacked = torch.stack(per_slice_views, dim=0)  # (nslices, tokens, rank)
+        amax = stacked.abs().float().amax(dim=(0, 2), keepdim=False).clamp(min=1e-12)
+        # amax shape: (total_tokens,)
+        a_scale = (amax / FP8_MAX).to(torch.float32).unsqueeze(1)  # (tokens, 1)
+        # Quantize all slices with the shared scale
+        inputs_fp8_2d = (
+            (inputs_2d_all.float() / a_scale.repeat(nslices, 1))
+            .clamp(FP8_MIN, FP8_MAX)
+            .to(FP8_DTYPE)
+        )
+        inputs_dequant_2d = (
+            inputs_fp8_2d.float() * a_scale.repeat(nslices, 1).float()
+        ).to(dtype)
+        inputs_fp8 = inputs_fp8_2d.reshape(nslices, total_tokens, rank)
+        inputs_dequant = inputs_dequant_2d.reshape(nslices, total_tokens, rank)
+
+    # Generate bf16 LoRA B weights
+    lora_b_weights_bf16 = []
+    for _ in range(nslices):
+        lora_b_weights_bf16.append(
+            torch.randn(num_loras, hidden_size, rank, dtype=dtype, device=device)
+        )
+
+    # Quantize LoRA B weights to FP8 and dequantize back for reference
+    b_scales = []
+    lora_b_weights_fp8 = []
+    lora_b_weights_dequant = []
+    for w in lora_b_weights_bf16:
+        if quant_mode == "per_tensor":
+            w_fp8, w_scale = quantize_to_fp8_per_tensor(w)
+            w_dequant = dequantize_fp8_per_tensor(w_fp8, w_scale, output_dtype=dtype)
+            w_scale = w_scale.expand(num_loras).contiguous()
+            lora_b_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_b_weights_dequant.append(w_dequant)
+        elif quant_mode == "per_channel":
+            # Per-channel along hidden_size dim: scale (num_loras, hidden_size)
+            w_fp8, w_scale = quantize_to_fp8_per_channel(w, channel_dim=1)
+            w_dequant = dequantize_fp8_per_channel(
+                w_fp8,
+                w_scale,
+                channel_dim=1,
+                output_dtype=dtype,
+            )
+            lora_b_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_b_weights_dequant.append(w_dequant)
+        elif quant_mode == "blockwise":
+            w_fp8, w_scale = quantize_to_fp8_blockwise(
+                w, group_n=group_n, group_k=group_k
+            )
+            w_dequant = dequantize_fp8_blockwise(
+                w_fp8,
+                w_scale,
+                group_n=group_n,
+                group_k=group_k,
+                output_dtype=dtype,
+            )
+            lora_b_weights_fp8.append(w_fp8)
+            b_scales.append(w_scale)
+            lora_b_weights_dequant.append(w_dequant)
+
+    # Output tensor (initialized randomly for add_inputs)
+    out_tensor = torch.randn(
+        total_tokens, hidden_size * nslices, dtype=dtype, device=device
+    )
+    ref_out_tensor = out_tensor.clone()
+
+    # Token-to-lora mapping
+    lora_indices_tensor = torch.randint(0, max(num_loras - 1, 1), (batches,)).to(device)
+    token_lora_mapping = torch.zeros(total_tokens, dtype=torch.long, device=device)
+    current_offset = 0
+    for b_id in range(batches):
+        lora_index = lora_indices_tensor[b_id]
+        sl = seq_len_tensor[b_id].item()
+        token_lora_mapping[current_offset : current_offset + sl] = lora_index
+        current_offset += sl
+
+    return {
+        "inputs_bf16": inputs_bf16,
+        "inputs_fp8": inputs_fp8,
+        "inputs_dequant": inputs_dequant,
+        "a_scale": a_scale,
+        "lora_b_bf16": lora_b_weights_bf16,
+        "lora_b_fp8": lora_b_weights_fp8,
+        "lora_b_dequant": lora_b_weights_dequant,
+        "b_scales": b_scales,
+        "out_tensor": out_tensor,
+        "ref_out_tensor": ref_out_tensor,
+        "token_lora_mapping": token_lora_mapping,
+        "seq_len_tensor": seq_len_tensor,
+        "b_seq_start_loc": b_seq_start_loc,
+        "lora_indices_tensor": lora_indices_tensor,
+        "total_tokens": total_tokens,
+    }
+
+
+# ============================================================================
+# FP8 Shrink Kernel Check
+# ============================================================================
+
+
+def check_lora_shrink_fp8_kernel(
+    batches: int,
+    num_loras: int,
+    rank: int,
+    hidden_size: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    seq_length: int,
+    scaling: float,
+    quant_mode: str,
+    group_k: int = 128,
+    group_n: int = 128,
+):
+    """Test FP8 shrink kernel against dequantized bf16 reference.
+
+    Instead of comparing FP8 kernel output against the original bf16 reference
+    (which conflates quantization error with kernel error), we:
+    1. Quantize bf16 inputs/weights to FP8
+    2. Dequantize them back to bf16
+    3. Run the bf16 reference (sgmv_shrink) with the dequantized values
+    4. Compare FP8 kernel output against this dequantized reference
+
+    This isolates kernel correctness from quantization precision loss,
+    allowing much tighter tolerances.
+    """
+    data = generate_fp8_shrink_data(
+        batches,
+        hidden_size,
+        num_loras,
+        rank,
+        seq_length,
+        nslices,
+        dtype,
+        device,
+        quant_mode,
+        group_k,
+        group_n,
+    )
+
+    total_tokens = data["total_tokens"]
+
+    # Setup LoRA kernel metadata
+    lora_meta = LoRAKernelMeta.make(
+        max_loras=num_loras, max_num_tokens=total_tokens, device=device
+    )
+    lora_meta.prepare_tensors(data["token_lora_mapping"])
+
+    out_tensor = data["out_tensor"]
+
+    # Determine quantization params for the kernel
+    per_channel = quant_mode == "per_channel"
+    gk = group_k if quant_mode == "blockwise" else 0
+    gn = group_n if quant_mode == "blockwise" else 0
+
+    with _dict_lock:
+        _LORA_A_PTR_DICT.clear()
+        _SHRINK_LORA_SCALE_PTR_DICT.clear()
+        triton_ops.lora_shrink_fp8(
+            data["inputs_fp8"],
+            data["lora_a_fp8"],
+            out_tensor,
+            *lora_meta.meta_args(token_nums=total_tokens, specialize_active_lora=False),
+            scaling,
+            data["b_scales"],
+            a_scale=data["a_scale"],
+            group_k=gk,
+            group_n=gn,
+            use_fp8_w8a8=True,
+            per_channel_quant=per_channel,
+        )
+
+    # Compute reference using dequantized (round-tripped) tensors.
+    # This means the reference sees the same quantization error as the kernel,
+    # so any difference is purely kernel error.
+    ref_out_tensor = data["ref_out_tensor"]
+    max_seq_length = data["seq_len_tensor"].max().item()
+    sgmv_shrink_for_nslices(
+        nslices,
+        data["inputs_dequant"],
+        data["lora_a_dequant"],
+        ref_out_tensor,
+        data["b_seq_start_loc"],
+        data["seq_len_tensor"],
+        data["lora_indices_tensor"],
+        batches,
+        max_seq_length,
+        total_tokens,
+        scaling,
+    )
+
+    # With dequantized reference, we can use much tighter tolerances
+    # since we're only measuring kernel error, not quantization error.
+    # Blockwise accumulation order differs from the bf16 reference, so
+    # allow a slightly larger margin for sporadic rounding outliers.
+    rtol, atol = 0.1, 0.25
+    torch.testing.assert_close(
+        out_tensor.to(dtype), ref_out_tensor.to(dtype), rtol=rtol, atol=atol
+    )
+
+
+# ============================================================================
+# FP8 Expand Kernel Check
+# ============================================================================
+
+
+def check_lora_expand_fp8_kernel(
+    batches: int,
+    num_loras: int,
+    rank: int,
+    hidden_size: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    seq_length: int,
+    add_inputs: bool,
+    quant_mode: str,
+    group_k: int = 128,
+    group_n: int = 128,
+):
+    """Test FP8 expand kernel (w8a8) against dequantized bf16 reference.
+
+    Instead of comparing FP8 kernel output against the original bf16 reference
+    (which conflates quantization error with kernel error), we:
+    1. Quantize bf16 inputs/weights to FP8
+    2. Dequantize them back to bf16
+    3. Run the bf16 reference (sgmv_expand) with the dequantized values
+    4. Compare FP8 kernel output against this dequantized reference
+
+    This isolates kernel correctness from quantization precision loss,
+    allowing much tighter tolerances.
