linux-kernel - Re: [PATCH 1/4] KVM: x86: Disable intercept for CORE cstate read

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Message-ID: <CANRm+CzD1Sc5bYk9B7yzfXnWkUZwB3cr_86a9x3h9W0ROEoksQ@mail.gmail.com>
Date:   Mon, 20 May 2019 19:29:01 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Liran Alon <liran.alon@...cle.com>
Subject: Re: [PATCH 1/4] KVM: x86: Disable intercept for CORE cstate read

On Mon, 20 May 2019 at 18:30, Paolo Bonzini <pbonzini@...hat.com> wrote:
>
> On 17/05/19 10:49, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@...cent.com>
> >
> > Allow guest reads CORE cstate when exposing host CPU power management capabilities
> > to the guest. PKG cstate is restricted to avoid a guest to get the whole package
> > information in multi-tenant scenario.
>
> Hmm, I am not sure about this.  I can see why it can be useful to run
> turbostat in the guest, but is it a good idea to share it with the

Yeah.

> guest, since it counts from machine reset rather than from VM reset?

I also saw amazon expose these in their nitro c5 instance.

>
> Maybe it could use a separate bit for KVM_CAP_X86_DISABLE_EXITS?

It could be.

Regards,
Wanpeng Li