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Xen 4.6 lands, complete with contributions from the NSA

Lots more security and ARM scalability in new release

Update The Xen Project has released version 4.6 of its eponymous hypervisor.

The US National Security Agency's again tossed in some code but not, as we reported earlier, to deliver support for version 2.0 of the Virtual Trusted Platform Module (vTPM).

That was the Xen team's error - BitDefender, not the NSA, contributed the vTPM 2.0 code.

The TPM is the Trusted Computing Group's secure storage and cryptographic standard that Intel uses in its Trusted Execution Technology product that helps users to verify that a workload is running on the physical server they desire. vTPM makes TPM available to guest VMs, so support for version 2.0 of the standard is a welcome addition to Xen.

So what did the NSA add? 459 new lines of code, while pulling 193 lines and working on eight change sets. Citrix was this release's biggest contributor, with Suse a distant second and Intel in third, among organisations.

Improved guest introspection, to allow easier interaction with security tools, has been included as promised.

Other highlights the Xen folk think are important this time around include:

  • The Xen Security Modules (XSM) now have a default policy that is regularly tested in the Xen Project Test Lab to make sure it is not broken by mistake. This will enable us to switch on XSM by default in the future.
  • A ticket lock to improve fairness, which provides better support of massive workloads from up to hundreds or thousands of VMs on a single host.
  • Support for new hardware platforms namely the Renesas R-Car Gen2, Thunder X, Huawei hip04-d04 and Xilinx ZynqMP SoC.
  • Intel Memory Bandwidth Monitoring allows system administrators to identify memory bandwidth saturation on a Xen host that may be caused by several memory-intensive VMs running on the same host. Taking corrective actions, such as migrating VMs to a different Xen host, increases scalability and performance in the data center.
  • Virtual Performance Monitoring Unit support makes it possible to profile the Xen Project Hypervisor with the Linux perf tool. Note that some work still needs to be completed within Linux to make perf fully functional.
  • ARM 64 platforms can now support 128 vCPUs, up from eight.
  • Live Migration support in libxc / libxl and has been replaced with a completely new implementation (Migration v2). The new version respects different layers in the Xen Software stack and has been designed to be more robust and extensible to better support next-generation infrastructures and work planned in subsequent hypervisor releases

There's more detail about the new release on its Release Features page and Documentation.

Don't rush your upgrade: leaving aside the risks of messing with fresh code, the Xen project has also advised of three embargoed flaws to be revealed on October 29th. ®

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