[Bug 1805841] [NEW] CPI information about kvm usage is lost during apt upgrade

Thu Nov 29 14:34:11 UTC 2018

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---Problem Description---
CPI information about kvm usage is lost during apt upgrade

---uname output---
4.15.0-42-generic

Machine Type = s390x lpar  

---Steps to Reproduce---

# cat /sys/firmware/cpi/*
cat: /sys/firmware/cpi/set: Permission denied

0x0000000000040f00

LINUX   
root at m83lp52:~# virsh start guest   # starting a guest does set the highest bit in
/sys/firmware/cpi/system_leveln  

root at m83lp52:~# cat /sys/firmware/cpi/*
cat: /sys/firmware/cpi/set: Permission denied

0x8000000000040f00   <---- see the 8

LINUX  

root at m83lp52:~# apt upgrade
[....]
has to upgrade at least one package, that will trigger some other code.
[....]

Now. some other code seems to have set values in /sys/firmware/cpi as
well dropping the kvm information.

root at m83lp52:~# cat /sys/firmware/cpi/*
cat: /sys/firmware/cpi/set: Permission denied
18 04 1  
0x0000000000040f00
UBUNTU  
LINUX  

The canonical place to handle /sys/firmware/cpi should be /lib/s390-tools/cpictl and /lib/systemd/system/cpi.service. So can we put the additional features (setting 18 04 1 and UBUNTU things also into
/etc/sysconfig/cpi
or
/lib/s390-tools/cpictl
)
and can we disable the other code that also sets /sys/firmware/cpi (I have not found out which code sets these values). This seems to be /lib/systemd/system-generators/s390-cpi-vars

** Affects: ubuntu-z-systems
     Importance: Undecided
         Status: New

** Affects: s390-tools (Ubuntu)
     Importance: Undecided
     Assignee: Skipper Bug Screeners (skipper-screen-team)
         Status: New

** Tags: architecture-s39064 bugnameltc-173674 severity-high targetmilestone-inin---
-- 
CPI information about kvm usage is lost during apt upgrade
https://bugs.launchpad.net/bugs/1805841
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