[KV Connector][ROCm] MoRIIO: hybrid READ for several attention groups and shared-group speculative methods

[MIR-AMD]

Purpose

MoRIIO hybrid (mamba/KDA) READ (added in #51052, extended in #57700) only supports one transferable attention group and DSpark as the only speculative method. GLM-5.3-Flash (Glm5NextForConditionalGeneration) satisfies neither: it has two attention groups — MLA + kpool indexer and the kpool tail ring — plus KDA groups, and it uses MTP. As a result it cannot start a hybrid-READ disaggregated deployment on main today.

This PR generalizes the hybrid-READ path to carry every attention group and to accept any speculative method whose drafter shares the target's attention group(s) (MTP, DSpark). The change is isolated to moriio_connector.py.

Root cause — three scheduler-side gates reject the model

GLM-5.3-Flash's grouping (_get_kv_cache_groups_glm5_next) yields G0 = UniformTypeKVCacheSpecs(MLA + kpool indexer), G1 = UniformTypeKVCacheSpecs(KpoolTailSpec), and G2.. = KDA MambaSpec; the MTP drafter is an MLA/DSA layer inside G0/G1. On main:

1. len(_attn_group_ids) != 1 → MoRIIOError: MoRIIO hybrid READ requires exactly one transferable attention group, got 2. The payload carried a single flat attention list.
2. _validate_hybrid_speculation allowed DSpark only → supports DSpark speculative decoding only, got method='mtp'. This was a validation allowlist, not a missing mechanism (see below).
3. The HMA spec check inspected the group spec itself, so a UniformTypeKVCacheSpecs wrapping a KpoolTailSpec (a SlidingWindowSpec) was rejected → NotImplementedError: ... Unsupported KV cache group spec(s): ['UniformTypeKVCacheSpecs']. sw_sizes_tokens also did not see the wrapper's window.

Changes (all in moriio_connector.py)

• Multi-group payload. remote_block_ids is now [*attn_groups, *mamba_groups] in transfer-group order. With a single attention group this is byte-identical to main's [attn, *mamba], so existing single-group models (K3/DSpark, Qwen3.5) are unaffected.
• Per-group decode alignment. update_state_after_alloc runs _align_read_blocks per attention group (groups can have different block sizes, e.g. MLA vs the kpool tail). On a full local prefix hit, attention groups that are not prefix-cacheable (the per-request kpool tail ring) are read along with the KDA recurrent state; prefix-cacheable groups are skipped ([]).
• Drop the DSpark allowlist. The two mechanisms the READ path relies on are already method-agnostic: KDA scratch slots are clipped by MambaSpec.num_speculative_blocks (clip_ssm_state_blocks), and the decode tail bound already includes num_speculative_tokens + num_lookahead_tokens. The gate is now "at least one attention group present." Scope: this supports methods whose drafter shares the target's attention group(s). A drafter that owns a separate transferable attention group is intentionally out of scope (output stays correct because the target re-verifies every draft, but that layout is untested); this is documented at the gate.
• Accept UniformTypeKVCacheSpecs. The HMA check and sw_sizes_tokens now see through the wrapper via iter_layer_specs / get_kv_cache_spec_sliding_window; a wrapper is accepted iff all its layer specs are supported. Acceptance is a strict superset of main's.
• KV zeroing. build_connector_meta excludes the READ destinations of every attention group (including the tail ring) from new_block_ids_to_zero; Mamba/recurrent destinations are still zeroed.
• Worker routing. _hybrid_payload_index_by_layer maps every hybrid layer (attention or KDA) to its payload index, and _read_blocks uses it per layer.

P/D flow (READ, GLM-5.3-Flash, MTP=1)

1. P allocates G0 (prompt blocks), G1 (1-block tail ring), and one KDA running-state slot + scratch slot per KDA group, then runs prefill (MLA, indexer, tail, and KDA state — MTP layer included).
2. P request_finished_all_groups → split_block_groups: G0 as allocated, G1 clipped to its window, KDA clipped to the running-state slot. Returns remote_block_ids = [G0, G1, KDA_0, KDA_1, ...] and holds the blocks.
3. D update_state_after_alloc: partial hit pairs each group's suffix with P's; full local hit yields [[], G1, KDA...]; a group-count mismatch fails closed.
4. D build_connector_meta keeps every attention group's READ destinations out of the zeroing list.
5. D worker start_load_kv → _read_blocks: each MLA/indexer layer reads payload 0, each tail layer payload 1, each KDA layer its own group; reads are awaited before the forward.
6. D decodes; the MTP drafter finds its MLA/indexer/tail KV in place.

Drafter caveat (method-agnostic, unchanged)

With hybrid READ, P's last prompt row is truncated (max(num_external_tokens - 1, 0)), so P's drafter KV at position N-2 is computed from P's sampled token rather than D's. This can lower acceptance on the first steps. It does not affect output correctness (the target verifies every draft), and DSpark is affected identically today.

