[PATCH v2 0/5] Enlightened VMCS support for KVM on Hyper-V

[Vitaly Kuznetsov]

Changes since v1:
- The only comment I got for v1 was from kbuild test robot. The issue
  was addressed by moving HV_X64_ENLIGHTENED_VMCS_RECOMMENDED definition
  to PATCH2.
- Rebased to current kvm/queue.

When running nested KVM on Hyper-V it's possible to use so called
'Enlightened VMCS' and do normal memory reads/writes instead of
doing VMWRITE/VMREAD instructions. In addition, clean field mask
provides a huge room for optimization on L0's side.

Tight CPUID loop test shows significant speedup (current kvm/queue on
E5-2667 v4 @ 3.20GHz):
 Before: 20766 cycles
 After: 8912 cycles

The series is based on current kvm/queue tree.

Ladi Prosek (1):
  x86/kvm: rename HV_X64_MSR_APIC_ASSIST_PAGE to
    HV_X64_MSR_VP_ASSIST_PAGE

Vitaly Kuznetsov (4):
  x86/hyper-v: allocate and use Virtual Processor Assist Pages
  x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits
  x86/hyper-v: detect nested features
  x86/kvm: use Enlightened VMCS when running on Hyper-V

 arch/x86/hyperv/hv_init.c          |  33 +++
 arch/x86/include/asm/mshyperv.h    |  12 +
 arch/x86/include/uapi/asm/hyperv.h | 223 ++++++++++++++-
 arch/x86/kernel/cpu/mshyperv.c     |   3 +
 arch/x86/kvm/hyperv.c              |   8 +-
 arch/x86/kvm/lapic.h               |   2 +-
 arch/x86/kvm/vmx.c                 | 561 ++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c                 |   2 +-
 8 files changed, 825 insertions(+), 19 deletions(-)

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2.14.3