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Re: [libvirt] [PATCH 0/4] Support mac and port profile for <interface type='hostdev'>

On 03/01/2012 04:02 AM, Roopa Prabhu wrote:
> This patch series is based on laines patches to support <interface type='hostdev'>.
> https://www.redhat.com/archives/libvir-list/2012-February/msg01126.html
> It support to set mac and port profile on an interface of type hostdev.
> * If virtualport is specified, the existing virtual port functions are
> called to set mac, vlan and port profile.

I'm unable to test that part, as I don't have any 802.1QbX capable
switches (and it sounds like the design is problematic anyway.)

> * If virtualport is not specified and device is a sriov virtual function,
> 	- mac is set using IFLA_VF_MAC

Success!! I tried this for VFs that have a netdev driver attached, and
VFs that don't, and it behaved properly in both cases - when the guest
is started, the MAC address is set properly for the guest to use, and
when the guest is stopped, the MAC address of that VF is restored to its
original value (implying that your code to save the old MAC address
works properly).

> * If virtualport is not specified and device is a non-sriov virtual function,
> 	- mac is set using existing SIOCGIFHWADDR (This requires that the
>         netdev be present on the host before starting the VM)

This one has a problem, at least with my non-sriov hardware (which
happens to be the onboard NetXtreme device of a Thinkstation, using the
tg3 driver) it appears the MAC address gets reset to its original
setting at some point after libvirt changes it. To help understand what
happens - assume the device's original MAC address is o:o:o:o:o:o, and
my xml looks like this:

  <interface type='hostdev' managed='yes'>
    <mac address='n:n:n:n:n:n'/>

When the guest boots up, ifconfig shows there is an interface with mac
address o:o:o:o:o:o.

Additionally, if I manually change the mac address to p:p:p:p:p:p on the
host before starting the guest, when the guest boots, ifconfig shows the
mac address as... o:o:o:o:o:o. So, whether or not libvirt is
successfully setting the mac address, it's getting reset (probably by
the card's firmware).

So perhaps this is another case of wanting to do something that just
isn't possible, and the way out is to simply generate an error on domain
startup if the netdev being passed through isn't a VF?

> This series implements the below :
> 01/4 pci: Add two new pci util pciDeviceGetVirtualFunctionInfo and pciConfigAddressToSysfsFile
> 02/4 virtnetdev: Add support functions for mac and portprofile associations on a hostdev
> 03/4 virnetdevvportprofile: Changes to support portprofiles for hostdevs
> 04/4 qemu_hostdev: Add support to install port profile and mac address on hostdev
> Stefan Berger is CC'ed for 802.1Qbg changes in patch 03/4. Current code for 
> 802.1Qbg uses macvtap ifname. And for network interfaces with type=hostdev a 
> macvtap ifname does not exist. This patch just adds a null check for ifname in 
> 802.1Qbg port profile handling code.

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