linux-kernel - [PATCH 2/4] xen/xenbus: Update xenbus event channel on resume

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Message-Id: <1430236333-11905-3-git-send-email-boris.ostrovsky@oracle.com>
Date:	Tue, 28 Apr 2015 11:52:11 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	david.vrabel@...rix.com, konrad.wilk@...cle.com
Cc:	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
	annie.li@...cle.com, boris.ostrovsky@...cle.com
Subject: [PATCH 2/4] 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@...cle.com>
---
 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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