Bug 1531076 - Support 'host-model' on aarch64
Support 'host-model' on aarch64
Status: NEW
Product: Virtualization Tools
Classification: Community
Component: libvirt (Show other bugs)
unspecified
aarch64 Linux
unspecified Severity unspecified
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Assigned To: Libvirt Maintainers
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Depends On:
Blocks:
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Reported: 2018-01-04 09:30 EST by Marcin Juszkiewicz
Modified: 2018-01-04 09:36 EST (History)
3 users (show)

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Attachments (Terms of Use)
nova log with domain xml (4.76 KB, text/plain)
2018-01-04 09:30 EST, Marcin Juszkiewicz
no flags Details


External Trackers
Tracker ID Priority Status Summary Last Updated
Launchpad 1741230 None None None 2018-01-04 09:30 EST

  None (edit)
Description Marcin Juszkiewicz 2018-01-04 09:30:14 EST
Created attachment 1376987 [details]
nova log with domain xml

Description of problem:

Nova (OpenStack component) defaults to cpu_mode = host-model on all architectures. And then all VM instances fail:

"Failed to start libvirt guest: libvirtError: unsupported configuration: CPU mode 'host-model' for aarch64 kvm domain on aarch64 host is not supported by hypervisor."

Popular workaround is to use 'host-passthrough' but that breaks live migration on cloud setups with different ARMv8a cpu cores.

Version-Release number of selected component (if applicable):

3.10.0

How reproducible:

always

Steps to Reproduce:
1. Deploy Nova compute component
2. Run VM instance

Actual results:

"Failed to start libvirt guest: libvirtError: unsupported configuration: CPU mode 'host-model' for aarch64 kvm domain on aarch64 host is not supported by hypervisor."

Expected results:

Instance runs.
Additional info:
Comment 1 Marcin Juszkiewicz 2018-01-04 09:34:33 EST
After some reading I tried 'cpu_mode=custom' + 'cpu_model=cortex-a53' but such setup broke Nova.

CPU snippet from domain definition was:

<cpu mode='custom' match='exact' check='partial'>
  <model fallback='allow'>cortex-a53</model>
  <topology sockets='1' cores='1' threads='1'/>
</cpu>

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