Re: [PATCH v2 24/38] timekeeping: Resume clocksources before reading persistent clock

[Thomas Gleixner]

On Wed, Feb 26 2025 at 18:18, 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.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>