[XPU] Add deepseek_scaling_rope fused kernel

[yitingw1]

Purpose

[XPU] Add the usage of the fused deepseek_scaling_rope kernel in PR for DeepseekScalingRotaryEmbedding. Previously, it ran with forward_native().

Test Plan

Test Result

Verified lm_eval with 4xBMG for DeepSeek-V2-Lite-Chat functionality locally.

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[gemini-code-assist]

Code Review

This pull request introduces a fused kernel for deepseek_scaling_rope on XPU to improve performance. The changes involve registering a new custom PyTorch operation and integrating it into the DeepseekScalingRotaryEmbedding layer. My review has identified a few critical issues related to thread safety, correctness of the operation registration, and potential runtime errors due to an uninitialized cache. I've also pointed out some type hint inconsistencies that could affect static analysis and torch.compile.

[jikunshang]

LGTM.

[Copilot]

Pull request overview

This PR adds a fused XPU kernel for DeepseekScalingRotaryEmbedding, replacing the previous forward_native() fallback with a dedicated forward_xpu() method that calls a custom registered op backed by torch.ops._xpu_C.deepseek_scaling_rope.

Changes:

• Adds forward_xpu() method to DeepseekScalingRotaryEmbedding that delegates to the new fused XPU op.
• Registers xpu_ops_deepseek_scaling_rope as a custom torch op with a fake implementation for tracing.
• Introduces a module-level _OPS_REGISTERED guard and register_ops_once() to prevent duplicate registration.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
vllm/model_executor/layers/rotary_embedding/deepseek_scaling_rope.py	Adds forward_xpu() method wiring the class to the new fused kernel op
vllm/_xpu_ops.py	Implements and registers the xpu_ops_deepseek_scaling_rope custom op with impl and fake functions

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[jikunshang]

Please resolve conflicts, thanks.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @yitingw1.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[yitingw1]

Please resolve conflicts, thanks.

Done.