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

[Frank Heimes]

** Changed in: ubuntu-z-systems
       Status: Fix Committed => Fix Released

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

Status in Ubuntu Cloud Archive:
  Invalid
Status in Ubuntu Cloud Archive pike series:
  Fix Released
Status in Ubuntu on IBM z Systems:
  Fix Released
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 <imbrenda at linux.vnet.ibm.com>
  AuthorDate: Thu Jan 18 18:51:44 2018 +0100
  Commit:     Cornelia Huck <cohuck at redhat.com>
  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: qemu-stable at nongnu.org
      Signed-off-by: Claudio Imbrenda <imbrenda at linux.vnet.ibm.com>
      Fixes: 903fd80b03243476 ("s390x/migration: Storage attributes device")
      Message-Id: <1516297904-18188-1-git-send-email-imbrenda at linux.vnet.ibm.com>
      Reviewed-by: Christian Borntraeger <borntraeger at de.ibm.com>
      Signed-off-by: Cornelia Huck <cohuck at redhat.com>

  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.

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