feat: support linux v6.12 balloon stat

[laushunyu]

Changes

Linux v6.12 add more balloon stat: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/include/uapi/linux/virtio_balloon.h?id=v6.12&id2=v6.11

related commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=74c025c5d7e4ac7c7ad269c1ee64da4bdfe4770c

I supported it, when kernel >= v6.12, stat:

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1835008,"actual_pages":1835008,"target_mib":7168,"actual_mib":7168,"swap_in":0,"swap_out":0,"major_faults":1360,"minor_faults":126031,"free_memory":142065664,"total_memory":8351473664,"available_memory":437428224,"disk_caches":470376448,"hugetlb_allocations":0,"hugetlb_failures":0,"oom_kill":0,"alloc_stall":0,"async_scan":524492800,"direct_scan":0,"async_reclaim":413532160,"direct_reclaim":0}

otherwise:

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1806336,"actual_pages":1806336,"target_mib":7056,"actual_mib":7056,"swap_in":0,"swap_out":0,"major_faults":1777,"minor_faults":788590,"free_memory":131616768,"total_memory":8352452608,"available_memory":536666112,"disk_caches":577331200,"hugetlb_allocations":0,"hugetlb_failures":0}

Reason

I run firecrack with vmlinux v6.12, and balloon stat crashed:

stat api show no memory stat.

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1806336,"actual_pages":1806336,"target_mib":7056,"actual_mib":7056}

License Acceptance

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CONTRIBUTING.md.

PR Checklist

• I have read and understand CONTRIBUTING.md.
• I have run tools/devtool checkbuild --all to verify that the PR passes
  build checks on all supported architectures.
• I have run tools/devtool checkstyle to verify that the PR passes the
  automated style checks.
• I have described what is done in these changes, why they are needed, and
  how they are solving the problem in a clear and encompassing way.
• I have updated any relevant documentation (both in code and in the docs)
  in the PR.
• I have mentioned all user-facing changes in CHANGELOG.md.
• If a specific issue led to this PR, this PR closes the issue.
• When making API changes, I have followed the
  Runbook for Firecracker API changes.
• I have tested all new and changed functionalities in unit tests and/or
  integration tests.
• I have linked an issue to every new TODO.

---

• This functionality cannot be added in rust-vmm.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.38%. Comparing base (0aa8f6c) to head (2a57348).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5516   +/-   ##
=======================================
  Coverage   83.38%   83.38%           
=======================================
  Files         277      277           
  Lines       29219    29237   +18     
=======================================
+ Hits        24363    24380   +17     
- Misses       4856     4857    +1     

Flag	Coverage Δ
5.10-m5n.metal	83.61% <100.00%> (+0.01%)	⬆️
5.10-m6a.metal	82.95% <100.00%> (+0.01%)	⬆️
5.10-m6g.metal	80.36% <100.00%> (+0.01%)	⬆️
5.10-m6i.metal	83.61% <100.00%> (+<0.01%)	⬆️
5.10-m7a.metal-48xl	82.94% <100.00%> (+0.01%)	⬆️
5.10-m7g.metal	80.36% <100.00%> (+0.01%)	⬆️
5.10-m7i.metal-24xl	83.59% <100.00%> (+0.01%)	⬆️
5.10-m7i.metal-48xl	83.59% <100.00%> (+<0.01%)	⬆️
5.10-m8g.metal-24xl	80.36% <100.00%> (+0.01%)	⬆️
5.10-m8g.metal-48xl	80.36% <100.00%> (+0.01%)	⬆️
6.1-m5n.metal	83.64% <100.00%> (+0.01%)	⬆️
6.1-m6a.metal	82.98% <100.00%> (+<0.01%)	⬆️
6.1-m6g.metal	80.36% <100.00%> (+0.01%)	⬆️
6.1-m6i.metal	83.64% <100.00%> (+<0.01%)	⬆️
6.1-m7a.metal-48xl	82.97% <100.00%> (+0.01%)	⬆️
6.1-m7g.metal	80.36% <100.00%> (+0.01%)	⬆️
6.1-m7i.metal-24xl	83.66% <100.00%> (+0.01%)	⬆️
6.1-m7i.metal-48xl	83.65% <100.00%> (+0.01%)	⬆️
6.1-m8g.metal-24xl	80.35% <100.00%> (+0.01%)	⬆️
6.1-m8g.metal-48xl	80.36% <100.00%> (+0.01%)	⬆️

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[JackThomson2]

Thanks @laushunyu for the PR looks good!

The rust style checks seem to be failing, you can run tools/devtool fmt and tools/devtool checkstyle to fix and verify that's been resolved. Also can we have a small description of the changes in the commit message.

[laushunyu]

Thanks @JackThomson2 for the review! ♥️

I've pushed the fixes and updated the commit message. Please take another look.

[laushunyu]

hello~ @pb8o @Manciukic @kalyazin @xmarcalx

Could you review this when convenient? Thanks!

[Manciukic]

Change lgtm, just a minor reword on the changelog entry.

Also, I think we should log an issue to do some followup work to not fail close but just log it and add a test to detect new features being added.

[Manciukic]

It'd also be nice to add the new metrics in docs/ballooning.md

[JackThomson2]

We could also have these in the swagger definition: https://github.com/firecracker-microvm/firecracker/blob/main/src/firecracker/swagger/firecracker.yaml#L787

[laushunyu]

hi~ @Manciukic @JackThomson2

I update the balloon doc, changelog and swagger.

[Manciukic]

A few more nits on the doc, but we're almost there!
Also, could you squash the commits into a single one?

Update: please, also make sure to run ./tools/devtool checkstyle to verify the CI style checks will pass to avoid back-and-forths for style issues.

[laushunyu]

hi, @Manciukic

Thanks for your reviewing🤗, I’ve updated the doc.

[JackThomson2]

Thanks for updating the docs, we're almost there 😃

[JackThomson2]

Thank you for your contribution!