+    """
+    data = generate_fp8_expand_data(
+        batches,
+        hidden_size,
+        num_loras,
+        rank,
+        seq_length,
+        nslices,
+        dtype,
+        device,
+        quant_mode,
+        group_k,
+        group_n,
+    )
+
+    total_tokens = data["total_tokens"]
+
+    # Setup LoRA kernel metadata
+    lora_meta = LoRAKernelMeta.make(
+        max_loras=num_loras, max_num_tokens=total_tokens, device=device
+    )
+    lora_meta.prepare_tensors(data["token_lora_mapping"])
+
+    out_tensor = data["out_tensor"]
+
+    # Determine quantization params for the kernel
+    per_channel = quant_mode == "per_channel"
+    gk = group_k if quant_mode == "blockwise" else 0
+    gn = group_n if quant_mode == "blockwise" else 0
+
+    with _dict_lock:
+        _LORA_B_PTR_DICT.clear()
+        _EXPAND_LORA_SCALE_PTR_DICT.clear()
+        triton_ops.lora_expand_fp8(
+            data["inputs_fp8"],
+            data["lora_b_fp8"],
+            out_tensor,
+            *lora_meta.meta_args(token_nums=total_tokens, specialize_active_lora=False),
+            data["b_scales"],
+            a_scale=data["a_scale"],
+            offset_start=0,
+            add_inputs=add_inputs,
+            group_k=gk,
+            group_n=gn,
+            use_fp8_w8a8=True,
+            per_channel_quant=per_channel,
+        )
+
+    # Compute reference using dequantized (round-tripped) tensors.
+    ref_out_tensor = data["ref_out_tensor"]
+    max_seq_length = data["seq_len_tensor"].max().item()
+    sgmv_expand_for_nslices(
+        nslices,
+        hidden_size,
+        data["inputs_dequant"],
+        data["lora_b_dequant"],
+        ref_out_tensor,
+        data["b_seq_start_loc"],
+        data["seq_len_tensor"],
+        data["lora_indices_tensor"],
+        batches,
+        max_seq_length,
+        total_tokens,
+        add_inputs=add_inputs,
+    )
+
+    # With dequantized reference, we can use much tighter tolerances
+    # since we're only measuring kernel error, not quantization error.
+    rtol, atol = 0.1, 0.15
+    torch.testing.assert_close(out_tensor, ref_out_tensor, rtol=rtol, atol=atol)
+
+
+# ============================================================================
+# FP8 Test Parameters
+# ============================================================================
+
+fp8_test_params = {
+    "hidden_sizes": [512, 1024, 2048],
+    "batches": [1, 4, 16],
+    "num_loras": [1, 4, 8],
+    "max_ranks": [8, 16, 32, 64],
+}
+
+
+# ============================================================================
+# FP8 Shrink Tests
+# ============================================================================
+
+
+@pytest.mark.parametrize("batches", fp8_test_params["batches"])
+@pytest.mark.parametrize("num_loras", fp8_test_params["num_loras"])
+@pytest.mark.parametrize("rank", fp8_test_params["max_ranks"])
+@pytest.mark.parametrize("hidden_size", fp8_test_params["hidden_sizes"])
+@pytest.mark.parametrize("nslices", [1, 2, 3])
+@pytest.mark.parametrize("dtype", [torch.bfloat16])
+@pytest.mark.parametrize("device", DEVICES)
+@pytest.mark.parametrize("seed", SEED)
+@pytest.mark.parametrize("quant_mode", ["per_tensor", "per_channel", "blockwise"])
+def test_lora_shrink_fp8(
+    batches: int,
+    num_loras: int,
+    rank: int,
+    hidden_size: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    seed: int,
+    quant_mode: str,
+):
+    """Test FP8 shrink kernel with per-tensor, per-channel, and block-wise
+    quantization, comparing against the bf16 baseline."""
+    torch.set_default_device(device)
+    set_random_seed(seed)
+
+    # For blockwise, group sizes must divide evenly or be handled by the kernel
+    group_k = 128
+    group_n = 128
+
+    # Adjust group sizes if they're larger than the dimensions
+    if quant_mode == "blockwise":
+        group_k = min(group_k, hidden_size)
+        group_n = min(group_n, rank)
+
+    check_lora_shrink_fp8_kernel(
+        batches=batches,
+        num_loras=num_loras,
+        rank=rank,
+        hidden_size=hidden_size,
+        nslices=nslices,
+        dtype=dtype,
+        device=device,
+        seq_length=128,
+        scaling=0.5,
+        quant_mode=quant_mode,
+        group_k=group_k,
+        group_n=group_n,
+    )
+
+
+# ============================================================================
+# FP8 Expand Tests
+# ============================================================================
+
+
+@pytest.mark.parametrize("batches", fp8_test_params["batches"])
+@pytest.mark.parametrize("num_loras", fp8_test_params["num_loras"])
+@pytest.mark.parametrize("rank", fp8_test_params["max_ranks"])
+@pytest.mark.parametrize("hidden_size", fp8_test_params["hidden_sizes"])
+@pytest.mark.parametrize("nslices", [1, 2, 3])
+@pytest.mark.parametrize("dtype", [torch.bfloat16])
+@pytest.mark.parametrize("device", DEVICES)
+@pytest.mark.parametrize("seed", SEED)
+@pytest.mark.parametrize("quant_mode", ["per_tensor", "per_channel", "blockwise"])
+def test_lora_expand_fp8(
+    batches: int,
+    num_loras: int,
+    rank: int,
+    hidden_size: int,
+    nslices: int,
+    dtype: torch.dtype,
+    device: str,
+    seed: int,
+    quant_mode: str,
+):
+    """Test FP8 expand kernel with per-tensor, per-channel, and block-wise
+    quantization, comparing against the bf16 baseline."""
+    torch.set_default_device(device)
+    set_random_seed(seed)
+
+    group_k = 128
+    group_n = 128
+
+    # Adjust group sizes if they're larger than the dimensions
+    if quant_mode == "blockwise":
+        group_k = min(group_k, rank)
+        group_n = min(group_n, hidden_size)
+
+    check_lora_expand_fp8_kernel(
+        batches=batches,
+        num_loras=num_loras,
+        rank=rank,
+        hidden_size=hidden_size,
+        nslices=nslices,
+        dtype=dtype,
+        device=device,
+        seq_length=128,
+        add_inputs=True,
+        quant_mode=quant_mode,
+        group_k=group_k,
+        group_n=group_n,
+    )

vllm/lora/ops/triton_ops/__init__.py

@@ -12,13 +12,17 @@ from vllm.lora.ops.triton_ops.fused_moe_lora_op import (
     fused_moe_lora_expand,
     fused_moe_lora_shrink,
 )
+from vllm.lora.ops.triton_ops.lora_expand_fp8_op import lora_expand_fp8
 from vllm.lora.ops.triton_ops.lora_expand_op import lora_expand
 from vllm.lora.ops.triton_ops.lora_kernel_metadata import LoRAKernelMeta
+from vllm.lora.ops.triton_ops.lora_shrink_fp8_op import lora_shrink_fp8
 from vllm.lora.ops.triton_ops.lora_shrink_op import lora_shrink
 
 __all__ = [
     "lora_expand",
+    "lora_expand_fp8",
     "lora_shrink",
+    "lora_shrink_fp8",
     "LoRAKernelMeta",
     "fused_moe_lora",
     "fused_moe_lora_shrink",

vllm/lora/ops/triton_ops/fp8_kernel_utils.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Utilities for Punica kernel construction.
+"""
+
+from vllm.triton_utils import tl, triton
+
+
+@triton.jit
+def _accumulate_mm(
+    tiled_a,
+    tiled_b,
+    accumulator,
+    a_scale_ptr,
+    b_scale_ptr,
+    a_scale_k_stride,
+    b_scale_k_stride,
+    iter_k,
+    group_k: tl.constexpr,
+    group_n: tl.constexpr,
+    use_fp8_w8a8: tl.constexpr,
+):
+    """
+    Core matrix multiplication and accumulation logic with quantization support.
+
+    Args:
+        tiled_a (tl.tensor): Loaded tile from A matrix
+        tiled_b (tl.tensor): Loaded tile from B matrix
+        accumulator (tl.tensor): Current accumulator value
+        a_scale_ptr (tl.tensor): Scale pointer for A matrix
+        b_scale_ptr (tl.tensor): Scale pointer for B matrix
+        a_scale_k_stride (int): K dimension stride for A's block-wise scales
+        b_scale_k_stride (int): K dimension stride for B's block-wise scales
+        iter_k (int): Current iteration's global K offset
+        group_k: Block size for K dimension in block-wise quantization
+        group_n: Block size for N dimension in block-wise quantization
+        use_fp8_w8a8: Whether using FP8 W8A8 quantization
+    """
+
+    if use_fp8_w8a8:
+        if group_k > 0 and group_n > 0:
+            # Block-wise quantization: scales are loaded per block
+            offs_ks = iter_k // group_k
+            # a_scale_ptr is (BLOCK_M,) tensor of base pointers per row
+            # Load scale for current K-group, result shape: (BLOCK_M,)
+            a_scale = tl.load(a_scale_ptr + offs_ks * a_scale_k_stride)
+            # b_scale_ptr is (BLOCK_N,) tensor with N-offset pre-baked
+            # Load scale for current K-group, result shape: (BLOCK_N,)
+            b_scale = tl.load(b_scale_ptr + offs_ks * b_scale_k_stride)
+            accumulator += (
+                tl.dot(tiled_a, tiled_b) * a_scale[:, None] * b_scale[None, :]
+            )
+        else:
+            # Tensor-wise or per-channel: accumulate and scale at end
+            accumulator = tl.dot(tiled_a, tiled_b, acc=accumulator)
+    else:
+        accumulator += tl.dot(tiled_a, tiled_b)
+    return accumulator
+
+
+@triton.jit
+def fp8_mm_k(
+    a_ptr,
+    b_ptr,
+    a_scale_ptr,
+    b_scale_ptr,
+    ak_stride,
+    bk_stride,
+    a_scale_k_stride,
+    b_scale_k_stride,
+    offset_k,
+    K: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    EVEN_K: tl.constexpr,
+    SPLIT_K: tl.constexpr,
+    group_k: tl.constexpr,
+    group_n: tl.constexpr,
+    use_fp8_w8a8: tl.constexpr,
+    per_channel_quant: tl.constexpr,
+    CAST_TYPE: tl.constexpr,
+    b_dtype: tl.constexpr,
+    USE_GDC: tl.constexpr,
+    base_k,
+):
+    """
+    FP8-compatible matrix multiplication kernel with quantization support.
