On Sat, Oct 6, 2018 at 1:29 PM Marcelo Tosatti wrote:
>
> On Thu, Oct 04, 2018 at 03:15:32PM -0700, Andy Lutomirski wrote:
> > For better or for worse, I'm trying to understand this code. So far,
> > I've come up with this patch:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/vdso-tglx=14fd71e12b1c4492a06f368f75041f263e6862bf
> >
> > Is it correct, or am I missing some subtlety?
>
> The master clock, when initialized, has a pair
>
> masterclockvalues=(TSC value, time-of-day data).
>
> When updating the guest clock, we only update relative to (TSC value)
> that was read on masterclock initialization.
I don't see the problem. The masterclock data is updated here:
host_tsc_clocksource = kvm_get_time_and_clockread(
>master_kernel_ns,
>master_cycle_now);
kvm_get_time_and_clockread() gets those values from
do_monotonic_boot(), which, barring bugs, should cause
get_kvmclock_ns() to return exactly the same thing as
ktime_get_boot_ns() + ka->kvmclock_offset, albeit in a rather
roundabout manner.
So what am I missing? Is there actually something wrong with my patch?
>
> See the following comment on x86.c:
I read that comment, and it's not obvious to me how it's related.
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