> -----邮件原件----- > 发件人: Paolo Bonzini [mailto:pbonzini@xxxxxxxxxx] > 发送时间: 2020年4月25日 0:30 > 收件人: Jim Mattson <jmattson@xxxxxxxxxx>; Sean Christopherson > <sean.j.christopherson@xxxxxxxxx> > 抄送: Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Li,Rongqing > <lirongqing@xxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; kvm list > <kvm@xxxxxxxxxxxxxxx>; the arch/x86 maintainers <x86@xxxxxxxxxx>; H . > Peter Anvin <hpa@xxxxxxxxx>; Borislav Petkov <bp@xxxxxxxxx>; Ingo Molnar > <mingo@xxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Joerg Roedel > <joro@xxxxxxxxxx>; Wanpeng Li <wanpengli@xxxxxxxxxxx>; Vitaly Kuznetsov > <vkuznets@xxxxxxxxxx> > 主题: Re: [PATCH] [RFC] kvm: x86: emulate APERF/MPERF registers > > On 24/04/20 18:25, Jim Mattson wrote: > >> Assuming we're going forward with this, at an absolute minimum the > >> RDMSRs need to be wrapped with checks on host _and_ guest support for > >> the emulated behavior. Given the significant overhead, this might > >> even be something that should require an extra opt-in from userspace to > enable. > > > > I would like to see performance data before enabling this unconditionally. > > I wouldn't want this to be enabled unconditionally anyway, because you need to > take into account live migration to and from processors that do not have > APERF/MPERF support. > > Paolo I will add a kvm parameter to consider whether enable MPERF/APERF emulations, and make default value to false Thanks -Li