+    Given a_ptr and b_ptr, that identify the rows of A (m x k) and columns of
+    B (k x n), iterate through the K dimension to compute the partial/complete
+    matrix block product with proper dequantization.
+
+    Args:
+        a_ptr (tl.tensor): Array of pointers, identifying rows of A
+            (FP8 or other dtype)
+        b_ptr (tl.tensor): Array of pointers, identifying columns of B
+            (FP8 dtype)
+        a_scale_ptr (tl.tensor): Scale pointer for A matrix
+            (per-token or block-wise)
+        b_scale_ptr (tl.tensor): Scale pointer for B matrix
+            (per-channel or block-wise)
+        ak_stride (int): K dimension stride of the A matrix
+        bk_stride (int): K dimension stride of the B matrix
+        a_scale_k_stride (int): K dimension stride for A's block-wise scales
+        b_scale_k_stride (int): K dimension stride for B's block-wise scales
+        offset_k (int): Base offset along K dimension
+        K: Length of the K dimension
+        BLOCK_M: M dimension of the output block m x n
+        BLOCK_N: N dimension of the output block m x n
+        BLOCK_K: K dimension atom
+        EVEN_K: True if the blocks of A and B can be loaded without masking
+        SPLIT_K: Parameter signifying parallelism in the K dimension
+        group_k: Block size for K dimension in block-wise quantization
+        group_n: Block size for N dimension in block-wise quantization
+        use_fp8_w8a8: Whether using FP8 W8A8 quantization
+        per_channel_quant: Whether using per-channel quantization
+        CAST_TYPE: if True, cast the values from the A matrix to the B
+            matrix dtype.
+        b_dtype: datatype of the B matrix
+        USE_GDC: Whether to use PDL. True indicates use.
+        base_k (int): Base offset along K dimension for current SPLIT_K group
+    """
+    accumulator = tl.zeros((BLOCK_M, BLOCK_N), dtype=tl.float32)
+
+    # Step size along K for each iteration
+    STEP_K = BLOCK_K * SPLIT_K
+
+    # Total number of iterations (compile-time constant)
+    num_iters = tl.cdiv(K, STEP_K)
+
+    for k in range(num_iters):
+        # Current iteration's global K offset
+        iter_k = k * STEP_K + base_k
+        block_end = iter_k + BLOCK_K
+
+        # Skip iterations that are entirely past the K boundary
+        if not EVEN_K and iter_k >= K:
+            pass
+        elif EVEN_K or block_end <= K:
+            # No masking needed: either K is evenly divisible (EVEN_K)
+            # or this block fits entirely within K
+            tiled_b = tl.load(b_ptr)
+            if USE_GDC:
+                tl.extra.cuda.gdc_wait()
+            tiled_a = tl.load(a_ptr)
+            if CAST_TYPE:
+                tiled_a = tiled_a.to(b_dtype)
+
+            accumulator = _accumulate_mm(
+                tiled_a,
+                tiled_b,
+                accumulator,
+                a_scale_ptr,
+                b_scale_ptr,
+                a_scale_k_stride,
+                b_scale_k_stride,
+                iter_k,
+                group_k,
+                group_n,
+                use_fp8_w8a8,
+            )
+        else:
+            # Partial block at the tail: mask out-of-bounds elements
+            k_offsets = tl.arange(0, BLOCK_K)
+            mask = iter_k + k_offsets < K
+            tiled_b = tl.load(b_ptr, mask=mask[:, None], other=0.0)
+            if USE_GDC:
+                tl.extra.cuda.gdc_wait()
+            tiled_a = tl.load(a_ptr, mask=mask[None, :], other=0.0)
+            if CAST_TYPE:
+                tiled_a = tiled_a.to(b_dtype)
+
+            accumulator = _accumulate_mm(
+                tiled_a,
+                tiled_b,
+                accumulator,
+                a_scale_ptr,
+                b_scale_ptr,
+                a_scale_k_stride,
+                b_scale_k_stride,
+                iter_k,
+                group_k,
+                group_n,
+                use_fp8_w8a8,
+            )
+
+        a_ptr += STEP_K * ak_stride
+        b_ptr += STEP_K * bk_stride
+
+    return accumulator
+
+
+@triton.jit
+def do_shrink_kernel_fp8(
+    pid_n,
+    pid_sk,
+    slice_id,
+    lora_index,
+    input_ptr,
+    lora_ptr,
+    out_ptr,
+    a_scale_ptr,
+    b_scale_ptr,
+    N,
+    K,
+    M_LEN,
+    ram,
+    # input strides
+    input_d0_stride,
+    input_d1_stride,
+    # lora strides
+    lora_d0_stride,
+    lora_d1_stride,
+    lora_d2_stride,
+    # scale strides
+    a_scale_m_stride,
+    a_scale_k_stride,
+    b_scale_l_stride,
+    b_scale_n_stride,
+    b_scale_k_stride,
+    # output strides
+    output_d0_stride,
+    output_d1_stride,
+    output_d2_stride,
+    scaling,
+    # block size for block-wise quantization
+    group_n: tl.constexpr,
+    group_k: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    EVEN_K: tl.constexpr,
+    SPLIT_K: tl.constexpr,
+    SLICE_NUM: tl.constexpr,
+    USE_GDC: tl.constexpr,
+    use_fp8_w8a8: tl.constexpr,
+    per_channel_quant: tl.constexpr,
+    launch_pdl: tl.constexpr,
+):
+    """
+    Given an array of integers that identifies the rows of A, ram,
+    a lora index that identifies which LoRA to use from lora_ptr, lora_index,
+    a slice_id that identifies the input/output slice, compute the
+    matrix product and store in the appropriate output location.
+    """
+
+    # Identify the lora_ptr from slice_id.
+    if SLICE_NUM == 1:
+        cur_lora_ptr = lora_ptr
+        cur_b_scale_ptr = b_scale_ptr
+    else:
+        cur_lora_ptr = (
+            tl.load(lora_ptr + slice_id).to(tl.pointer_type(tl.float8e4nv))
+            if b_scale_ptr is not None
+            else tl.load(lora_ptr + slice_id).to(
+                tl.pointer_type(input_ptr.dtype.element_ty)
+            )
+        )
+        cur_b_scale_ptr = (
+            tl.load(b_scale_ptr + slice_id).to(tl.pointer_type(tl.float32))
+            if b_scale_ptr is not None
+            else b_scale_ptr
+        )
+
+    # Identify the column indices of B to process.
