from dataclasses import dataclass
from typing import (TYPE_CHECKING, ClassVar, NamedTuple, Optional, Tuple, Type,
                    TypeVar)

import torch
import torch_npu
from torch import nn
from vllm.attention.backends.abstract import (AttentionBackend,
                                              AttentionMetadata,
                                              MLAAttentionImpl)
from vllm.config import VllmConfig, get_current_vllm_config
from vllm.distributed import get_tensor_model_parallel_world_size
from vllm.forward_context import ForwardContext, get_forward_context
from vllm.model_executor.layers.linear import (LinearBase,
                                               UnquantizedLinearMethod)
from vllm.utils import cdiv, round_down
from vllm.v1.attention.backends.utils import AttentionCGSupport

from vllm_ascend import envs
from vllm_ascend.ascend_config import get_ascend_config
from vllm_ascend.attention.attention_v1 import AscendAttentionState
from vllm_ascend.attention.utils import (AscendCommonAttentionMetadata,
                                         maybe_save_kv_layer_to_connector,
                                         split_decodes_and_prefills,
                                         trans_rope_weight, transdata,
                                         wait_for_kv_layer_from_connector)
from vllm_ascend.compilation.acl_graph import get_graph_params
from vllm_ascend.multistream.base import MSAttentionMetadataSplitConfig
from vllm_ascend.multistream.context import get_multistream_comm_context
from vllm_ascend.multistream.ms_split import model_input_split_v1_mla_attn
from vllm_ascend.ops.weight_prefetch import maybe_npu_prefetch
from vllm_ascend.utils import (ACL_FORMAT_FRACTAL_ND, ACL_FORMAT_FRACTAL_NZ,
                               is_enable_nz)
from vllm_ascend.worker.npu_input_batch import InputBatch

if TYPE_CHECKING:
    from vllm.v1.core.sched.output import SchedulerOutput


class AscendMLABackend(AttentionBackend):

    accept_output_buffer: bool = True

    @staticmethod
    def get_name() -> str:
        return "ASCEND_MLA"

    @staticmethod
    def get_metadata_cls() -> type["AttentionMetadata"]:
        return AscendMLAMetadata

    @staticmethod
    def get_builder_cls():
        return AscendMLAMetadataBuilder

    @staticmethod
    def get_kv_cache_shape(num_blocks: int, block_size: int, num_kv_heads: int,
                           head_size: int) -> tuple[int, ...]:
        return (num_blocks, block_size, num_kv_heads, head_size)

    @staticmethod
    def get_impl_cls() -> Type["MLAAttentionImpl"]:
        return AscendMLAImpl


@dataclass
class AscendMLAPrefillMetadata:
    """ Prefill Specific Metadata for Ascend"""

    @dataclass
    class ChunkedContextMetadata:
        # New for MLA (compared to FlashAttention)
        # For handling chunked prefill
        cu_seq_lens: torch.Tensor
        starts: torch.Tensor
        seq_tot: list[int]
        max_seq_lens: list[int]
        workspace: torch.Tensor
        chunk_seq_lens: torch.Tensor

    attn_mask: torch.Tensor
    query_lens: torch.Tensor
    seq_lens: list[int]
    context_lens: torch.Tensor
    input_positions: torch.Tensor
    query_start_loc: torch.Tensor
    block_table: torch.Tensor
    max_query_len: int
    max_seq_lens: int
    chunked_context: Optional[ChunkedContextMetadata] = None
    sin: torch.Tensor = None
    cos: torch.Tensor = None


@dataclass
class AscendMLADecodeMetadata:
    # Input positions for rotrary embeddings since for MLA the rotary
    # position embeddings are applied inside the attention backend
    input_positions: torch.Tensor
    block_table: torch.Tensor
    seq_lens: torch.Tensor
    max_seq_lens: int
    seq_lens_list: list[int]
    actual_seq_lengths_q: Optional[list[int]] = None
    attn_mask: Optional[torch.Tensor] = None
    sin: torch.Tensor = None
    cos: torch.Tensor = None


@dataclass
class AscendMLAMetadata:
    """Metadata for MLACommon.

    NOTE: Please read the comment at the top of the file before trying to
    understand this class
    """
    # NOTE(sang): Definition of context_len, query_len, and seq_len.
    # |---------- N-1 iteration --------|
    # |---------------- N iteration ---------------------|
    # |- tokenA -|......................|-- newTokens ---|
    # |---------- context_len ----------|
    # |-------------------- seq_len ---------------------|
    #                                   |-- query_len ---|

    num_actual_tokens: int  # Number of tokens excluding padding.
    slot_mapping: torch.Tensor
    query_start_loc: torch.Tensor
    seq_lens: torch.Tensor
    block_tables: torch.Tensor

    # New for MLA (compared to FlashAttention)
    # For handling prefill decode split
    num_decodes: int
    num_decode_tokens: int
    num_prefills: int

    # For logging.
    num_input_tokens: int = 0  # Number of tokens including padding.

    query_lens: Optional[list[int]] = None
    # The dimension of the attention heads
    head_dim: Optional[int] = None
    attn_mask: torch.Tensor = None
    # chunked prefill by default if no attn_states passed
    attn_state: AscendAttentionState = AscendAttentionState.ChunkedPrefill

    decode: Optional[AscendMLADecodeMetadata] = None
    prefill: Optional[AscendMLAPrefillMetadata] = None
    enable_dbo_across_dp: bool = False

    def __post_init__(self):
        pass
        # supported_head_sizes = AscendMLABackend.get_supported_head_sizes()
        # if self.head_dim is not None and self.head_dim \
        #         not in supported_head_sizes:
        #     raise ValueError(
        #         f"Only {supported_head_sizes} are supported for head_dim,",
        #         f"received {self.head_dim}.")

    def split_metadata_for_multistream(
        self,
        ms_split_config: MSAttentionMetadataSplitConfig,
    ) -> list["AscendMLAMetadata"]:
        """Split metadata for multi-stream with AscendMLAMetadata"""
        return model_input_split_v1_mla_attn(
            ms_split_config=ms_split_config,
            attn_metadata=self,
            _metadata_cls=AscendMLAMetadata,
        )


M = TypeVar("M", bound=AscendMLAMetadata)


class AscendMLAMetadataBuilder:
    # Does this backend/builder support ACL Graphs for attention (default: no).
    aclgraph_support: ClassVar[AttentionCGSupport] = \
        AttentionCGSupport.UNIFORM_SINGLE_TOKEN_DECODE
    """
    NOTE: Please read the comment at the top of the file before trying to
    understand this class
    """

