[ROCm] [BugFix] Fix Quark GLM-5.2 Checkpoint inference: indexer wk per-channel FP8 dequant + missing sparse-MLA metadata fields

[ColinZ22]

Summary

This PR addresses two independent bugs blocking quark quantized GLM-5.2 checkpoints with Attn quantized to PTPC FP8 from running end-to-end on ROCm (MI355X / gfx950).

Per-channel FP8 scale for fused indexer wk (deepseek_v2.py):

_try_load_fp8_indexer_wk dequantizes the FP8 indexer wk weight to BF16 at load time so it can be fused with weights_proj. However, it unconditionally reads scale_inv.shape[1], assuming a 2-D block-wise scale. Checkpoints that store wk with a 1-D per-output-channel scale crash at load with:

IndexError: tuple index out of range
# deepseek_v2.py: block_size = weight_fp8.shape[1] // scale_inv.shape[1]

Fix Added: branch on scale_inv.ndim. For a 1-D scale, use GroupShape(1, in_features) (per-output-channel); the original 2-D block path is unchanged.

Missing sparse-MLA metadata fields on the ROCm aiter backend:

#47327 refactored the shared MLA forward (mla_attention.py) to read num_decodes, num_prefills, num_decode_tokens, and prefill_max_seq_len from attention metadata, and updated the FlashMLA / FlashAttn sparse backends accordingly. ROCMAiterMLASparseMetadata was not updated, so inference crashes during graph capture with

AttributeError: 'ROCMAiterMLASparseMetadata' object has no attribute 'num_decodes'
AttributeError: 'ROCMAiterMLASparseMetadata' object has no attribute 'prefill_max_seq_len'

The ROCm sparse impl only implements forward_mqa (no forward_mha), so the dense-MHA prefill path added by #47327 was not viable on ROCm.

Fix:

• Add the metadata fields; populate num_decodes / num_prefills / num_decode_tokens in build() via the existing split_decodes_and_prefills helper.
• Add a supports_dense_mha_prefill: ClassVar[bool] = True capability flag to the base AttentionImplBase, set False on ROCMAiterMLASparseImpl. When a sparse impl declares no dense-MHA path, mla_attention.py sets prefill_backend = None up front, so the shared forward takes the MQA-only path (existing behavior prior to [1/N] Add dense MHA path for sparse MLA short sequences #47327).

Test plan / results

Tested on 4x MI355X GPUs

lm_eval --model vllm \
  --model_args 'pretrained=<GLM-5.2-mxfp4-AttnFP8>,tensor_parallel_size=4,dtype=auto,\
quantization=quark,gpu_memory_utilization=0.85,max_model_len=32768,trust_remote_code=True' \
  --tasks gsm8k --batch_size auto

gsm8k (5-shot) evaluated using lm_eval:

flexible-extract	strict-match
0.9295	0.9295

---

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[tjtanaa]

LGTM. Accept has hot patch. We do a follow up to implement the dense mha path for rocm aiter sparse mla .

[Rohan138]

btw @tjtanaa there's another PR to fix the sparse MLA patch: #48722, we can close one of them

[ColinZ22]

btw @tjtanaa there's another PR to fix the sparse MLA patch: #48722, we can close one of them

Hi @Rohan138, I checked before opening this PR but must've missed that PR, sorry about that.

Seems like changes in #48722 is a subset of this PR, and this PR is already reviewed and approved. If possible, let's land this one instead?

[Rohan138]

@ColinZ22 sounds good! We're rerunning the one failed test+requesting merge, thanks for the PR

[tjtanaa]

@ColinZ22 let's stop merge with main. Let me try to retry the failed job. They might just be flaky.

[ColinZ22]

@ColinZ22 let's stop merge with main. Let me try to retry the failed job. They might just be flaky.

Got it, thanks a lot!

[jimmy-adams]

We independently hit the same ROCMAiterMLASparseMetadata missing-num_decodes crash on AMD MI350 (gfx950) with GLM-5.1-NVFP4 + MTP, and can confirm this fix resolves it — thanks! Separately, we found NVFP4 checkpoints also ship MTP/nextn draft layers as bf16 without exclude entries, which crashes Quark loading independently of the indexer wk path fixed here. Opened #49275 for that; it's orthogonal and complementary to this PR.

[fanxingran]

Hi @ColinZ22, thanks for the fix! Since #48886 already covers the sparse-MLA metadata fix (and additionally handles the indexer wk per-channel dequant), I'll drop my #48722 rather than pushing it separately.

One thing I'd love to carry over: my PR ships a dedicated regression test for this bug that would give the fix some protection:

tests/kernels/attention/test_rocm_aiter_mla_sparse_metadata_sync.py (~75 lines, ROCm-gated) — see the file / commit in #48722.
Would you be willing to cherry-pick that commit from my branch? If you cherry-pick, please keep the co-author trailer, thanks!

Co-authored-by: fanxingran xingran.fan@amd.com
I'll close #48722 and link back here afterwards. Thanks again!

[ColinZ22]

Hi @ColinZ22, thanks for the fix! Since #48886 already covers the sparse-MLA metadata fix (and additionally handles the indexer wk per-channel dequant), I'll drop my #48722 rather than pushing it separately.

One thing I'd love to carry over: my PR ships a dedicated regression test for this bug that would give the fix some protection:
...

Added test, thanks!

[Rohan138]

@ColinZ22 please avoid merging main, your previous build had already passed

[ColinZ22]

@ColinZ22 please avoid merging main, your previous build had already passed

Got it, I thought I had to merge since the only test that failed was due to my branch not being within 1 day behind main. @tjtanaa sorry for all the trouble, could you please help take a look and merge if possible? Thanks!