Sunday, October 20, 2019

Ubuntu 19.10 released

Ubuntu Server 19.10 is out!
It ships For a detailed list of KVM on Z changes, see the release notes here.

Tuesday, October 1, 2019

KVM on IBM z15 Features

To take advantage of the new features of z15, the latest addition to the IBM Z family as previously announced here, use any of the following CPU models in your guest's domain XML:
  • Pre-defined model for z15
      <cpu mode='custom'>
  • Use z15 features in a migration-safe way (recommended). E.g. when running on z15 this will be a superset of the gen15a model, and feature existence will be verified on the target system prior to a live migration:
      <cpu mode='host-model'/>
  • Use z15 features in a non-migration-safe way. I.e. feature existence will not be verified on the target system prior to a live migration:
      <cpu mode='host-passthrough'/>
Here is a list of features of the new hardware generation as supported in Linux kernel 5.2 and QEMU 4.1, all activated by default in the CPU models listed above:
  • Miscellaneous Instructions
    Following the example of previous machines, new helper and general purpose instructions were
      minste3     Miscellaneous-Instruction-Extensions Facility 3 
  • SIMD Extensions
    Following up to the SIMD instructions as introduced with the previous z13 and z14 models, this feature again provides further vector instructions, which can again be used in KVM guests.
    These new vector instructions can be used to improve decimal calculations as well as for implementing high performance variants of certain cryptographic operations.
    In the z15 CPU models, the respective feature is:
      vxpdeh      Vector-Packed-Decimal-Enhancement Facility
      vxeh2       Vector enhancements facility 2
  • Deflate Conversion
    Provide acceleration for zlib compression and decompression
    In the z15 CPU model, the respective feature is:
      dflt        Deflate conversion facility
  • MSA Updates
    z15 introduces a new Message Security Assist MSA9, providing elliptic curve cryptography. It supports message authentication, the generation of elliptic curve keys, and scalar multiplication.
    This feature can be exploited in KVM guests' kernels and userspace applications independently (i.e. a KVM guest's userspace applications can take advantage of these features irrespective of the guest's kernel version).
    In the z15 CPU model, the respective feature is:
      msa9        Message-security-assist-extension 9 facility
      msa9_pckmo  Message-security-assist-extension 9 PCKMO
                  subfunctions for protected ECC keys
The z15 CPU model was backported into several Linux distributions. It is readily available in RHEL8.1, SLES 15 SP1 (via maintweb updates for kernel and qemu) and Ubuntu 18.04.

Thursday, September 12, 2019

IBM z15 announced

Today, IBM announced the new IBM Z models:
Furthermore, check the updated IBM Z tested platforms matrix here.
We will look at features in support of the new IBM Z model in a separate blog entry soon.

Monday, September 2, 2019

virt-manager 2.2 released

virt-manager v2.2 was released a while ago. One feature we contributed is the ability to choose a temporary boot device. Here is a quick write-up on how to use that feature.

virt-xml is a simple command line tool for editing domain definitions. It can be used interactively or for batch processing. Starting with virt-manager v2.2, virt-xml allows to boot a guest with a temporarily changed domain definition. This allows us to specify a boot configuration other than the guest's current domain definition. This is especially useful as the IBM Z architecture allows for only a single boot device, and therefore the boot order settings do not work the way they do on other platforms: If the first boot device fails to boot, there is no attempt made to boot from the next boot device. In addition, the architecture/BIOS has no support for interactively changing the boot device during the boot/IPL process.
Therefore, two new command line options were introduced:
  • --no-define makes any changes to the domain definition transient (i.e. the guest's persistent domain XML will not be modified)
  • --start allows the user to start the domain after the changes to the domain XML were applied
Here is a simple example illustrating the usage:
  1. First, select the device which should be changed by a selector. In this example, the unique target name of the disk is used. See man virt-xml for a list of further possibilities.
  2. Temporarily modify the boot order, assign the first slot to device vdc, and start the guest right away:

      $ virt-xml --edit target='vdc' --disk='boot_order=1' --start \
                 --no-define sample_domain

    Note: If there was another device that already had boot_order=1, its boot order would be incremented.
As soon the guest is stopped, the changes will vanish.

Friday, August 23, 2019

Webinar: How to Virtualize with KVM in Live Demo, August 28

We will explain basic KVM concepts, including CPU and memory virtualization, storage, network management, as well as a brief overview about commonalities and differences with other virtualization environments. Furthermore, a live demo will demonstrate how to use the KVM management tools to create and install Linux guests, how to operate and monitor.

Christian Bornträger, Chief Product Owner Linux and KVM on IBM Z.

Register here. You can check the system requirements here.
After registering, you will receive a confirmation email containing information about joining the webinar.

Replay & Archive
All sessions are recorded. For the archive as well as a replay and handout of this session and all previous webcasts see here.

Monday, August 19, 2019

QEMU v4.1 released

QEMU v4.1 is out. For highlights from a KVM on Z perspective see the Release Notes.
Note: The DASD IPL feature is still considered experimental.

Friday, August 9, 2019