    # _attn_mask_builder = None
    def __init__(self,
                 kv_cache_spec,
                 layer_names,
                 vllm_config: VllmConfig,
                 device: torch.device,
                 metadata_cls: Optional[AscendMLAMetadata] = None):
        self.metadata_cls: Optional[AscendMLAMetadata] = metadata_cls \
            if metadata_cls is not None else AscendMLAMetadata  # type: ignore
        self.vllm_config = vllm_config
        self.model_config = vllm_config.model_config
        self.device = device
        scheduler_config = vllm_config.scheduler_config
        self.block_size = vllm_config.cache_config.block_size
        self.max_blocks = (vllm_config.model_config.max_model_len +
                           self.block_size - 1) // self.block_size
        self.chunked_prefill_enabled = scheduler_config.chunked_prefill_enabled

        self.speculative_config = vllm_config.speculative_config
        self.decode_threshold = 1
        if self.speculative_config:
            spec_token_num = self.speculative_config.num_speculative_tokens
            self.decode_threshold += spec_token_num
            assert self.decode_threshold <= 16, f"decode_threshold exceeded \
                npu_fused_infer_attention_score TND layout's limit of 16, \
                got {self.decode_threshold}"

        self.reorder_batch_threshold = self.decode_threshold

        if self.chunked_prefill_enabled:
            self.chunked_prefill_workspace_size = min(
                # Max sure there is enough for 8 full length request or at least
                # 4 pages of cache per request
                max(8 * self.model_config.max_model_len,
                    4 * scheduler_config.max_num_seqs * self.block_size),
                # For long-context models try not to over-allocate limiting
                # kv-cache space, limiting it to 64k tokens,
                # which would result in the workspace being:
                #   2*(576)*(64*1024) = 144mb
                # (assuming 576 MLA head dim, and fp16)
                # which would result in up-projected context being
                #   2*(192*128)*(64*1024) = 3gb
                # (assuming 192 QK head dim, 128 heads, and fp16)
                128 * 1024)
            assert self.chunked_prefill_workspace_size >= \
                scheduler_config.max_num_seqs * self.block_size
            self.chunked_prefill_workspace = torch.empty(
                (self.chunked_prefill_workspace_size,
                 self.model_config.get_head_size()),
                dtype=self.model_config.dtype,
                device=device,
            )
        self.rope_dim = self.model_config.hf_text_config.qk_rope_head_dim
        self.cos_cache = None
        self.sin_cache = None

    def reorder_batch(self, input_batch: "InputBatch",
                      scheduler_output: "SchedulerOutput") -> bool:
        # We now want to reorder the batch so that the "decode" requests are at
        # the front and the "prefill" requests are at the using the least amount
        # swaps possible. (NOTE for now we loosely use "decode" to mean requests
        # where attention is likely memory-bound and "prefill" to mean requests
        # where attention is likely compute-bound, TODO(lucas): figure out a
        # better naming here)
        decodes = []
        prefills = []

        for i, req_id in enumerate(input_batch.req_ids):
            num_tokens = scheduler_output.num_scheduled_tokens[req_id]
            if num_tokens <= self.decode_threshold:
                decodes.append(i)
            else:
                prefills.append(i)

        # We hope that this is fairly minimal since decodes
        # should be around for a number of iterations so hopefully they are
        # relatively stationary (and new request are generally appended to the
        # persistent batch so already should be at the back)
        # To achieve this we loop over the decodes in descending order and
        # the prefills in ascending order. We swap decodes from the  "back"
        # i.e. past where the last decode should be in the reodorered with
        # prefills from the front of the batch.
        # `decodes` and `prefills` are already in ascending order just based on
        # the above loop
        num_decodes = len(decodes)
        num_prefills = len(prefills)
        first_prefill = 0
        modified_batch = False

        for i in range(1, min(num_decodes, num_prefills) + 1):
            # If the decode is at the "back" of the batch, i, we can swap it
            # with the prefill closest to the front of the batch
            if decodes[num_decodes - i] >= num_decodes:
                input_batch.swap_states(prefills[first_prefill],
                                        decodes[num_decodes - i])
                first_prefill += 1
                modified_batch = True
            else:
                break

        # Save for next `build` call
        # TODO(lucas): this is a bit of a hack, we should probably have a
        # better way of doing this
        return modified_batch

    def build(
        self,
        common_prefix_len: int,
        common_attn_metadata: AscendCommonAttentionMetadata,
        model: nn.Module,
    ) -> AscendMLAMetadata:
        num_reqs = common_attn_metadata.num_reqs
        num_actual_tokens = common_attn_metadata.num_actual_tokens
        query_start_loc = common_attn_metadata.query_start_loc
        query_start_loc_cpu = common_attn_metadata.query_start_loc_cpu
        num_decodes, num_prefills, num_decode_tokens, num_prefill_tokens = \
            split_decodes_and_prefills(common_attn_metadata, decode_threshold=self.decode_threshold)
        assert num_decodes + num_prefills == num_reqs
        assert num_decode_tokens + num_prefill_tokens == num_actual_tokens

        # Note(simon): be careful about the CPU <> GPU memory movement in this
        # function. We should avoid GPU -> CPU sync as much as possible because
        # it blocks on all previous kernels.
        device = self.device

        block_table = (common_attn_metadata.block_table_tensor[:num_reqs])
        slot_mapping = common_attn_metadata.slot_mapping[:num_actual_tokens]
        input_positions = common_attn_metadata.positions[:
                                                         num_actual_tokens].long(
                                                         )

        if self.cos_cache is None:
            self.cos_cache = model.model.layers[
                model.model.start_layer].self_attn.rotary_emb.cos_cached
            self.sin_cache = model.model.layers[
                model.model.start_layer].self_attn.rotary_emb.sin_cached
        if self.cos_cache.dtype != self.model_config.dtype:  # type: ignore
            self.cos_cache = self.cos_cache.to(  # type: ignore
                self.model_config.dtype)  # type: ignore
            self.sin_cache = self.sin_cache.to(  # type: ignore
                self.model_config.dtype)  # type: ignore

        query_seq_lens_cpu = query_start_loc_cpu[1:] - query_start_loc_cpu[:-1]
        query_lens = query_seq_lens_cpu[:num_reqs]
        seq_lens = common_attn_metadata.seq_lens_cpu[:num_reqs]
        num_computed_tokens_cpu = (seq_lens - query_lens)

        prefill_metadata = None
        chunked_context_metadata = None
        if num_prefills > 0:
            reqs_start = num_decodes  # prefill_start
            tokens_start = num_decode_tokens
            max_query_len = query_lens[reqs_start:].max().item()
            max_seq_lens = seq_lens[reqs_start:].max().item()
            prefill_query_start_loc = query_start_loc[
                reqs_start:] - query_start_loc[reqs_start]

            context_lens_cpu = num_computed_tokens_cpu[reqs_start:num_reqs]
            max_context_len_cpu = context_lens_cpu.max().item()
            num_prefills_with_context_cpu = (context_lens_cpu > 0).sum().item()
            if self.chunked_prefill_enabled and max_context_len_cpu > 0:
                max_context_chunk = (self.chunked_prefill_workspace_size //
                                     num_prefills_with_context_cpu)
                max_context_chunk = round_down(max_context_chunk,
                                               self.block_size)

