fix(roles): ask the driver before writing a vGPU profile

[Aleksei Sviridkin (lexfrei)]

Summary

The boot unit wrote current_vgpu_type on cards whose driver does not report Host VGPU Mode: SR-IOV. A card that reports Non SR-IOV runs vGPU through the legacy mdev path, and a write to one of its functions can disturb the vGPUs that path already placed there. Only the virtual-function stage asked the driver for that mode. The profile stage did not, so it wrote to a card the function stage had refused, and to a card declared with a profile alone, which that stage never sees at all.

Changes

• Both stages ask the driver for the card's mode and leave the card alone unless it reports SR-IOV. They call one helper, so the check and the line it logs exist once, and the flag that carried the function stage's decision into the profile stage is gone.
• The stages test covers both paths: a card declared with sriov and a profile, and a card declared with a profile and no sriov. Each keeps the functions it exposes, and each asserts the profile node is unchanged after the run.
• README says the skip covers such a card whatever was declared for it.

Test plan

• ansible-lint passes
• ansible-test sanity passes
• Tested on a live cluster (describe environment)
• Idempotency verified (second run: changed=0)

No vGPU hardware here, so the stages ran against the fake nvidia-smi, sriov-manage and PCI tree under tests/, on Ubuntu 24.04 with systemd.

Summary by CodeRabbit

• Bug Fixes

  • NVIDIA vGPU restore now safely skips virtual-function and profile configuration when the driver reports a non-SR-IOV mode.
  • Skipped cards no longer cause the restore operation to fail.
  • Unsupported profile-only configurations are handled as successful skips with clear log messages.

• Documentation

  • Updated NVIDIA vGPU documentation to describe non-SR-IOV handling and skip behavior.

• Tests

  • Expanded coverage for declined cards, profile-only configurations, and multi-GPU restore scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 7a523d3f-4d75-4905-9bce-8f5376ed3765

📥 Commits

Reviewing files that changed from the base of the PR and between 89ef8dd and ccbdcd8.

📒 Files selected for processing (3)

• README.md
• roles/nvidia_vgpu_host/templates/cozystack-nvidia-vgpu-restore.sh.j2
• tests/test-nvidia-vgpu-host-stages.yml

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The restore script now uses one helper to check host VGPU mode before VF and profile stages. Non-SR-IOV cards are logged and skipped successfully. Tests cover declined cards and profile-only declarations, and the README documents the behavior.

Changes

SR-IOV mode handling

Layer / File(s)	Summary
Shared SR-IOV refusal flow roles/nvidia_vgpu_host/templates/cozystack-nvidia-vgpu-restore.sh.j2	The script adds refuse_unless_sriov and uses it in both VF and profile stages. Declined cards are no longer tracked between stages.
Skip behavior validation and documentation tests/test-nvidia-vgpu-host-stages.yml, README.md	Tests verify successful skips, unchanged profile state, mode logging, and profile-only declarations. The README documents the non-SR-IOV path.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant VFProfileStage
  participant refuse_unless_sriov
  participant NVIDIADriver
  VFProfileStage->>refuse_unless_sriov: validate declared card mode
  refuse_unless_sriov->>NVIDIADriver: query host_vgpu_mode
  NVIDIADriver-->>refuse_unless_sriov: return observed mode
  refuse_unless_sriov-->>VFProfileStage: allow SR-IOV or decline stage

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Merge Risk: ⚪ Minimal · up to ccbdc

Non-SR-IOV cards are skipped without changing virtual functions or profiles, while supported cards continue through the existing stages. No actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: checking the driver before writing a vGPU profile. It is concise and specific.
Description check	✅ Passed	The description includes all required sections, explains the change, lists the main updates, and documents the test results and environment. It clearly states that live-cluster testing was not perform…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

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