+    offset_n = tl.arange(0, BLOCK_N) + pid_n * BLOCK_N
+    rbn = tl.max_contiguous(tl.multiple_of(offset_n % N, BLOCK_N), BLOCK_N)
+
+    # Identify A and B block pointers
+    offset_k = pid_sk * BLOCK_K + tl.arange(0, BLOCK_K)
+    a_ptr = (
+        input_ptr + ram[:, None] * input_d0_stride + offset_k[None, :] * input_d1_stride
+    )
+    b_ptr = (
+        cur_lora_ptr
+        + lora_d0_stride * lora_index
+        + rbn[None, :] * lora_d1_stride
+        + offset_k[:, None] * lora_d2_stride
+    )
+
+    # Load scales for tensor-wise or per-channel quantization (outside the loop)
+    # Block-wise scales are loaded inside fp8_mm_k
+    if use_fp8_w8a8:
+        if group_k > 0 and group_n > 0:
+            # Block-wise: compute scale pointers for fp8_mm_k
+            # a_scale: per-row base pointers, shape (BLOCK_M,)
+            # Each pointer points to the start of that row's scale data
+            mm_a_scale_ptr = a_scale_ptr + ram * a_scale_m_stride
+
+            # b_scale: pre-compute N-dimension offset
+            # We need to bake in the N-group offset since fp8_mm_k doesn't know pid_n
+            n_offset = pid_n * BLOCK_N
+            offs_ns = (n_offset + tl.arange(0, BLOCK_N)) // group_n
+            # Base pointer with lora offset + N-group offset baked in, shape (BLOCK_N,)
+            mm_b_scale_ptr = (
+                cur_b_scale_ptr
+                + lora_index * b_scale_l_stride
+                + offs_ns * b_scale_n_stride
+            )
+        elif per_channel_quant:
+            # Per-channel for weights, per-token for activations
+            b_scale_ptrs = (
+                cur_b_scale_ptr + lora_index * b_scale_l_stride + rbn * b_scale_n_stride
+            )
+            b_scale = tl.load(b_scale_ptrs)
+            # Per-token activation scale
+            a_scale = tl.load(a_scale_ptr + ram * a_scale_m_stride)[:, None]
+            # For non-block-wise, pass original pointers (not used in mm loop)
+            mm_a_scale_ptr = a_scale_ptr
+            mm_b_scale_ptr = cur_b_scale_ptr
+        else:
+            # Tensor-wise quantization
+            a_scale = tl.load(a_scale_ptr) if a_scale_ptr is not None else 1.0
+            b_scale = tl.load(cur_b_scale_ptr + lora_index * b_scale_l_stride)
+            # For non-block-wise, pass original pointers (not used in mm loop)
+            mm_a_scale_ptr = a_scale_ptr
+            mm_b_scale_ptr = cur_b_scale_ptr
+    else:
+        # Non-quantized path
+        mm_a_scale_ptr = a_scale_ptr
+        mm_b_scale_ptr = cur_b_scale_ptr
+
+    # Compute partial/complete block matrix product.
+    accumulator = fp8_mm_k(
+        a_ptr,
+        b_ptr,
+        mm_a_scale_ptr,
+        mm_b_scale_ptr,
+        input_d1_stride,
+        lora_d2_stride,
+        a_scale_k_stride,
+        b_scale_k_stride,
+        offset_k,
+        K,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        EVEN_K,
+        SPLIT_K,
+        group_k,
+        group_n,
+        use_fp8_w8a8,
+        per_channel_quant,
+        False,
+        cur_lora_ptr.dtype.element_ty,
+        USE_GDC,
+        base_k=pid_sk * BLOCK_K,
+    )
+    # GDC launch dependents hints the runtime system to launch dependent kernels.
+    if USE_GDC:
+        tl.extra.cuda.gdc_launch_dependents()
+
+    # Apply dequantization scales for tensor-wise/per-channel quantization
+    if use_fp8_w8a8:
+        if group_k > 0 and group_n > 0:
+            # Block-wise: already applied in fp8_mm_k
+            pass
+        else:
+            # Tensor-wise or per-channel: apply scales after accumulation
+            accumulator = accumulator * a_scale * b_scale
+
+    # Apply LoRA scaling factor
+    accumulator *= scaling
+
+    # Identify the C output pointers to store the results of the accumulator.
+    offset_cn = tl.arange(0, BLOCK_N) + pid_n * BLOCK_N
+    offset_cm = tl.arange(0, BLOCK_M)
+    cur_out_ptr = out_ptr if SLICE_NUM == 1 else out_ptr + slice_id * output_d0_stride
+    c_ptr = (
+        cur_out_ptr
+        + ram[:, None] * output_d1_stride
+        + offset_cn[None, :] * output_d2_stride
+    )
+    c_mask = (offset_cm[:, None] < M_LEN) & (offset_cn[None, :] < N)
+
+    # Cast accumulator to output dtype
+    accumulator = accumulator.to(out_ptr.dtype.element_ty)
+
+    # handles write-back with reduction-splitting
+    if SPLIT_K == 1:
+        tl.store(c_ptr, accumulator, mask=c_mask)
+    else:
+        tl.atomic_add(c_ptr, accumulator, mask=c_mask, sem="relaxed")
+
+
+@triton.jit
+def do_expand_kernel_fp8(
+    pid_n,
+    lora_index,
+    slice_id,
+    input_ptr,
+    lora_ptr,
+    out_ptr,
+    a_scale_ptr,
+    b_scale_ptr,
+    N,
+    K,
+    M_LEN,
+    ram,  # array identifying the rows of Input ptr to operate on
+    slice_start_loc,
+    # input ptr strides
+    input_d0_stride,
+    input_d1_stride,
+    input_d2_stride,
+    # lora ptr strides
+    ls_d0_ptr,
+    ls_d1_ptr,
+    ls_d2_ptr,
+    # scale strides
+    a_scale_m_stride,
+    a_scale_k_stride,
+    b_scale_l_stride,
+    b_scale_n_stride,
+    b_scale_k_stride,
+    # out ptr strides
+    output_d0_stride,
+    output_d1_stride,
+    # block size for block-wise quantization
+    group_n: tl.constexpr,
+    group_k: tl.constexpr,
+    # constants
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    SAME_STRIDE: tl.constexpr,
+    SLICE_NUM: tl.constexpr,
+    EVEN_K: tl.constexpr,
+    CAST_TYPE: tl.constexpr,
+    ADD_INPUTS: tl.constexpr,
+    USE_GDC: tl.constexpr,
+    use_fp8_w8a8: tl.constexpr,
+    per_channel_quant: tl.constexpr,
+):
+    """
+    FP8-compatible expand kernel for LoRA.
+    Given an array of integers that identifies the rows of A, ram,
+    a lora index that identifies which LoRA to use from lora_ptr, lora_index,
+    a slice_id that identifies the input/output slice,
+    compute the matrix product with FP8 quantization support and store in
+    the appropriate output location.
+
+    For expand kernel, the input (shrink output) may be in FP32/FP16/BF16,
+    while the LoRA B weights can be in FP8.
+
+    Supports:
+    - FP8 W8A8 quantization for LoRA B weights
+    - Block-wise quantization with configurable group_k and group_n
+    - Per-channel quantization
+    - Tensor-wise quantization
+    """
+
+    # ls_d*_ptr can be either an integer or a pointer
+    if SAME_STRIDE:
+        cur_lora_d0_stride = ls_d0_ptr
+        cur_lora_d1_stride = ls_d1_ptr
+        cur_lora_d2_stride = ls_d2_ptr
+    else:
+        cur_lora_d0_stride = tl.load(ls_d0_ptr + slice_id)
+        cur_lora_d1_stride = tl.load(ls_d1_ptr + slice_id)
+        cur_lora_d2_stride = tl.load(ls_d2_ptr + slice_id)
+
+    # Identify the input_ptr and lora_ptr from slice_id.
+    if SLICE_NUM == 1:
+        cur_input_ptr = input_ptr
+        if use_fp8_w8a8:
+            cur_lora_ptr = lora_ptr
+            cur_b_scale_ptr = b_scale_ptr
+        else:
+            cur_lora_ptr = lora_ptr
+            cur_b_scale_ptr = b_scale_ptr  # May be None for non-quantized
+    else:
+        cur_input_ptr = input_ptr + slice_id * input_d0_stride
+        if use_fp8_w8a8:
+            cur_lora_ptr = tl.load(lora_ptr + slice_id).to(
+                tl.pointer_type(tl.float8e4nv)
+            )
+            cur_b_scale_ptr = tl.load(b_scale_ptr + slice_id).to(
+                tl.pointer_type(tl.float32)
+            )
+        else:
+            cur_lora_ptr = tl.load(lora_ptr + slice_id).to(
+                tl.pointer_type(out_ptr.dtype.element_ty)
+            )
+            cur_b_scale_ptr = (
+                tl.load(b_scale_ptr + slice_id).to(tl.pointer_type(tl.float32))
+                if b_scale_ptr is not None
+                else None
+            )
+
+    # Identify the column indices of B to process.