                assert max_context_chunk > 0
                num_chunks = cdiv(max_context_len_cpu, max_context_chunk)
                chunk_starts = torch.arange(num_chunks, dtype=torch.int32) \
                    .unsqueeze(1).expand(-1, num_prefills) * max_context_chunk
                chunk_ends = torch.min(context_lens_cpu.unsqueeze(0),
                                       chunk_starts + max_context_chunk)
                chunk_seq_lens = (chunk_ends - chunk_starts).clamp(min=0)
                cu_seq_lens_cpu = torch.zeros(num_chunks,
                                              num_prefills + 1,
                                              dtype=torch.int32,
                                              pin_memory=True)
                torch.cumsum(chunk_seq_lens,
                             dim=1,
                             out=cu_seq_lens_cpu[:, 1:],
                             dtype=torch.int32)
                chunked_context_metadata = \
                    AscendMLAPrefillMetadata.ChunkedContextMetadata(
                    cu_seq_lens=cu_seq_lens_cpu.to(device, non_blocking=True),
                    starts=chunk_starts.to(device, non_blocking=True),
                    seq_tot=chunk_seq_lens.sum(dim=1).tolist(),
                    max_seq_lens=chunk_seq_lens.max(dim=1).values.tolist(),
                    chunk_seq_lens=chunk_seq_lens,
                    workspace=self.chunked_prefill_workspace,
                )
            prefill_input_positions = input_positions[tokens_start:]
            cos = self.cos_cache[
                prefill_input_positions].unsqueeze(  # type: ignore
                    1).unsqueeze(2)
            sin = self.sin_cache[
                prefill_input_positions].unsqueeze(  # type: ignore
                    1).unsqueeze(2)
            prefill_metadata = AscendMLAPrefillMetadata(
                attn_mask=common_attn_metadata.attn_mask,
                query_lens=query_lens[reqs_start:].to(torch.int32),
                seq_lens=seq_lens,
                context_lens=seq_lens[reqs_start:],
                input_positions=prefill_input_positions,
                block_table=block_table[reqs_start:, ...],
                max_query_len=max_query_len,
                max_seq_lens=max_seq_lens,
                query_start_loc=prefill_query_start_loc,
                chunked_context=chunked_context_metadata,
                sin=sin,
                cos=cos,
            )

        decode_metadata = None
        if num_decodes > 0:
            cos = common_attn_metadata.cos
            sin = common_attn_metadata.sin
            # Notice that num_decodes != num_decode_tokens in SpecDecoding Scenario
            actual_seq_lengths_q = query_start_loc[1:num_decodes + 1].tolist()
            max_seq_lens = seq_lens[:num_decodes].max().item()
            seq_lens = seq_lens[:num_decodes]
            input_positions = input_positions[:num_decode_tokens]
            block_table = block_table[:num_decodes, ...]
            seq_lens_list = seq_lens.tolist()

            # TODO: After the fullgraph supports MTP, the if branch needs to deleted
            assert self.cos_cache is not None
            assert self.sin_cache is not None
            if cos is None and sin is None:
                cos = self.cos_cache[
                    input_positions].unsqueeze(  # type: ignore
                        1).unsqueeze(2)
                sin = self.sin_cache[
                    input_positions].unsqueeze(  # type: ignore
                        1).unsqueeze(2)

                decode_metadata = AscendMLADecodeMetadata(
                    input_positions=input_positions,
                    block_table=block_table,
                    seq_lens=seq_lens,
                    seq_lens_list=seq_lens_list,
                    max_seq_lens=max_seq_lens,
                    attn_mask=common_attn_metadata.spec_attn_mask,
                    actual_seq_lengths_q=actual_seq_lengths_q,
                    sin=sin,
                    cos=cos)
            else:
                cos[:num_decodes,
                    ...] = self.cos_cache[input_positions].unsqueeze(
                        1).unsqueeze(2)
                sin[:num_decodes,
                    ...] = self.sin_cache[input_positions].unsqueeze(
                        1).unsqueeze(2)

                decode_metadata = AscendMLADecodeMetadata(
                    input_positions=input_positions,
                    block_table=block_table,
                    seq_lens=seq_lens,
                    seq_lens_list=seq_lens_list,
                    max_seq_lens=max_seq_lens,
                    attn_mask=common_attn_metadata.spec_attn_mask,
                    actual_seq_lengths_q=actual_seq_lengths_q,
                    sin=sin[:num_decodes, ...],
                    cos=cos[:num_decodes, ...])

        return self.metadata_cls(  # type: ignore
            num_actual_tokens=num_actual_tokens,
            query_lens=query_lens.tolist(),
            slot_mapping=slot_mapping,
            head_dim=self.model_config.get_head_size(),
            num_decodes=num_decodes,
            num_decode_tokens=num_decode_tokens,
            num_prefills=num_prefills,
            attn_mask=common_attn_metadata.attn_mask,
            attn_state=common_attn_metadata.attn_state,
            prefill=prefill_metadata,
            decode=decode_metadata,
            query_start_loc=query_start_loc,
            block_tables=block_table,
            seq_lens=seq_lens,
            enable_dbo_across_dp=common_attn_metadata.enable_dbo_across_dp,
        )

    def build_for_graph_capture(
        self,
        common_attn_metadata: AscendCommonAttentionMetadata,
        attn_state: AscendAttentionState = AscendAttentionState.DecodeOnly,
        model: Optional[nn.Module] = None,
    ):
        if attn_state == AscendAttentionState.DecodeOnly:
            attn_metadata = self.build(
                common_prefix_len=0,
                common_attn_metadata=common_attn_metadata,
                model=model,
            )
        else:
            raise NotImplementedError(
                "Currently we only support building dummy metadata for DecodeOnly state"
            )

        attn_metadata.attn_state = attn_state
        return attn_metadata


class DecodeMLAPreprocessResult(NamedTuple):
    ql_nope: Optional[torch.Tensor] = None
    q_pe: Optional[torch.Tensor] = None
    k_nope: Optional[torch.Tensor] = None
    k_pe: Optional[torch.Tensor] = None


class PrefillMLAPreprocessResult(NamedTuple):
    q_nope: Optional[torch.Tensor] = None
    q_pe: Optional[torch.Tensor] = None
    k_nope: Optional[torch.Tensor] = None
    k_pe: Optional[torch.Tensor] = None
    value: Optional[torch.Tensor] = None


class AscendMLAImpl(MLAAttentionImpl):
    """
    NOTE: Please read the comment at the top of the file before trying to
    understand this class
    """

    def __init__(
        self,
        num_heads: int,
        head_size: int,
        scale: float,
        num_kv_heads: int,
        alibi_slopes: Optional[list[float]],
        sliding_window: Optional[int],
        kv_cache_dtype: str,
        logits_soft_cap: Optional[float],
        attn_type: str,
        kv_sharing_target_layer_name: Optional[str],
        **kwargs,
    ) -> None:
        self.num_heads = num_heads
        self.head_size = head_size
        self.scale = float(scale)
        self.num_kv_heads = num_kv_heads
        self.kv_cache_dtype = kv_cache_dtype

