Reverting to VM Snapshots fail if VM is powered off+on

[Sean Lair <sl...@ippathways.com>]

We are seeing a strange problem in our ACS environments.  We are running Centos7 as our hypervisors.  When we take a VM Snapshot and then later revert to it, it works as long as we haven't stopped and started the VM.  If we stop the VM and start it again - even if it is still on the same host - we cannot revert back to a VM Snapshot.  Here is the error and further information.   Any ideas?  It is 100% reproducible for us.


2021-12-13 22:50:51,731 DEBUG [c.c.a.t.Request] (AgentManager-Handler-12:null) (logid:) Seq 101-5603885311332466879: Processing:  { Ans: , MgmtId: 345051498372, via: 101, Ver: v1, Flags: 10, [{"com.cloud.agent.api.RevertToVMSnapshotAnswer":{"result":false,"details":" Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0","wait":0}}] }
2021-12-13 22:50:51,732 ERROR [o.a.c.s.v.DefaultVMSnapshotStrategy] (Work-Job-Executor-64:ctx-1767fb85 job-130106/job-130111 ctx-ab4680c7) (logid:87cc475a) Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0
com.cloud.utils.exception.CloudRuntimeException: Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0
2021-12-13 22:50:51,743 ERROR [c.c.v.VmWorkJobHandlerProxy] (Work-Job-Executor-64:ctx-1767fb85 job-130106/job-130111 ctx-ab4680c7) (logid:87cc475a) Invocation exception, caused by: com.cloud.utils.exception.CloudRuntimeException: Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0
2021-12-13 22:50:51,743 INFO  [c.c.v.VmWorkJobHandlerProxy] (Work-Job-Executor-64:ctx-1767fb85 job-130106/job-130111 ctx-ab4680c7) (logid:87cc475a) Rethrow exception com.cloud.utils.exception.CloudRuntimeException: Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0
com.cloud.utils.exception.CloudRuntimeException: Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0
Caused by: com.cloud.utils.exception.CloudRuntimeException: Revert VM: i-2-317-VM to snapshot: i-2-317-VM_VS_20211213224802 failed due to  Revert to VM snapshot failed due to org.libvirt.LibvirtException: revert requires force: Target CPU feature count 3 does not match source 0


[root@labcloudkvm02 ~]# virsh dumpxml 33
...
  <cpu mode='custom' match='exact' check='full'>
    <model fallback='forbid'>IvyBridge</model>
    <feature policy='require' name='hypervisor'/>
    <feature policy='require' name='arat'/>
    <feature policy='require' name='xsaveopt'/>
  </cpu>
...


[root@labcloudkvm02 ~]# virsh dumpxml 33 --migratable
...
  <cpu mode='custom' match='exact' check='partial'>
    <model fallback='forbid'>IvyBridge</model>
  </cpu>
...


[root@labcloudkvm02 ~]# virsh snapshot-dumpxml 33 i-2-317-VM_VS_20211213224802
...
    <cpu mode='custom' match='exact' check='full'>
      <model fallback='forbid'>IvyBridge</model>
      <feature policy='require' name='hypervisor'/>
      <feature policy='require' name='arat'/>
      <feature policy='require' name='xsaveopt'/>
    </cpu>
...

In agent.properties:
guest.cpu.model=IvyBridge
guest.cpu.mode=custom