Re: [PATCH v3 24/41] timekeeping: Resume clocksources before reading persistent clock

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Fri, 2026-05-15 at 12:19 -0700, Sean Christopherson wrote:
> When resuming timekeeping after suspend, restore clocksources prior to
> reading the persistent clock.  Paravirt clocks, e.g. kvmclock, tie the
> validity of a PV persistent clock to a clocksource, i.e. reading the PV
> persistent clock will return garbage if the underlying PV clocksource
> hasn't been enabled.  The flaw has gone unnoticed because kvmclock is a
> mess and uses its own suspend/resume hooks instead of the clocksource
> suspend/resume hooks, which happens to work by sheer dumb luck (the
> kvmclock resume hook runs before timekeeping_resume()).
> 
> Note, there is no evidence that any clocksource supported by the kernel
> depends on a persistent clock.
> 
> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>

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