group.of.nepali.translators team mailing list archive

[Tim Gardner <tim.gardner@xxxxxxxxxxxxx>]

commit fa73c3b25bd8 ("KVM: PPC: Book3s PR: Allow access to unprivileged
MMCR2 register" was part of v4.4.25 stable which was released in
Ubuntu-4.4.0-48.69.

I've submitted commit 708e75a3ee750dce1072134e630d66c4e6eaf63c ('KVM:
PPC: Book3S PR: Fix illegal opcode emulation') for review:

https://lists.ubuntu.com/archives/kernel-team/2017-January/081774.html

** Also affects: linux (Ubuntu Zesty)
   Importance: Undecided
     Assignee: Taco Screen team (taco-screen-team)
       Status: New

** Also affects: linux (Ubuntu Xenial)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu Xenial)
       Status: New => In Progress

** Changed in: linux (Ubuntu Xenial)
     Assignee: (unassigned) => Tim Gardner (timg-tpi)

** Changed in: linux (Ubuntu Zesty)
       Status: New => Fix Released

** Changed in: linux (Ubuntu Zesty)
     Assignee: Taco Screen team (taco-screen-team) => (unassigned)

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भाषा समायोजकहरुको समूह, which is subscribed to Xenial.
Matching subscriptions: Ubuntu 16.04 Bugs
https://bugs.launchpad.net/bugs/1634129

Title:
  Couldn't emulate instruction 0x7813427c

Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Xenial:
  In Progress
Status in linux source package in Zesty:
  Fix Released

Bug description:
  Couldn't emulate instruction 0x7813427c
  -------------------------------------------------------

  Cannot boot nested VMs in Xenial or Yakkety w/ kvm accel.
  It worked until Vivid (in spite of not being possible in x86)
  TCG mode works fine, but very slow.

  TCG full emulation is the mode in the x86 world for nested virt.
  However, in Power, we've been using in OpenStack CI w/ kvm accel
  (native virtualization) to speed up 2nd level VMs. It worked until
  Vivid.

  Is the case that kvm accel isn't possible anymore for nested virt
  (aligned with x86 KVM) ? So full emulation TCG mode is the only
  possible mode in newer kernels ?

  qemu-system-ppc64le -machine pseries,accel=kvm,usb=off -m 1G -enable-
  kvm -cpu POWER8E -display none -nographic cirros-d161007-ppc64le-
  disk.img

  lsmod |grep kvm
  kvm_pr                 96452  1
  kvm                   152984  4 kvm_pr

  
  Nested VM console:

  OF stdout device is: /vdevice/vty@71000000
  Preparing to boot Linux version 4.4.0-28-generic (buildd@bos01-ppc64el-018) (gcc version 5.3.1 20160413 (Ubuntu/IBM 5.3.1-14ubuntu2.1) ) #47-Ubuntu SMP Fri Jun 24 10:09:20 UTC 2016 (Ubuntu 4.4.0-28.47-generic 4.4.13)
  Detected machine type: 0000000000000101
  Max number of cores passed to firmware: 2048 (NR_CPUS = 2048)
  Calling ibm,client-architecture-support... done
  command line: BOOT_IMAGE=/boot/vmlinux-4.4.0-28-generic LABEL=cirros-rootfs ro
  memory layout at init:
    memory_limit : 0000000000000000 (16 MB aligned)
    alloc_bottom : 0000000004210000
    alloc_top    : 0000000010000000
    alloc_top_hi : 0000000040000000
    rmo_top      : 0000000010000000
    ram_top      : 0000000040000000
  found display   : /pci@800000020000000/vga@0, opening... done
  instantiating rtas at 0x000000000daf0000... done
  prom_hold_cpus: skipped
  copying OF device tree...
  Building dt strings...
  Building dt structure...
  Device tree strings 0x0000000004220000 -> 0x0000000004220aa9
  Device tree struct  0x0000000004230000 -> 0x0000000004240000
  Quiescing Open Firmware ...
  Booting Linux via __start() ?

  <The nested VM hangs here>


  /var/log/syslog & /var/log/kern.log

  Oct 13 14:07:38 patricia-ub16-10 kernel: [64072.186975] kvmppc_handle_exit_pr: emulation at 700 failed (7813427c)
  Oct 13 14:07:38 patricia-ub16-10 kernel: [64072.187023] Couldn't emulate instruction 0x7813427c (op 30 xop 318)
  Oct 13 14:07:38 patricia-ub16-10 kernel: [64072.187066] kvmppc_handle_exit_pr: emulation at 700 failed (7813427c)
  Oct 13 14:07:38 patricia-ub16-10 kernel: [64072.187113] Couldn't emulate instruction 0x7813427c (op 30 xop 318)
  Oct 13 14:07:38 patricia-ub16-10 kernel: [64072.187156] kvmppc_handle_exit_pr: emulation at 700 failed (7813427c)

  <syslog and kern.log fills up with this error forever, until get the
  disk full>

  Host:
  cpu		: POWER8E (raw), altivec supported
  clock		: 3690.000000MHz
  revision	: 2.1 (pvr 004b 0201)

  timebase	: 512000000
  platform	: PowerNV
  model		: 8247-22L
  machine		: PowerNV 8247-22L
  firmware	: OPAL v3

  
  Guest: Xenial or Yakkety
  Description: Ubuntu 16.10
  Release: 16.10
  Codename: yakkety

  Nested VM:
  CirrOS
  http://download.cirros-cloud.net/daily/20161007/cirros-d161007-ppc64le-disk.img

  
  This seems to be related
  https://patchwork.kernel.org/patch/9121881/

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