Sync from v0.13

vllm/attention/utils/fa_utils.py

@@ -0,0 +1,118 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from vllm.logger import init_logger
+from vllm.platforms import current_platform
+
+logger = init_logger(__name__)
+
+if current_platform.is_cuda():
+    from vllm import _custom_ops as ops
+
+    reshape_and_cache_flash = ops.reshape_and_cache_flash
+    from vllm.vllm_flash_attn import flash_attn_varlen_func, get_scheduler_metadata
+elif current_platform.is_xpu():
+    from vllm._ipex_ops import ipex_ops as ops
+
+    reshape_and_cache_flash = ops.reshape_and_cache_flash
+    flash_attn_varlen_func = ops.flash_attn_varlen_func
+    get_scheduler_metadata = ops.get_scheduler_metadata
+elif current_platform.is_rocm():
+    try:
+        from flash_attn import flash_attn_varlen_func  # noqa: F401
+    except ImportError as e:
+        raise ImportError(
+            "Rocm platform requires upstream flash-attn "
+            "to be installed. Please install flash-attn first."
+        ) from e
+
+
+def get_flash_attn_version(requires_alibi: bool = False) -> int | None:
+    # import here to avoid circular dependencies
+    from vllm.platforms import current_platform
+
+    if current_platform.is_xpu():
+        return 2
+    try:
+        from vllm.vllm_flash_attn.flash_attn_interface import (
+            fa_version_unsupported_reason,
+            is_fa_version_supported,
+        )
+
+        device_capability = current_platform.get_device_capability()
+
+        assert device_capability is not None
+
+        # 1. default version depending on platform
+        fa_version = (
+            3 if (device_capability.major == 9 and is_fa_version_supported(3)) else 2
+        )
+
+        # 2. override if passed by environment or config
+        from vllm.config import get_current_vllm_config
+
+        vllm_config = get_current_vllm_config()
+        if vllm_config.attention_config.flash_attn_version is not None:
+            fa_version = vllm_config.attention_config.flash_attn_version
+
+        # 3. fallback for unsupported combinations
+        if device_capability.major == 10 and fa_version == 3:
+            logger.warning_once(
+                "Cannot use FA version 3 on Blackwell platform "
+                "defaulting to FA version 2."
+            )
+            fa_version = 2
+
+        if requires_alibi and fa_version == 3:
+            logger.warning_once(
+                "Cannot use FA version 3 with ALiBi, defaulting to FA version 2."
+            )
+            fa_version = 2
+
+        if not is_fa_version_supported(fa_version):
+            logger.error(
+                "Cannot use FA version %d is not supported due to %s",
+                fa_version,
+                fa_version_unsupported_reason(fa_version),
+            )
+
+        assert is_fa_version_supported(fa_version)
+        return fa_version
+    except (ImportError, AssertionError):
+        return None
+
+
+def flash_attn_supports_fp8() -> bool:
+    return (
+        get_flash_attn_version() == 3
+        and current_platform.get_device_capability().major == 9
+    )
+
+
+def flash_attn_supports_sinks() -> bool:
+    if current_platform.is_xpu():
+        return True
+    else:
+        return get_flash_attn_version() == 3
+
+
+def flash_attn_supports_mla():
+    from vllm.platforms import current_platform
+
+    if current_platform.is_cuda():
+        try:
+            from vllm.vllm_flash_attn.flash_attn_interface import (
+                is_fa_version_supported,
+            )
+
+            return (
+                is_fa_version_supported(3)
+                and current_platform.get_device_capability()[0] == 9
+            )
+        except (ImportError, AssertionError):
+            pass
+    return False
+
+
+def is_flash_attn_varlen_func_available() -> bool:
+    return current_platform.is_cuda() or current_platform.is_xpu()