xen/events: Remove disfunct affinity spreading

This function can only ever work when the event channels:

  - are already established
  - interrupts assigned to them
  - the affinity has been set by user space already

because any newly set up event channel is forced to be bound to CPU0 and
the affinity mask of the interrupt is forced to contain cpumask_of(0).

As the CPU0 enforcement was in place _before_ this was implemented it's
entirely unclear how that can ever have worked at all.

Remove it as preparation for doing it proper.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20201210194045.065115500@linutronix.de

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index d6458e439c7823d535cab7e71dd8dcb933e2c139..9cade1994785b1bf9a6641f5059b068433573d06 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1696,15 +1696,6 @@ static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
        return ret;
 }
 
-/* To be called with desc->lock held. */
-int xen_set_affinity_evtchn(struct irq_desc *desc, unsigned int tcpu)
-{
-       struct irq_data *d = irq_desc_get_irq_data(desc);
-
-       return set_affinity_irq(d, cpumask_of(tcpu), false);
-}
-EXPORT_SYMBOL_GPL(xen_set_affinity_evtchn);
-
 static void enable_dynirq(struct irq_data *data)
 {
        evtchn_port_t evtchn = evtchn_from_irq(data->irq);

diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 5dc016d68f833dff83c3d589cd3d6a477ef766cd..a7a85719a8c8ab98b5b23516495a33e5cf3d4586 100644 (file)
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -421,36 +421,6 @@ static void evtchn_unbind_from_user(struct per_user_data *u,
        del_evtchn(u, evtchn);
 }
 
-static DEFINE_PER_CPU(int, bind_last_selected_cpu);
-
-static void evtchn_bind_interdom_next_vcpu(evtchn_port_t evtchn)
-{
-       unsigned int selected_cpu, irq;
-       struct irq_desc *desc;
-       unsigned long flags;
-
-       irq = irq_from_evtchn(evtchn);
-       desc = irq_to_desc(irq);
-
-       if (!desc)
-               return;
-
-       raw_spin_lock_irqsave(&desc->lock, flags);
-       selected_cpu = this_cpu_read(bind_last_selected_cpu);
-       selected_cpu = cpumask_next_and(selected_cpu,
-                       desc->irq_common_data.affinity, cpu_online_mask);
-
-       if (unlikely(selected_cpu >= nr_cpu_ids))
-               selected_cpu = cpumask_first_and(desc->irq_common_data.affinity,
-                               cpu_online_mask);
-
-       this_cpu_write(bind_last_selected_cpu, selected_cpu);
-
-       /* unmask expects irqs to be disabled */
-       xen_set_affinity_evtchn(desc, selected_cpu);
-       raw_spin_unlock_irqrestore(&desc->lock, flags);
-}
-
 static long evtchn_ioctl(struct file *file,
                         unsigned int cmd, unsigned long arg)
 {
@@ -508,10 +478,8 @@ static long evtchn_ioctl(struct file *file,
                        break;
 
                rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
-               if (rc == 0) {
+               if (rc == 0)
                        rc = bind_interdomain.local_port;
-                       evtchn_bind_interdom_next_vcpu(rc);
-               }
                break;
        }