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* [PATCH RFC v2 0/5] KVM: nVMX: Enlightened VMCS for Hyper-V on KVM
@ 2018-05-11 13:37 Vitaly Kuznetsov
  2018-05-11 13:37 ` [PATCH RFC v2 1/5] KVM: hyperv: define VP assist page helpers Vitaly Kuznetsov
                   ` (4 more replies)
  0 siblings, 5 replies; 8+ messages in thread
From: Vitaly Kuznetsov @ 2018-05-11 13:37 UTC (permalink / raw)
  To: kvm
  Cc: Paolo Bonzini, Radim Krčmář,
	Roman Kagan, K. Y. Srinivasan, Haiyang Zhang, Stephen Hemminger,
	Michael Kelley (EOSG),
	Mohammed Gamal, Cathy Avery, linux-kernel, Jim Mattson

It's been a while since RFCv1 (https://lwn.net/Articles/741846/). After the
initial submission I decided to implement Enlightened VMCS for KVM on
Hyper-V first and this is now fully merged. Time to resume this work.

This is an initial implementation of Enlightened VMCS for nested Hyper-V on
KVM. Using it helps to spare 1100 cpu cycles for nested vmexit (tight cpuid
loop in WS2016 with Hyper-V role on KVM: 15200 cycles -> 14100 cycles).

'RFC' mostly goes to the last patch in the series. Currently, we have
prepare_vmcs02()/prepare_vmcs02_full() split which is only valid for Shadow
VMCS. Enlightened VMCS has 'clean fields' idea and I'm having hard times
incorporating it. The simplest way is implemented in the patch: we just
wrap groups of vmwrites with 'if (!hv_evmcs||evmcs_needs_write(vmx, ...))'
checks. This works and doesn't give much overhead for non-eVMCS case 
(compared to e.g. wrapping each vmwrite with such check) but this is not
flexible and ugly. In case we'll need to implement additional ideas later
(eVMCSv2 when it comes, something similar for KVM-on-KVM,...) it will be
really hard. So.. looking forward to your ideas!

Ladi Prosek (1):
  KVM: hyperv: define VP assist page helpers

Vitaly Kuznetsov (4):
  KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability
  KVM: nVMX: add enlightened VMCS state
  KVM: nVMX: implement enlightened VMPTRLD and VMCLEAR
  KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case

 arch/x86/include/asm/kvm_host.h |   3 +
 arch/x86/kvm/hyperv.c           |  23 +-
 arch/x86/kvm/hyperv.h           |   4 +
 arch/x86/kvm/lapic.c            |   4 +-
 arch/x86/kvm/lapic.h            |   2 +-
 arch/x86/kvm/svm.c              |   9 +
 arch/x86/kvm/vmx.c              | 807 +++++++++++++++++++++++++++++++++-------
 arch/x86/kvm/x86.c              |  17 +-
 include/uapi/linux/kvm.h        |   1 +
 9 files changed, 728 insertions(+), 142 deletions(-)

-- 
2.14.3

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2018-05-15 11:11 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-05-11 13:37 [PATCH RFC v2 0/5] KVM: nVMX: Enlightened VMCS for Hyper-V on KVM Vitaly Kuznetsov
2018-05-11 13:37 ` [PATCH RFC v2 1/5] KVM: hyperv: define VP assist page helpers Vitaly Kuznetsov
2018-05-11 13:37 ` [PATCH RFC v2 2/5] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability Vitaly Kuznetsov
2018-05-11 13:37 ` [PATCH RFC v2 3/5] KVM: nVMX: add enlightened VMCS state Vitaly Kuznetsov
2018-05-14 16:22   ` Paolo Bonzini
2018-05-15 11:11     ` Vitaly Kuznetsov
2018-05-11 13:37 ` [PATCH RFC v2 4/5] KVM: nVMX: implement enlightened VMPTRLD and VMCLEAR Vitaly Kuznetsov
2018-05-11 13:37 ` [PATCH RFC v2 5/5] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case Vitaly Kuznetsov

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