scsi passthrough differs between guests

[daggs]

Greetings,

I have two machines running the same distro, both running qemu 5.1.0, one runs libvirt 6.7.0, the other 6.8.0.
I've decided to test the viability of passing through my sata cdrom into a vm, so I went to the libvirt docs, read a bit and added the following to a debian10 uefi vm running on libvirt 6.8.0:
<controller type='scsi' index='0' model='virtio-scsi'>
  <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
</controller>
<hostdev mode='subsystem' type='scsi' managed='no'>
  <source>
    <adapter name='scsi_host11'/>
    <address bus='0' target='0' unit='0'/>
  </source>
  <readonly/>
  <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</hostdev>
I've booted the vm and saw the cdrom in the vm, eject worked and so did mount.

I've decided to move it to another machine running libvirt 6.7.0, I've verified the cdrom is visible on the new system, seE:
# lsscsi
[0:0:0:0]    cd/dvd  HL-DT-ST DVDRAM GH24NSD1  LW00  /dev/sr0

I've inserted the same xml into another vm running libreelec uefi but changed the host from 11 to 0, it looks like this:
<controller type='scsi' index='0' model='virtio-scsi'>
  <alias name='scsi0'/>
  <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
</controller>
<hostdev mode='subsystem' type='scsi' managed='no'>
    <source>
    <adapter name='scsi_host0'/>
    <address bus='0' target='0' unit='0'/>
  </source>
  <readonly/>
  <alias name='hostdev0'/>
  <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</hostdev>

but when I boot the vm, I see no cdrom, lspci shows this:
03:00.0 SCSI storage controller: Red Hat, Inc. Virtio block device (rev 01)
07:01.0 SCSI storage controller: Red Hat, Inc. Virtio SCSI

as there is no lsscsi or /proc/scsi/scsi I cannot see other possible scsis.
I know for a fact that libreelec supports scsi/sata cdroms as it is a frequent he for streamers.
I'm baffled about the two scsi controllers I see and why I cannot see the device.
is there a known issue in 6.7.0 with scsi pass-trough?

Dagg.