        # MLA Args
        self.q_lora_rank = kwargs['q_lora_rank']
        self.kv_lora_rank = kwargs['kv_lora_rank']
        self.qk_nope_head_dim = kwargs['qk_nope_head_dim']
        self.qk_rope_head_dim = kwargs['qk_rope_head_dim']
        self.qk_head_dim = kwargs['qk_head_dim']
        self.v_head_dim = kwargs['v_head_dim']
        self.rotary_emb = kwargs['rotary_emb']
        self.q_proj = kwargs['q_proj']
        self.kv_b_proj = kwargs['kv_b_proj']
        self.o_proj = kwargs['o_proj']
        self.kv_a_proj_with_mqa = kwargs.get('kv_a_proj_with_mqa', None)
        self.kv_a_layernorm = kwargs.get('kv_a_layernorm', None)
        self.q_a_proj = kwargs.get('q_a_proj', None)
        self.q_a_layernorm = kwargs.get('q_a_layernorm', None)
        self.num_queries_per_kv = self.num_heads // self.num_kv_heads
        self.tp_size = get_tensor_model_parallel_world_size()

        ascend_config = get_ascend_config()
        self.enable_shared_expert_dp = ascend_config.enable_shared_expert_dp
        self.enable_prefetch = ascend_config.weight_prefetch_config.enabled
        self.enable_kv_nz = ascend_config.torchair_graph_config.enable_kv_nz

        vllm_config = get_current_vllm_config()
        self.ring_mla_mask_size = 512
        self.prefill_mask = None

        self.speculative_config = vllm_config.speculative_config

    def _v_up_proj(self, x):
        # Convert from (B, N, L) to (N, B, L)
        x = x.view(-1, self.num_heads, self.kv_lora_rank).transpose(0, 1)
        # Multiply (N, B, L) x (N, L, V) -> (N, B, V)
        x = torch.bmm(x, self.W_UV)
        # Convert from (N, B, V) to (B, N * V)
        x = x.transpose(0, 1).reshape(-1, self.num_heads * self.v_head_dim)
        return x

    # Return `ql_nope`, `q_pe`
    def _q_proj_and_k_up_proj(self, x):
        q_nope, q_pe = self.q_proj(x)[0]\
            .view(-1, self.num_heads, self.qk_head_dim)\
            .split([self.qk_nope_head_dim, self.qk_rope_head_dim], dim=-1)

        # Convert from (B, N, P) to (N, B, P)
        q_nope = q_nope.transpose(0, 1)
        # Multiply (N, B, P) x (N, P, L) -> (N, B, L)
        ql_nope = torch.bmm(q_nope, self.W_UK_T)
        # Convert from (N, B, L) to (B, N, L)
        return ql_nope.transpose(0, 1), q_pe

    def process_weights_after_loading(self, act_dtype: torch.dtype):

        def get_layer_weight(layer):
            WEIGHT_NAMES = ("weight", "qweight", "weight_packed")
            for attr in WEIGHT_NAMES:
                if hasattr(layer, attr):
                    return getattr(layer, attr)
            raise AttributeError(
                f"Layer '{layer}' has no recognized weight attribute:"
                f" {WEIGHT_NAMES}.")

        def get_and_maybe_dequant_weights(layer: LinearBase):
            if not isinstance(layer.quant_method, UnquantizedLinearMethod):
                # NOTE: This should only be used offline, since it's O(N^3)
                eye = torch.eye(layer.input_size_per_partition,
                                dtype=act_dtype,
                                device=get_layer_weight(layer).device)
                dequant_weights = layer.quant_method.apply(layer,
                                                           eye,
                                                           bias=None)
                del eye
                # standardize to (output, input)
                return dequant_weights.T
            # Weight will be reshaped next. To be on the safe side, the format
            # of the weight should be reverted to FRACTAL_AND.
            layer.weight.data = torch_npu.npu_format_cast(
                layer.weight.data, ACL_FORMAT_FRACTAL_ND)
            return layer.weight

        # we currently do not have quantized bmm's which are needed for
        # `W_UV` and `W_UK_T`, we we just store fp16/bf16 copies and perform
        # the bmm's in 16-bit, the extra memory overhead of this is fairly low
        kv_b_proj_weight = get_and_maybe_dequant_weights(self.kv_b_proj).T
        assert kv_b_proj_weight.shape == (
            self.kv_lora_rank,
            self.num_heads * (self.qk_nope_head_dim + self.v_head_dim)), (
                f"{kv_b_proj_weight.shape=}, "
                f"{self.kv_lora_rank=}, "
                f"{self.num_heads=}, "
                f"{self.qk_nope_head_dim=}, "
                f"{self.v_head_dim=}")
        kv_b_proj_weight = kv_b_proj_weight.view(
            self.kv_lora_rank,
            self.num_heads,
            self.qk_nope_head_dim + self.v_head_dim,
        )

        W_UK, W_UV = kv_b_proj_weight.split(
            [self.qk_nope_head_dim, self.v_head_dim], dim=-1)

        # Convert from (L, N, V) to (N, L, V)
        self.W_UV = W_UV.transpose(0, 1).contiguous()
        # Convert from (L, N, P) to (N, P, L)
        self.W_UK_T = W_UK.permute(1, 2, 0).contiguous()

        # Function `get_and_maybe_dequant_weights` will cast the weights to
        # FRACTAL_AND. So we need to cast to FRACTAL_NZ again.
        if is_enable_nz():
            self.kv_b_proj.weight.data = torch_npu.npu_format_cast(
                self.kv_b_proj.weight.data, ACL_FORMAT_FRACTAL_NZ)

        # Waiting for BMM NZ support
        # self.W_UV.data = torch_npu.npu_format_cast(self.W_UV.data, 29)
        # self.W_UK_T.data = torch_npu.npu_format_cast(self.W_UK_T.data, 29)

        if envs.VLLM_ASCEND_ENABLE_MLAPO:
            self._process_weights_for_fused_mlapo(act_dtype)

    def _process_weights_for_fused_mlapo(self, act_dtype: torch.dtype):
        kv_a_proj_wt = self.kv_a_proj_with_mqa.weight.data
        kv_a_proj_wt = kv_a_proj_wt.t().contiguous()
        kv_a_proj_wt = trans_rope_weight(kv_a_proj_wt, self.qk_rope_head_dim)
        kv_a_proj_wt = kv_a_proj_wt.t().contiguous()
        wd_qkv = torch.cat((kv_a_proj_wt, self.q_a_proj.weight.data), dim=-1)
        wd_qkv = wd_qkv.t().contiguous()
        wd_qkv = transdata(wd_qkv,
                           block_size=(16, 32)).unsqueeze(0).contiguous()
        self.wd_qkv = torch_npu.npu_format_cast(wd_qkv, 29)

