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 + 'reenlightenment' series.
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(-)
--
2.14.3
