Hi All,
I'm encountering an issue with live migrating between 2 Compute nodes with
different CPU models. Host A has a Westmere CPU and host B has a Broadwell.
I can migrate an instance from the Westmere host A to the Broadwell host B,
but when I attempt to live migrate a VM from the Broadwell host B to the older
Westmere host I get the following error;
Live Migration failure: unsupported configuration: guest and host CPU are not
compatible: Host CPU does not provide required features: fma, x2apic, movbe,
tsc-deadline, xsave, osxsave, avx, f16c, rdrand, fsgsbase, tsc_adjust, bmi1,
hle, avx2, smep, bmi2, erms, invpcid, rtm, rdseed, adx, smap, xsaveopt, abm,
3dnowprefetch; try using 'Broadwell-noTSX' CPU model
How can I avoid this error, without rebooting any VMs?
Host B with the Broadwell CPU has the libvirt CPU masking enabled in its
nova.conf;
...
[libvirt]
cpu_mode = custom
cpu_model = Westmere
Host A with the Westmere CPU, never had the cpu_mode set in nova.conf but as
its KVM it should default to the following;
[libvirt]
cpu_mode = host-model
The "host-model" cpu_mode appears to enable more CPU features on the guest the
then what is enabled by cpu_model = Westmere. For instance, when a VM is
started on Host A (Westmere CPU & cpu_mode = host-model) the VM get the
following CPU configuration;
<cpu mode='host-model'>
<model fallback='allow'>Westmere</model>
<vendor>Intel</vendor>
<topology sockets='1' cores='1' threads='1'/>
<feature policy='require' name='vme'/>
<feature policy='require' name='ds'/>
<feature policy='require' name='acpi'/>
<feature policy='require' name='ss'/>
<feature policy='require' name='ht'/>
<feature policy='require' name='tm'/>
<feature policy='require' name='pbe'/>
<feature policy='require' name='pclmuldq'/>
<feature policy='require' name='dtes64'/>
<feature policy='require' name='monitor'/>
<feature policy='require' name='ds_cpl'/>
<feature policy='require' name='vmx'/>
<feature policy='require' name='smx'/>
<feature policy='require' name='est'/>
<feature policy='require' name='tm2'/>
<feature policy='require' name='xtpr'/>
<feature policy='require' name='pdcm'/>
<feature policy='require' name='pcid'/>
<feature policy='require' name='dca'/>
<feature policy='require' name='arat'/>
<feature policy='require' name='pdpe1gb'/>
<feature policy='require' name='rdtscp'/>
</cpu>
But when the instance is booted on Host B (Broadwell CPU & cpu_model = Westmere)
<cpu mode='custom' match='exact'>
<model fallback='allow'>Westmere</model>
<topology sockets='1' cores='1' threads='1'/>
</cpu>
Interestingly once a host is booted on Host B and has the above CPU config, it
can be migrated back to Host A without any error.
Host A Capabilities;
<cpu>
<arch>x86_64</arch>
<model>Westmere</model>
<vendor>Intel</vendor>
<topology sockets='1' cores='4' threads='2'/>
<feature name='vme'/>
<feature name='ds'/>
<feature name='acpi'/>
<feature name='ss'/>
<feature name='ht'/>
<feature name='tm'/>
<feature name='pbe'/>
<feature name='pclmuldq'/>
<feature name='dtes64'/>
<feature name='monitor'/>
<feature name='ds_cpl'/>
<feature name='vmx'/>
<feature name='smx'/>
<feature name='est'/>
<feature name='tm2'/>
<feature name='xtpr'/>
<feature name='pdcm'/>
<feature name='pcid'/>
<feature name='dca'/>
<feature name='arat'/>
<feature name='pdpe1gb'/>
<feature name='rdtscp'/>
<feature name='invtsc'/>
<pages unit='KiB' size='4'/>
<pages unit='KiB' size='2048'/>
<pages unit='KiB' size='1048576'/>
</cpu>
Host B Capabilities;
<cpu>
<arch>x86_64</arch>
<model>Broadwell</model>
<vendor>Intel</vendor>
<topology sockets='1' cores='12' threads='2'/>
<feature name='vme'/>
<feature name='ds'/>
<feature name='acpi'/>
<feature name='ss'/>
<feature name='ht'/>
<feature name='tm'/>
<feature name='pbe'/>
<feature name='dtes64'/>
<feature name='monitor'/>
<feature name='ds_cpl'/>
<feature name='vmx'/>
<feature name='smx'/>
<feature name='est'/>
<feature name='tm2'/>
<feature name='xtpr'/>
<feature name='pdcm'/>
<feature name='dca'/>
<feature name='osxsave'/>
<feature name='f16c'/>
<feature name='rdrand'/>
<feature name='arat'/>
<feature name='tsc_adjust'/>
<feature name='cmt'/>
<feature name='xsaveopt'/>
<feature name='mbm_total'/>
<feature name='mbm_local'/>
<feature name='pdpe1gb'/>
<feature name='abm'/>
<feature name='invtsc'/>
<pages unit='KiB' size='4'/>
<pages unit='KiB' size='2048'/>
<pages unit='KiB' size='1048576'/>
</cpu>
Oisin O'Malley
Systems Engineer
Iocane Pty Ltd
763 South Road
Black Forest SA 5035
Office:+61 (8) 8413 1010
Fax:+61 (8) 8231 2050
Email:oisin.omal...@iocane.com.au
Web:www.iocane.com.au
Better for business
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