[Bug 1768104] Re: systemd sometimes misdetects Xen VMs (fixed up-stream)

[dana]

Hi Steve,

This build seems to work OK for me as well. Thanks!

% dpkg-query -Wf '${Package}: ${Version}\n' | rg systemd
libnss-systemd: 237-3ubuntu10.2
libpam-systemd: 237-3ubuntu10.2
libsystemd0: 237-3ubuntu10.2
python3-systemd: 234-1build1
systemd: 237-3ubuntu10.2
systemd-sysv: 237-3ubuntu10

% SYSTEMD_LOG_LEVEL=debug systemd-detect-virt
Failed to read $container of PID 1, ignoring: Permission denied
Found container virtualization none.
Virtualization Xen found in DMI (/sys/class/dmi/id/sys_vendor)
Virtualization XEN, found /sys/hypervisor/properties/features with value 00002705, XENFEAT_dom0 (indicating the 'hardware domain') is not set.
Found VM virtualization xen
xen

% systemctl is-active xe-daemon
active


** Tags removed: verification-needed-bionic
** Tags added: verification-done-bionic

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https://bugs.launchpad.net/bugs/1768104

Title:
  systemd sometimes misdetects Xen VMs (fixed up-stream)

Status in systemd package in Ubuntu:
  Fix Committed
Status in systemd source package in Bionic:
  Fix Committed
Status in systemd source package in Cosmic:
  Fix Committed

Bug description:
  [Impact]

   * XEN virtualization missidentified as hyperv
   * This may cause units limited to a virtualisation not to be started; or redundant units for the other type of virtualisation to be started instead.
   * Previously xen & hyper-v were detected correctly separately, even when xen emulates/suggests that it is hyper-v.

  [Test Case]

   * Execute systemd-detect-virt and check that it detects Xen & Hyperv

  [Regression Potential]

   * Things that "fake" xen might not work as the detection code
  branches are changed, but it would affect previous releases and future
  releases of systemd-detect-virt. So far such things are not known to
  exist, and if such things appear in the future support for them would
  need to land upstream first.

  [Other Info]
   
   * Original bug report

  Cherrypick
  https://github.com/systemd/systemd/commit/f2fe2865cd19cd4318b82d01b9b62d22b1697b3a

  It appears that Xen-based VMs sometimes report themselves as Microsoft
  Hyper-V via CPUID — apparently this is for compatibility with Windows
  guests. systemd 237 (as found in Bionic) gives preference to this
  CPUID information when detecting Xen, and thus it erroneously assumes
  that the guest is running under Hyper-V. This causes Xen-related
  services (and anything else that relies on systemd's VM-detection
  functionality) to fail.

  I *believe* this is a regression from systemd 229 as used in Xenial —
  we have at least a few Xen-based VMs that report as Hyper-V via CPUID
  and don't have this issue on that version — but i haven't confirmed
  that for certain.

  Anyway, i've submitted a ticket with more details to the up-stream
  project, and that has now been resolved through a fairly simple change
  which applies cleanly to the Bionic systemd sources:

  https://github.com/systemd/systemd/issues/8844

  Would it be possible to pull this down? As mentioned, Xen-based Ubuntu
  VMs can seriously misbehave without it.

  Thanks!

  See also:
  https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1728573

  ---

  % lsb_release -rd
  Description:	Ubuntu 18.04 LTS
  Release:	18.04

  % apt-cache policy systemd
  systemd:
    Installed: 237-3ubuntu10
    Candidate: 237-3ubuntu10
    Version table:
   *** 237-3ubuntu10 500
          500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
          100 /var/lib/dpkg/status

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