GLM-5

    def __init__(self, config: "GlmMoeDsaConfig", layer_idx: int):
        super().__init__()
        self.config = config
        self.layer_idx = layer_idx

        self.hidden_size: int = config.hidden_size
        self.n_heads: int = config.index_n_heads
        self.head_dim: int = config.index_head_dim
        self.qk_rope_head_dim: int = config.qk_rope_head_dim
        self.index_topk: int = config.index_topk
        self.q_lora_rank: int = config.q_lora_rank

        self.wq_b = nn.Linear(self.q_lora_rank, self.n_heads * self.head_dim, bias=False)
        self.wk = nn.Linear(self.hidden_size, self.head_dim, bias=False)
        self.k_norm = nn.LayerNorm(self.head_dim, eps=1e-6)
        self.weights_proj = nn.Linear(self.hidden_size, self.n_heads, bias=False)
        self.softmax_scale = self.head_dim**-0.5

… lines 194–648 omitted …

    _keep_in_fp32_modules = ["indexer.weights_proj"]

    @torch.no_grad()
    def forward(
        self,
        hidden_states: torch.Tensor,
        q_resid: torch.Tensor,
        position_embeddings: tuple[torch.Tensor, torch.Tensor],
        attention_mask: torch.Tensor,
        position_ids: torch.Tensor,  # Kept for BC
        past_key_values: Cache | None = None,
    ) -> torch.Tensor:
        """
        Selects the top-k tokens per query for DeepSeek Sparse Attention (DSA).

        Same as [`DeepseekV32Indexer.forward`], but the indexer applies **interleaved** RoPE
        rather than the non-interleaved half-split RoPE used by DeepSeek-V3.2.

        Args:
            hidden_states: Input hidden states `[B, S, hidden_size]`.
            q_resid: Query residual from `q_a_layernorm(q_a_proj(x))`, shape `[B, S, q_lora_rank]`.
            position_embeddings: `(cos, sin)` from RotaryEmbedding.
            attention_mask: Causal mask, broadcastable to `[B, S, T]`.
            past_key_values: Cache object containing the indexer key cache for this layer.

        Returns:
            `torch.Tensor`: the `int32` top-k token indices of shape `[B, S, topk]`. The eager / SDPA paths
                turn these into an additive sparse mask; the `flash-mla` kernel consumes them directly.
        """
        batch_size, seq_len, _ = hidden_states.shape
        cos, sin = position_embeddings
        q = self.wq_b(q_resid)  # [B, S, H*D]
        q = q.view(batch_size, seq_len, self.n_heads, self.head_dim)  # [B, S, H, D]
        q_rot, q_pass = torch.split(q, [self.qk_rope_head_dim, self.head_dim - self.qk_rope_head_dim], dim=-1)

        k = self.k_norm(self.wk(hidden_states)).unsqueeze(2)  # [B, S, 1, D]
        k_rot, k_pass = torch.split(k, [self.qk_rope_head_dim, self.head_dim - self.qk_rope_head_dim], dim=-1)

        # GLM-MoE-DSA uses interleaved RoPE in the indexer
        q_rot, k_rot = apply_rotary_pos_emb_interleave(q_rot, k_rot, cos, sin, unsqueeze_dim=2)
        q = torch.cat([q_rot, q_pass], dim=-1)  # [B, S, H, D]
        k = torch.cat([k_rot, k_pass], dim=-1).squeeze(2)  # [B, S, D]

        if past_key_values is not None:
            k = past_key_values.update_indexer(k, self.layer_idx)

        scores = torch.matmul(q.float(), k.transpose(-1, -2).float().unsqueeze(1)) * self.softmax_scale
        scores = F.relu(scores)

        # Weight per head and sum across heads: [B, S, 1, H] @ [B, S, H, T] → [B, S, T]
        weights = self.weights_proj(hidden_states.to(self.weights_proj.weight.dtype)).float() * (self.n_heads**-0.5)
        index_scores = torch.matmul(weights.unsqueeze(-2), scores).squeeze(-2)

        # Causality needs to be taken into account when computing scores so padding tokens don't affect computation
        if attention_mask.dtype == torch.bool:
            index_scores = index_scores.masked_fill(~attention_mask, float("-inf"))
        else:
            index_scores = index_scores + attention_mask

        topk = min(self.index_topk, index_scores.shape[-1])
        return index_scores.topk(topk, dim=-1).indices.to(torch.int32)  # [B, S, topk]

        scores = torch.matmul(q.float(), k.transpose(-1, -2).float().unsqueeze(1)) * self.softmax_scale
        scores = F.relu(scores)

