xen/evtchn: modify evtchn_alloc_unbound to allocate specified port

Currently evtchn_alloc_unbound() always allocates the next available
port. Static event channel support for dom0less domains requires
allocating a specified port.

Modify the evtchn_alloc_unbound() 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.

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/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index f89976686036f91a218c8ee860135e5e2be83c88..7192293068b60209467b7897af7e86cc2574061d 100644 (file)
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -3171,7 +3171,7 @@ static int __init alloc_xenstore_evtchn(struct domain *d)
 
     alloc.dom = d->domain_id;
     alloc.remote_dom = hardware_domain->domain_id;
-    rc = evtchn_alloc_unbound(&alloc);
+    rc = evtchn_alloc_unbound(&alloc, 0);
     if ( rc )
     {
         printk("Failed allocating event channel for domain\n");

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 565ab71881709d77c22b5b57734f5b306807fb4e..f546e81758ad4a79a0c12861bfb1f2bb758f433a 100644 (file)
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -317,11 +317,15 @@ static int evtchn_get_port(struct domain *d, evtchn_port_t port)
     return rc ?: port;
 }
 
-int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
+/*
+ * If port is zero get the next free port and allocate. If port is non-zero
+ * allocate the specified port.
+ */
+int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc, evtchn_port_t port)
 {
     struct evtchn *chn;
     struct domain *d;
-    int            port, rc;
+    int            rc;
     domid_t        dom = alloc->dom;
 
     d = rcu_lock_domain_by_any_id(dom);
@@ -330,8 +334,11 @@ int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
 
     write_lock(&d->event_lock);
 
-    if ( (port = get_free_port(d)) < 0 )
-        ERROR_EXIT_DOM(port, d);
+    port = rc = evtchn_get_port(d, port);
+    if ( rc < 0 )
+        ERROR_EXIT(rc);
+    rc = 0;
+
     chn = evtchn_from_port(d, port);
 
     rc = xsm_evtchn_unbound(XSM_TARGET, d, chn, alloc->remote_dom);
@@ -1222,7 +1229,7 @@ long do_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct evtchn_alloc_unbound alloc_unbound;
         if ( copy_from_guest(&alloc_unbound, arg, 1) != 0 )
             return -EFAULT;
-        rc = evtchn_alloc_unbound(&alloc_unbound);
+        rc = evtchn_alloc_unbound(&alloc_unbound, 0);
         if ( !rc && __copy_to_guest(arg, &alloc_unbound, 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 f3021fe3043aa3ee06ffaef06e183a32598715b0..f31963703ff7244b661f75dbbe33d6f15abc2699 100644 (file)
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -72,7 +72,8 @@ void evtchn_free(struct domain *d, struct evtchn *chn);
 int evtchn_allocate_port(struct domain *d, unsigned int port);
 
 /* Allocate a new event channel */
-int __must_check evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc);
+int __must_check evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc,
+                                      evtchn_port_t port);
 
 /* Unmask a local event-channel port. */
 int evtchn_unmask(unsigned int port);