[PATCH 0/2] Expose KVM API to Linux Kernel

[Anastassios Nanos]

To spawn KVM-enabled Virtual Machines on Linux systems, one has to use
QEMU, or some other kind of VM monitor in user-space to host the vCPU
threads, I/O threads and various other book-keeping/management mechanisms.
This is perfectly fine for a large number of reasons and use cases: for
instance, running generic VMs, running general purpose Operating systems
that need some kind of emulation for legacy boot/hardware etc.

What if we wanted to execute a small piece of code as a guest instance,
without the involvement of user-space? The KVM functions are already doing
what they should: VM and vCPU setup is already part of the kernel, the only
missing piece is memory handling.

With these series, (a) we expose to the Linux Kernel the bare minimum KVM
API functions in order to spawn a guest instance without the intervention
of user-space; and (b) we tweak the memory handling code of KVM-related
functions to account for another kind of guest, spawned in kernel-space.

PATCH #1 exposes the needed stub functions, whereas PATCH #2 introduces the
changes in the KVM memory handling code for x86_64 and aarch64.

An example of use is provided based on kvmtest.c
[https://lwn.net/Articles/658512/] at
https://github.com/cloudkernels/kvmmtest

Anastassios Nanos (2):
  KVMM: export needed symbols
  KVMM: Memory and interface related changes

 arch/arm64/include/asm/kvm_host.h   |   6 ++
 arch/arm64/kvm/fpsimd.c             |   8 +-
 arch/arm64/kvm/guest.c              |  48 +++++++++++
 arch/x86/include/asm/fpu/internal.h |  10 ++-
 arch/x86/kvm/cpuid.c                |  25 ++++++
 arch/x86/kvm/emulate.c              |   3 +-
 arch/x86/kvm/vmx/vmx.c              |   3 +-
 arch/x86/kvm/x86.c                  |  38 ++++++++-
 include/linux/kvm_host.h            |  36 +++++++++
 virt/kvm/arm/arm.c                  |  18 +++++
 virt/kvm/arm/mmu.c                  |  34 +++++---
 virt/kvm/async_pf.c                 |   4 +-
 virt/kvm/coalesced_mmio.c           |   6 ++
 virt/kvm/kvm_main.c                 | 120 ++++++++++++++++++++++------
 14 files changed, 316 insertions(+), 43 deletions(-)

-- 
2.20.1