From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Thursday, November 14, 2019 10:49 PM
> > From: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> > Sent: Tuesday, November 12, 2019 5:12 PM
> > ...
> > @@ -190,14 +278,20 @@ void hv_stimer_free(void)
> > void hv_stimer_global_cleanup(void)
> > {
> > int cpu;
> > ...
> > + /*
> > + * hv_stime_legacy_cleanup() will stop the stimer if Direct
> > + * Mode is not enabled, and fallback to the LAPIC timer.
> > + */
> > + for_each_present_cpu(cpu) {
> > + hv_stimer_legacy_cleanup(cpu);
> > }
> > +
> > + /*
> > + * If Direct Mode is enabled, the cpuhp teardown callback
> > + * (hv_stimer_cleanup) will be run on all CPUs to stop the
> > + * stimers.
> > + */
> > hv_stimer_free();
> > }
>
> In the case of direct_mode_enabled == true: When hv_vmbus unloads,
> vmbus_exit() -> hv_stimer_global_cleanup() -> hv_stimer_free() ->
> cpuhp_remove_state() disables the direct mode timers.
>
> This does not look symmetric since hv_stimer_alloc() is called before
> hv_vmbus loads, but I suppose this is not a real issue because hv_vmbus
> should never unload in practice. :-)
Thanks for the review. Looking at this a bit more, ideally
hv_stimer_global_cleanup() should go away entirely. vmbus_exit() should
let the call to cpuhp_remove_state() clean up the stimer on each CPU via
hv_synic_cleanup(). But vmbus_exit() shuts down the VMbus first, which
is really the wrong order.
As you say, vmbus_exit() never gets called in practice, so it's not a
current issue. But I'll look at fixing this in a future patch so that it
makes logical sense.
Michael
>
> Tested-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
