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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] The use of evtchn_upcall_mask
Hi, everyone When I trace code of hypervisor, I can't find the use of evtchn_upcall_mask. As the comment in include/public/xen.h, evtchn_upcall_mask is read before making an event upcall to the guest.
After I search the mailing lists, I find the following changelog: [XEN] Replace direct common-code access of evtchn_upcall_mask with local_event_delivery_* accessors.
diff -r ea4829e30092 -r ddc25d4ebf60 xen/common/event_channel.c
--- a/xen/common/event_channel.c Sat Jun 10 11:05:11 2006 +0100
+++ b/xen/common/event_channel.c Sat Jun 10 11:07:11 2006 +0100
@@ -499,7 +499,7 @@ void evtchn_set_pending(struct vcpu *v,
evtchn_notify(v);
}
else if ( unlikely(test_bit(_VCPUF_blocked, &v->vcpu_flags) &&
- v->vcpu_info->evtchn_upcall_mask) )
+ !local_event_delivery_is_enabled()) )
diff -r d7543cff88ae -r aced0ee216aa xen/common/event_channel.c
--- a/xen/common/event_channel.c Sun Jun 11 14:33:16 2006 +0100
+++ b/xen/common/event_channel.c Sun Jun 11 19:23:31 2006 +0100
@@ -498,14 +498,14 @@ void evtchn_set_pending(struct vcpu *v,
{
evtchn_notify(v);
}
- else if ( unlikely(test_bit(_VCPUF_blocked, &v->vcpu_flags) &&
- !local_event_delivery_is_enabled()) )
- {
- /*
- * Blocked and masked will usually mean that the VCPU executed
- * SCHEDOP_poll. Kick the VCPU in case this port is in its poll list.
- */
- vcpu_unblock(v);
+
+ /* Check if some VCPU might be polling for this event. */
+ if ( unlikely(test_bit(_DOMF_polling, &d->domain_flags)) &&
+ likely(test_and_clear_bit(_DOMF_polling, &d->domain_flags)) )
+ {
+ for_each_vcpu ( d, v )
+ if ( test_and_clear_bit(_VCPUF_polling, &v->vcpu_flags) )
+ vcpu_unblock(v);
}
} I think evtchn_set_pending() is the function to decide whether to make an event upcall to the guest, and the first patch is the last patch which I see evtchn_upcall_mask in evtchn_set_pending().
I also find that local_event_delivery_is_enabled() is not used in hypervisor. I don't know if i understand this part correctly, it seems that evtchn_upcall_mask is useless. Can somebody tell me the use of evtchn_upcall_mask?
Any suggestions will be greatly appreciated, thanks in advance.
Best regards, Yao-Jing Wen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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