graphic: 0.983
semantic: 0.983
instruction: 0.981
other: 0.980
network: 0.978
assembly: 0.977
device: 0.975
socket: 0.973
mistranslation: 0.970
vnc: 0.967
boot: 0.960
KVM: 0.956

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

== 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 <email address hidden>
AuthorDate: Thu Jan 18 18:51:44 2018 +0100
Commit:     Cornelia Huck <email 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: <email address hidden>
    Signed-off-by: Claudio Imbrenda <email address hidden>
    Fixes: 903fd80b03243476 ("s390x/migration: Storage attributes device")
    Message-Id: <email address hidden>
    Reviewed-by: Christian Borntraeger <email address hidden>
    Signed-off-by: Cornelia Huck <email 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.

As discussed on IRC, this isn't important for the last week of Artful before EOL.
But it is for the Cloud Archives longer time I'd think.

So I added a UCA task for them to take a look.

Hello Christian and Frank,

Thanks for reporting this and making Ubuntu better. Very much appreciate your details bug description as well.

I'm working on backporting this to Pike and will update the bug with more details soon.

Thanks,
Corey

Hello bugproxy, or anyone else affected,

Accepted qemu into pike-proposed. The package will build now and be available in the Ubuntu Cloud Archive in a few hours, and then in the -proposed repository.

Please help us by testing this new package. To enable the -proposed repository:

  sudo add-apt-repository cloud-archive:pike-proposed
  sudo apt-get update

Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-pike-needed to verification-pike-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-pike-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

------- Comment From <email address hidden> 2018-06-29 03:41 EDT-------
Fix verified with
2.10+dfsg-0ubuntu3.8~cloud1

Thanks for testing. Tagging verification-pike-done according to comment #4 results.

The verification of the Stable Release Update for qemu has completed successfully and the package has now been released to -updates. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.


This bug was fixed in the package qemu - 1:2.10+dfsg-0ubuntu3.8~cloud1
---------------

 qemu (1:2.10+dfsg-0ubuntu3.8~cloud1) xenial-pike; urgency=medium
 .
   * d/p/s390x-fix-storage-attrs-migration-for-non-small-guests.patch:
     Backported from upstream 2.11.1 release to enable successful migration
     of non-small guests (LP: #1779162).


------- Comment From <email address hidden> 2018-07-03 09:10 EDT-------
IBM bugzilla status ->closed : Fix Released by Canonical