Re: [PATCH 4/5] xen: events, exposes evtchn_alloc_unbound_domain

[Jean Guyader <jean.guyader@citrix.com>]

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On 10/08 08:35, Jan Beulich wrote:
> >>> On 10.08.12 at 01:25, Jean Guyader <jean.guyader@citrix.com> wrote:
> >--- a/xen/common/event_channel.c
> >+++ b/xen/common/event_channel.c
> >@@ -159,9 +159,8 @@ static int get_free_port(struct domain *d)
> > 
> > static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
> > {
> >-    struct evtchn *chn;
> >     struct domain *d;
> >-    int            port;
> >+    evtchn_port_t  port;
> >     domid_t        dom = alloc->dom;
> >     long           rc;
> > 
> >@@ -169,26 +168,47 @@ static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
> >     if ( rc )
> >         return rc;
> > 
> >+    rc = evtchn_alloc_unbound_domain(d, &port,
> 
> Any reason you can't pass &alloc->port here directly?
> 
> >+            alloc->remote_dom == DOMID_SELF ? current->domain->domain_id
> >+                                            : alloc->remote_dom);
> 
> Any reason this can't/shouldn't be done in the called function?
> 

No specific reason for both of those thing. Here is a new version based
on your comments.

Thanks for reviewing,
Jean

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commit 208384d74852df9ae26294236d79e33967a75afa
Author: Jean Guyader <jean.guyader@citrix.com>
Date:   Thu Aug 2 16:19:23 2012 +0100

    xen: events, exposes evtchn_alloc_unbound_domain
    
    Exposes evtchn_alloc_unbound_domain to the rest of
    Xen so we can create allocated unbound evtchn within Xen.

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 53777f8..fd626bf 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -159,36 +159,53 @@ static int get_free_port(struct domain *d)
 
 static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
 {
-    struct evtchn *chn;
     struct domain *d;
-    int            port;
-    domid_t        dom = alloc->dom;
     long           rc;
 
-    rc = rcu_lock_target_domain_by_id(dom, &d);
+    rc = rcu_lock_target_domain_by_id(alloc->dom, &d);
     if ( rc )
         return rc;
 
+    rc = evtchn_alloc_unbound_domain(d, &alloc->port, alloc->remote_dom);
+    if ( rc )
+        ERROR_EXIT_DOM((int)rc, d);
+
+ out:
+    rcu_unlock_domain(d);
+
+    return rc;
+}
+
+int evtchn_alloc_unbound_domain(struct domain *d, evtchn_port_t *port,
+                                domid_t remote_domid)
+{
+    struct evtchn *chn;
+    int           rc;
+    int           free_port;
+
     spin_lock(&d->event_lock);
 
-    if ( (port = get_free_port(d)) < 0 )
-        ERROR_EXIT_DOM(port, d);
-    chn = evtchn_from_port(d, port);
+    rc = free_port = get_free_port(d);
+    if ( free_port < 0 )
+        goto out;
 
-    rc = xsm_evtchn_unbound(d, chn, alloc->remote_dom);
+    chn = evtchn_from_port(d, free_port);
+    rc = xsm_evtchn_unbound(d, chn, remote_domid);
     if ( rc )
         goto out;
 
     chn->state = ECS_UNBOUND;
-    if ( (chn->u.unbound.remote_domid = alloc->remote_dom) == DOMID_SELF )
+    if ( (chn->u.unbound.remote_domid = remote_domid) == DOMID_SELF )
         chn->u.unbound.remote_domid = current->domain->domain_id;
 
-    alloc->port = port;
+    chn->u.unbound.remote_domid = remote_domid;
+
+    *port = free_port;
+    /* Everything is fine, returns 0 */
+    rc = 0;
 
  out:
     spin_unlock(&d->event_lock);
-    rcu_unlock_domain(d);
-
     return rc;
 }
 
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 71c3e92..1a0c832 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -69,6 +69,9 @@ int guest_enabled_event(struct vcpu *v, uint32_t virq);
 /* Notify remote end of a Xen-attached event channel.*/
 void notify_via_xen_event_channel(struct domain *ld, int lport);
 
+int evtchn_alloc_unbound_domain(struct domain *d, evtchn_port_t *port,
+                                domid_t remote_domid);
+
 /* Internal event channel object accessors */
 #define bucket_from_port(d,p) \
     ((d)->evtchn[(p)/EVTCHNS_PER_BUCKET])

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