tools/helpers: fix broken xenstore stubdom init

Commit 1787cc1 ("libs/guest: Move the guest ABI check earlier
into xc_dom_parse_image()") broke starting the xenstore stubdom. This
is due to a rather special way the xenstore stubdom domain config is
being initialized: in order to support both, PV and PVH stubdom,
init-xenstore-domain is using xc_dom_parse_image() to find the correct
domain type. Unfortunately above commit requires xc_dom_boot_xen_init()
to have been called before using xc_dom_parse_image(). This requires
the domid, which is known only after xc_domain_create(), which requires
the domain type.

In order to break this circular dependency, call xc_dom_boot_xen_init()
with an arbitrary domid first, and then set dom->guest_domid later.

Fixes: 1787cc1 ("libs/guest: Move the guest ABI check earlier into xc_dom_parse_image()")
Signed-off-by: Juergen Gross <jgross@suse.com>
Release-acked-by: Ian Jackson <iwj@xenproject.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/helpers/init-xenstore-domain.c

@@ -132,6 +132,13 @@ static int build(xc_interface *xch)
         }
     }
 
+    rv = xc_dom_boot_xen_init(dom, xch, domid);
+    if ( rv )
+    {
+        fprintf(stderr, "xc_dom_boot_xen_init failed\n");
+        goto err;
+    }
+
     dom->container_type = XC_DOM_HVM_CONTAINER;
     rv = xc_dom_parse_image(dom);
     if ( rv )
@@ -214,16 +221,11 @@ static int build(xc_interface *xch)
     else
         snprintf(cmdline, 512, "--event %d --internal-db", rv);
 
+    dom->guest_domid = domid;
     dom->cmdline = xc_dom_strdup(dom, cmdline);
     dom->xenstore_domid = domid;
     dom->console_evtchn = console_evtchn;
 
-    rv = xc_dom_boot_xen_init(dom, xch, domid);
-    if ( rv )
-    {
-        fprintf(stderr, "xc_dom_boot_xen_init failed\n");
-        goto err;
-    }
     rv = xc_dom_mem_init(dom, memory);
     if ( rv )
     {