        kv_a_proj_deq_scl = self.kv_a_proj_with_mqa.deq_scale
        kv_a_proj_deq_scl = kv_a_proj_deq_scl.reshape(
            self.kv_lora_rank + self.qk_rope_head_dim, -1).contiguous()
        kv_a_proj_deq_scl = trans_rope_weight(kv_a_proj_deq_scl,
                                              self.qk_rope_head_dim)
        kv_a_proj_deq_scl = kv_a_proj_deq_scl.view(
            self.kv_lora_rank + self.qk_rope_head_dim).contiguous()
        self.deq_scale_qkv = torch.cat(
            (kv_a_proj_deq_scl, self.q_a_proj.deq_scale), dim=-1).contiguous()

        kv_a_proj_qt_bias = self.kv_a_proj_with_mqa.quant_bias
        kv_a_proj_qt_bias = kv_a_proj_qt_bias.reshape(
            self.kv_lora_rank + self.qk_rope_head_dim, -1).contiguous()
        kv_a_proj_qt_bias = trans_rope_weight(kv_a_proj_qt_bias,
                                              self.qk_rope_head_dim)
        kv_a_proj_qt_bias = kv_a_proj_qt_bias.view(
            self.kv_lora_rank + self.qk_rope_head_dim).contiguous()
        self.quant_bias_qkv = torch.cat(
            (kv_a_proj_qt_bias, self.q_a_proj.quant_bias),
            dim=-1).contiguous()

        wu_q = self.q_proj.weight.data
        wu_q = wu_q.t().reshape(self.num_heads,
                                self.qk_nope_head_dim + self.qk_rope_head_dim,
                                -1)
        wu_q = trans_rope_weight(wu_q, self.qk_rope_head_dim)
        wu_q = wu_q.reshape(
            self.num_heads * (self.qk_nope_head_dim + self.qk_rope_head_dim),
            -1)
        wu_q = transdata(wu_q, block_size=(16, 32)).unsqueeze(0).contiguous()
        self.wu_q = torch_npu.npu_format_cast(wu_q, 29)

        qb_deq_scl = self.q_proj.deq_scale.data
        qb_deq_scl = qb_deq_scl.reshape(
            self.num_heads, self.qk_nope_head_dim + self.qk_rope_head_dim, -1)
        qb_deq_scl = trans_rope_weight(qb_deq_scl, self.qk_rope_head_dim)
        self.qb_deq_scl = qb_deq_scl.reshape(
            self.num_heads * (self.qk_nope_head_dim + self.qk_rope_head_dim))

        qb_qt_bias = self.q_proj.quant_bias.data
        qb_qt_bias = qb_qt_bias.reshape(
            self.num_heads, self.qk_nope_head_dim + self.qk_rope_head_dim, -1)
        qb_qt_bias = trans_rope_weight(qb_qt_bias, self.qk_rope_head_dim)
        self.qb_qt_bias = qb_qt_bias.reshape(
            self.num_heads * (self.qk_nope_head_dim + self.qk_rope_head_dim))

        device = self.q_a_proj.weight.device
        self.gamma0 = torch.ones(
            [self.q_a_proj.weight.shape[-1]],
            dtype=act_dtype,
            device=device,
        )
        self.beta0 = torch.zeros(
            [self.q_a_proj.weight.shape[-1]],
            dtype=act_dtype,
            device=device,
        )
        self.gamma1 = self.q_a_layernorm.weight.data
        self.beta1 = self.q_a_layernorm.bias.data
        self.gamma2 = self.kv_a_layernorm.weight.data
        self.quant_scale0 = self.q_a_proj.input_scale.data
        self.quant_offset0 = self.q_a_proj.input_offset.data
        self.quant_scale1 = self.q_proj.input_scale.data
        self.quant_offset1 = self.q_proj.input_offset.data
        self.ctkv_scale = torch.tensor([1], dtype=act_dtype, device=device)
        self.q_nope_scale = torch.tensor([1], dtype=act_dtype, device=device)

    def _compute_prefill_context(
        self,
        q_nope: torch.Tensor,
        q_pe: torch.Tensor,
        kv_c_and_k_pe_cache: Tuple[torch.Tensor],
        rope_dim: int,
        attn_metadata: AscendMLAMetadata,
        prefix_output: torch.Tensor,
        prefix_lse: torch.Tensor,
    ):
        assert len(kv_c_and_k_pe_cache) > 1
        prefill_metadata = attn_metadata.prefill
        if prefill_metadata is None or prefill_metadata.chunked_context is None:
            return prefix_output, prefix_lse

        iters = len(prefill_metadata.chunked_context.seq_tot)

        seq_len1 = torch.tensor(prefill_metadata.query_lens, dtype=torch.int32)
        cache_kv_c = kv_c_and_k_pe_cache[0]
        cache_k_pe = kv_c_and_k_pe_cache[1]
        num_heads = cache_k_pe.size(2)
        latent_kv_dim = kv_c_and_k_pe_cache[0].size(-1)
        for i in range(iters):
            toks = prefill_metadata.chunked_context.seq_tot[i]

            seq_len2 = prefill_metadata.chunked_context.chunk_seq_lens[i]
            seq_len = torch.stack([seq_len1, seq_len2])
            kv_c_normed = torch.empty(toks,
                                      num_heads,
                                      latent_kv_dim,
                                      dtype=q_nope.dtype,
                                      device=q_nope.device)
            k_pe = torch.empty(toks,
                               num_heads,
                               rope_dim,
                               dtype=q_nope.dtype,
                               device=q_nope.device)

            torch_npu.atb.npu_paged_cache_load(
                cache_kv_c,
                cache_k_pe,
                prefill_metadata.block_table,
                seq_len2.to(q_nope.device),
                seq_starts=prefill_metadata.chunked_context.starts[i],
                key=kv_c_normed,
                value=k_pe,
            )

            kv_c_normed = kv_c_normed.squeeze()
            kv_nope = self.kv_b_proj(kv_c_normed)[0].view( \
                -1, self.num_heads, self.qk_nope_head_dim + self.v_head_dim)
            k_nope, v = kv_nope\
                .split([self.qk_nope_head_dim, self.v_head_dim], dim=-1)
            k_pe = k_pe.expand((*k_nope.shape[:-1], -1))
            torch_npu.atb.npu_ring_mla(
                q_nope=q_nope,
                q_rope=q_pe,
                k_nope=k_nope,
                k_rope=k_pe,
                value=v,
                mask=self.prefill_mask,
                seqlen=seq_len,
                head_num=self.num_heads,
                kv_head_num=self.num_heads,
                pre_out=prefix_output,
                prev_lse=prefix_lse,
                qk_scale=self.scale,
                kernel_type="kernel_type_high_precision",
                mask_type="no_mask",
                input_layout="type_bsnd",
                calc_type="calc_type_default",
                output=prefix_output,
                softmax_lse=prefix_lse)
        return prefix_output, prefix_lse

