Re: [Qemu-devel] [PATCH v3 1/5] virtio_net: Add VIRTIO_NET_F_STANDBY feature bit.

[Dongli Zhang]

Hi Samudrala,

On 2019/1/9 上午8:18, Samudrala, Sridhar wrote:
> On 1/8/2019 4:14 PM, Dongli Zhang wrote:
>> Hi Venu,
>>
>> On 2019/1/9 上午1:25, Venu Busireddy wrote:
>>> On 2019-01-09 00:56:38 +0800, Dongli Zhang wrote:
>>>> I am not familiar with libvirt and I would like to play with this only 
>>>> with qemu.
>>>>
>>>> With failover, we need to hotplug the VF on destination server to VM after 
>>>> live
>>>> migration. However, the VF on destination server would have different mac 
>>>> address.
>>>>
>>>> How can we specify the mac for the new VF to hotplug via qemu, as VF is 
>>>> only a
>>>> vfio pci device?
>>> How is the VF device on the destination host any different from the VF
>>> on the source host?
>>>
>>> As you do on the source host, you first assign the MAC address of
>>> 00:00:00:00:00:00 to the VF. After the migration, you assign the same
>>> MAC address as that of the virtio_net device to the VF, and hotadd the VF
>> This was what I was wondering.
>>
>> How the mac address is configured for VF (or any NIC like PF) after it is
>> assigned to vfio?
> 
> ip link set <pf> vf  <vf-num>  mac <MAC>
> 
> See https://www.kernel.org/doc/html/latest/networking/net_failover.html
> for a sample script that shows the steps to initiate live migration with VF 
> and virtio-net in standby mode.

Thank you very much for the help!

Sorry that I did not ask the question in the right way.

Although I was talking about VF, I would like to passthrough the entire PF (with
sriov_numvfs=0) to guest VM.

In this situation, I am not able to configure the mac address when the entire PF
(or NIC) is assigned to VFIO. <pf> does not exist as it is belong to VFIO.

Thank you very much!

Dongli Zhang

> 
> 
>> Thank you very much!
>>
>> Dongli Zhang
>>
>>
>>> device to the VM. And then, after you receive the FAILOVER_PRIMARY_CHANGED
>>> event, set the macvtap device to down state.
>>>
>>> Venu
>>>
>>>> I am trying to play with this with only qemu (w/o libvirt).
>>>>
>>>> Thank you very much!
>>>>
>>>> Dongli Zhang
>>>>
>>>> On 01/08/2019 06:29 AM, Venu Busireddy wrote:
>>>>> From: Sridhar Samudrala <address@hidden>
>>>>>
>>>>> This feature bit can be used by a hypervisor to indicate to the virtio_net
>>>>> device that it can act as a standby for another device with the same MAC
>>>>> address.
>>>>>
>>>>> Signed-off-by: Sridhar Samudrala <address@hidden>
>>>>> Signed-off-by: Venu Busireddy <address@hidden>
>>>>> ---
>>>>>  hw/net/virtio-net.c | 2 ++
>>>>>  1 file changed, 2 insertions(+)
>>>>>
>>>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>>>>> index 385b1a0..411f8fb 100644
>>>>> --- a/hw/net/virtio-net.c
>>>>> +++ b/hw/net/virtio-net.c
>>>>> @@ -2198,6 +2198,8 @@ static Property virtio_net_properties[] = {
>>>>>                       true),
>>>>>      DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
>>>>>      DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
>>>>> +    DEFINE_PROP_BIT64("standby", VirtIONet, host_features, 
>>>>> VIRTIO_NET_F_STANDBY,
>>>>> +                      false),
>>>>>      DEFINE_PROP_END_OF_LIST(),
>>>>>  };
>>>>>  
>>>>>