Re: [PATCH 02/10] KVM: x86: Improve accuracy of KVM clock when TSC scaling is in force

[Paolo Bonzini]

On Thu, Apr 18, 2024 at 9:51 PM David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
>         gpa_t time;
>         struct pvclock_vcpu_time_info hv_clock;
> -       unsigned int hw_tsc_khz;
> +       unsigned int hw_tsc_hz;

Why not change this to u64? 4.3 GHz is scarily close to current
processors, though I expect that it will break a lot more software
than just KVM.

>  static int kvm_guest_time_update(struct kvm_vcpu *v)
>  {
> -       unsigned long flags, tgt_tsc_khz;
> +       unsigned long flags;
> +       uint64_t tgt_tsc_hz;

.. especially considering that you did use a 64-bit integer here
(though---please use u64 not uint64_t; and BTW if you want to add a
patch to change kvm_get_time_scale() to u64, please do.

Thanks,

Paolo