+    offset_n = tl.arange(0, BLOCK_N) + pid_n * BLOCK_N
+    rbn = tl.max_contiguous(tl.multiple_of(offset_n % N, BLOCK_N), BLOCK_N)
+
+    # Identify A and B block pointers
+    offset_k = tl.arange(0, BLOCK_K)
+    a_ptr = (
+        cur_input_ptr
+        + ram[:, None] * input_d1_stride
+        + offset_k[None, :] * input_d2_stride
+    )
+    b_ptr = (
+        cur_lora_ptr
+        + cur_lora_d0_stride * lora_index
+        + offset_k[:, None] * cur_lora_d2_stride
+        + rbn[None, :] * cur_lora_d1_stride
+    )
+
+    # Setup scale pointers for FP8/INT8 quantization
+    if use_fp8_w8a8:
+        if group_k > 0 and group_n > 0:
+            # Block-wise quantization - compute scale pointers for fp8_mm_k
+            # a_scale: per-row base pointers, shape (BLOCK_M,)
+            mm_a_scale_ptr = a_scale_ptr + ram * a_scale_m_stride
+
+            # b_scale: pre-compute N-dimension offset since fp8_mm_k doesn't know pid_n
+            n_offset = pid_n * BLOCK_N
+            offs_ns = (n_offset + tl.arange(0, BLOCK_N)) // group_n
+            # Base pointer with lora offset + N-group offset baked in, shape (BLOCK_N,)
+            mm_b_scale_ptr = (
+                cur_b_scale_ptr
+                + lora_index * b_scale_l_stride
+                + offs_ns * b_scale_n_stride
+            )
+        elif per_channel_quant:
+            # Per-channel for weights, shape (BLOCK_N,)
+            b_scale_ptrs = (
+                cur_b_scale_ptr + lora_index * b_scale_l_stride + rbn * b_scale_n_stride
+            )
+            b_scale = tl.load(b_scale_ptrs)
+            # Per-token activation scale, only if a_scale_ptr provided
+            a_scale = tl.load(a_scale_ptr + ram * a_scale_m_stride)[:, None]
+            # For non-block-wise, pass original pointers (not used in mm loop)
+            mm_a_scale_ptr = a_scale_ptr
+            mm_b_scale_ptr = cur_b_scale_ptr
+        else:
+            # Tensor-wise quantization
+            a_scale = tl.load(a_scale_ptr) if a_scale_ptr is not None else 1.0
+            b_scale = tl.load(cur_b_scale_ptr + lora_index * b_scale_l_stride)
+            # For non-block-wise, pass original pointers (not used in mm loop)
+            mm_a_scale_ptr = a_scale_ptr
+            mm_b_scale_ptr = cur_b_scale_ptr
+    else:
+        # Non-quantized path
+        mm_a_scale_ptr = a_scale_ptr
+        mm_b_scale_ptr = cur_b_scale_ptr
+
+    # Compute the block matrix product using fp8_mm_k
+    # Note: For expand kernel, SPLIT_K=1, so we pass 1 for SPLIT_K
+    accumulator = fp8_mm_k(
+        a_ptr,
+        b_ptr,
+        mm_a_scale_ptr,
+        mm_b_scale_ptr,
+        input_d2_stride,  # ak_stride
+        cur_lora_d2_stride,  # bk_stride
+        a_scale_k_stride,
+        b_scale_k_stride,
+        offset_k,
+        K,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        EVEN_K,
+        1,  # SPLIT_K = 1 for expand kernel
+        group_k,
+        group_n,
+        use_fp8_w8a8,
+        per_channel_quant,
+        CAST_TYPE,  # CAST_TYPE - cast FP8 B to A's dtype
+        cur_lora_ptr.dtype.element_ty,
+        USE_GDC,
+        base_k=0,
+    )
+
+    # Apply dequantization scales for non-block-wise quantization
+    if use_fp8_w8a8:
+        if group_k > 0 and group_n > 0:
+            pass  # Already applied per block in fp8_mm_k
+        else:
+            # Tensor-wise or per-channel: apply scales after accumulation
+            accumulator = accumulator * a_scale * b_scale
+
+    tiled_c = accumulator.to(out_ptr.dtype.element_ty)
+    if SLICE_NUM == 1:
+        cur_slice_start = slice_start_loc
+    else:
+        cur_slice_start = tl.load(slice_start_loc + slice_id)
+
+    # Identify the C output pointers to store the results of the accumulator.
+    offset_cn = tl.arange(0, BLOCK_N) + pid_n * BLOCK_N + cur_slice_start
+    offset_cm = tl.arange(0, BLOCK_M)
+    c_ptr = (
+        out_ptr
+        + ram[:, None] * output_d0_stride
+        + offset_cn[None, :] * output_d1_stride
+    )
+    c_mask = (offset_cm[:, None] < M_LEN) & (offset_cn[None, :] < (cur_slice_start + N))
+
+    if ADD_INPUTS:
+        tiled_out = tl.load(c_ptr, mask=c_mask)
+        tiled_c += tiled_out
+    tl.store(c_ptr, tiled_c, mask=c_mask)

vllm/lora/ops/triton_ops/lora_expand_fp8_op.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Based on:
+Chen, L., Ye, Z., Wu, Y., Zhuo, D., Ceze, L., & Krishnamurthy, A. (2023).
+Punica: Multi-Tenant LoRA Serving.
+https://arxiv.org/abs/2310.18547
+"""
+
+import torch
+
+from vllm.lora.ops.triton_ops.fp8_kernel_utils import do_expand_kernel_fp8
+from vllm.lora.ops.triton_ops.utils import (
+    _get_lora_b_ptr,
+    get_lora_op_configs,
+)
+from vllm.triton_utils import tl, triton
+from vllm.utils.torch_utils import direct_register_custom_op
+
+_EXPAND_LORA_SCALE_PTR_DICT: dict[tuple[int, ...], torch.tensor] = {}
+
+
+def _get_expand_lora_scale_ptr(lora_weights: list[torch.Tensor], device: torch.device):
+    """
+    `_EXPAND_LORA_SCALE_PTR_DICT` collects the required information during
+    `profile_run`,
+    After this, it remains constant and subsequent usage is through LUT.
+    Refer to:
+    https://github.com/triton-lang/triton/blob/release/3.1.x/python/tutorials/08-grouped-gemm.py
+    """
+    key = tuple(lora_weight.data_ptr() for lora_weight in lora_weights)
+
+    if (ptr_tensor := _EXPAND_LORA_SCALE_PTR_DICT.get(key)) is not None:
+        return ptr_tensor
+
+    if len(lora_weights) > 1:
+        tensor_ptrs = []
+        for lora_weight in lora_weights:
+            tensor_ptrs.append(lora_weight.data_ptr())
+        ptr_tensor = torch.tensor(tensor_ptrs, device=device, dtype=torch.uint64)
+    else:
+        # Single slice: return the actual tensor so the kernel can use it
+        # directly without pointer indirection (matches SLICE_NUM == 1 path).
+        ptr_tensor = lora_weights[0]
+
+    _EXPAND_LORA_SCALE_PTR_DICT[key] = ptr_tensor
+    return _EXPAND_LORA_SCALE_PTR_DICT.get(key)
+
+
+@triton.jit
+def _lora_expand_kernel_fp8(
+    input_ptr,
+    lora_ptr,
+    out_ptr,
+    a_scale_ptr,
+    b_scale_ptr,
+    M,
+    N,
+    K,
+    token_indices_sorted_by_lora_ids,
+    num_tokens_per_lora,
+    lora_token_start_loc,
+    lora_ids,
+    slice_start_loc,
+    input_d0_stride,
+    input_d1_stride,
+    input_d2_stride,
+    ls_d0_ptr,
+    ls_d1_ptr,
+    ls_d2_ptr,
+    a_scale_m_stride,
+    a_scale_k_stride,
+    b_scale_l_stride,
+    b_scale_n_stride,
+    b_scale_k_stride,
+    output_d0_stride,
+    output_d1_stride,
+    output_hs_ptr,
+    group_n: tl.constexpr,
+    group_k: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    EVEN_K: tl.constexpr,
+    ADD_INPUTS: tl.constexpr,
+    CAST_TYPE: tl.constexpr,
+    SLICE_NUM: tl.constexpr,
+    SAME_STRIDE: tl.constexpr,
+    USE_GDC: tl.constexpr,
+    use_fp8_w8a8: tl.constexpr,
+    per_channel_quant: tl.constexpr,
+    launch_pdl: tl.constexpr,
+):
+    """
+    FP8-compatible expand kernel wrapper.
+    """
+    cta_n_num = tl.cdiv(N, BLOCK_N)
+    cta_m_num = tl.cdiv(M, BLOCK_M)
+
+    pid_mn = tl.program_id(axis=0)
+    pid_m = pid_mn % cta_m_num
+    pid_n = (pid_mn // cta_m_num) % cta_n_num
+
+    slice_id = tl.program_id(axis=1)
+    lora_idx = tl.program_id(axis=2)
+
+    lora_id = tl.load(lora_ids + lora_idx)
+    if lora_id == -1:
+        return
+
+    lora_m_size = tl.load(num_tokens_per_lora + lora_idx)
+
+    cta_m_offset = pid_m * BLOCK_M
+    if cta_m_offset >= lora_m_size:
+        return
+
+    curr_N = N if SAME_STRIDE else tl.load(output_hs_ptr + slice_id)
+    if pid_n * BLOCK_N >= curr_N:
+        return
+
+    cta_m_len = min(BLOCK_M, lora_m_size - cta_m_offset)
+
+    lora_m_indices_start = tl.load(lora_token_start_loc + lora_idx)
+    cta_lora_seq_indices = (
+        token_indices_sorted_by_lora_ids + lora_m_indices_start + cta_m_offset
+    )
+
+    offset_m = tl.arange(0, BLOCK_M) % cta_m_len
+    ram = tl.load(cta_lora_seq_indices + offset_m)
+
+    do_expand_kernel_fp8(
+        pid_n,
+        lora_id,
+        slice_id,
+        input_ptr,
+        lora_ptr,
+        out_ptr,
+        a_scale_ptr,
+        b_scale_ptr,
+        curr_N,
+        K,
+        cta_m_len,
+        ram,
+        slice_start_loc,
+        input_d0_stride,
+        input_d1_stride,
+        input_d2_stride,
+        ls_d0_ptr,
+        ls_d1_ptr,
+        ls_d2_ptr,
+        a_scale_m_stride,
+        a_scale_k_stride,
+        b_scale_l_stride,
+        b_scale_n_stride,
+        b_scale_k_stride,
+        output_d0_stride,
+        output_d1_stride,
+        group_n,
+        group_k,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        SAME_STRIDE,
+        SLICE_NUM,
+        EVEN_K,
+        CAST_TYPE,
+        ADD_INPUTS,
+        USE_GDC,
+        use_fp8_w8a8,
+        per_channel_quant,
+    )
+
+
+@torch.inference_mode()
+def _lora_expand_fp8(
+    inputs: torch.Tensor,  # shape [num_slices, num_tokens, lora_rank]
+    lora_b_weights: list[torch.Tensor],  # FP8 [num_lora, hidden_size, lora_rank]
+    output_tensor: torch.Tensor,  # shape [num_tokens, hidden_size * num_slices]
+    token_lora_mapping: torch.Tensor,
+    token_indices_sorted_by_lora_ids: torch.Tensor,
+    num_tokens_per_lora: torch.Tensor,
+    lora_token_start_loc: torch.Tensor,
+    lora_ids: torch.Tensor,
+    no_lora_flag_cpu: torch.Tensor,  # shape [1]
+    num_active_loras: int,  # number of active LoRAs (unused here, for API compat)
+    b_scale: list[torch.Tensor],  # LoRA B weight scale per slice
+    a_scale: torch.Tensor | None = None,  # Scale for shrink output (optional)
+    offset_start: int = 0,
+    add_inputs: bool = False,
+    group_k: int = 0,
+    group_n: int = 0,
+    use_fp8_w8a8: bool = False,
+    per_channel_quant: bool = False,
+) -> None:
+    """
+    FP8-compatible LoRA expand operation.
