1. Please describe the problem:
In the coreos-assembler ,we use supermin to create a qemu VM inside an F33 container (on a RHEL8 host). As part of the VM a virtioserialport is created:


https://github.com/coreos/coreos-assembler/blob/master/src/cmdlib.sh#L528

Lately, we have seen error messages like this:

```
+ tee /dev/virtio-ports/cosa-cmdout
+ bash /srv/tmp/build.qemu/cmd.sh
tee: /dev/virtio-ports/cosa-cmdout: No such file or directory
```

which seem to suggest the device is not available.

When the kernel-core and kernel-modules packages were downgraded from    5.10.7-200.fc33.s390x to 5.9.16-200.fc33.s390x, the issue was doesn't show up.

After a little bit of testing - the build this started failing was : 5.10.6-200.fc33.s390x

This also happens on f32 when going from  5.9.16-100.fc32 --> 5.10.7-100.fc32

2. What is the Version-Release number of the kernel:
5.10.7-200.fc33.s390x

3. Did it work previously in Fedora? If so, what kernel version did the issue
   *first* appear?  Old kernels are available for download at
   https://koji.fedoraproject.org/koji/packageinfo?packageID=8 :
5.10.6-200.fc33.s390x

4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:
create a qemu VM with a virtio serial port and try to access it.