[PATCH RFC V2 0/2] KVM: x86: Support using the VMX preemption timer for APIC Timer periodic/oneshot mode

[Wanpeng Li]

Most windows guests which I have on hand currently still utilize APIC Timer 
periodic/oneshot mode instead of APIC Timer tsc-deadline mode:
- windows 2008 server r2
- windows 2012 server r2
- windows 7
- windows 10 

This patchset adds the support using the VMX preemption timer for APIC Timer 
periodic/oneshot mode. 

I add periodic mode testcase to kvm-unit-tests/apic.flat and observed that w/ patch 
the latency is ~13% of w/o patch. I think maybe something is still not right in the 
patchset. Your comments to improve the patchset is a great appreciated.

v1 -> v2:
 * remember the timeout when setting up the timer to get a correct TMCCT
 * move apic->lapic_timer.period/tscdeadline caculations to start_apic_timer()

Wanpeng Li (2):
  KVM: lapic: introduce start_sw_period() to handle oneshot/periodic mode
  KVM: x86: Support using the VMX preemption timer for APIC Timer periodic/oneshot mode

 arch/x86/kvm/lapic.c | 166 ++++++++++++++++++++++++++++++++-------------------
 arch/x86/kvm/lapic.h |   1 +
 2 files changed, 107 insertions(+), 60 deletions(-)

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1.9.1