if ethernet1 & ethernet2 are the interfaces in the Dom0, there should be not problem: You create a bridge per interface (ie “brvlan1” and “brvlan2”), connect brvlan1 to ethernet1 and brvlan2 to ethernet2. Now you’re set to connect your DomU’s interfaces to either brvlan1 or brvlan2.
As long as you don’t create a bridge between ethernet1 and ethernet2, either by adding both interfaces to a single bridge in Dom0 or by bridging around in the DomUs, everything should be working fine.
PS: You could instead set up an 802.1q link between the switch and Dom0, create VLANs inside Dom0 and then create the bridges against the VLANs. The only thing I’ve found not to work is to pass through the 802.1q to one DomU (an create the VLAN(s) there) while having other DomUs bridged to the similar VLANs (created in Dom0). The traffic won’t make it from the “802.1q-DomU” to a “VLAN-attached” DomU, although both seem to be in the same VLAN. It looks like the packets from the 802.1q-DomU are forwarded directly onto the network and don’t make it to the Dom0 VLAN code.