    def _forward_prefill(
        self,
        q_nope: torch.Tensor,
        q_pe: torch.Tensor,
        k_nope: torch.Tensor,
        k_pe: torch.Tensor,
        value: torch.Tensor,
        kv_c_and_k_pe_cache: Tuple[torch.Tensor],
        attn_metadata: AscendMLAMetadata,
    ) -> torch.Tensor:
        assert attn_metadata.prefill is not None
        assert len(kv_c_and_k_pe_cache) > 1
        num_tokens = q_nope.size(0)
        attn_output = torch.empty(num_tokens,
                                  self.num_heads,
                                  self.v_head_dim,
                                  dtype=q_nope.dtype,
                                  device=q_nope.device)
        attn_lse = torch.empty(self.num_heads,
                               num_tokens,
                               dtype=torch.float32,
                               device=q_nope.device)
        if self.prefill_mask is None:
            if q_nope.dtype == torch.float16:
                mask_value = torch.finfo(torch.float32).min
            else:
                mask_value = 1
            prefill_mask = torch.triu(
                torch.ones(self.ring_mla_mask_size,
                           self.ring_mla_mask_size,
                           device=q_nope.device,
                           dtype=q_nope.dtype), 1)
            self.prefill_mask = torch.where(prefill_mask == 1, mask_value,
                                            0).to(q_nope.dtype)
        torch_npu.atb.npu_ring_mla(q_nope=q_nope,
                                   q_rope=q_pe,
                                   k_nope=k_nope,
                                   k_rope=k_pe,
                                   value=value,
                                   mask=self.prefill_mask,
                                   seqlen=attn_metadata.prefill.query_lens,
                                   head_num=self.num_heads,
                                   kv_head_num=self.num_heads,
                                   pre_out=None,
                                   prev_lse=None,
                                   qk_scale=self.scale,
                                   kernel_type="kernel_type_high_precision",
                                   mask_type="mask_type_triu",
                                   input_layout="type_bsnd",
                                   calc_type="calc_type_first_ring",
                                   output=attn_output,
                                   softmax_lse=attn_lse)
        attn_output, attn_lse = self._compute_prefill_context( \
            q_nope, q_pe, kv_c_and_k_pe_cache, self.qk_rope_head_dim, attn_metadata, attn_output, attn_lse)

        attn_output = attn_output.reshape(
            [num_tokens, self.num_heads * self.v_head_dim])
        return attn_output

    def exec_kv_decode(
        self,
        kv_no_split: torch.Tensor,
        cos: torch.Tensor,
        sin: torch.Tensor,
        kv_cache: Tuple,
        slots: torch.Tensor,
    ):
        B = kv_no_split.shape[0]
        N = self.num_kv_heads
        S = 1
        # npu_kv_rmsnorm_rope_cache needs [B, N, S, D]
        kv_no_split = kv_no_split.view(
            B, N, S, self.kv_lora_rank + self.qk_rope_head_dim)
        cache_mode = "PA_NZ" if self.enable_kv_nz else "PA"
        k_pe, k_nope, _, _ = torch_npu.npu_kv_rmsnorm_rope_cache(
            kv_no_split,
            self.kv_a_layernorm.weight,
            cos,
            sin,
            slots.to(torch.int64),
            kv_cache[1],
            kv_cache[0],
            epsilon=self.kv_a_layernorm.variance_epsilon,
            cache_mode=cache_mode,
        )
        return k_pe, k_nope

    def exec_kv_prefill(
        self,
        kv_no_split: torch.Tensor,
        cos: torch.Tensor,
        sin: torch.Tensor,
        kv_cache: Tuple,
        slots: torch.Tensor,
    ):
        B = kv_no_split.shape[0]
        N = self.num_kv_heads
        S = 1
        # npu_kv_rmsnorm_rope_cache needs [B, N, S, D]
        kv_no_split = kv_no_split.view(
            B, N, S, self.kv_lora_rank + self.qk_rope_head_dim)
        cache_mode = "PA_NZ" if self.enable_kv_nz else "PA"
        _, _, k_pe, k_nope = torch_npu.npu_kv_rmsnorm_rope_cache(
            kv_no_split,
            self.kv_a_layernorm.weight,
            cos,
            sin,
            slots.to(torch.int64),
            kv_cache[1],
            kv_cache[0],
            epsilon=self.kv_a_layernorm.variance_epsilon,
            cache_mode=cache_mode,
            is_output_kv=True,
        )
        return k_pe, k_nope

    def rope_single(
        self,
        x: torch.Tensor,
        cos: torch.Tensor,
        sin: torch.Tensor,
    ) -> torch.Tensor:
        B, N, D = x.shape
        S = 1
        x = x.view(B, N, S, D)
        x = torch_npu.npu_interleave_rope(x, cos, sin)
        return x.view(B, N, D)

    def _forward_decode(
        self,
        q_nope: torch.Tensor,
        q_pe: torch.Tensor,
        k_nope: torch.Tensor,
        k_pe: torch.Tensor,
        block_size: int,
        attn_metadata: AscendMLAMetadata,
    ) -> torch.Tensor:
        decode_meta = attn_metadata.decode
        assert decode_meta is not None
        num_tokens = q_nope.size(0)
        # shape of knope/k_pe for npu graph mode should be:
        # [num_blocks, num_kv_heads, block_size, self.kv_lora_rank/self.qk_rope_head_dim]
        actual_seq_lengths = None
        if self.enable_kv_nz:
            k_nope = k_nope.view(-1, self.num_kv_heads,
                                 self.kv_lora_rank // 16, block_size, 16)
            k_pe = k_pe.view(-1, self.num_kv_heads,
                             self.qk_rope_head_dim // 16, block_size, 16)
            input_layout = "BSND"
        else:
            k_nope = k_nope.view(-1, self.num_kv_heads, block_size,
                                 self.kv_lora_rank)
            k_pe = k_pe.view(-1, self.num_kv_heads, block_size,
                             self.qk_rope_head_dim)
            input_layout = "BNSD"

        if attn_metadata.attn_state in [
                AscendAttentionState.SpecDecoding,
                AscendAttentionState.ChunkedPrefill
        ] and self.speculative_config is not None:
            # Use TND layout for pure SpecDecoding and SpecDecoding in ChunkedPrefill
            input_layout = "TND"
            # [bs * q_seq_len, num_heads_per_rank, dim]
            q_nope = q_nope.view(num_tokens, self.num_heads, -1)
            q_pe = q_pe.view(num_tokens, self.num_heads, -1)
            sparse_mode = 3
            spec_attn_mask = attn_metadata.decode.attn_mask  # type:ignore
            actual_seq_lengths = decode_meta.actual_seq_lengths_q
        else:
            if self.enable_kv_nz:
                q_nope = q_nope.view(num_tokens, 1, self.num_heads, -1)
                q_pe = q_pe.view(num_tokens, 1, self.num_heads, -1)
            else:
                q_nope = q_nope.view(num_tokens, self.num_heads, 1, -1)
                q_pe = q_pe.view(num_tokens, self.num_heads, 1, -1)
            sparse_mode = 0
            spec_attn_mask = None

