[KVM] Allow passing the OS type machine for KVM XML domains through VM setting

[nvazquez]

Description

This PR allows passing the OS type machine for KVM XML domains through the VM setting with name: kvm.guest.os.machine.type.

Fixes: #11512

Specifically, this allows fixing UUID retrieval of Windows VMs on Ubuntu 24 when passing the machine type = 'pc-i440fx-8.0' (see #11512 and https://gitlab.com/libvirt/libvirt/-/issues/807#note_2724045702)

# virsh dumpxml 108 | grep machine
    <partition>/machine</partition>
    <type arch='x86_64' machine='pc-i440fx-8.0'>hvm</type>

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Tested on Ubuntu 24 KVM host - deploying Windows VM and retrieving the UUID through the wmic command

How did you try to break this feature and the system with this change?

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 17.36%. Comparing base (3d6ec29) to head (3c1064b).

Files with missing lines	Patch %	Lines
...ervisor/kvm/resource/LibvirtComputingResource.java	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #11569      +/-   ##
============================================
- Coverage     17.36%   17.36%   -0.01%     
+ Complexity    15237    15236       -1     
============================================
  Files          5888     5888              
  Lines        525741   525743       +2     
  Branches      64164    64165       +1     
============================================
- Hits          91274    91270       -4     
- Misses       424167   424172       +5     
- Partials      10300    10301       +1     

Flag	Coverage Δ
uitests	3.63% <ø> (ø)
unittests	18.39% <0.00%> (-0.01%)	⬇️

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[nvazquez]

@blueorangutan package

[blueorangutan]

@nvazquez a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[github-actions]

This pull request has merge conflicts. Dear author, please fix the conflicts and sync your branch with the base branch.

[nvazquez]

@blueorangutan package

[blueorangutan]

@nvazquez a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✖️ debian ✔️ suse15. SL-JID 14836

[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 14837

[nvazquez]

@blueorangutan test

[blueorangutan]

@nvazquez a [SL] Trillian-Jenkins test job (ol8 mgmt + kvm-ol8) has been kicked to run smoke tests

[weizhouapache]

@nvazquez
maybe machine.type, not type.machine

Can it be set by regular user ?

[Pearl1594]

Would it make sense to have a documentation PR - adding a note on the limitation with retrieving UUID on a Windows VM, and how it can be mitigated using this @nvazquez.

[weizhouapache]

@nvazquez
should the target branch be 4.20 ?

[nvazquez]

Thanks @Pearl1594 I'll create a doc PR for that.

@weizhouapache as discussed offline let's keep it targeted to main branch to avoid feature loss on upgrade to 4.21

[rohityadavcloud]

@nvazquez is this worth raising the PR for 4.20 branch, could you check & change the base branch?

[rohityadavcloud]

LGTM; ideally the machine type could be detected automatically though?

[blueorangutan]

[SF] Trillian test result (tid-14206)
Environment: kvm-ol8 (x2), zone: Advanced Networking with Mgmt server ol8
Total time taken: 55385 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr11569-t14206-kvm-ol8.zip
Smoke tests completed. 141 look OK, 0 have errors, 0 did not run
Only failed and skipped tests results shown below:

Test	Result	Time (s)	Test File

[jmgsky]

This looks like it will fix my issue with booting a Juniper VSRX on cloudstack, but I think an option to set other parameters on the underlying qemu virtual machine would be more sustainable.

Specifically, you can set smbios-entry-point-type on the machine (even newer i440fx-8.2 and beyond) and have it still use the older 32-bit smbios 2.x interface. Here is the best example I can find of it's usage with qemu.

[weizhouapache]

@nvazquez is this worth raising the PR for 4.20 branch, could you check & change the base branch?

@rohityadavcloud
I have discussed with @nvazquez , our concern is, when users upgrade from 4.20.2 (assume this PR is included) to 4.21.0 (released already), the setting will be gone.

my opinion is, unless very necessary, let's not introduce new api params, api responses, settings or db changes in minor versions.

[nvazquez]

Hi @jmgsky thanks for your input. I think that can be addressed on a separate PR.
I couldn't find references for this attribute on the libvirt documentation, but seems it should be wrapped as a feature on the XML domain. Can you please confirm if this snippet looks correct for a running domain?

<type arch='x86_64' machine='pc-i440fx-8.0'>hvm</type>
<features>
   <sm-bios-entry-point-type value='32'/>
</features>

[jmgsky]

@nvazquez - I'm actually not sure if that's right or not. I was trying to do it with extraconfig and qemu:args, but my VM wouldn't even start at that point. I switched to testing using virsh edit manually, and it doesn't like that xml snippet or qemu:args, so I'm honestly not even sure if there's a way to achieve that with libvirt.

[nvazquez]

@jmgsky thanks, the extraconfig will attempt to append the snippet as well on the XML domain, should have similar results than editing the XML directly. I couldn't find it mentioned on: https://libvirt.org/formatdomain.html, however checking the example you mentioned can you try the following?

<type arch='x86_64' machine='pc-i440fx-8.0' sm-bios-entry-point-type='32'>hvm</type>