Re: [PATCH qemu-server] fix #6490: network: add bridge fdb entries when hotplugging a nic

[Fiona Ebner <f.ebner@proxmox.com>]

Am 14.10.26 um 11:40 AM schrieb Gabriel Goller:
> On 13.10.2026 11:58, Rémi PAETA wrote:
>> [snip]
>> diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
>> index 74772fdd..4c2bd334 100644
>> --- a/src/PVE/QemuServer.pm
>> +++ b/src/PVE/QemuServer.pm
>> @@ -5126,6 +5126,8 @@ sub vmconfig_update_net {
>>                      $newnet->{trunks},
>>                      $newnet->{rate},
>>                  );
>> +                # unplugging the interface dropped its forwarding database entries
>> +                PVE::QemuServer::Network::add_nets_bridge_fdb({ $opt => $value }, $vmid);
>>  
>>              } elsif (safe_num_ne($oldnet->{rate}, $newnet->{rate})) {
>>                  # Rate can be applied on its own but any change above needs to
>> @@ -5155,6 +5157,7 @@ sub vmconfig_update_net {
>>              $newnet->{bridge}, $newnet->{macaddr}, $vmid, $conf->{name},
>>          );
>>          vm_deviceplug($storecfg, $conf, $vmid, $opt, $newnet, $arch, $machine_type);
>> +        PVE::QemuServer::Network::add_nets_bridge_fdb({ $opt => $value }, $vmid);
>>      } else {
>>          die "skip\n";
>>      }
> 
> Not a qemu-server expert, but one thing I noticed:
> 
> I think we need an eval around the two calls, otherwise when the `bridge fdb
> add` fails, the tap interface is created but the hotplug fails (which means we
> have a diverging config).

Yes, I think it's preferable to only warn about failure here, while
still proceeding, so that the VM config is updated.

> I think we also should relax a bit the del_nets_bridge_fdb() function so that a
> missing entry doesn't die (again add an eval around the `bridge fdb del`).

Sounds good to me too :)

> @Fiona what do you think? :)