[libvirt] [PATCH 1/1 V2] Migrate per-port data for Open vSwitch ports during Qemu Live Migration

[Kyle Mestery (kmestery)]

On Sep 6, 2012, at 12:35 AM, Daniel Veillard wrote:
> On Tue, Sep 04, 2012 at 04:35:24PM -0400, Kyle Mestery wrote:
>> Add the ability to migrate per-port data on Open vSwitch
>> ports during qemu live migration. A controller can use this
>> to store data relating to each port, and have it migrated
>> with the virtual machine and populated on the destination
>> host.
>> 
>> Signed-off-by: Kyle Mestery <kmestery at cisco.com>
>> Cc: Laine Stump <laine at laine.org>
> [....]
>> +static void qemuMigrationCookieOvsPortDataXMLFormat(virBufferPtr buf,
>> +                                                    qemuMigrationCookieOvsPortDataPtr optr)
>> +{
>> +    int i;
>> +
>> +    virBufferAsprintf(buf, "  <ovsportdata nnets='%d'>\n", optr->nnets);
>> +    if (optr->nnets > 0)
>> +        virBufferAsprintf(buf, "    <vifs>\n");
>> +    for (i = 0; i < optr->nnets; i++) {
>> +        virBufferAsprintf(buf, "      <vif num='%d' portdata='%s'/>\n",
>> +                          i, optr->portdata[i]);
>> +    }
>> +    if (optr->nnets > 0)
>> +        virBufferAsprintf(buf, "    </vifs>\n");
>> +
>> +    virBufferAddLit(buf, "  </ovsportdata>\n");
>> +}
> 
>  I'm not specialist of the networking layer, but it looks to me that
> this should work (but can someone explain the error scenario if the
> receiving end don't understand the extra XML passed in the migration
> data ?). My main concern is tying that generic mechanism to OVS, seems
> to me this should be split in 2 patches:
>   - one patch adding the generic framework to adding XML networking
>     related data to the XML passed along the domain in the migration
>   - one patch using that generic mechanism to carry the OpenVSwitch 
>     per port data
> The first part defining the data extension etc ought to be generic
> (but probably network related) and the second part specific to OVS
> 
>  Laine, am I off track ?
> 
> Daniel


Thanks for the review Daniel. Laine and I spoke offline, and he had similar
comments to you. I will rework the patch as you describe above, and incorporate
any additional comments Laine has as well.

Thanks!
Kyle