xen/xenbus: Update xenbus event channel on resume

After a resume the hypervisor/tools may change xenbus event
channel number. We should re-query it.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 564b31584860..5390a674b5e3 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -57,6 +57,7 @@
 #include <xen/xen.h>
 #include <xen/xenbus.h>
 #include <xen/events.h>
+#include <xen/xen-ops.h>
 #include <xen/page.h>
 
 #include <xen/hvm.h>
@@ -735,6 +736,30 @@ static int __init xenstored_local_init(void)
         return err;
 }
 
+static int xenbus_resume_cb(struct notifier_block *nb,
+                            unsigned long action, void *data)
+{
+        int err = 0;
+
+        if (xen_hvm_domain()) {
+                uint64_t v;
+
+                err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
+                if (!err && v)
+                        xen_store_evtchn = v;
+                else
+                        pr_warn("Cannot update xenstore event channel: %d\n",
+                                err);
+        } else
+                xen_store_evtchn = xen_start_info->store_evtchn;
+
+        return err;
+}
+
+static struct notifier_block xenbus_resume_nb = {
+        .notifier_call = xenbus_resume_cb,
+};
+
 static int __init xenbus_init(void)
 {
         int err = 0;
@@ -793,6 +818,10 @@ static int __init xenbus_init(void)
                 goto out_error;
         }
 
+        if ((xen_store_domain_type != XS_LOCAL) &&
+            (xen_store_domain_type != XS_UNKNOWN))
+                xen_resume_notifier_register(&xenbus_resume_nb);
+
 #ifdef CONFIG_XEN_COMPAT_XENFS
         /*
          * Create xenfs mountpoint in /proc for compatibility with