Open Stack

Hi,
the CPU model that we expose to the guest VMs varies considering the
compute node use case.
We use "cpu_mode=host-passthrough" for the compute nodes that run batch
processing VMs and "cpu_mode=host-model" for the compute nodes for service
VMs. The reason to have "cpu_mode=host-model" is because we assumed that
new CPUs (in the libvirt map) will continue to support previous features
allowing for live migration when we need to move the VMs to a new CPU
generation.

We recently upgraded from CentOS7.3 (libvirt 2.0.0) to CentOS7.4 (libvirt
3.2.0) and noticed that now libvirt maps a slightly different CPU for the
guests. For example, still "Haswell no-TSX" but no mention to the feature
"cmt". This blocks suspended VMs to restore and live migrate.

Has anyone experienced this same problem?

We are thinking in few solutions but none of them are nice (downgrade
libvirt? hard reboot instances? ...)

thanks,
Belmiro
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