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Re: [libvirt] [PATCH 3/4] virnetdevvportprofile: Changes to support portprofiles for hostdevs



On Thu, 2012-03-01 at 13:02 -0500, Laine Stump wrote:
> In the case of hostdev though, there is not necessarily any netdev
> driver at all in the host (and thus no "linkdev" to attach a macvtap
> to), certainly not after it's attached to the guest - control of the
> PCI
> device is given over to the guest.
> 
> So is the problem here that 802.1QbX stuff can only work if there's an
> associated macvtap device? Although it might be possible to
> temporarily
> create a macvtap device and attach it to the PCI device's netdev
> driver
> prior to passing it through, that would only work if a netdev driver
> was
> bound to the PCI device (which isn't always the case, especially for
> SRIOV VFs), yet that netdev driver would then immediately need to be
> unbound prior to assigning the device to the guest, and most likely
> that
> would kill the macvtap device; even if the setup done using that
> macvtap
> device wasn't undone in the process, would it be possible to undo it
> later when the guest terminates (or the device is detached from the
> guest)? 

I wondered how the complete XML fragment for Qbh would look like and
came up with the following:

<interface type='hostdev'>
    <source dev='eth0' mode='private'/>
    <mac address='52:54:00:8b:c9:51'>
    <virtualport type='802.1Qbh'>
        <parameters profileid='finance'/>
    </virtualport>
</interface>

Can someone confirm?

For Qbg, we would need then something like this:

<interface type='hostdev'>
    <source dev='eth0' mode='vepa'/>
    <mac address='52:54:00:8b:c9:51'>
    <virtualport type="802.1Qbg">
        <parameters managerid="11" typeid="1193047" typeidversion="2" instanceid="09b11c53-8b5c-4eeb-8f00-d84eaa0aaa4f" vlanid="2"/>
    </virtualport>
</interface>

to be of any use. Note the additional vlanid attribute. The semantic
would be that the host establishes a Qbg association for 
(managerid, typeid, typeidversion, instanceid, vlanid)
and that the VM would need to add the correct VLAN tag in order to be
able to communicate.

Does that make sense?

Best regards, 

Gerhard Stenzel, Hybrid Technologies, LTC
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