        common_kwargs = {
            'query_rope': q_pe,
            'key_rope': k_pe,
            'num_heads': self.num_heads,
            'num_key_value_heads': self.num_kv_heads,
            'input_layout': input_layout,
            'atten_mask': spec_attn_mask,
            'sparse_mode': sparse_mode,
            'scale': self.scale,
            'antiquant_mode': 0,
            'antiquant_scale': None,
            'block_table': decode_meta.block_table,
            'block_size': block_size,
            "actual_seq_lengths": actual_seq_lengths,
            "actual_seq_lengths_kv": decode_meta.seq_lens_list,
        }
        graph_params = get_graph_params()
        forward_context: ForwardContext = get_forward_context()
        if forward_context.capturing:
            stream = torch_npu.npu.current_stream()

            event = torch.npu.ExternalEvent()
            event.wait(stream)
            event.reset(stream)
            graph_params.events[num_tokens].append(event)

            workspace = graph_params.workspaces.get(num_tokens)
            if workspace is None:
                workspace = torch_npu._npu_fused_infer_attention_score_get_max_workspace(
                    q_nope, k_nope, k_nope, **common_kwargs)
                graph_params.workspaces[num_tokens] = workspace

            attn_output = torch.empty_like(q_nope)
            softmax_lse = torch.empty(num_tokens,
                                      dtype=q_nope.dtype,
                                      device=q_nope.device)

            graph_params.attn_params[num_tokens].append(
                (q_nope, k_nope, q_pe, k_pe, self.num_heads, self.num_kv_heads,
                 input_layout, spec_attn_mask, sparse_mode, self.scale,
                 decode_meta.block_table, block_size,
                 decode_meta.seq_lens_list, actual_seq_lengths, workspace,
                 attn_output, softmax_lse))

            torch.npu.graph_task_group_begin(stream)
            torch_npu.npu_fused_infer_attention_score.out(
                q_nope,
                k_nope,
                k_nope,
                **common_kwargs,
                workspace=workspace,
                out=[attn_output, softmax_lse])
            handle = torch.npu.graph_task_group_end(stream)
            graph_params.handles[num_tokens].append(handle)
        else:
            attn_output, _ = torch_npu.npu_fused_infer_attention_score(
                q_nope, k_nope, k_nope, **common_kwargs)

        current_ms_metadata = get_multistream_comm_context()
        if current_ms_metadata is None:
            return self._v_up_proj(attn_output)
        else:
            current_ms_metadata.before_comm_event.record()
            with torch.npu.stream(current_ms_metadata.comm_stream):
                current_ms_metadata.before_comm_event.wait()
                return self._v_up_proj(attn_output)

    def _mla_decode_preprocess(self, hidden_states, kv_cache, attn_metadata):
        bsz = attn_metadata.num_decode_tokens
        hidden_states = hidden_states[:bsz]

        cos_shape = attn_metadata.decode.cos.shape
        cos = attn_metadata.decode.cos.view(cos_shape[0], cos_shape[-1])
        sin = attn_metadata.decode.sin.view(cos_shape[0], cos_shape[-1])

        decode_k_nope, decode_k_pe = kv_cache[0], kv_cache[1]
        decode_q_nope = torch.empty(
            (hidden_states.shape[0], self.W_UK_T.shape[0],
             decode_k_nope.shape[-1]),
            dtype=hidden_states.dtype,
            device=hidden_states.device,
        )
        decode_q_pe = torch.empty(
            (hidden_states.shape[0], self.W_UK_T.shape[0],
             decode_k_pe.shape[-1]),
            dtype=hidden_states.dtype,
            device=hidden_states.device,
        )

        torch.ops._C_ascend.mla_preprocess(
            hidden_states,
            self.gamma0,
            self.beta0,
            self.wd_qkv,
            self.deq_scale_qkv,
            self.gamma1,
            self.beta1,
            self.wu_q,
            self.qb_deq_scl,
            self.gamma2,
            cos,
            sin,
            self.W_UK_T,
            decode_k_nope,
            decode_k_pe,
            attn_metadata.slot_mapping[:bsz].flatten(),
            quant_scale0=self.quant_scale0,
            quant_offset0=self.quant_offset0,
            bias0=self.quant_bias_qkv,
            quant_scale1=self.quant_scale1,
            quant_offset1=self.quant_offset1,
            bias1=self.qb_qt_bias,
            ctkv_scale=self.ctkv_scale,
            q_nope_scale=self.q_nope_scale,
            cache_mode="krope_ctkv",
            quant_mode="per_tensor_quant_asymm",
            q_out0=decode_q_nope,
            kv_cache_out0=decode_k_nope,
            q_out1=decode_q_pe,
            kv_cache_out1=decode_k_pe,
        )
        decode_q_nope = decode_q_nope.view(bsz, self.num_heads,
                                           self.kv_lora_rank)
        decode_q_pe = decode_q_pe.view(bsz, self.num_heads, -1)

        decode_preprocess_res = DecodeMLAPreprocessResult(
            decode_q_nope, decode_q_pe, decode_k_nope, decode_k_pe)
        return decode_preprocess_res, None

    def _mla_preprocess(self, layer_name, hidden_states, kv_cache,
                        attn_metadata, need_gather_q_kv):
        # MLA Preprocess:
        # 1. Perform q_a_proj and q_a_layernorm to obtain q_c
        # 2. Perform kv_a_proj_with_mqa to obtain kv_no_split
        # 3. If need_gather_q_kv, perform all_gather.
        # 4. Preprocess decode tokens, write kv cache and get:
        # decode_ql_nope, decode_q_pe, decode_k_pe, decode_k_nope
        # 5. Preprocess prefill tokens, write kv cache and get:
        # prefill_q_nope, prefill_q_pe, prefill_k_nope, prefill_k_pe, prefill_value
        has_decode = attn_metadata.num_decodes > 0
        has_prefill = attn_metadata.num_prefills > 0
        num_decode_tokens = attn_metadata.num_decode_tokens
        num_actual_tokens = attn_metadata.num_actual_tokens
        if self.q_a_proj is not None:
            maybe_npu_prefetch(inputs=self.q_a_proj.weight,
                               dependency=hidden_states,
                               enabled=self.enable_prefetch)
            ckq = self.q_a_proj(hidden_states)[0]
            q_c = self.q_a_layernorm(ckq)
        else:
            q_c = hidden_states

