libxl: create xenstore nodes for control/feature-XXX flags

The xenstore-paths documentation specifies various control/feature-XXX
flags to allow a guest to tell a toolstack about its abilities to
respond to values written to control/shutdown. However, because the
parent control xenstore key is created read-only to the guest, unless
empty nodes for the feature flags are also created reat/write by the
toolstack, the guest will not be able to set any flags.

This patch adds code to create all specified feature flag nodes at
domain creation time.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

tools/libxl/libxl_create.c

@@ -645,6 +645,23 @@ retry_transaction:
     libxl__xs_mknod(gc, t,
                     GCSPRINTF("%s/control/shutdown", dom_path),
                     rwperm, ARRAY_SIZE(rwperm));
+    libxl__xs_mknod(gc, t,
+                    GCSPRINTF("%s/control/feature-poweroff", dom_path),
+                    rwperm, ARRAY_SIZE(rwperm));
+    libxl__xs_mknod(gc, t,
+                    GCSPRINTF("%s/control/feature-reboot", dom_path),
+                    rwperm, ARRAY_SIZE(rwperm));
+    libxl__xs_mknod(gc, t,
+                    GCSPRINTF("%s/control/feature-suspend", dom_path),
+                    rwperm, ARRAY_SIZE(rwperm));
+    if (info->type == LIBXL_DOMAIN_TYPE_HVM) {
+        libxl__xs_mknod(gc, t,
+                        GCSPRINTF("%s/control/feature-s3", dom_path),
+                        rwperm, ARRAY_SIZE(rwperm));
+        libxl__xs_mknod(gc, t,
+                        GCSPRINTF("%s/control/feature-s4", dom_path),
+                        rwperm, ARRAY_SIZE(rwperm));
+    }
     libxl__xs_mknod(gc, t,
                     GCSPRINTF("%s/device/suspend/event-channel", dom_path),
                     rwperm, ARRAY_SIZE(rwperm));