Tracing instrument

[JonathanWoollett-Light]

Changes

Adds code instrumentation.

Reason

This opens support for tracing and profiling via this instrumentation.

skip_all is avoided as it is removed in the latest version of tracing, while we can use it here, it would need to be removed later.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following
Developer Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.

PR Checklist

• If a specific issue led to this PR, this PR closes the issue.
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• API changes follow the Runbook for Firecracker API changes.
• User-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.
• New TODOs link to an issue.
• Commits meet contribution quality standards.

---

• This functionality cannot be added in rust-vmm.

[JonathanWoollett-Light]

Blocked on #3808

[codecov]

Codecov Report

Patch coverage: 86.95% and project coverage change: -11.60% ⚠️

Comparison is base (6bf22c2) 82.66% compared to head (40f5eaa) 71.07%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3810       +/-   ##
===========================================
- Coverage   82.66%   71.07%   -11.60%     
===========================================
  Files         221      219        -2     
  Lines       28192     9084    -19108     
===========================================
- Hits        23306     6456    -16850     
+ Misses       4886     2628     -2258     

Flag	Coverage Δ
4.14-c7g.metal	66.10% <82.59%> (-12.03%)	⬇️
4.14-m5d.metal	69.92% <84.50%> (-9.98%)	⬇️
4.14-m6a.metal	69.87% <84.32%> (-9.18%)	⬇️
4.14-m6g.metal	66.10% <82.59%> (-12.03%)	⬇️
4.14-m6i.metal	69.92% <84.50%> (-9.98%)	⬇️
5.10-c7g.metal	67.13% <85.53%> (-13.94%)	⬇️
5.10-m5d.metal	70.83% <87.45%> (-11.76%)	⬇️
5.10-m6a.metal	70.78% <87.28%> (-11.05%)	⬇️
5.10-m6g.metal	67.13% <85.53%> (-13.94%)	⬇️
5.10-m6i.metal	70.83% <87.45%> (-11.75%)	⬇️
6.1-c7g.metal	67.13% <85.53%> (-13.94%)	⬇️
6.1-m5d.metal	70.83% <87.45%> (-11.76%)	⬇️
6.1-m6a.metal	70.78% <87.28%> (-11.05%)	⬇️
6.1-m6g.metal	67.13% <85.53%> (-13.94%)	⬇️
6.1-m6i.metal	70.83% <87.45%> (-11.76%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/firecracker/src/api_server_adapter.rs	0.00% <0.00%> (ø)
src/firecracker/src/main.rs	1.16% <0.00%> (+0.93%)	⬆️
src/jailer/src/chroot.rs	0.00% <0.00%> (ø)
...c/vmm/src/arch/aarch64/gic/gicv2/regs/dist_regs.rs	0.00% <0.00%> (ø)
...rc/vmm/src/arch/aarch64/gic/gicv2/regs/icc_regs.rs	0.00% <0.00%> (ø)
src/vmm/src/arch/aarch64/gic/gicv2/regs/mod.rs	0.00% <0.00%> (ø)
src/vmm/src/signal_handler.rs	28.04% <ø> (-53.49%)	⬇️
src/vmm/src/vmm_config/balloon.rs	85.71% <ø> (-12.02%)	⬇️
src/vmm/src/vmm_config/boot_source.rs	50.00% <ø> (-40.48%)	⬇️
src/vmm/src/vmm_config/drive.rs	100.00% <ø> (+2.06%)	⬆️
... and 195 more

... and 1 file with indirect coverage changes

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[JonathanWoollett-Light]

Moved to feature branch to store work for historical reference https://github.com/firecracker-microvm/firecracker/tree/feature/tokio-tracing.