[libvirt] RFC: setting mac address on network devices being assigned to a guest via PCI passthrough (<hostdev>)

[Roopa Prabhu]

On 1/31/12 1:16 AM, "Laine Stump" <laine at laine.org> wrote:

> On 01/30/2012 08:16 PM, Roopa Prabhu wrote:
>> Laine, I haven't gone through your whole email yet. Was just curious about
>> one quick thing,
>> 
>> For sriov VF's, are we expecting that a net device (eth interface) be
>> present on the host if its being used as a hostdev ?.
> 
> 
> Either should be possible. If the VF is bound to a net dev, it can be
> specified either with dev='ethxx' or using its pci address, and will be
> unbound before assigning to the guest. If it's not bound to a net dev,
> then a pci address must be used to describe it in the config.
> 
> 
>>   If yes, then libvirt
>> will need to do an unbind of the driver on the VF before assigning it to the
>> VM. Which today it does not do (correct me if I am wrong).
> 
> 
> That may have been the case in the past, but with libvirt-0.9.9 (the
> first version that I've tested with sriov and PCI passthrough - I'm a
> newbie to both), the net driver is unbound prior to assigning to the
> guest, and when the the device is detached from the guest, the net
> driver is once again bound to the device.
> 
> 
>> Which is still
>> ok. Just wanted to call that out.
>> Plus ideally it would be nice to not have an expectation that a vf netdevice
>> be present on the host. Because for sriov vf's, it would mean that the vf
>> driver has to be loaded on the host. Which is really not required for vfs
>> because mac and port profile can be set via the pf with the vf index as
>> argument.
> 
> Right. For sriov VFs, I intend that the MAC address will always be set
> via the PF. I hadn't previously thought through the details for
> non-sriov devices, but your event sequence list below made me realize
> that, at least for non-sriov, the MAC address and virtual port setup
> will need to be done *before* unbinding the driver (my intent, for sriov
> at least, was that this would happen *after* unbinding the driver). I
> guess that will take some experimentation.
> 
> Anyway, at the moment I'm slogging around in the data structures.
> 

ok. Thanks Laine.