xen: Initialize xenbus for dom0.

Do initial xenbus/xenstore setup in dom0.  In dom0 we need to actually
allocate the xenstore resources, rather than being given them from
outside.

[ Impact: initialize Xenbus ]

Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 28 insertions, 1 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index d409495876f1..d242610597c0 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -801,6 +801,7 @@ device_initcall(xenbus_probe_initcall);
 static int __init xenbus_init(void)
 {
         int err = 0;
+        unsigned long page = 0;
 
         DPRINTK("");
 
@@ -821,7 +822,31 @@ static int __init xenbus_init(void)
          * Domain0 doesn't have a store_evtchn or store_mfn yet.
          */
         if (xen_initial_domain()) {
-                /* dom0 not yet supported */
+                struct evtchn_alloc_unbound alloc_unbound;
+
+                /* Allocate Xenstore page */
+                page = get_zeroed_page(GFP_KERNEL);
+                if (!page)
+                        goto out_error;
+
+                xen_store_mfn = xen_start_info->store_mfn =
+                        pfn_to_mfn(virt_to_phys((void *)page) >>
+                                   PAGE_SHIFT);
+
+                /* Next allocate a local port which xenstored can bind to */
+                alloc_unbound.dom        = DOMID_SELF;
+                alloc_unbound.remote_dom = 0;
+
+                err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+                                                  &alloc_unbound);
+                if (err == -ENOSYS)
+                        goto out_error;
+
+                BUG_ON(err);
+                xen_store_evtchn = xen_start_info->store_evtchn =
+                        alloc_unbound.port;
+
+                xen_store_interface = mfn_to_virt(xen_store_mfn);
         } else {
                 if (xen_hvm_domain()) {
                         uint64_t v = 0;
@@ -867,6 +892,8 @@ static int __init xenbus_init(void)
         bus_unregister(&xenbus_frontend.bus);
 
   out_error:
+        if (page != 0)
+                free_page(page);
         return err;
 }