Re: [PATCH 7/7] xen/arm: Restore IRQ affinity after hotplugging a CPU

[Mirela Simonovic <mirela.simonovic@aggios.com>]

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Hi Stefano,

v->processor has to be updated before the sched_move_irqs is called. Since
updating v->processor is done after the 'if (v->affinity_broken)' check I
had to put sched_move_irqs below, where it is.

Thanks,
Mirela

On Thu, Apr 12, 2018 at 2:20 AM, Stefano Stabellini <sstabellini@kernel.org>
wrote:

> On Wed, 11 Apr 2018, Mirela Simonovic wrote:
> > Secondary pCPUs will be offlined on system suspend and hotplugged
> > on resume. When offlining secondary CPUs all interrupts targeted
> > to those CPUs will be routed to the boot CPU. The boot CPU
> > is responsible for finalizing suspend procedure. All wake-up
> > interrupts are therefore targeted to the boot CPU. Existing code
> > was missing the restoration of interrupts affinity after
> > hotplugging a CPU. This patch restores the IRQ affinity after
> > a CPU is hotplugged.
> >
> > Signed-off-by: Mirela Simonovic <mirela.simonovic@aggios.com>
> > ---
> >  xen/common/schedule.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/xen/common/schedule.c b/xen/common/schedule.c
> > index 343ab6306e..e3956019bc 100644
> > --- a/xen/common/schedule.c
> > +++ b/xen/common/schedule.c
> > @@ -692,6 +692,7 @@ void restore_vcpu_affinity(struct domain *d)
> >      for_each_vcpu ( d, v )
> >      {
> >          spinlock_t *lock;
> > +        bool affinity_was_broken = v->affinity_broken;
> >
> >          ASSERT(!vcpu_runnable(v));
> >
> > @@ -724,6 +725,9 @@ void restore_vcpu_affinity(struct domain *d)
> >          lock = vcpu_schedule_lock_irq(v);
> >          v->processor = SCHED_OP(vcpu_scheduler(v), pick_cpu, v);
> >          spin_unlock_irq(lock);
> > +
> > +        if ( affinity_was_broken )
> > +            sched_move_irqs(v);
> >      }
> >
> >      domain_update_node_affinity(d);
>
> I am no expert of this code, but it looks correct to me. You might want
> to move the setting of affinity_was_broken to inside the existing if (
> v->affinity_broken ) check.
>

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