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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

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@xxxxxxxxxx>
> ---
>  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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