[libvirt-users] Revert to internal snapshot - XML error: Non-empty feature list specified without CPU model

[Kashyap Chamarthy]

On Fri, Oct 24, 2014 at 03:43:55PM +0200, Kashyap Chamarthy wrote:
> Versions:
> 
>   $ rpm -q libvirt-daemon-kvm qemu-system-x86
>   libvirt-daemon-kvm-1.2.9-3.fc21.x86_64
>   qemu-system-x86-2.1.2-4.fc21.x86_64
> 
> 
> When I attempt to revert to an internal snapshot:
> 
>   $ virsh snapshot-list node1
>    Name                 Creation Time             State
>   ------------------------------------------------------------
>    snap1                2014-06-03 14:07:28 -0400 running
> 
>   $ virsh snapshot-revert node1 snap1                                                              
>   error: XML error: Non-empty feature list specified without CPU model
> 
> 
> Contextual guest XML:
> 
>   $ virsh dumpxml node1 | grep features -A3
>     <features>
>       <acpi/>
>       <apic/>
>       <pae/>
>     </features>
>     <cpu mode='host-passthrough'>
>     </cpu>
>     <clock offset='utc'>
> 
> 
> I see it's thrown from here, src/conf/cpu_conf.c, from function:
> virCPUDefParseXML:371
> 
>     [. . .]
>     367     if (n > 0) {
>     368         if (!def->model && def->mode != VIR_CPU_MODE_HOST_MODEL) {
>     369             virReportError(VIR_ERR_XML_ERROR, "%s",
>     370                            _("Non-empty feature list specified without "
>     371                              "CPU model"));
>     372             goto error;
>     373         }
>     [. . .]
> 
> 
> I can manually revert this snapshot via `qemu-img`, but wondering if
> this error from libvirt expected in this case?

Forgot, there's an existing old bug report that I tested and confirmed
here:

    https://bugzilla.redhat.com/show_bug.cgi?id=1030793 --
    snapshot-revert fails if cpu mode=passthrough -- XML error:
    Non-empty feature list specified without CPU model

Comment from Eric Blake on IRC: Sounds like yet another incarnation of
us not outputting correct information in our dumpxml output.

-- 
/kashyap