Re: [PATCH v3 26/41] x86/kvmclock: WARN if wall clock is read while kvmclock is suspended

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Fri, 2026-05-15 at 12:19 -0700, Sean Christopherson wrote:
> WARN if kvmclock is still suspended when its wallclock is read, i.e. when
> the kernel reads its persistent clock.  The wallclock subtly depends on
> the BSP's kvmclock being enabled, and returns garbage if kvmclock is
> disabled.
> 
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>


Although I still hate the whole KVM wallclock thing, as the kvmclock
itself is monotonic_raw, so adding that to the wallclock epoch is kind
of wrong.

Maybe the host should updated the wallclock occasionally to keep it up
to date...


Or maybe the guest should prefer the KVM_HC_CLOCK_PAIRING hypercall if
it exists, over kvm-wallclock.

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