Dependency & merge order (#58585)

This PR is a runtime boot prerequisite away from a full deployment: #58585 ("Allow MoRIIO HMA per-layer block_len", open) adds the worker-side per-layer block_len handling that lets GLM-5.3-Flash's kpool layers register, without which a hybrid-READ deployment does not start. The two PRs edit the same two files but in different regions — #58585 in the worker section (MoRIIOConnectorWorker) and a late test block; this PR in the scheduler section and earlier tests — so they do not textually conflict (verified: a 3-way merge of #58585 into this branch applies cleanly with zero conflicts). They can land in either order; no rebase conflict either way. This PR is independently correct and mergeable against main; #58585 is only required at runtime for the end-to-end GLM-5.3-Flash deployment.

Two further pieces are required for the full deployment but are not in this PR: the kernel-block-split kpool indexer geometry (companion branch upstream/moriio-hybrid-kbpb) and the kpool indexer kernel-block selection (#59412, merged).

Not a duplicate

Re-validated against current origin/main: both relaxed gates (single-attn-group and the DSpark allowlist) are still present and no open PR lifts them. Related PRs: #58968 (closed), #58585 (open — the prerequisite above), #59412 (merged — dependency), #57309 (NIXL/Mooncake hybrid only), #57700 / #51052 (introduced the gates).

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Test Plan

Unit tests in the ROCm container (vllm/vllm-openai-rocm:nightly, MI300X), with the worktree vllm/ overlaid onto the installed package:

python -m pytest -q tests/v1/kv_connector/unit/test_moriio_hma_scheduler.py
python -m pytest -q tests/v1/kv_connector/unit/test_moriio_*.py   # full MoRIIO suite

New / updated tests in test_moriio_hma_scheduler.py:

• test_scheduler_accepts_glm5_next_groups_with_mtp — builds the real GLM groups via get_kv_cache_groups; asserts the drafter lands in G0/G1, the attention/Mamba group ids, the tail-is-state flag, tail SW clipping, one KDA scratch slot, and a 1-block decode tail.
• test_glm5_next_mtp_read_pairs_every_group[0|1500] — producer→consumer payload through update_state_after_alloc + build_connector_meta; covers a partial hit (pairs all 4 groups, zeros only the unread block) and a full local hit (reads only tail + KDA).
• test_read_blocks_routes_each_hybrid_layer_to_its_group — worker _read_blocks gives MLA/indexer, tail, and KDA layers their own local/remote groups.
• test_exchange_clipped_blocks_match_select_for_single_full_attention — locks the single-full-attention-group back-compat invariant: get_exchange_clipped_blocks reduces to select_transfer_block_ids (byte-identical wire payload).
• test_scheduler_rejects_hybrid_without_attention_group — the new fail-closed gate.

End-to-end (OCI, GLM-5.3-Flash-FP8 1P/1D, MoRIIO READ, MTP=1): boot + registration, NIAH recall across contexts, full-local-hit repeat (second request reads only tail + KDA; output must match), MTP acceptance vs colocated, and a K3/DSpark regression pass.

Test Result

• test_moriio_hma_scheduler.py: 71 passed. The full test_moriio_*.py suite passes (235 on origin/main, plus the new multi-group cases here). The new behavior tests fail on main with requires exactly one transferable attention group, got 2 and the DSpark/UniformTypeKVCacheSpecs rejections — i.e. they pin exactly what this PR enables.
• Lint: pre-commit run ruff-check / ruff-format and mypy-3.12 (manual) pass on the changed files.
• E2E (combined integration stack, OCI job 460455): GLM-5.3-Flash-FP8 1P/1D MoRIIO READ with this branch + the companion GLM-5.3 branches + [Bugfix][ROCm][Disagg] Allow MoRIIO HMA per-layer block_len #58585 (pinned at 69d996d01e) + [Bugfix][ROCm] Select page-aligned kernel blocks for pooled indexers so the block table addresses storage pages (GLM-5.3-Flash) #59412 — both legs boot, chat correct, NIAH 10/10 at 2K/8K/32K/96K words, zero errors. Caveat: 3-seed recall at 96K/300K occasionally drops to 1–3/10; the fork image shows the same flakiness at KV block 4 and 8, so it is not attributable to this branch.

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PR checklist

• Design fit — connector-only; reuses _align_read_blocks, clip_ssm_state_blocks, get_exchange_clipped_blocks, iter_layer_specs, get_kv_cache_spec_sliding_window; no GLM special-casing; no new CPU/GPU sync.
• Back-compat — single-attention-group wire layout unchanged (pinned by a byte-identity test); acceptance is a strict superset; WRITE-mode hybrid rejection and non-hybrid MLA paths untouched.
• Tests — new tests fail on main and pass here; CPU-only SimpleNamespace/stubbed-worker logic (no timing/FP asserts, not flaky); covered by the AMD/Intel tests/v1/kv_connector/unit CI jobs.
• Code quality — docstrings for split_block_groups / request_finished updated; two short constraint comments; no unrelated formatting changes.
• PR contents — root cause (with main's exact errors), P/D flow, dependency/merge order, duplicate check, and the drafter caveat all documented.

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