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

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Date:   Tue, 11 Oct 2016 20:17:18 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Yunhong Jiang <yunhong.jiang@...el.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH RFC 0/2] KVM: x86: Support using the VMX preemption timer for APIC Timer periodic/oneshot mode

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 a print in oneshot mode testcase of kvm-unit-tests/apic.flat and observed
that w/ patch the latency is ~2% of w/o patch. I think maybe something is still 
not right in the patchset, in addition, tmcct in apic_get_tmcct() maybe is not 
calculated correctly. Your comments to improve the patchset is a great appreciated.

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

 arch/x86/kvm/lapic.c | 162 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 95 insertions(+), 67 deletions(-)

-- 
1.9.1