On Wed, 07 Dec 2011, Avi Kivity wrote:
> On 12/05/2011 10:19 PM, Eric B Munson wrote:
> > When a host stops or suspends a VM it will set a flag to show this. The
> > watchdog will use these functions to determine if a softlockup is real, or
> > the
> > result of a suspended VM.
> >
> > +bool kvm_check_and_clear_guest_paused(int cpu)
> > +{
> > + bool ret = false;
> > + struct pvclock_vcpu_time_info *src;
> > +
> > + /*
> > + * per_cpu() is safe here because this function is only called from
> > + * timer functions where preemption is already disabled.
> > + */
> > + WARN_ON(!in_atomic());
> > + src = &per_cpu(hv_clock, cpu);
>
> __get_cpu_var(); drop the cpu argument
>
Will change for V6.
> > + if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
> > + src->flags = src->flags & (~PVCLOCK_GUEST_STOPPED);
>
> Isn't this racy? Between reading and writing src->flags, we can exit to
> the hypervisor and add/remove new flags. The write then overrides those
> new flags.
>
If I understand (please correct me if this is wrong) because this is only
called from the watchdog, which disables preemption, we should be protected
from something else writing to these flags.
> > + ret = true;
> > + }
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(kvm_check_and_clear_guest_paused);
> > +
> > static struct clocksource kvm_clock = {
> > .name = "kvm-clock",
> > .read = kvm_clock_get_cycles,
>
>
> --
> error compiling committee.c: too many arguments to function
>
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