+
+    Args:
+        inputs: Input tensor from shrink operation [num_slices, num_tokens, lora_rank]
+        lora_b_weights: List of FP8 LoRA B weights per slice
+        output_tensor: Output tensor
+        a_scale: Optional scale for input (if input is quantized)
+        b_scale: Weight quantization scales per slice
+        token_lora_mapping: Token to LoRA ID mapping
+        token_indices_sorted_by_lora_ids: Sorted token indices
+        num_tokens_per_lora: Number of tokens per LoRA
+        lora_token_start_loc: Start location for each LoRA's tokens
+        lora_ids: LoRA IDs to process
+        no_lora_flag_cpu (torch.Tensor): A CPU tensor of size 1, that indicates
+            if there are any requests that require LoRA.
+        offset_start (int, optional): Offset start for output_tensor.
+            Defaults to 0.
+        add_inputs (bool, optional): Whether to add the input tensor to the
+            output tensor. Defaults to False.
+        group_k (int, optional): Block size for K in block-wise quantization.
+        group_n (int, optional): Block size for N in block-wise quantization.
+        use_fp8_w8a8 (bool, optional): Whether to use FP8 W8A8 quantization.
+        per_channel_quant (bool, optional): Whether to use per-channel quantization.
+    """
+    assert no_lora_flag_cpu.numel() == 1
+    if no_lora_flag_cpu.item():
+        # None of the inputs require LoRA.
+        return
+
+    if use_fp8_w8a8:
+        assert inputs.dtype in [
+            torch.float8_e4m3fn,
+            torch.float8_e5m2,
+        ]
+        for weight in lora_b_weights:
+            assert weight.dtype in [
+                torch.float8_e5m2,
+                torch.float8_e4m3fn,
+            ]
+    else:
+        assert inputs.dtype in [torch.float16, torch.bfloat16, torch.float32]
+        for weight in lora_b_weights:
+            assert weight.dtype in [torch.float16, torch.bfloat16]
+    assert inputs.size(0) == len(lora_b_weights)
+    assert output_tensor.is_contiguous()
+
+    # metadata sanity check.
+    M = inputs.size(1)
+    assert token_lora_mapping.size(0) == M
+    assert token_lora_mapping.size(0) == token_indices_sorted_by_lora_ids.size(0)
+    assert lora_ids.size(0) == num_tokens_per_lora.size(0)
+    assert lora_token_start_loc.size(0) == lora_ids.size(0) + 1
+
+    (
+        slice_start_tensor,
+        lora_ptr_tensor,
+        lora_strides_d0_tensor,
+        lora_strides_d1_tensor,
+        lora_strides_d2_tensor,
+        hidden_sizes_tensor,
+        same_stride,
+        MAX_N,
+    ) = _get_lora_b_ptr(lora_b_weights, offset_start, inputs.device)
+
+    # Get scale pointers
+    if b_scale is not None:
+        b_scale_ptr_tensor = _get_expand_lora_scale_ptr(b_scale, inputs.device)
+    else:
+        b_scale_ptr_tensor = None
+    K = lora_b_weights[0].shape[-1]
+    ADD_INPUTS = add_inputs
+    MAX_LORAS = lora_ids.size(0)
+
+    CAST_TYPE = False
+    NUM_SLICES = len(lora_b_weights)
+
+    # Triton kernel configs.
+    kernel_config = get_lora_op_configs(
+        op_type="expand",
+        max_loras=MAX_LORAS,
+        batch=M,
+        hidden_size=MAX_N,
+        rank=K,
+        num_slices=NUM_SLICES,
+        add_inputs=add_inputs,
+    )
+    BLOCK_M = kernel_config["block_m"]
+    BLOCK_N = kernel_config["block_n"]
+    BLOCK_K = kernel_config["block_k"]
+    NUM_WARPS = kernel_config["num_warps"]
+    NUM_CTAS = kernel_config.get("num_ctas", 1)
+    NUM_STAGES = kernel_config["num_stages"]
+
+    EVEN_K = K % BLOCK_K == 0
+
+    grid = (
+        triton.cdiv(M, BLOCK_M) * triton.cdiv(MAX_N, BLOCK_N),
+        NUM_SLICES,
+        num_active_loras,
+    )
+    # We disable PDL temporarily because LoRA kernels are not launching back-to-back,
+    # making PDL invalid and affecting the kernel performance.
+    use_gdc = False  # supports_pdl(inputs.device)
+    # Get scale strides
+    if a_scale is not None:
+        a_scale_m_stride = a_scale.stride(0) if a_scale.dim() > 1 else 0
+        a_scale_k_stride = a_scale.stride(-1) if a_scale.dim() > 1 else 0
+    else:
+        a_scale_m_stride = 0
+        a_scale_k_stride = 0
+
+    if b_scale is not None and b_scale[0].dim() > 0:
+        b_scale_l_stride = b_scale[0].stride(0) if b_scale[0].dim() > 0 else 0
+        b_scale_n_stride = (
+            b_scale[0].stride(-2)
+            if b_scale[0].dim() > 2
+            else (b_scale[0].stride(-1) if b_scale[0].dim() > 1 else 1)
+        )
+        b_scale_k_stride = b_scale[0].stride(-1) if b_scale[0].dim() > 2 else 0
+    else:
+        b_scale_l_stride = 1
+        b_scale_n_stride = 0
+        b_scale_k_stride = 0
+
+    _lora_expand_kernel_fp8[grid](
+        inputs,
+        lora_ptr_tensor,
+        output_tensor,
+        a_scale,
+        b_scale_ptr_tensor,
+        M,
+        MAX_N,
+        K,
+        token_indices_sorted_by_lora_ids,
+        num_tokens_per_lora,
+        lora_token_start_loc,
+        lora_ids,
+        slice_start_tensor,
+        inputs.stride(0),
+        inputs.stride(1),
+        inputs.stride(2),
+        lora_strides_d0_tensor,
+        lora_strides_d1_tensor,
+        lora_strides_d2_tensor,
+        a_scale_m_stride,
+        a_scale_k_stride,
+        b_scale_l_stride,
+        b_scale_n_stride,
+        b_scale_k_stride,
+        output_tensor.stride(0),
+        output_tensor.stride(1),
+        hidden_sizes_tensor,
+        group_n,
+        group_k,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        EVEN_K,
+        ADD_INPUTS,
+        CAST_TYPE,
+        NUM_SLICES,
+        same_stride,
+        use_gdc,
+        use_fp8_w8a8=use_fp8_w8a8,
+        per_channel_quant=per_channel_quant,
+        num_warps=NUM_WARPS,
+        num_ctas=NUM_CTAS,
+        num_stages=NUM_STAGES,
+        launch_pdl=use_gdc,
+    )
+
+    return
+
+
+def _lora_expand_fp8_fake(
+    inputs: torch.Tensor,
+    lora_b_weights: list[torch.Tensor],
+    output_tensor: torch.Tensor,
+    token_lora_mapping: torch.Tensor,
+    token_indices_sorted_by_lora_ids: torch.Tensor,
+    num_tokens_per_lora: torch.Tensor,
+    lora_token_start_loc: torch.Tensor,
+    lora_ids: torch.Tensor,
+    no_lora_flag_cpu: torch.Tensor,
+    num_active_loras: int,
+    b_scale: list[torch.Tensor],
+    a_scale: torch.Tensor | None = None,
+    offset_start: int = 0,
+    add_inputs: bool = False,
+    group_k: int = 0,
+    group_n: int = 0,
+    use_fp8_w8a8: bool = False,
+    per_channel_quant: bool = False,
+) -> None:
+    return
+
+
+try:
+    direct_register_custom_op(
+        op_name="lora_expand_fp8",
+        op_func=_lora_expand_fp8,
+        mutates_args=["output_tensor"],
+        fake_impl=_lora_expand_fp8_fake,
+    )
+    lora_expand_fp8 = torch.ops.vllm.lora_expand_fp8
+
+except AttributeError:
+    lora_expand_fp8 = _lora_expand_fp8

vllm/lora/ops/triton_ops/lora_shrink_fp8_op.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Based on:
+Chen, L., Ye, Z., Wu, Y., Zhuo, D., Ceze, L., & Krishnamurthy, A. (2023).
