Nested Virtualization — KVM, Intel, with VMCS Shadowing

[Previous installments on Nested Virtualization with KVM and Intel.]

This is part of some recent testing that I’ve been doing with upstream KVM (for 3.10.1). The threads linked here has initial tests bench-marking kernel compile (with make defconfig, a default config file) times in L2. And some minimal guestfish appliance start-up timings in L1.

Some details:

  • Setup information to test with VMCS (Virtual Machine Control Structure) Shadowing. In brief, VMCS Shadowing — a processor specific feature — as described upstream, can reduce the overhead of nested virtualization by reducing the number of VMExits from L1 to L0.
  • Simple scripts used to create L1 and L2.
  • Libvirt XMLs of L1, L2 guests, for reference.

The gritty details of reasons for VMExits are described in Intel architecture manuals, Volume 3b, APPENDIX 1.

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One response to “Nested Virtualization — KVM, Intel, with VMCS Shadowing

  1. Pingback: OpenStack Community Weekly Newsletter (May 10-17) » The OpenStack Blog

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