Re: [PATCH][v2] kvm: x86: emulate APERF/MPERF registers

[Peter Zijlstra]

On Wed, Apr 29, 2020 at 01:46:36PM +0800, Li RongQing wrote:
> Guest kernel reports a fixed cpu frequency in /proc/cpuinfo,
> this is confused to user when turbo is enable, and aperf/mperf
> can be used to show current cpu frequency after 7d5905dc14a
> "(x86 / CPU: Always show current CPU frequency in /proc/cpuinfo)"
> so we should emulate aperf mperf to achieve it
> 
> the period of aperf/mperf in guest mode are accumulated as
> emulated value, and add per-VM knod to enable emulate mperfaperf
> 
> diff v1:
> 1. support AMD
> 2. support per-vm capability to enable

Would it make sense to provide a pass-through APERF/MPERF for
KVM_HINTS_REALTIME ? Because that hint guarantees we have a 1:1 vCPU:CPU
binding and guaranteed no over-commit.