[CentOS] rd.lvm.lv on CentOS Stream 9 (first-boot failure)

Sun Jan 9 23:37:09 UTC 2022
Gordon Messmer <gordon.messmer at gmail.com>

I've install a CentOS Stream 9 system from a kickstart file that 
specified (among other things) several logical volumes:

logvol / --fstype="ext4" --size=10240 --name=lv_root --vgname=VolGroup
logvol /var --fstype="ext4" --size=4096 --name=lv_var --vgname=VolGroup
logvol swap --fstype="swap" --size=2048 --name=lv_swap --vgname=VolGroup

When that system rebooted, the kernel args did specify 
"rd.lvm.lv=VolGroup/lv_root rd.lvm.lv=VolGroup/lv_swap", but did not 
specify "rd.lvm.lv=VolGroup/lv_var", so boot failed because the 
filesystem required for /var couldn't be found.

The dracut.cmdline documentation does record that it will only activate 
the LVs given as "rd.lvm.lv", but I'm confused about several things.

1: The system also includes a volume group named "BackupGroup" and that 
group activates on boot (post-dracut).  Why are those LVs activated when 
rd.lvm.lv is specified?
2: Why didn't Anaconda add the "var" LV to the kernel arguments?
3: This seems like a change from earlier releases, but I can't find any 
documentation to that effect.  Under CentOS 7, after dracut had 
finished, the remaining logical volumes in that group would be 
activated.  Because they aren't, currently, libvirtd cannot start any of 
its guests until I manually activate the group.  How can I restore the 
old behavior of activating all of the LVs on boot?