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73 changes: 73 additions & 0 deletions vllm/_xpu_ops.py
Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,72 @@ def _int4_gemm_w4a16_fake(
return torch.empty((M, N), dtype=input.dtype, device=input.device)


def _gdn_attention_core_xpu_impl(
core_attn_out: torch.Tensor,
z: torch.Tensor,
projected_states_qkvz: torch.Tensor,
projected_states_ba: torch.Tensor,
layer_name: str,
) -> None:
"""Custom op wrapping the XPU SYCL GDN kernel for torch.compile."""
from vllm.forward_context import get_forward_context
from vllm.v1.attention.backends.gdn_attn import GDNAttentionMetadata

forward_context = get_forward_context()
self = forward_context.no_compile_layers[layer_name]
attn_metadata = forward_context.attn_metadata

if attn_metadata is None:

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When attn_metadata is None, this implementation returns without writing to z (and z is created with torch.empty_like in forward_xpu). That leaves z uninitialized but it is subsequently consumed by the output projection (self.norm(core_attn_out, z)), producing nondeterministic outputs/NaNs during compile/profile passes that run with attn_metadata=None. To keep behavior well-defined, initialize z (e.g., zero-fill or another safe default) before returning in the attn_metadata is None path, or allocate z as zeros in forward_xpu for the no-metadata case.

Suggested change
if attn_metadata is None:
if attn_metadata is None:
z.zero_()

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return

assert isinstance(attn_metadata, dict)
attn_metadata = attn_metadata[self.prefix]
assert isinstance(attn_metadata, GDNAttentionMetadata)

# TODO: xpu does not support speculative decoding yet
assert attn_metadata.spec_sequence_masks is None

conv_weights = self.conv1d.weight.view(
self.conv1d.weight.size(0), self.conv1d.weight.size(2)
)

torch.ops._xpu_C.gdn_attention(
core_attn_out,
z,
projected_states_qkvz,
projected_states_ba,
self.num_k_heads,
self.num_v_heads,
self.head_k_dim,
self.head_v_dim,
conv_state=self.kv_cache[0],
ssm_state=self.kv_cache[1],
conv_weights=conv_weights,
conv_bias=self.conv1d.bias,
activation=self.activation,
A_log=self.A_log,
dt_bias=self.dt_bias,
num_prefills=attn_metadata.num_prefills,
num_decodes=attn_metadata.num_decodes,
has_initial_state=attn_metadata.has_initial_state,
non_spec_query_start_loc=attn_metadata.non_spec_query_start_loc,
non_spec_state_indices_tensor=attn_metadata.non_spec_state_indices_tensor,
num_actual_tokens=attn_metadata.num_actual_tokens,
tp_size=self.tp_size,
reorder_input=not self.gqa_interleaved_layout,
)


def _gdn_attention_core_xpu_fake(
core_attn_out: torch.Tensor,
z: torch.Tensor,
projected_states_qkvz: torch.Tensor,
projected_states_ba: torch.Tensor,
layer_name: str,
) -> None:
return


def _xpu_ops_deepseek_scaling_rope_impl(
positions: torch.Tensor,
query: torch.Tensor,
Expand Down Expand Up @@ -618,6 +684,13 @@ def register_ops_once() -> None:
fake_impl=_xpu_mxfp4_quantize_fake,
)

direct_register_custom_op(
op_name="gdn_attention_core_xpu",
op_func=_gdn_attention_core_xpu_impl,
mutates_args=["core_attn_out", "z"],
fake_impl=_gdn_attention_core_xpu_fake,
)

_OPS_REGISTERED = True


Expand Down
1 change: 1 addition & 0 deletions vllm/config/compilation.py
Original file line number Diff line number Diff line change
Expand Up @@ -742,6 +742,7 @@ class CompilationConfig:
"vllm::linear_attention",
"vllm::plamo2_mamba_mixer",
"vllm::gdn_attention_core",
"vllm::gdn_attention_core_xpu",
"vllm::olmo_hybrid_gdn_full_forward",
"vllm::kda_attention",
"vllm::sparse_attn_indexer",
Expand Down
47 changes: 7 additions & 40 deletions vllm/model_executor/layers/mamba/gdn_linear_attn.py
Original file line number Diff line number Diff line change
Expand Up @@ -620,53 +620,20 @@ def forward_xpu(
# ============================================================
# Part 2: Core Attention
# ============================================================
forward_context = get_forward_context()
attn_metadata: AttentionMetadata = forward_context.attn_metadata
core_attn_out = torch.zeros(
(num_tokens, self.num_v_heads // self.tp_size, self.head_v_dim),
dtype=hidden_states.dtype,
device=hidden_states.device,
)
z = torch.empty_like(core_attn_out)
if attn_metadata is not None:
attn_metadata = attn_metadata[self.prefix]

# TODO: xpu does not support this param yet
spec_sequence_masks = attn_metadata.spec_sequence_masks
assert spec_sequence_masks is None

conv_weights = self.conv1d.weight.view(
self.conv1d.weight.size(0), self.conv1d.weight.size(2)
)

conv_state = self.kv_cache[0]
ssm_state = self.kv_cache[1]

torch.ops._xpu_C.gdn_attention(
core_attn_out,
z,
projected_states_qkvz,
projected_states_ba,
self.num_k_heads,
self.num_v_heads,
self.head_k_dim,
self.head_v_dim,
conv_state=conv_state,
ssm_state=ssm_state,
conv_weights=conv_weights,
conv_bias=self.conv1d.bias,
activation=self.activation,
A_log=self.A_log,
dt_bias=self.dt_bias,
num_prefills=attn_metadata.num_prefills,
num_decodes=attn_metadata.num_decodes,
has_initial_state=attn_metadata.has_initial_state,
non_spec_query_start_loc=attn_metadata.non_spec_query_start_loc,
non_spec_state_indices_tensor=attn_metadata.non_spec_state_indices_tensor,
num_actual_tokens=attn_metadata.num_actual_tokens,
tp_size=self.tp_size,
reorder_input=not self.gqa_interleaved_layout,
)
torch.ops.vllm.gdn_attention_core_xpu(
core_attn_out,
z,
projected_states_qkvz,
projected_states_ba,
self.prefix,
)
Comment on lines +628 to +634

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torch.ops.vllm.gdn_attention_core_xpu is registered in vllm/_xpu_ops.py, but this module is not imported anywhere in this file. If the runtime path that hits forward_xpu hasn’t already imported vllm._xpu_ops, the operator won’t exist and this call will raise at runtime. Consider importing vllm._xpu_ops (or from vllm._xpu_ops import xpu_ops to trigger registration) under the XPU path before invoking the op, or registering the op alongside gdn_attention_core in this module to make registration unconditionally happen when this layer is imported.

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# ============================================================
# Part 3: Output Projection
Expand Down
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