linux-kernel - Re: [PATCH v11 023/113] KVM: TDX: allocate/free TDX vcpu structure

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Date:   Tue, 28 Feb 2023 12:20:31 -0800
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     Zhi Wang <zhi.wang.linux@...il.com>
Cc:     Isaku Yamahata <isaku.yamahata@...il.com>,
        isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH v11 023/113] KVM: TDX: allocate/free TDX vcpu structure

On Tue, Feb 28, 2023 at 07:55:09PM +0200,
Zhi Wang <zhi.wang.linux@...il.com> wrote:

> On Mon, 27 Feb 2023 15:49:14 -0800
> Isaku Yamahata <isaku.yamahata@...il.com> wrote:

> > > 2) Move 
> > > 
> > > > +	apic_base_msr.data = APIC_DEFAULT_PHYS_BASE | LAPIC_MODE_X2APIC;
> > > > +	if (kvm_vcpu_is_reset_bsp(vcpu))
> > > > +		apic_base_msr.data |= MSR_IA32_APICBASE_BSP;
> > > > +	apic_base_msr.host_initiated = true;
> > > 
> > > to:
> > > 
> > > void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
> > > {
> > >         struct kvm_lapic *apic = vcpu->arch.apic;
> > >         u64 msr_val;
> > >         int i;
> > > 
> > >         if (!init_event) {
> > >                 msr_val = APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE;
> > > 
> > > 		/* here */
> > > 		if (is_td_vcpu(vcpu)) 
> > > 			msr_val = xxxx;
> > >                 if (kvm_vcpu_is_reset_bsp(vcpu))
> > >                         msr_val |= MSR_IA32_APICBASE_BSP;
> > >                 kvm_lapic_set_base(vcpu, msr_val);
> > >         }
> > 
> > No. Because I'm trying to contain is_td/is_td_vcpu in vmx specific and not use
> > in common x86 code.
> >
> 
> I guess so. Centeralizing the initialization would be the nice and greatly
> improve the readablity of the code. Maybe adding a new callback in kvm x86_ops
> like .get_default_msr_val instead.

Finally I can eliminate cpuid/APIC BASE MSR, and move it user space VMM, qemu.
-- 
Isaku Yamahata <isaku.yamahata@...il.com>