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

[Frank Heimes]

** Also affects: ubuntu-z-systems
   Importance: Undecided
       Status: New

** Package changed: linux (Ubuntu) => s390-tools (Ubuntu)

** Changed in: ubuntu-z-systems
       Status: New => Triaged

** Changed in: ubuntu-z-systems
   Importance: Undecided => Medium

** Changed in: ubuntu-z-systems
     Assignee: (unassigned) => Dimitri John Ledkov (xnox)

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Title:
  CPI information about kvm usage is lost during apt upgrade

Status in Ubuntu on IBM z Systems:
  Triaged
Status in s390-tools package in Ubuntu:
  New

Bug description:
  ---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

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