xen/events: reset active flag for lateeoi events later

commit 3de218ff39b9e3f0d453fe3154f12a174de44b25 upstream.

In order to avoid a race condition for user events when changing
cpu affinity reset the active flag only when EOI-ing the event.

This is working fine as all user events are lateeoi events. Note that
lateeoi_ack_mask_dynirq() is not modified as there is no explicit call
to xen_irq_lateeoi() expected later.

Cc: stable@vger.kernel.org
Reported-by: Julien Grall <julien@xen.org>
Fixes: b6622798bc50b62 ("xen/events: avoid handling the same event on two cpus at the same time")
Tested-by: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrvsky@oracle.com>
Link: https://lore.kernel.org/r/20210623130913.9405-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 9cc77f039779752e5d15acc588609b92457ede43..de825df4abf6ac77a480d7afc88019ebba4f9e0e 100644 (file)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -525,6 +525,9 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious)
        }
 
        info->eoi_time = 0;
+
+       /* is_active hasn't been reset yet, do it now. */
+       smp_store_release(&info->is_active, 0);
        do_unmask(info, EVT_MASK_REASON_EOI_PENDING);
 }
 
@@ -1781,10 +1784,22 @@ static void lateeoi_ack_dynirq(struct irq_data *data)
        struct irq_info *info = info_for_irq(data->irq);
        evtchn_port_t evtchn = info ? info->evtchn : 0;
 
-       if (VALID_EVTCHN(evtchn)) {
-               do_mask(info, EVT_MASK_REASON_EOI_PENDING);
-               ack_dynirq(data);
-       }
+       if (!VALID_EVTCHN(evtchn))
+               return;
+
+       do_mask(info, EVT_MASK_REASON_EOI_PENDING);
+
+       if (unlikely(irqd_is_setaffinity_pending(data)) &&
+           likely(!irqd_irq_disabled(data))) {
+               do_mask(info, EVT_MASK_REASON_TEMPORARY);
+
+               clear_evtchn(evtchn);
+
+               irq_move_masked_irq(data);
+
+               do_unmask(info, EVT_MASK_REASON_TEMPORARY);
+       } else
+               clear_evtchn(evtchn);
 }
 
 static void lateeoi_mask_ack_dynirq(struct irq_data *data)