xen/evtchn: modify evtchn_bind_interdomain to support static evtchn

Static event channel support will be added for dom0less domains. Modify
evtchn_bind_interdomain to support static evtchn.

It is necessary to have access to the evtchn_bind_interdomain function
to do that, so make evtchn_bind_interdomain global and also make it
__must_check.

Currently evtchn_bind_interdomain() always allocates the next available
local port. Static event channel support for dom0less domains requires
allocating a specified port. Modify the evtchn_bind_interdomain to
accept the port number as an argument and allocate the specified port
if available. If the port number argument is zero, the next available
port will be allocated.

Currently evtchn_bind_interdomain() finds the local domain from
"current->domain" pointer. evtchn_bind_interdomain() will be called from
the XEN to create static event channel during domain creation.
"current" pointer is not valid at that time, therefore modify the
evtchn_bind_interdomain() to pass domain as an argument.

Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index f546e81758ad4a79a0c12861bfb1f2bb758f433a..f5e0b12d15209d3d43ba1877e9def37b31ca32b7 100644 (file)
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -381,11 +381,16 @@ static void double_evtchn_unlock(struct evtchn *lchn, struct evtchn *rchn)
     evtchn_write_unlock(rchn);
 }
 
-static int evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
+/*
+ * If lport is zero get the next free port and allocate. If port is non-zero
+ * allocate the specified lport.
+ */
+int evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind, struct domain *ld,
+                            evtchn_port_t lport)
 {
     struct evtchn *lchn, *rchn;
-    struct domain *ld = current->domain, *rd;
-    int            lport, rc;
+    struct domain *rd;
+    int            rc;
     evtchn_port_t  rport = bind->remote_port;
     domid_t        rdom = bind->remote_dom;
 
@@ -405,8 +410,11 @@ static int evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
         write_lock(&ld->event_lock);
     }
 
-    if ( (lport = get_free_port(ld)) < 0 )
-        ERROR_EXIT(lport);
+    lport = rc = evtchn_get_port(ld, lport);
+    if ( rc < 0 )
+        ERROR_EXIT(rc);
+    rc = 0;
+
     lchn = evtchn_from_port(ld, lport);
 
     rchn = _evtchn_from_port(rd, rport);
@@ -1239,7 +1247,7 @@ long do_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct evtchn_bind_interdomain bind_interdomain;
         if ( copy_from_guest(&bind_interdomain, arg, 1) != 0 )
             return -EFAULT;
-        rc = evtchn_bind_interdomain(&bind_interdomain);
+        rc = evtchn_bind_interdomain(&bind_interdomain, current->domain, 0);
         if ( !rc && __copy_to_guest(arg, &bind_interdomain, 1) )
             rc = -EFAULT; /* Cleaning up here would be a mess! */
         break;

diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index f31963703ff7244b661f75dbbe33d6f15abc2699..8eae9984a9f1687313c0877343c6d976afbe4a43 100644 (file)
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -75,6 +75,11 @@ int evtchn_allocate_port(struct domain *d, unsigned int port);
 int __must_check evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc,
                                       evtchn_port_t port);
 
+/* Bind an event channel port to interdomain */
+int __must_check evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind,
+                                         struct domain *ld,
+                                         evtchn_port_t port);
+
 /* Unmask a local event-channel port. */
 int evtchn_unmask(unsigned int port);