Revert "[Bugfix] Disable TRTLLM attention with KV transfer enabled (#33192)" (#34832)

Signed-off-by: Zhanqiu Hu <zh338@cornell.edu>

vllm/v1/attention/backends/flashinfer.py

@@ -575,20 +575,6 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
         # try to use fp8 q if kv cache is fp8, and will fall back to model dtype
         # if TRTLLM attention kernel is not used when building attn metadata
         can_use_trtllm = can_use_trtllm_attention(self.num_qo_heads, self.num_kv_heads)
-
-        # TRTLLM attention requires strictly contiguous KV cache tensors.
-        # When KV transfer (P/D disaggregation) is enabled, the KV cache may be
-        # permuted into non-contiguous views, which causes assertion failures.
-        self._kv_transfer_enabled = vllm_config.kv_transfer_config is not None
-        if can_use_trtllm and self._kv_transfer_enabled:
-            logger.info_once(
-                "TRTLLM attention is disabled because KV transfer "
-                "(P/D disaggregation) is enabled. TRTLLM attention requires "
-                "strictly contiguous KV cache tensors which may not be "
-                "guaranteed with KV transfer."
-            )
-            can_use_trtllm = False
-
         if (
             can_use_trtllm
             and not vllm_config.attention_config.disable_flashinfer_q_quantization
@@ -865,9 +851,6 @@ class FlashInferMetadataBuilder(AttentionMetadataBuilder[FlashInferMetadata]):
             has_sinks=self.has_sinks,
             has_spec=uses_spec_reorder,
         )
-        # KV transfer requires non-contiguous KV cache views, incompatible with TRTLLM
-        if self._kv_transfer_enabled:
-            prefill_use_trtllm = False
         decode_use_trtllm = (
             self.use_trtllm_decode_attention and self.dcp_world_size <= 1
         )