[libvirt-users] How to disable kvm_steal_time feature

[Martin Kletzander]

On Fri, Nov 20, 2015 at 04:31:56PM +0100, Piotr Rybicki wrote:
>Hi.
>
>I would like to workaround a bug, when after live-migration of KVM
>guest, there is a 100% steal time shown in guest.
>
>I've read, that disabling 'kvm_steal_time' feature should workarund
>this bug, but i can't find a way to disable it in libvirt's domain xml
>file.
>

There is no support for that in libvirt.  Either we must addit ad a
feature (patches welcome), but if that's there just for a workaround,
I would suggest chasing the original bug.

If you just want to check that the workaround works, you could check
how the '-cpu ' parameter looks like when the domain is running and
then use the unsupported way of adding parameters to the qemu
commandline to specify the -cpu parameter again (qemu should use the
last one, so it should work), something like this:

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
...
  <qemu:commandline>
    <qemu:arg value='-cpu'/>
    <qemu:arg value='${CPU_SPEC},-kvm_steal_time'/>
  </qemu:commandline>
</domain>

where ${CPU_SPEC} is the next parameter after the '-cpu' one from the
command line, so for qemu command line similar to this:

  qemu-kvm ... -cpu Nehalem,+feat,something ...

the line in XML would be:

  <qemu:arg value='Nehalem,+feat,something,-kvm_steal_time'/>

HTH,

Martin

>Tried in <cpu> section:
><feature policy='disable' name='kvm_steal_time'/>
>but that doesn't work.
>
>Also, couldn't find any related information in libvirt documentation.
>Google helps neither.
>
>How can I disable this feature?
>
>Thanks in advance.
>Piotr Rybicki
>
>_______________________________________________
>libvirt-users mailing list
>libvirt-users at redhat.com
>https://www.redhat.com/mailman/listinfo/libvirt-users
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/libvirt-users/attachments/20151127/be43d23b/attachment.sig>