+Punica: Multi-Tenant LoRA Serving.
+https://arxiv.org/abs/2310.18547
+"""
+
+import torch
+
+from vllm.lora.ops.triton_ops.fp8_kernel_utils import do_shrink_kernel_fp8
+from vllm.lora.ops.triton_ops.utils import _get_lora_a_ptr, get_lora_op_configs
+from vllm.triton_utils import tl, triton
+from vllm.utils.torch_utils import direct_register_custom_op
+
+_SHRINK_LORA_SCALE_PTR_DICT: dict[tuple[int, ...], tuple] = {}
+
+
+def _get_shrink_lora_scale_ptr(
+    lora_scale_weights: list[torch.Tensor], device: torch.device
+):
+    """
+    `_SHRINK_LORA_SCALE_PTR_DICT` collects the required information during
+    `profile_run`. After this, it remains constant and subsequent usage is
+    through LUT.
+
+    Returns a tuple of (scale_ptr_tensor, l_stride, n_stride, k_stride).
+
+    Supports scale tensors of varying dimensionality:
+    - 1D: (lora_num,) — tensor-wise quantization
+    - 2D: (lora_num, N) — per-channel quantization
+    - 3D: (lora_num, N, K) — block-wise quantization
+    - 4D: (lora_num, 1, N, K) — block-wise with extra dim (squeezed to 3D)
+
+    Refer to:
+    https://github.com/triton-lang/triton/blob/release/3.1.x/python/tutorials/08-grouped-gemm.py
+    """
+    key = tuple(lora_weight.data_ptr() for lora_weight in lora_scale_weights)
+
+    if values := _SHRINK_LORA_SCALE_PTR_DICT.get(key):
+        return values
+
+    tensor_ptrs = []
+    scale_l_strides = []
+    scale_n_strides = []
+    scale_k_strides = []
+    for lora_scale_weight in lora_scale_weights:
+        if lora_scale_weight.ndim == 4:  # shape:(lora_num,1,size,rank)
+            assert lora_scale_weight.size(1) == 1
+            lora_scale_weight = lora_scale_weight.squeeze(dim=1)
+        assert 1 <= lora_scale_weight.ndim <= 3
+        assert lora_scale_weight.is_contiguous()
+        tensor_ptrs.append(lora_scale_weight.data_ptr())
+        scale_l_strides.append(
+            lora_scale_weight.stride(0) if lora_scale_weight.ndim > 0 else 0
+        )
+        scale_n_strides.append(
+            lora_scale_weight.stride(-2)
+            if lora_scale_weight.ndim > 2
+            else (lora_scale_weight.stride(-1) if lora_scale_weight.ndim > 1 else 1)
+        )
+        scale_k_strides.append(
+            lora_scale_weight.stride(-1) if lora_scale_weight.ndim > 2 else 0
+        )
+    if len(lora_scale_weights) > 1:
+        scale_ptr_tensor = torch.tensor(tensor_ptrs, device=device, dtype=torch.uint64)
+    else:
+        scale_ptr_tensor = lora_scale_weights[0]
+
+    if (
+        len(set(scale_l_strides)) > 1
+        or len(set(scale_n_strides)) > 1
+        or len(set(scale_k_strides)) > 1
+    ):
+        raise ValueError("All LoRA scale weights must have the same stride.")
+
+    _SHRINK_LORA_SCALE_PTR_DICT[key] = (
+        scale_ptr_tensor,
+        scale_l_strides[0],
+        scale_n_strides[0],
+        scale_k_strides[0],
+    )
+    return _SHRINK_LORA_SCALE_PTR_DICT.get(key)
+
+
+@triton.jit
+def _lora_shrink_kernel_fp8(
+    input_ptr,
+    lora_ptr,
+    out_ptr,
+    a_scale_ptr,
+    b_scale_ptr,
+    M,
+    N,
+    K,
+    token_indices_sorted_by_lora_ids,
+    num_tokens_per_lora,
+    lora_token_start_loc,
+    lora_ids,
+    scaling,
+    input_d0_stride,
+    input_d1_stride,
+    lora_d0_stride,
+    lora_d1_stride,
+    lora_d2_stride,
+    a_scale_m_stride,
+    a_scale_k_stride,
+    b_scale_l_stride,
+    b_scale_n_stride,
+    b_scale_k_stride,
+    output_d0_stride,
+    output_d1_stride,
+    output_d2_stride,
+    group_n: tl.constexpr,
+    group_k: tl.constexpr,
+    BLOCK_M: tl.constexpr,
+    BLOCK_N: tl.constexpr,
+    BLOCK_K: tl.constexpr,
+    EVEN_K: tl.constexpr,
+    SPLIT_K: tl.constexpr,
+    GROUP_SIZE_M: tl.constexpr,
+    SLICE_NUM: tl.constexpr,
+    USE_GDC: tl.constexpr,  ## should always be false in shrink kernel
+    use_fp8_w8a8: tl.constexpr,
+    per_channel_quant: tl.constexpr,
+    launch_pdl: tl.constexpr,
+):
+    cta_n_num = tl.cdiv(N, BLOCK_N)
+    cta_m_num = tl.cdiv(M, BLOCK_M)
+
+    pid_sk_m_n = tl.program_id(axis=0)
+    pid_sk = pid_sk_m_n % SPLIT_K
+
+    pid_m_n = pid_sk_m_n // SPLIT_K
+    num_pid_in_group = GROUP_SIZE_M * cta_n_num
+    group_id = pid_m_n // num_pid_in_group
+    first_pid_m = group_id * GROUP_SIZE_M
+
+    group_size_m = min(cta_m_num - first_pid_m, GROUP_SIZE_M)
+
+    # Column-major ordering within groups for better cache reuse
+    pid_m = first_pid_m + ((pid_m_n % num_pid_in_group) % group_size_m)
+    pid_n = (pid_m_n % num_pid_in_group) // group_size_m
+
+    slice_id = tl.program_id(axis=1)
+    lora_idx = tl.program_id(axis=2)
+
+    lora_id = tl.load(lora_ids + lora_idx)
+    if lora_id == -1:
+        # Early exit for the no-lora case.
+        return
+
+    lora_m_size = tl.load(num_tokens_per_lora + lora_idx)
+
+    cta_m_offset = pid_m * BLOCK_M
+    if cta_m_offset >= lora_m_size:
+        # Early exit CTA.
+        return
+
+    # num rows this CTA should process.
+    cta_m_len = min(BLOCK_M, lora_m_size - cta_m_offset)
+
+    # Identify all rows that this CTA should process.
+    lora_m_indices_start = tl.load(lora_token_start_loc + lora_idx)
+    cta_lora_seq_indices = (
+        token_indices_sorted_by_lora_ids + lora_m_indices_start + cta_m_offset
+    )
+
+    # Load all relevant row indices.