        kv_no_split = self.kv_a_proj_with_mqa(hidden_states)[0]
        # Process for Flash Comm V1
        q_c = torch.ops.vllm.maybe_all_gather_and_maybe_unpad(
            q_c, need_gather_q_kv)
        kv_no_split = torch.ops.vllm.maybe_all_gather_and_maybe_unpad(
            kv_no_split, need_gather_q_kv)
        decode_preprocess_res = None
        prefill_preprocess_res = None
        if has_prefill:
            wait_for_kv_layer_from_connector(layer_name)
        # Preprocess for decode tokens
        if has_decode:
            decode_q_c = q_c[:num_decode_tokens]
            cos = attn_metadata.decode.cos
            sin = attn_metadata.decode.sin
            decode_ql_nope, decode_q_pe = \
                self._q_proj_and_k_up_proj(decode_q_c)
            decode_q_pe = self.rope_single(decode_q_pe, cos, sin)
            decode_slots = attn_metadata.slot_mapping[:num_decode_tokens]
            decode_kv_no_split = kv_no_split[:num_decode_tokens]
            decode_k_pe, decode_k_nope = self.exec_kv_decode(
                decode_kv_no_split, cos, sin, kv_cache, decode_slots)
            decode_preprocess_res = DecodeMLAPreprocessResult(
                decode_ql_nope, decode_q_pe, decode_k_nope, decode_k_pe)
        # Preprocess for prefill tokens
        if has_prefill:
            prefill_kv_no_split = kv_no_split[
                num_decode_tokens:num_actual_tokens]
            prefill_q_c = q_c[num_decode_tokens:num_actual_tokens]
            prefill_q = self.q_proj(prefill_q_c)[0]\
                .view(-1, self.num_heads, self.qk_head_dim)
            prefill_q_pe = prefill_q[..., self.qk_nope_head_dim:]
            prefill_q_nope = prefill_q[..., :self.qk_nope_head_dim]
            cos = attn_metadata.prefill.cos
            sin = attn_metadata.prefill.sin
            prefill_slots = attn_metadata.slot_mapping[
                num_decode_tokens:num_actual_tokens]
            prefill_q_pe = self.rope_single(prefill_q_pe, cos, sin)
            prefill_k_pe, prefill_k_c_normed = self.exec_kv_prefill(
                prefill_kv_no_split, cos, sin, kv_cache, prefill_slots)
            prefill_k_pe = prefill_k_pe.view(prefill_q_c.shape[0],
                                             self.num_kv_heads, -1)
            prefill_k_nope, prefill_value = self.kv_b_proj(
                prefill_k_c_normed)[0].view(
                    -1, self.num_heads,
                    self.qk_nope_head_dim + self.v_head_dim).split(
                        [self.qk_nope_head_dim, self.v_head_dim], dim=-1)
            prefill_k_pe = prefill_k_pe.expand(
                (*prefill_k_nope.shape[:-1], -1))
            prefill_preprocess_res = PrefillMLAPreprocessResult(
                prefill_q_nope, prefill_q_pe, prefill_k_nope, prefill_k_pe,
                prefill_value)
        return decode_preprocess_res, prefill_preprocess_res

    def forward(
        self,
        layer_name,
        hidden_states: torch.Tensor,  # query in unified attn
        kv_cache: Tuple[torch.Tensor],
        attn_metadata: M,
        need_gather_q_kv: bool = False,
        output: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        assert output is not None, "Output tensor must be provided."
        if attn_metadata is None:
            # Profiling run.
            return output
        num_actual_tokens = attn_metadata.num_actual_tokens
        assert attn_metadata.num_decodes is not None and \
        attn_metadata.num_prefills is not None and \
        attn_metadata.num_decode_tokens is not None
        num_decode_tokens = attn_metadata.num_decode_tokens
        # Inputs and outputs may be padded for CUDA graphs
        output_padded = output
        o_proj_input_shape = (get_forward_context().num_tokens,
                              self.num_heads * self.v_head_dim)
        o_proj_input = torch.empty(o_proj_input_shape,
                                   dtype=hidden_states.dtype,
                                   device=hidden_states.device)

        # MLA Preprocess
        forward_context = get_forward_context()
        if (envs.VLLM_ASCEND_ENABLE_MLAPO and
            (attn_metadata is None or not forward_context.with_prefill)):
            decode_preprocess_res, prefill_preprocess_res = self._mla_decode_preprocess(
                hidden_states, kv_cache, attn_metadata)
        else:
            decode_preprocess_res, prefill_preprocess_res = self._mla_preprocess(
                layer_name, hidden_states, kv_cache, attn_metadata,
                need_gather_q_kv)

        if decode_preprocess_res is not None:
            # MLA Preprocess for decoding
            output_decode = self._forward_decode(decode_preprocess_res.ql_nope,
                                                 decode_preprocess_res.q_pe,
                                                 decode_preprocess_res.k_nope,
                                                 decode_preprocess_res.k_pe,
                                                 kv_cache[0].shape[1],
                                                 attn_metadata)
            current_ms_metadata = get_multistream_comm_context()
            if current_ms_metadata is not None:
                with torch.npu.stream(current_ms_metadata.comm_stream):
                    o_proj_input[:num_decode_tokens] = output_decode
                    current_ms_metadata.after_comm_event.record()
            else:
                o_proj_input[:num_decode_tokens] = output_decode

        if prefill_preprocess_res is not None:
            # FIX: aicore move should be also placed on the comm stream in dbo,
            # otherwise it may affect the accuracy
            # TODO: use an elegant way to overlap
            output_prefill = self._forward_prefill(
                prefill_preprocess_res.q_nope, prefill_preprocess_res.q_pe,
                prefill_preprocess_res.k_nope, prefill_preprocess_res.k_pe,
                prefill_preprocess_res.value, kv_cache, attn_metadata)
            current_ms_metadata = get_multistream_comm_context()
            if current_ms_metadata is not None:
                with torch.npu.stream(current_ms_metadata.comm_stream):
                    o_proj_input[num_decode_tokens:] = output_prefill
                    current_ms_metadata.after_comm_event.record()
            else:
                o_proj_input[
                    num_decode_tokens:num_actual_tokens] = output_prefill
        # O proj
        current_ms_metadata = get_multistream_comm_context()
        MAX_O_PROJ_PREFETCH_SIZE = 16 * 1024 * 1024
        if current_ms_metadata is None:
            maybe_npu_prefetch(inputs=self.o_proj.weight,
                               dependency=o_proj_input,
                               max_size=MAX_O_PROJ_PREFETCH_SIZE,
                               enabled=self.enable_prefetch)

            output[...] = self.o_proj(o_proj_input)[0]
        else:
            with torch.npu.stream(current_ms_metadata.comm_stream):
                maybe_npu_prefetch(inputs=self.o_proj.weight,
                                   dependency=o_proj_input,
                                   max_size=MAX_O_PROJ_PREFETCH_SIZE,
                                   enabled=self.enable_prefetch)
                output[...] = self.o_proj(o_proj_input)[0]
                current_ms_metadata.after_comm_event.record()
        del o_proj_input

        has_prefill = attn_metadata.num_prefills > 0
        if has_prefill:
            maybe_save_kv_layer_to_connector(layer_name, list(kv_cache))
        return output_padded
