xen: Switch to libxenevtchn interface for compat shims.

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxenevtchn which provides access to event
channels.

In preparation for this switch the compatibility layer in xen_common.h
(which support building with older versions of Xen) to use what will
be the new library API. This means that the evtchn shim will disappear
for versions of Xen which include libxenevtchn.

To simplify things for the <= 4.0.0 support we wrap the int fd in a
malloc(sizeof int) such that the handle is always a pointer. This
leads to less typedef headaches and the need for
XC_HANDLER_INITIAL_VALUE etc for these interfaces.

Note that this patch does not add any support for actually using
libxenevtchn, it just adjusts the existing shims.

Note that xc_evtchn_alloc_unbound functionality remains in libxenctrl,
since that functionality is not exposed by /dev/xen/evtchn.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 16 insertions, 15 deletions

diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index 2510e2e4ff..ae2a1f01bd 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -243,19 +243,19 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
     xendev->debug      = debug;
     xendev->local_port = -1;
 
-    xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
-    if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
+    xendev->evtchndev = xenevtchn_open(NULL, 0);
+    if (xendev->evtchndev == NULL) {
         xen_be_printf(NULL, 0, "can't open evtchn device\n");
         g_free(xendev);
         return NULL;
     }
-    fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
+    fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 
     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
         xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
         if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
             xen_be_printf(NULL, 0, "can't open gnttab device\n");
-            xc_evtchn_close(xendev->evtchndev);
+            xenevtchn_close(xendev->evtchndev);
             g_free(xendev);
             return NULL;
         }
@@ -306,8 +306,8 @@ static struct XenDevice *xen_be_del_xendev(int dom, int dev)
             g_free(xendev->fe);
         }
 
-        if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
-            xc_evtchn_close(xendev->evtchndev);
+        if (xendev->evtchndev != NULL) {
+            xenevtchn_close(xendev->evtchndev);
         }
         if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
             xc_gnttab_close(xendev->gnttabdev);
@@ -691,13 +691,14 @@ static void xen_be_evtchn_event(void *opaque)
     struct XenDevice *xendev = opaque;
     evtchn_port_t port;
 
-    port = xc_evtchn_pending(xendev->evtchndev);
+    port = xenevtchn_pending(xendev->evtchndev);
     if (port != xendev->local_port) {
-        xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected %d)\n",
+        xen_be_printf(xendev, 0,
+                      "xenevtchn_pending returned %d (expected %d)\n",
                       port, xendev->local_port);
         return;
     }
-    xc_evtchn_unmask(xendev->evtchndev, port);
+    xenevtchn_unmask(xendev->evtchndev, port);
 
     if (xendev->ops->event) {
         xendev->ops->event(xendev);
@@ -740,14 +741,14 @@ int xen_be_bind_evtchn(struct XenDevice *xendev)
     if (xendev->local_port != -1) {
         return 0;
     }
-    xendev->local_port = xc_evtchn_bind_interdomain
+    xendev->local_port = xenevtchn_bind_interdomain
         (xendev->evtchndev, xendev->dom, xendev->remote_port);
     if (xendev->local_port == -1) {
-        xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
+        xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
         return -1;
     }
     xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
-    qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
+    qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
                         xen_be_evtchn_event, NULL, xendev);
     return 0;
 }
@@ -757,15 +758,15 @@ void xen_be_unbind_evtchn(struct XenDevice *xendev)
     if (xendev->local_port == -1) {
         return;
     }
-    qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
-    xc_evtchn_unbind(xendev->evtchndev, xendev->local_port);
+    qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
+    xenevtchn_unbind(xendev->evtchndev, xendev->local_port);
     xen_be_printf(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
     xendev->local_port = -1;
 }
 
 int xen_be_send_notify(struct XenDevice *xendev)
 {
-    return xc_evtchn_notify(xendev->evtchndev, xendev->local_port);
+    return xenevtchn_notify(xendev->evtchndev, xendev->local_port);
 }
 
 /*