[Xen-devel] [PATCH 2/4] xen/xenbus: Update xenbus event channel on resume

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

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

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 drivers/xen/xenbus/xenbus_probe.c |   28 ++++++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c 
b/drivers/xen/xenbus/xenbus_probe.c
index 564b315..31737a4 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 +818,9 @@ static int __init xenbus_init(void)
                goto out_error;
        }
 
+       if (!xen_initial_domain())
+               xen_resume_notifier_register(&xenbus_resume_nb);
+
 #ifdef CONFIG_XEN_COMPAT_XENFS
        /*
         * Create xenfs mountpoint in /proc for compatibility with
-- 
1.7.1


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