QEMU-SYSTEM-PPC64 Regression QEMU-4.0.0

[Jose Santiago]

I have been using QEMU-SYSTEM-PPC64 v3.1.0 to run CentOS7 PPC emulated system. It stopped working when I upgraded to QEMU-4.0.0 . I downgraded back to QEMU-3.1.0 and it started working again. The problem is that my CentOS7 image will not boot up udner QEMU-4.0.0, but works fine under QEMU-3.1.0.

I have an QCOW2 image available at https://www.mediafire.com/file/d8dda05ro85whn1/linux-centos7-ppc64.qcow2/file . NOTE: It is 15GB. Kind of large.

I run it as follows:

   qemu-system-ppc64 \
      -name "CENTOS7-PPC64" \
      -cpu POWER7 -machine pseries \
      -m 4096 \
      -netdev bridge,id=netbr0,br=br0 \
      -device e1000,netdev=netbr0,mac=52:54:3c:13:21:33 \
      -hda "./linux-centos7-ppc64.qcow2" \
      -monitor stdio

HOST: I am using Manjaro Linux on an Intel i7 machine with the QEMU packages installed via the package manager of the distribution.

[jsantiago@jlsws0 ~]$ uname -a
Linux jlsws0.haivision.com 4.19.42-1-MANJARO #1 SMP PREEMPT Fri May 10 20:52:43 UTC 2019 x86_64 GNU/Linux

jsantiago@jlsws0 ~]$ cpuinfo
Intel(R) processor family information utility, Version 2019 Update 3 Build 20190214 (id: b645a4a54)
Copyright (C) 2005-2019 Intel Corporation. All rights reserved.

===== Processor composition =====
Processor name : Intel(R) Core(TM) i7-6700K
Packages(sockets) : 1
Cores : 4
Processors(CPUs) : 8
Cores per package : 4
Threads per core : 2

===== Processor identification =====
Processor Thread Id. Core Id. Package Id.
0 0 0 0
1 0 1 0
2 0 2 0
3 0 3 0
4 1 0 0
5 1 1 0
6 1 2 0
7 1 3 0
===== Placement on packages =====
Package Id. Core Id. Processors
0 0,1,2,3 (0,4)(1,5)(2,6)(3,7)

===== Cache sharing =====
Cache Size Processors
L1 32 KB (0,4)(1,5)(2,6)(3,7)
L2 256 KB (0,4)(1,5)(2,6)(3,7)
L3 8 MB (0,1,2,3,4,5,6,7)

[Mark Cave-Ayland (mark-cave-ayland)]

I suspect that this may be related to the VSR register conversion. Can you try applying all of the patches below on top of 4.0 to see if they resolve the issue?

https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg01254.html
https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg01256.html
https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg01257.html
https://lists.gnu.org/archive/html/qemu-devel/2019-05/msg01260.html

[Jose Santiago (jlsantiago0)]

I applied the four patches you indicated and the image boots up and runs. Everything seems to be working now. Thank You.

[Ivan Warren (ivmn)]

I also have a regression issue between 3.1.0 and 4.0.0 (actually latest git) on qemu-system-ppc64 but it involves an AIX guest instead (fail to boot). Should I open a new ticket or hop on this one ?

[Mark Cave-Ayland (mark-cave-ayland)]

David has already queued the patches in his ppc-for-4.1 branch at https://github.com/dgibson/qemu/commits/ppc-for-4.1 so they will get merged soon. If you're working with git then I'd try testing the queued branch first and see if that resolves the issue.

Once the patches have been applied to master we'll add a CC to the stable list so the fixes will be included in the next 4.0 update.

[Ivan Warren (ivmn)]

Same thing here using https://github.com/dgibson/qemu/commits/ppc-for-4.1 ... It might be a completely different problem (athough it looks like a MMU problem).

[Alex Bennée (ajbennee)]

Is this fixed now? Can we mark as fix committed?

[Jose Santiago (jlsantiago0)]

It is fixed with the 4.1.0 release. Thank you.