Replace `nn.ConvNd` with vLLM's `ConvNdLayer` for Transformers modeling backend (#31498)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/model_executor/models/transformers/base.py

@@ -47,6 +47,7 @@ from vllm.model_executor.models.transformers.utils import (
     get_feature_request_tip,
     init_on_device_without_buffers,
     log_replacement,
+    replace_conv_class,
     replace_linear_class,
     replace_rms_norm_class,
 )
@@ -314,6 +315,8 @@ class Base(
                     new_module = replace_linear_class(
                         child_module, style, self.quant_config, prefix=qual_name
                     )
+                elif isinstance(child_module, (nn.Conv2d, nn.Conv3d)):
+                    new_module = replace_conv_class(child_module)
                 elif child_module.__class__.__name__.endswith("RMSNorm"):
                     new_module = replace_rms_norm_class(
                         child_module, self.text_config.hidden_size

vllm/model_executor/models/transformers/utils.py

@@ -25,6 +25,7 @@ from torch import nn
 
 from vllm.config.utils import getattr_iter
 from vllm.logger import init_logger
+from vllm.model_executor.layers.conv import Conv2dLayer, Conv3dLayer
 from vllm.model_executor.layers.layernorm import GemmaRMSNorm, RMSNorm
 from vllm.model_executor.layers.linear import (
     ColumnParallelLinear,
@@ -136,6 +137,45 @@ def replace_linear_class(
     )
 
 
+TorchConv = nn.Conv2d | nn.Conv3d
+VllmConv = Conv2dLayer | Conv3dLayer
+
+
+def replace_conv_class(conv: TorchConv) -> VllmConv | TorchConv:
+    """Replace a Transformers Conv2d/Conv3d with vLLM's Conv2d/Conv3d.
+
+    Args:
+        conv: `nn.Conv2d` or `nn.Conv3d` to be replaced.
+    Returns:
+        The new `Conv2dLayer` or `Conv3dLayer`. If the conv module is not supported,
+        returns the original conv module.
+    """
+    # vLLM does not handle non-zero padding modes
+    if conv.padding_mode != "zeros":
+        return conv
+
+    vllm_conv_cls = {
+        nn.Conv2d: Conv2dLayer,
+        nn.Conv3d: Conv3dLayer,
+    }.get(type(conv))
+
+    if vllm_conv_cls is None:
+        return conv
+
+    return vllm_conv_cls(
+        in_channels=conv.in_channels,
+        out_channels=conv.out_channels,
+        kernel_size=conv.kernel_size,
+        stride=conv.stride,
+        padding=conv.padding,
+        dilation=conv.dilation,
+        groups=conv.groups,
+        bias=conv.bias is not None,
+        padding_mode=conv.padding_mode,
+        params_dtype=conv.weight.dtype,
+    )
+
+
 def replace_rms_norm_class(rms_norm: nn.Module, hidden_size: int) -> RMSNorm:
     """Replace a Transformers RMSNorm with vLLM's RMSNorm.