+    offset_m = tl.arange(0, BLOCK_M) % cta_m_len
+    ram = tl.load(cta_lora_seq_indices + offset_m)
+
+    do_shrink_kernel_fp8(
+        pid_n,
+        pid_sk,
+        slice_id,
+        lora_id,
+        input_ptr,
+        lora_ptr,
+        out_ptr,
+        a_scale_ptr,
+        b_scale_ptr,
+        N,
+        K,
+        cta_m_len,
+        ram,  # array identifying the rows of Input ptr to operate on
+        # input strides
+        input_d0_stride,
+        input_d1_stride,
+        # lora strides
+        lora_d0_stride,
+        lora_d1_stride,
+        lora_d2_stride,
+        # scale strides
+        a_scale_m_stride,
+        a_scale_k_stride,
+        b_scale_l_stride,
+        b_scale_n_stride,
+        b_scale_k_stride,
+        # output strides
+        output_d0_stride,
+        output_d1_stride,
+        output_d2_stride,
+        scaling,
+        # block size for block-wise quantization
+        group_n,
+        group_k,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        EVEN_K,
+        SPLIT_K,
+        SLICE_NUM,
+        USE_GDC,
+        use_fp8_w8a8,
+        per_channel_quant,
+        launch_pdl,
+    )
+
+
+@torch.inference_mode()
+def _lora_shrink_fp8(
+    inputs: torch.Tensor,  # shape [num_tokens, hidden_size] - FP8 or FP16/BF16
+    lora_a_weights: list[
+        torch.Tensor
+    ],  # shape [num_loras, lora_rank, hidden_size] - FP8 or FP16/BF16
+    output_tensor: torch.Tensor,  # shape [num_slices, num_tokens, lora_rank]
+    token_lora_mapping: torch.Tensor,  # shape [num_tokens]
+    token_indices_sorted_by_lora_ids: torch.Tensor,  # shape [num_tokens]
+    num_tokens_per_lora: torch.Tensor,  # shape [max-loras + 1]
+    lora_token_start_loc: torch.Tensor,  # shape [max-loras + 2]
+    lora_ids: torch.Tensor,  # shape [max-loras + 1]
+    no_lora_flag_cpu: torch.Tensor,  # shape [1]
+    num_active_loras: int,  # number of active LoRAs (unused here, for API compat)
+    scaling: float,
+    b_scale: list[torch.Tensor],  # LoRA weight scale per slice
+    a_scale: torch.Tensor | None = None,  # Activation scale - per-token or block-wise
+    group_k: int = 0,  # Block size for K in block-wise quantization (0 = tensor-wise)
+    group_n: int = 0,  # Block size for N in block-wise quantization
+    use_fp8_w8a8: bool = False,
+    per_channel_quant: bool = False,
+) -> None:
+    """
+    Args:
+        inputs: FP8 or FP16/BF16 input tensor [num_tokens, hidden_size]
+        lora_a_weights: List of FP8 or FP16/BF16 LoRA A weights per slice
+        output_tensor: Output tensor (FP16/BF16/FP32)
+        token_lora_mapping: Token to LoRA ID mapping
+        token_indices_sorted_by_lora_ids: Sorted token indices
+        num_tokens_per_lora: Number of tokens per LoRA
+        lora_token_start_loc: Start location for each LoRA's tokens
+        lora_ids: LoRA IDs to process
+        scaling: LoRA scaling factor
+        a_scale: Activation quantization scales
+        b_scale: Weight quantization scales per slice
+        group_k: Block size for K dimension quantization
+        group_n: Block size for N dimension quantization
+        use_fp8_w8a8: Whether to use FP8 weights and activations
+        per_channel_quant: Whether to use per-channel quantization
+    """
+    assert no_lora_flag_cpu.numel() == 1
+    if no_lora_flag_cpu.item():
+        # None of the inputs require LoRA.
+        return
+
+    assert inputs.size(1) == lora_a_weights[0].size(-1)
+    assert inputs.is_contiguous()
+    assert output_tensor.is_contiguous()
+
+    # metadata sanity check
+    M = inputs.size(0)
+    assert token_lora_mapping.size(0) == M
+    assert token_lora_mapping.size(0) == token_indices_sorted_by_lora_ids.size(0)
+    assert lora_ids.size(0) == num_tokens_per_lora.size(0)
+    assert lora_token_start_loc.size(0) == lora_ids.size(0) + 1
+
+    output_tensor.zero_()
+
+    # Get LoRA weight pointers
+    (lora_ptr_tensor, lora_strides_d0, lora_strides_d1, lora_strides_d2) = (
+        _get_lora_a_ptr(lora_a_weights, inputs.device)
+    )
+
+    # Get scale pointers if using FP8
+    if use_fp8_w8a8:
+        assert a_scale is not None, "a_scale required for FP8 w8a8"
+        assert b_scale is not None, "b_scale required for FP8"
+
+        b_scale_ptr_tensor, b_scale_l_stride, b_scale_n_stride, b_scale_k_stride = (
+            _get_shrink_lora_scale_ptr(b_scale, inputs.device)
+        )
+        a_scale_ptr = (
+            a_scale if a_scale is not None else torch.tensor(1.0, device=inputs.device)
+        )
+    else:
+        b_scale_ptr_tensor = torch.tensor(0, device=inputs.device)
+        b_scale_l_stride = 0
+        b_scale_n_stride = 0
+        b_scale_k_stride = 0
+        a_scale_ptr = torch.tensor(0, device=inputs.device)
+
+    N, K = lora_a_weights[0].shape[-2:]  # K=hidden_size, N=rank
+    NUM_SLICES = len(lora_a_weights)
+    MAX_LORAS = lora_ids.size(0)
+
+    # Triton kernel configs
+    kernel_config = get_lora_op_configs(
+        "shrink",
+        max_loras=MAX_LORAS,
+        batch=M,
+        hidden_size=K,
+        rank=N,
+        num_slices=NUM_SLICES,
+    )
+    BLOCK_M = kernel_config["block_m"]
+    BLOCK_N = kernel_config["block_n"]
+    BLOCK_K = kernel_config["block_k"]
+    SPLIT_K = kernel_config["split_k"]
+    NUM_WARPS = kernel_config["num_warps"]
+    NUM_STAGES = kernel_config["num_stages"]
+    NUM_CTAS = kernel_config["num_ctas"]
+    GROUP_SIZE_M = kernel_config.get("group_size_m", 8)
+    assert BLOCK_K is not None and SPLIT_K is not None
+    EVEN_K = K % (BLOCK_K * SPLIT_K) == 0
+
+    # Grid configuration with column-major ordering support
+    grid = (
+        SPLIT_K * triton.cdiv(M, BLOCK_M) * triton.cdiv(N, BLOCK_N),
+        NUM_SLICES,
+        num_active_loras,
+    )
+
+    # Determine scale strides
+    if use_fp8_w8a8:
+        if a_scale is not None and a_scale.ndim == 2:
+            a_scale_m_stride = a_scale.stride(0)
+            a_scale_k_stride = a_scale.stride(1)
+        else:
+            a_scale_m_stride = 0
+            a_scale_k_stride = 0
+    else:
+        a_scale_m_stride = 0
+        a_scale_k_stride = 0
+
+    # We disable PDL temporarily because LoRA kernels are not launching back-to-back,
+    # making PDL invalid and affecting the kernel performance.
+    use_gdc = False  # supports_pdl(inputs.device)
+    _lora_shrink_kernel_fp8[grid](
+        inputs,
+        lora_ptr_tensor,
+        output_tensor,
+        a_scale_ptr,
+        b_scale_ptr_tensor,
+        M,
+        N,
+        K,
+        token_indices_sorted_by_lora_ids,
+        num_tokens_per_lora,
+        lora_token_start_loc,
+        lora_ids,
+        scaling,
+        inputs.stride(0),
+        inputs.stride(1),
+        lora_strides_d0,
+        lora_strides_d1,
+        lora_strides_d2,
+        a_scale_m_stride,
+        a_scale_k_stride,
+        b_scale_l_stride,
+        b_scale_n_stride,
+        b_scale_k_stride,
+        output_tensor.stride(0),
+        output_tensor.stride(1),
+        output_tensor.stride(2),
+        group_n,
+        group_k,
+        BLOCK_M,
+        BLOCK_N,
+        BLOCK_K,
+        EVEN_K,
+        SPLIT_K,
+        GROUP_SIZE_M,
+        NUM_SLICES,
+        use_gdc,
+        use_fp8_w8a8,
+        per_channel_quant,
+        use_gdc,
+        num_warps=NUM_WARPS,
+        num_ctas=NUM_CTAS,
+        num_stages=NUM_STAGES,
+    )
+
+    return
+
+
+def _lora_shrink_fp8_fake(
+    inputs: torch.Tensor,
+    lora_a_weights: list[torch.Tensor],
+    output_tensor: torch.Tensor,
+    token_lora_mapping: torch.Tensor,
+    token_indices_sorted_by_lora_ids: torch.Tensor,
+    num_tokens_per_lora: torch.Tensor,
+    lora_token_start_loc: torch.Tensor,
+    lora_ids: torch.Tensor,
+    no_lora_flag_cpu: torch.Tensor,
+    num_active_loras: int,
+    scaling: float,
+    b_scale: list[torch.Tensor],  # LoRA weight scale per slice
+    a_scale: torch.Tensor | None = None,  # Activation scale - per-token or block-wise
+    group_k: int = 0,  # Block size for K in block-wise quantization (0 = tensor-wise)
+    group_n: int = 0,  # Block size for N in block-wise quantization
+    use_fp8_w8a8: bool = False,
+    per_channel_quant: bool = False,
+) -> None:
+    return
+
+
+try:
+    direct_register_custom_op(
+        op_name="lora_shrink_fp8",
+        op_func=_lora_shrink_fp8,
+        mutates_args=["output_tensor"],
+        fake_impl=_lora_shrink_fp8_fake,
+    )
+    lora_shrink_fp8 = torch.ops.vllm.lora_shrink_fp8
+
+except AttributeError:
+    lora_shrink_fp8 = _lora_shrink_fp8

vllm/lora/ops/triton_ops/utils.py

@@ -252,7 +252,7 @@ def get_lora_op_configs(
         default = {
             "block_m": 64,
             "block_n": 64 if num_slices > 1 else 128,
-            "block_k": 16,
+            "block_k": 32,
             "num_warps": 4,
             "num_ctas": 1,
             "num_stages": 2,