[libvirt PATCH 4/9] conf: add passt XML additions to schema

[Laine Stump]

On 1/11/23 1:33 PM, Daniel P. Berrangé wrote:
> On Sun, Jan 08, 2023 at 11:11:07PM -0500, Laine Stump wrote:
>> Initial support for network devices using passt (https://passt.top)
>> for the backend connection will require:
>>
>> * new attributes of the <backend> subelement:
>>    * "type" that can have the value "passt" (to differentiate from
>>      slirp, because both slirp and passt will use <interface
>>      type='user'>)
>>    * "logFile" (a path to a file that passt should use for its logging)
>>    * "upstream" (a netdev name, e.g. "eth0").
> 
> IMHO this attribute is inappropriate for <backend>....
> 
[...]
>> +    <interface type='user'>
>> +      <mac address='00:11:22:33:44:55'/>
>> +      <ip address='172.17.2.0' family='ipv4' prefix='24'/>
>> +      <ip address='2001:db8:ac10:fd01::feed' family='ipv6'/>
>> +      <portForward proto='tcp' address='2001:db8:ac10:fd01::1:10'>
>> +        <range start='22' to='2022'/>
>> +        <range start='1000' end='1050'/>
>> +        <range start='1020' exclude='yes'/>
>> +        <range start='1030' end='1040' exclude='yes'/>
>> +      </portForward>
>> +      <portForward proto='udp' address='1.2.3.4' dev='eth0'>
>> +        <range start='5000' end='5020' to='6000'/>
>> +        <range start='5010' end='5015' exclude='yes'/>
>> +      </portForward>
>> +      <portForward proto='tcp'>
>> +        <range start='80'/>
>> +      </portForward>
>> +      <portForward proto='tcp'>
>> +        <range start='443' to='344'/>
>> +      </portForward>
>> +      <model type='rtl8139'/>
>> +      <backend type='passt' logFile='/var/log/loglaw.blog' upstream='eth42'/>
> 
> I don't think that 'upstream' is really describing a property of the
> backend.
> 
> This is expressing a traffic routing restriction for the 'user'
> networking type. IMHO it should probably be using the existing
> <source dev="xxxx"/> element, that is currently used by the
> 'direct' networking type.

I'm still not sure *exactly* what it does; it apparently grabs the 
routes that are fed to the guest from the given host interface; I should 
probably ask Stefano to explain it to me again (he described it once, 
but that was along with explanations of several other things).

So it's not *exactly* the same as <source dev='xxx'/> for type='direct' 
(which determines the link-level connection rather than IP routing), but 
definitely very similar.


> Can we see about fixing this before release.

Yes, that makes sense. I'm not sure why I didn't think of it (usually I 
try *too* hard to re-use existing XML).

I'll make a patch and send it later today.