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

On 3/2/12 11:04 AM, "Laine Stump" <laine laine org> wrote:

> 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.)
The design is still fine for 802.1Qbh. I have tested it. 802.1Qbh does not
need a macvtap device. For 802.1Qbg in v2 (was planning on pushing it the
next hr), I have put a check for 802.1Qbg and hostdevs and fail as suggested
by stefan.

>> * 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).

Nice. Thanks for trying it out.

>> * 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'/>
>     ...
>   </interface>
> 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).

Yes this I kind of expected. It depends on the driver. I thought there are
some drivers that remember the mac address set by SIOCGIFHWADDR. But my
assumption was totally based on the fact that we wanted to add support for
all devices. Having the code there just means we try to set the device mac.
It takes effect only if the hw supports it.
> 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?
We can do this too. Only support it for sriov vf's.


>> 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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