Comment 8 for bug 1969365

Apologies, I completely missed your comment, Nick! I was just able to reproduce this using uvtool.

To launch the VM (and monitor the console output):

uvt-simplestreams-libvirt sync release=focal arch=amd64
uvt-kvm create firsttest release=focal
virsh console firsttest

Then, within the instance via `uvt-kvm ssh firsttest`:

sudo apt update
sudo apt install kexec-tools
sudo reboot # I wanted to check `virsh console` was getting output

After reboot and reconnecting:

cd /boot
sudo kexec -l vmlinuz --initrd initrd.img --append 'BOOT_IMAGE=/boot/vmlinuz-5.4.0-167-generic root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0'
sudo reboot

I then observed the following in `virsh console`'s output (note the "Unmount All Filesystems", which is what I think is causing the problem):

[ OK ] Reached target Unmount All Filesystems.
         Stopping Monitoring of LVM…meventd or progress polling...
         Stopping Device-Mapper Multipath Device Controller...
[ OK ] Stopped Create Static Device Nodes in /dev.
[ OK ] Stopped Create System Users.
[ OK ] Stopped Remount Root and Kernel File Systems.
[ OK ] Stopped File System Check on Root Device.
[ OK ] Stopped Device-Mapper Multipath Device Controller.
[ OK ] Stopped Monitoring of LVM2… dmeventd or progress polling.
[ OK ] Reached target Shutdown.
[ OK ] Reached target Final Step.
         Starting Reboot via kexec...
[ 53.030829] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [960] did not accept message, killing the worker: Connection refused
[ 53.032915] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [954] did not accept message, killing the worker: Connection refused
[ 53.034697] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [953] did not accept message, killing the worker: Connection refused
[ 53.036756] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [955] did not accept message, killing the worker: Connection refused
[ 53.039144] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [956] did not accept message, killing the worker: Connection refused
[ 53.041049] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [958] did not accept message, killing the worker: Connection refused
[ 53.042673] systemd-udevd[372]: proc_inode_cache(1258:kexec.service): Worker [961] did not accept message, killing the worker: Connection refused
[ 53.123845] shutdown[1]: (sd-kexec) failed with exit status 1.
[ 53.138542] reboot: Restarting system
[ 0.000000] Linux version 5.4.0-167-generic (buildd@lcy02-amd64-010) (gcc version 9.4.0 (Ubuntu 9.4.0-1ubuntu1~20.04.2)) #184-Ubuntu SMP Tue Oct 31 09:21:49 UTC 2023 (Ubuntu 5.4.0-167.184-generic 5.4.252)

(I initially tried to re-reproduce using an Incus VM (and so a community image rather than a cloud-images one) and could not do so. Executing the above `kexec` command produced "ima: impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall." in the console. Adding `-s`/`--kexec-file-syscall` to the kexec command caused it to exit zero, and the VM did then successfully kexec on `reboot`.)