[Bugfix] Revert Qwen2-VL part of change in #28271 (#30542)

Signed-off-by: Zifei Tong <zifeitong@gmail.com>

vllm/model_executor/models/qwen2_vl.py

@@ -50,7 +50,7 @@ from vllm.attention.layer import (
 )
 from vllm.config import VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
-from vllm.distributed import parallel_state
+from vllm.distributed import parallel_state, tensor_model_parallel_all_gather
 from vllm.distributed import utils as dist_utils
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import QuickGELU
@@ -360,10 +360,21 @@ class Qwen2VisionAttention(nn.Module):
     def split_qkv(self, qkv: torch.Tensor) -> tuple[torch.Tensor, ...]:
         # [s, b, 3 * head * head_dim]
         seq_len, bs, _ = qkv.shape
+        if self.tp_size > 1:
+            qkv = tensor_model_parallel_all_gather(qkv)
 
         # [s, b, 3 * head * head_dim] -> 3 * [s, b, head * head_dim]
         q, k, v = qkv.chunk(3, dim=2)
 
+        # 3 * [s, b, head * head_dim]
+        if self.tp_size > 1:
+            splitter = partial(
+                dist_utils.split_tensor_along_last_dim, num_partitions=self.tp_size
+            )
+            q = splitter(q)[self.tp_rank]
+            k = splitter(k)[self.tp_rank]
+            v = splitter(v)[self.tp_rank]
+
         # 3 * [s, b, head * head_dim] -> 3 * [s, b, head, head_dim]
         new_shape = (
             seq_len,