[xen staging] evtchn: closing of vIRQ-s doesn't require looping over all vCPU-s

[patchbot@xxxxxxx]

commit 7cf8a2d0ec5cf1ec84a213c54fd14aa18d1609ac
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jan 11 14:53:55 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jan 11 14:53:55 2021 +0100

    evtchn: closing of vIRQ-s doesn't require looping over all vCPU-s
    
    Global vIRQ-s have their event channel association tracked on vCPU 0.
    Per-vCPU vIRQ-s can't have their notify_vcpu_id changed. Hence it is
    well-known which vCPU's virq_to_evtchn[] needs updating.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/common/event_channel.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 37592028c8..d590ddad99 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -606,7 +606,6 @@ static long evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
 int evtchn_close(struct domain *d1, int port1, bool guest)
 {
     struct domain *d2 = NULL;
-    struct vcpu   *v;
     struct evtchn *chn1, *chn2;
     int            port2;
     long           rc = 0;
@@ -657,17 +656,19 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
         break;
     }
 
-    case ECS_VIRQ:
-        for_each_vcpu ( d1, v )
-        {
-            unsigned long flags;
+    case ECS_VIRQ: {
+        struct vcpu *v;
+        unsigned long flags;
+
+        v = d1->vcpu[virq_is_global(chn1->u.virq) ? 0 : chn1->notify_vcpu_id];
+
+        write_lock_irqsave(&v->virq_lock, flags);
+        ASSERT(read_atomic(&v->virq_to_evtchn[chn1->u.virq]) == port1);
+        write_atomic(&v->virq_to_evtchn[chn1->u.virq], 0);
+        write_unlock_irqrestore(&v->virq_lock, flags);
 
-            write_lock_irqsave(&v->virq_lock, flags);
-            if ( read_atomic(&v->virq_to_evtchn[chn1->u.virq]) == port1 )
-                write_atomic(&v->virq_to_evtchn[chn1->u.virq], 0);
-            write_unlock_irqrestore(&v->virq_lock, flags);
-        }
         break;
+    }
 
     case ECS_IPI:
         break;
--
generated by git-patchbot for /home/xen/git/xen.git#staging