[XPU]fallback to TRITON_ATTN on xpu when use float32 dtype (#31762)

Signed-off-by: sihao.li <sihao.li@intel.com>

vllm/platforms/xpu.py

@@ -52,11 +52,18 @@ class XPUPlatform(Platform):
             "only NHD layout is supported by XPU attention kernels."
         )
 
+        dtype = attn_selector_config.dtype
         if attn_selector_config.use_sparse:
             raise NotImplementedError("Sparse Attention is not supported on XPU.")
         if selected_backend == AttentionBackendEnum.TRITON_ATTN:
             logger.info_once("Using Triton backend.")
             return AttentionBackendEnum.TRITON_ATTN.get_path()
+        elif dtype == torch.float32:
+            logger.warning_once(
+                "Flash Attention on XPU does not support float32 dtype. "
+                "Falling back to Triton Attention backend."
+            )
+            return AttentionBackendEnum.TRITON_ATTN.get_path()
         elif selected_backend == AttentionBackendEnum.FLASH_ATTN:
             logger.info_once("Using Flash Attention backend.")
             return AttentionBackendEnum.FLASH_ATTN.get_path()