KVM on S390x


One Line Summary

Where are we, where are we going and why do we need KVM on S390x?


Virtualization has a long standing tradition on IBM’s S/360 line of platforms. It reaches as far back as the 1970s. Back then the instruction set received an additional instruction to set the machine in a virtualized mode.

When KVM was originally opened to more than just x86, the S390x was the architecture that got added first. It’s thus the second platform ever supported by KVM.

But KVM itself only implements virtualization of the CPU. To actually create a virtual machine you also need virtualized hardware. That’s the task qemu takes over in the KVM world.

Unfortunately the original S390x hardware – especially the console – is not really suited for direct use with Linux. The ways of using virtual machines on S390x is also unused to most Linux users. So we took on the challenge to set a new paradigm. The virtual machine for S390 should behave as similar as possible to lguest. That way things become vastly easier for everyone. Now management tools written for x86 virtual machines can be used on the mainframe.

This talk will show where, how and why S390 is different in qemu from any other architecture it has supported before. It will explain the novel virtio bus structure used in the virtual machine. If possible, a demonstration of a working virtual machine is given.

It will furthermore discuss where we’re taking the S390x software stack and what things are still left unsolved, like hotplugging and a framebuffer.


KVM, S390, S390x, z Series, System z, Linux, Virtualization


  • Biography

    Alexander started working for Novell about 3 years ago. Since then he worked on fancy things like mkinitrd, qemu and KVM.

    Whenever something really useful comes to his mind, he tends to implement it. Among his more well-known projects are Mac OS X virtualization, the modular SUSE initrd and nested SVM. He is also the official maintainer of KVM for PowerPC and Qemu for S390x.

    On the publicly invisible side he worked on SUSE Studio backend parts, keeping appliance building secure and fast.

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