[Diffusion] Add paged KV cache support for HunyuanImage3 DiT on NPU and GPU (#6563)

Signed-off-by: Acerak01-fy <wfy2003324@163.com>
Signed-off-by: zwhzzz0821 <zwhzzz0821@users.noreply.github.com>
Signed-off-by: zwhzzz0821 <2831474076@qq.com>
Co-authored-by: zwhzzz0821 <zwhzzz0821@users.noreply.github.com>
Co-authored-by: zwhzzz0821 <2831474076@qq.com>

tests/platforms/npu/test_diffusion_platform.py

@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+
+import importlib.util
+from types import SimpleNamespace
+
+import pytest
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+@pytest.mark.parametrize("available", [False, True])
+def test_dense_flash_capability_tracks_mindiesd(monkeypatch, available):
+    pytest.importorskip("vllm_ascend")
+    from vllm_omni.platforms.npu.platform import NPUOmniPlatform
+
+    monkeypatch.setattr(
+        importlib.util,
+        "find_spec",
+        lambda name: object() if name == "mindiesd" and available else None,
+    )
+
+    assert NPUOmniPlatform.supports_diffusion_dense_flash_attention() is available
+
+
+def test_paged_config_uses_ascend_kernel_block_size() -> None:
+    pytest.importorskip("vllm_ascend")
+    from vllm_ascend.attention.attention_v1 import AscendAttentionBackend
+
+    from vllm_omni.diffusion.diffusion_kv.config import DiffusionKVCacheMode
+    from vllm_omni.platforms.npu.platform import NPUOmniPlatform
+
+    vllm_config = SimpleNamespace(cache_config=SimpleNamespace(block_size=16))
+    NPUOmniPlatform.configure_diffusion_vllm_config(
+        vllm_config,
+        SimpleNamespace(diffusion_kv_mode=DiffusionKVCacheMode.PAGED_SCHEDULER),
+    )
+
+    assert vllm_config.cache_config.block_size == AscendAttentionBackend.get_supported_kernel_block_sizes()[0]
+
+
+def test_strict_ulysses_paged_backend_bypasses_ascend_pcp() -> None:
+    pytest.importorskip("vllm_ascend")
+    from vllm_ascend.attention.attention_v1 import (
+        AscendAttentionBackend,
+        AscendAttentionBackendImpl,
+        AscendAttentionMetadataBuilder,
+    )
+
+    from vllm_omni.platforms.npu.platform import NPUOmniPlatform
+
+    assert (
+        NPUOmniPlatform.get_diffusion_paged_kv_attn_backend(
+            AscendAttentionBackend,
+            ulysses_degree=1,
+        )
+        is AscendAttentionBackend
+    )
+    backend = NPUOmniPlatform.get_diffusion_paged_kv_attn_backend(
+        AscendAttentionBackend,
+        ulysses_degree=2,
+    )
+    assert backend.get_impl_cls() is AscendAttentionBackendImpl
+    assert backend.get_builder_cls() is AscendAttentionMetadataBuilder