[Hardware] Support platforms and plugin system (#774)

Signed-off-by: gcanlin <canlinguosdu@gmail.com>

vllm_omni/diffusion/hooks/sequence_parallel.py

@@ -335,10 +335,7 @@ class SequenceParallelSplitHook(ModelHook):
         2. Creates an attention mask indicating valid vs padding positions
         3. Stores the mask and padding info in ForwardContext
         """
-        from vllm_omni.diffusion.attention.selector import (
-            _BACKENDS_SUPPORT_ATTENTION_MASK,
-            get_attn_backend,
-        )
+        from vllm_omni.diffusion.attention.selector import get_attn_backend
         from vllm_omni.diffusion.distributed.parallel_state import (
             get_ring_parallel_world_size,
             get_sequence_parallel_rank,
@@ -359,7 +356,7 @@ class SequenceParallelSplitHook(ModelHook):
 
         # Check backend compatibility
         attn_backend = get_attn_backend(-1)
-        if attn_backend.get_name() not in _BACKENDS_SUPPORT_ATTENTION_MASK:
+        if not attn_backend.supports_attention_mask:
             raise ValueError(
                 f"Sequence length ({seq_len}) is not divisible by SP world size ({world_size}). "
                 f"Cannot use {attn_backend.get_name()} which does not support attention_mask. "