linux-kernel - Re: 答复: 答复: [PATCH][v6] KVM: X86: support APERF/MPERF registers

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Message-ID: <d4edabf8-b8c6-e60b-1a78-6aaa9bb7b5e1@redhat.com>
Date:   Fri, 5 Jun 2020 13:15:51 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     "Li,Rongqing" <lirongqing@...du.com>,
        Like Xu <like.xu@...ux.intel.com>,
        "like.xu@...el.com" <like.xu@...el.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "wanpengli@...cent.com" <wanpengli@...cent.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "sean.j.christopherson@...el.com" <sean.j.christopherson@...el.com>,
        "xiaoyao.li@...el.com" <xiaoyao.li@...el.com>,
        "wei.huang2@....com" <wei.huang2@....com>
Subject: Re: 答复: 答复: [PATCH][v6] KVM: X86: support APERF/MPERF registers

On 05/06/20 11:41, Li,Rongqing wrote:
>>
>> As you said, "Pass-though: it is only suitable for KVM_HINTS_REALTIME", which
>> means, KVM needs to make sure the kvm->arch.aperfmperf_mode value could
>> "only" be set to KVM_APERFMPERF_PT when the check
>> kvm_para_has_hint(KVM_HINTS_REALTIME) is passed.
>>
> pining vcpu can ensure that guest get correct mperf/aperf, but a user
> has the choice to not pin, at that condition, do not think it is bug, this wants to say

Also, userspace can also pin without exposing KVM_HINTS_REALTIME.  So
it's better not to check.

Paolo