On Sat, Apr 25, 2020 at 8:24 PM Li,Rongqing <lirongqing@xxxxxxxxx> wrote: > > > > > -----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 Wouldn't it be better to add a per-VM capability to enable this feature?
