KVM x86 Enabling Nested Virtualization By Default, Other Virtualization Work
Written by Michael Larabel in Virtualization on 25 October 2018 at 12:35 AM EDT. 5 Comments
VIRTUALIZATION --
The initial round of Kernel-based Virtual Machine (KVM) updates has been sent in for the in-development Linux 4.20/5.0 kernel.

Notable on the KVM x86 front is that nested virtualization is enabled by default for running a KVM guest within a KVM guest. This support for allowing KVM guests to use VMX (VT-x) instructions is being enabled by default now that live migration support is squared away and other functionality that ensures for a stable user-space ABI. The capability has of nested KVM on x86_64 has been available for years but required the module parameter to enable the functionality.

Also on the nested KVM front, the POWER architecture code has nested HV KVM support for radix guests on POWER9 that leads to much better performance. Some of the other KVM changes this cycle include various ARM clean-ups, the POWER code adds a one-VM-per-core mode in order to avoid potential data leak scenario, there is also a POWER PCI pass-through optimization, initial AP crypto virtualization for s390, coalesced PIO accesses for x86, and Hyper-V IPI x86 hypercalls support.

A complete list of the latest KVM Linux changes can be found via this PR.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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