Re: [PATCH 4.19 043/190] KVM: hyperv: define VP assist page helpers

[Sasha Levin]

On Sun, Sep 15, 2019 at 09:01:30PM +0200, Pavel Machek wrote:
> On Fri 2019-09-13 14:04:58, Greg Kroah-Hartman wrote:
> > [ Upstream commit 72bbf9358c3676bd89dc4bd8fb0b1f2a11c288fc ]
> >
> > The state related to the VP assist page is still managed by the LAPIC
> > code in the pv_eoi field.
>
> I don't get it.
>
> > +bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu)
> > +{
> > +	if (!(vcpu->arch.hyperv.hv_vapic & HV_X64_MSR_VP_ASSIST_PAGE_ENABLE))
> > +		return false;
> > +	return vcpu->arch.pv_eoi.msr_val & KVM_MSR_ENABLED;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_hv_assist_page_enabled);
> > +
> > +bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu,
> > +			    struct hv_vp_assist_page *assist_page)
> > +{
> > +	if (!kvm_hv_assist_page_enabled(vcpu))
> > +		return false;
> > +	return !kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.pv_eoi.data,
> > +				      assist_page, sizeof(*assist_page));
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_hv_get_assist_page);
> > +
>
> This adds two functions, but not their users. What bug is it fixing? I
> don't see any users in the next patch, either.

Look closer at the following patch.

--
Thanks,
Sasha