        # Weight per head and sum across heads: [B, S, 1, H] @ [B, S, H, T] → [B, S, T]
        weights = self.weights_proj(hidden_states.to(self.weights_proj.weight.dtype)).float() * (self.n_heads**-0.5)
        index_scores = torch.matmul(weights.unsqueeze(-2), scores).squeeze(-2)

def eager_attention_forward(
    module: nn.Module,
    query: torch.Tensor,
    key: torch.Tensor,
    value: torch.Tensor,
    attention_mask: torch.Tensor | None,
    scaling: float,
    dropout: float = 0.0,
    **kwargs: Unpack[TransformersKwargs],
):
    key_states = repeat_kv(key, module.num_key_value_groups)
    value_states = repeat_kv(value, module.num_key_value_groups)

    attn_weights = torch.matmul(query, key_states.transpose(2, 3)) * scaling
    if attention_mask is not None:
        attn_weights = attn_weights + attention_mask

    attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query.dtype)
    attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)
    attn_output = torch.matmul(attn_weights, value_states)
    attn_output = attn_output.transpose(1, 2).contiguous()

    return attn_output, attn_weights

… lines 291–403 omitted …

        cos, sin = position_embeddings
        q_rot, k_rot = apply_rotary_pos_emb_interleave(q_rot, k_rot, cos, sin)

        # Cache read / write is performed while latent KV is still compressed
        if past_key_values is not None:
            k_pass, k_rot = past_key_values.update(k_pass, k_rot, self.layer_idx)

        query_states = torch.cat((q_pass, q_rot), dim=-1)

        key_states, value_states = self.expand_kv(k_pass, k_rot)

        # DSA: select this layer's top-k tokens, or reuse the previous full layer's on `"shared"` layers.
        if self.indexer is not None:
            topk_indices = self.indexer(
                hidden_states,
                q_resid,
                position_embeddings,
                attention_mask[:, 0, :, :],
                position_ids,  # Kept for BC
                past_key_values=past_key_values,
            )  # [B, S, topk]
        else:
            if prev_topk_indices is None:
                raise ValueError("Shared DSA layers require top-k indices from a previous full indexer layer.")
            topk_indices = prev_topk_indices

        sparse_indices = None
        if self.config._attn_implementation in ("eager", "sdpa"):
            index_mask = (
                topk_indices.new_ones((batch_size, seq_length, key_states.shape[2]), dtype=torch.bool)
                .scatter(-1, topk_indices.long(), False)
                .unsqueeze(1)
            )

            if attention_mask.dtype == torch.bool:
                attention_mask = attention_mask & ~index_mask
            else:
                attention_mask = attention_mask.masked_fill(index_mask, torch.finfo(hidden_states.dtype).min)
        else:
            sparse_indices = topk_indices

        attention_interface: Callable = ALL_ATTENTION_FUNCTIONS.get_interface(
            self.config._attn_implementation, eager_attention_forward
        )
        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask,
            dropout=0.0 if not self.training else self.attention_dropout,
            scaling=self.scaling,
            indices=sparse_indices,  # consumed by flash_mla_with_kvcache; ignored by eager / SDPA
            **kwargs,
        )

def yarn_get_mscale(scale=1, mscale=1):
    if scale <= 1:
        return 1.0
    return 0.1 * mscale * math.log(scale) + 1.0


def yarn_apply_mscale(rope_parameters, scaling):
    if rope_parameters.get("rope_type", "default") != "default":
        mscale_all_dim = rope_parameters.get("mscale_all_dim", 0)
        scaling_factor = rope_parameters["factor"]
        if mscale_all_dim:
            mscale = yarn_get_mscale(scaling_factor, mscale_all_dim)
            scaling = scaling * mscale * mscale
    return scaling

… lines 307–325 omitted …

        self.q_lora_rank = config.q_lora_rank
        self.qk_rope_head_dim = config.qk_rope_head_dim
        self.kv_lora_rank = config.kv_lora_rank
        self.v_head_dim = config.v_head_dim
        self.qk_nope_head_dim = config.qk_nope_head_dim
        self.qk_head_dim = config.qk_nope_head_dim + config.qk_rope_head_dim
        self.num_key_value_groups = config.num_attention_heads // config.num_key_value_heads

        self.is_causal = True
        self.q_a_proj = nn.Linear(self.hidden_size, self.q_lora_rank, bias=config.attention_bias)
        self.q_a_layernorm = GlmMoeDsaRMSNorm(self.q_lora_rank)
        self.q_b_proj = nn.Linear(self.q_lora_rank, self.num_heads * self.qk_head_dim, bias=False)

        self.kv_a_proj_with_mqa = nn.Linear(
            self.hidden_size,
            config.kv_lora_rank + config.qk_rope_head_dim,
            bias=config.attention_bias,
        )
        self.kv_a_layernorm = GlmMoeDsaRMSNorm(config.kv_lora_rank)
        self.kv_b_proj = nn.Linear(
            config.kv_lora_rank,
            self.num_heads * (self.qk_nope_head_dim + self.v_head_dim),
            bias=False,
        )

        self.o_proj = nn.Linear(
            self.num_heads * self.v_head_dim,
            self.hidden_size,
            bias=config.attention_bias,
        )

        self.scaling = yarn_apply_mscale(config.rope_parameters, self.qk_head_dim ** (-0.5))
        # Refer: https://arxiv.org/abs/2603.12201 for more details.
        self.skip_topk = config.indexer_types[layer_idx] == "shared"
        self.indexer = None if self.skip_topk else GlmMoeDsaIndexer(config, layer_idx)