[Qemu-devel] [Bug 1779162] Re: qemu versions 2.10 and 2.11 have error during migration of larger guests

[Frank Heimes]

** Also affects: qemu
   Importance: Undecided
       Status: New

** No longer affects: qemu

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

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

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1779162

Title:
  qemu versions 2.10 and 2.11 have error during migration of larger
  guests

Status in Ubuntu Cloud Archive:
  New
Status in Ubuntu on IBM z Systems:
  New
Status in qemu package in Ubuntu:
  Fix Released
Status in qemu source package in Artful:
  Won't Fix

Bug description:
  == Comment: #0 - Christian Borntraeger  - 2018-06-28 06:39:27 ==
  Migration fails with larger guests (e.g. 10GB)  on a z system prints an error 
message in the log 

  see /var/log/libvirt/qemu/...
  [...]
  qemu-system-s390x: KVM_S390_SET_CMMA_BITS failed: Bad address

  This messes up guest state for the CMMA values (guest data corruption)

  This is fixed with

  commit 46fa893355e0bd88f3c59b886f0d75cbd5f0bbbe
  Author:     Claudio Imbrenda <address@hidden>
  AuthorDate: Thu Jan 18 18:51:44 2018 +0100
  Commit:     Cornelia Huck <address@hidden>
  CommitDate: Mon Jan 22 11:04:52 2018 +0100

      s390x: fix storage attributes migration for non-small guests
      
      Fix storage attribute migration so that it does not fail for guests
      with more than a few GB of RAM.
      With such guests, the index in the buffer would go out of bounds,
      usually by large amounts, thus receiving -EFAULT from the kernel.
      Migration itself would be successful, but storage attributes would then
      not be migrated completely.
      
      This patch fixes the out of bounds access, and thus migration of all
      storage attributes when the guest have large amounts of memory.
      
      Cc: address@hidden
      Signed-off-by: Claudio Imbrenda <address@hidden>
      Fixes: 903fd80b03243476 ("s390x/migration: Storage attributes device")
      Message-Id: <address@hidden>
      Reviewed-by: Christian Borntraeger <address@hidden>
      Signed-off-by: Cornelia Huck <address@hidden>

  This fix is part of 2.11.1 so the qemu in bionic is fine.
  The qemu in artful, as well as the qemu in the cloud archives for 16.04 need 
this fix, so we have
  affected qemus in 17.10 and 16.04. 

  Regarding 16.04:
  The bug only triggers for host kernels >= 4.13 - in other words when you 
combine HWE kernel with the qemu from the cloud archive.

To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-archive/+bug/1779162/+subscriptions