What were you trying to do that didn't work?

As subject

What is the impact of this issue to you?

Lack of information in error msg

Please provide the package NVR for which the bug is seen:

libvirt-11.6.0-1.el9.x86_64
qemu-kvm-10.1.52-2.el10.wrb250924.x86_64

How reproducible is this bug?:

100%

Steps to reproduce

1. Prepare a tap device with multi_queue in the host

➜  ~ ip tuntap add mode tap name tap1 multi_queue;ip link set tap1 up
➜  ~ ip a show dev tap1
41: tap1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 66:69:f3:08:9e:f5 brd ff:ff:ff:ff:ff:ff

1. Add the no-queue ethernet net with the tap to VM

➜  ~ cat /tmp/tap1.xml                     
    <interface type='ethernet'>
      <mac address='52:54:00:41:fe:77'/>
      <target dev='tap1' managed='no'/>
      <model type='virtio'/>
    </interface>

➜  ~ virsh attach-device RHEL /tmp/tap1.xml --config  
Device attached successfully 

1.  Start the VM:

➜  ~ virsh start RHEL  
error: Failed to start domain 'RHEL'
error: Unable to create tap device tap1: Invalid argument

Since the managed=no, libvirt will not create tap device. So the error Unable to create tap device tap1 is misleading. And the error Invalid argument is lack of information. It hard for user to figure out the reason from the err msgs. We can provide better err msg like https://issues.redhat.com/browse/RHEL-55749?focusedId=25814165&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-25814165

Expected results

Actual results