linux-kernel - Re: [PATCH v3 09/15] KVM: nSVM: Use KVM-governed feature framework to track "TSC scaling enabled"

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Message-ID: <20230816230310.qfa347ujhkj25vqj@yy-desk-7060>
Date:   Thu, 17 Aug 2023 07:03:10 +0800
From:   Yuan Yao <yuan.yao@...ux.intel.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Zeng Guang <guang.zeng@...el.com>,
        Yuan Yao <yuan.yao@...el.com>
Subject: Re: [PATCH v3 09/15] KVM: nSVM: Use KVM-governed feature framework
 to track "TSC scaling enabled"

On Wed, Aug 16, 2023 at 06:44:42AM -0700, Sean Christopherson wrote:
> On Wed, Aug 16, 2023, Yuan Yao wrote:
> > On Tue, Aug 15, 2023 at 01:36:47PM -0700, Sean Christopherson wrote:
> > > @@ -2981,7 +2982,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> > >
> > >  		svm->tsc_ratio_msr = data;
> > >
> > > -		if (svm->tsc_scaling_enabled && is_guest_mode(vcpu))
> > > +		if (guest_can_use(vcpu, X86_FEATURE_TSCRATEMSR) &&
> > > +		    is_guest_mode(vcpu))
> >
> > I prefer (is_guest_mode(vcpu) && ....), so I can skip them more quickly LOL.
> > but anyway depends on you :-)
>
> For this series, I want to do as much of a straight replacement as possible, i.e.
> not change any ordering unless it's "necessary".

Yeah, I'm fine with this.