From: Juergen Gross jgross@suse.com
stable inclusion from linux-4.19.197 commit cda326e5033fc1e7912ca31887b05fa7cd8060f3
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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 Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/xen/events/events_base.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 409c761919fe5..914a07d4238e2 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -511,6 +511,9 @@ 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); }
@@ -1767,10 +1770,22 @@ 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)