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

On Thu, Apr 18, 2024 at 9:51 PM David Woodhouse dwmw2@infradead.org 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