On Mon, May 24, 2021, Paolo Bonzini wrote:
> On 21/05/21 12:24, Ilias Stamatis wrote:
> > @@ -3537,10 +3539,14 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> > * return L1's TSC value to ensure backwards-compatible
> > * behavior for migration.
> > */
> > - u64 tsc_offset = msr_info->host_initiated ? vcpu->arch.l1_tsc_offset :
> > - vcpu->arch.tsc_offset;
> > -
> > - msr_info->data = kvm_scale_tsc(vcpu, rdtsc()) + tsc_offset;
> > + if (msr_info->host_initiated)
> > + msr_info->data = kvm_scale_tsc(
> > + vcpu, rdtsc(), vcpu->arch.l1_tsc_scaling_ratio
> > + ) + vcpu->arch.l1_tsc_offset;
>
> Better indentation:
>
> msr_info->data = vcpu->arch.l1_tsc_offset +
> kvm_scale_tsc(vcpu, rdtsc(),
I like this more, but it's still a bit ugly.
> vcpu->arch.tsc_scaling_ratio);
Wrong pairing of ratio and offset (not necessarily what you queued, obviously).
>
> Same below.
Alternatively, what about something like this?
u64 offset, ratio;
if (msr_info->host_initiated) {
offset = vcpu->arch.l1_tsc_offset;
ratio = vcpu->arch.l1_tsc_scaling_ratio;
} else {
offset = vcpu->arch.tsc_offset;
ratio = vcpu->arch.tsc_scaling_ratio;
}
msr_info->data = kvm_scale_tsc(vcpu, rdtsc(), ratio) + offset;
or an option that would require additional refactoring:
struct kvm_guest_tsc *tsc;
tsc = msr_info->host_initiated ? &vcpu->arch.l1_tsc :
&vcpu->arch.current_tsc;
msr_info->data = tsc->offset +
kvm_scale_tsc(vcpu, rdtsc(), tsc->scaling_ratio);
>
> Paolo
>
> > + else
> > + msr_info->data = kvm_scale_tsc(
> > + vcpu, rdtsc(), vcpu->arch.tsc_scaling_ratio
> > + ) + vcpu->arch.tsc_offset;
> > break;
> > }
> > case MSR_MTRRcap:
> >
>
