[PATCH v3 2/5] xen: make evtchn_alloc_unbound public

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Luca Miccio <lucmiccio@xxxxxxxxx>

The xenstore event channel will be allocated for dom0less domains. It is
necessary to have access to the evtchn_alloc_unbound function to do
that, so make evtchn_alloc_unbound public.

Add a skip_xsm parameter to allow disabling the XSM check in
evtchn_alloc_unbound (xsm_evtchn_unbound wouldn't work for a call
originated from Xen before running any domains.)

Signed-off-by: Luca Miccio <lucmiccio@xxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
---
Changes v3:
- expose evtchn_alloc_unbound, assing a skip_xsm parameter
---
 xen/common/event_channel.c | 13 ++++++++-----
 xen/include/xen/event.h    |  3 +++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index da88ad141a..be57d00a15 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -284,7 +284,7 @@ void evtchn_free(struct domain *d, struct evtchn *chn)
     xsm_evtchn_close_post(chn);
 }
 
-static int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
+int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc, bool skip_xsm)
 {
     struct evtchn *chn;
     struct domain *d;
@@ -301,9 +301,12 @@ static int evtchn_alloc_unbound(evtchn_alloc_unbound_t 
*alloc)
         ERROR_EXIT_DOM(port, d);
     chn = evtchn_from_port(d, port);
 
-    rc = xsm_evtchn_unbound(XSM_TARGET, d, chn, alloc->remote_dom);
-    if ( rc )
-        goto out;
+    if ( !skip_xsm )
+    {
+        rc = xsm_evtchn_unbound(XSM_TARGET, d, chn, alloc->remote_dom);
+        if ( rc )
+            goto out;
+    }
 
     evtchn_write_lock(chn);
 
@@ -1195,7 +1198,7 @@ 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, false);
         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 21c95e14fd..0a2cdedf7d 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -68,6 +68,9 @@ int evtchn_close(struct domain *d1, int port1, bool guest);
 /* Free an event channel. */
 void evtchn_free(struct domain *d, struct evtchn *chn);
 
+/* Create a new event channel port */
+int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc, bool skip_xsm);
+
 /* Allocate a specific event channel port. */
 int evtchn_allocate_port(struct domain *d, unsigned int port);
 
-- 
2.25.1