hv_netvsc: Add the support of hibernation

The existing netvsc_detach() and netvsc_attach() APIs make it easy to
implement the suspend/resume callbacks.
Signed-off-by: NDexuan Cui <decui@microsoft.com>
Reviewed-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

drivers/net/hyperv/hyperv_net.h

@@ -952,6 +952,9 @@ struct net_device_context {
 	u32 vf_alloc;
 	/* Serial number of the VF to team with */
 	u32 vf_serial;
+
+	/* Used to temporarily save the config info across hibernation */
+	struct netvsc_device_info *saved_netvsc_dev_info;
 };
 
 /* Per channel data */

drivers/net/hyperv/netvsc_drv.c

@@ -2421,6 +2421,61 @@ static int netvsc_remove(struct hv_device *dev)
 	return 0;
 }
 
+static int netvsc_suspend(struct hv_device *dev)
+{
+	struct net_device_context *ndev_ctx;
+	struct net_device *vf_netdev, *net;
+	struct netvsc_device *nvdev;
+	int ret;
+
+	net = hv_get_drvdata(dev);
+
+	ndev_ctx = netdev_priv(net);
+	cancel_delayed_work_sync(&ndev_ctx->dwork);
+
+	rtnl_lock();
+
+	nvdev = rtnl_dereference(ndev_ctx->nvdev);
+	if (nvdev == NULL) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
+	if (vf_netdev)
+		netvsc_unregister_vf(vf_netdev);
+
+	/* Save the current config info */
+	ndev_ctx->saved_netvsc_dev_info = netvsc_devinfo_get(nvdev);
+
+	ret = netvsc_detach(net, nvdev);
+out:
+	rtnl_unlock();
+
+	return ret;
+}
+
+static int netvsc_resume(struct hv_device *dev)
+{
+	struct net_device *net = hv_get_drvdata(dev);
+	struct net_device_context *net_device_ctx;
+	struct netvsc_device_info *device_info;
+	int ret;
+
+	rtnl_lock();
+
+	net_device_ctx = netdev_priv(net);
+	device_info = net_device_ctx->saved_netvsc_dev_info;
+
+	ret = netvsc_attach(net, device_info);
+
+	rtnl_unlock();
+
+	kfree(device_info);
+	net_device_ctx->saved_netvsc_dev_info = NULL;
+
+	return ret;
+}
 static const struct hv_vmbus_device_id id_table[] = {
 	/* Network guid */
 	{ HV_NIC_GUID, },
@@ -2435,6 +2490,8 @@ static struct  hv_driver netvsc_drv = {
 	.id_table = id_table,
 	.probe = netvsc_probe,
 	.remove = netvsc_remove,
+	.suspend = netvsc_suspend,
+	.resume = netvsc_resume,
 	.driver = {
 		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 	},