[Kernel] Pipe attn_logits_soft_cap through paged attention TPU kernels

[fenghuizhang]

Pipe attn_logits_soft_cap through paged_attention, this will unblock some of our models' adoption.

Note that the changed code currently doesn't have unit tests. I will add one later.

Signed-off-by: Fenghui Zhang fhzhang@google.com

[github-actions]

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[robertgshaw2-redhat]

Can you add a correctness test for gemma in the ci so this codepath is flexed? Thanks!

[mgoin]

Ditto, LGTM when we can add test case to CI

[fenghuizhang]

Thanks for the quick turnaround.

I think CI (https://buildkite.com/vllm/fastcheck/builds/12156#01948bc4-58cd-4863-9eca-e2ea098879f9) exposed another issue in pt/xla code, I sent pytorch/xla#8600 to fix it and will verify things there first.

Will come back to this PR afterwards.

[fenghuizhang]

Local tests with the latest pt/xla code pass now, we may need to update the nightly build label for CI to pass:

PYTHONPATH=/home/fhzhang/xla python3 examples/offline_inference/tpu.py

The error in https://buildkite.com/vllm/fastcheck/builds/12156#01948bc4-58cd-4863-9eca-e2ea098879f9 went away.