--- zzzz-none-000/linux-3.10.107/drivers/net/xen-netback/xenbus.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/net/xen-netback/xenbus.c	2021-02-04 17:41:59.000000000 +0000
@@ -15,11 +15,12 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "common.h"
+#include <linux/vmalloc.h>
+#include <linux/rtnetlink.h>
 
 struct backend_info {
 	struct xenbus_device *dev;
@@ -37,13 +38,194 @@
 	const char *hotplug_script;
 };
 
-static int connect_rings(struct backend_info *);
-static void connect(struct backend_info *);
-static void backend_create_xenvif(struct backend_info *be);
+static int connect_rings(struct backend_info *be, struct xenvif_queue *queue);
+static void connect(struct backend_info *be);
+static int read_xenbus_vif_flags(struct backend_info *be);
+static int backend_create_xenvif(struct backend_info *be);
 static void unregister_hotplug_status_watch(struct backend_info *be);
+static void xen_unregister_watchers(struct xenvif *vif);
 static void set_backend_state(struct backend_info *be,
 			      enum xenbus_state state);
 
+#ifdef CONFIG_DEBUG_FS
+struct dentry *xen_netback_dbg_root = NULL;
+
+static int xenvif_read_io_ring(struct seq_file *m, void *v)
+{
+	struct xenvif_queue *queue = m->private;
+	struct xen_netif_tx_back_ring *tx_ring = &queue->tx;
+	struct xen_netif_rx_back_ring *rx_ring = &queue->rx;
+	struct netdev_queue *dev_queue;
+
+	if (tx_ring->sring) {
+		struct xen_netif_tx_sring *sring = tx_ring->sring;
+
+		seq_printf(m, "Queue %d\nTX: nr_ents %u\n", queue->id,
+			   tx_ring->nr_ents);
+		seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
+			   sring->req_prod,
+			   sring->req_prod - sring->rsp_prod,
+			   tx_ring->req_cons,
+			   tx_ring->req_cons - sring->rsp_prod,
+			   sring->req_event,
+			   sring->req_event - sring->rsp_prod);
+		seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n",
+			   sring->rsp_prod,
+			   tx_ring->rsp_prod_pvt,
+			   tx_ring->rsp_prod_pvt - sring->rsp_prod,
+			   sring->rsp_event,
+			   sring->rsp_event - sring->rsp_prod);
+		seq_printf(m, "pending prod %u pending cons %u nr_pending_reqs %u\n",
+			   queue->pending_prod,
+			   queue->pending_cons,
+			   nr_pending_reqs(queue));
+		seq_printf(m, "dealloc prod %u dealloc cons %u dealloc_queue %u\n\n",
+			   queue->dealloc_prod,
+			   queue->dealloc_cons,
+			   queue->dealloc_prod - queue->dealloc_cons);
+	}
+
+	if (rx_ring->sring) {
+		struct xen_netif_rx_sring *sring = rx_ring->sring;
+
+		seq_printf(m, "RX: nr_ents %u\n", rx_ring->nr_ents);
+		seq_printf(m, "req prod %u (%d) cons %u (%d) event %u (%d)\n",
+			   sring->req_prod,
+			   sring->req_prod - sring->rsp_prod,
+			   rx_ring->req_cons,
+			   rx_ring->req_cons - sring->rsp_prod,
+			   sring->req_event,
+			   sring->req_event - sring->rsp_prod);
+		seq_printf(m, "rsp prod %u (base) pvt %u (%d) event %u (%d)\n\n",
+			   sring->rsp_prod,
+			   rx_ring->rsp_prod_pvt,
+			   rx_ring->rsp_prod_pvt - sring->rsp_prod,
+			   sring->rsp_event,
+			   sring->rsp_event - sring->rsp_prod);
+	}
+
+	seq_printf(m, "NAPI state: %lx NAPI weight: %d TX queue len %u\n"
+		   "Credit timer_pending: %d, credit: %lu, usec: %lu\n"
+		   "remaining: %lu, expires: %lu, now: %lu\n",
+		   queue->napi.state, queue->napi.weight,
+		   skb_queue_len(&queue->tx_queue),
+		   timer_pending(&queue->credit_timeout),
+		   queue->credit_bytes,
+		   queue->credit_usec,
+		   queue->remaining_credit,
+		   queue->credit_timeout.expires,
+		   jiffies);
+
+	dev_queue = netdev_get_tx_queue(queue->vif->dev, queue->id);
+
+	seq_printf(m, "\nRx internal queue: len %u max %u pkts %u %s\n",
+		   queue->rx_queue_len, queue->rx_queue_max,
+		   skb_queue_len(&queue->rx_queue),
+		   netif_tx_queue_stopped(dev_queue) ? "stopped" : "running");
+
+	return 0;
+}
+
+#define XENVIF_KICK_STR "kick"
+#define BUFFER_SIZE     32
+
+static ssize_t
+xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
+		     loff_t *ppos)
+{
+	struct xenvif_queue *queue =
+		((struct seq_file *)filp->private_data)->private;
+	int len;
+	char write[BUFFER_SIZE];
+
+	/* don't allow partial writes and check the length */
+	if (*ppos != 0)
+		return 0;
+	if (count >= sizeof(write))
+		return -ENOSPC;
+
+	len = simple_write_to_buffer(write,
+				     sizeof(write) - 1,
+				     ppos,
+				     buf,
+				     count);
+	if (len < 0)
+		return len;
+
+	write[len] = '\0';
+
+	if (!strncmp(write, XENVIF_KICK_STR, sizeof(XENVIF_KICK_STR) - 1))
+		xenvif_interrupt(0, (void *)queue);
+	else {
+		pr_warn("Unknown command to io_ring_q%d. Available: kick\n",
+			queue->id);
+		count = -EINVAL;
+	}
+	return count;
+}
+
+static int xenvif_dump_open(struct inode *inode, struct file *filp)
+{
+	int ret;
+	void *queue = NULL;
+
+	if (inode->i_private)
+		queue = inode->i_private;
+	ret = single_open(filp, xenvif_read_io_ring, queue);
+	filp->f_mode |= FMODE_PWRITE;
+	return ret;
+}
+
+static const struct file_operations xenvif_dbg_io_ring_ops_fops = {
+	.owner = THIS_MODULE,
+	.open = xenvif_dump_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = xenvif_write_io_ring,
+};
+
+static void xenvif_debugfs_addif(struct xenvif *vif)
+{
+	struct dentry *pfile;
+	int i;
+
+	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
+		return;
+
+	vif->xenvif_dbg_root = debugfs_create_dir(vif->dev->name,
+						  xen_netback_dbg_root);
+	if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root)) {
+		for (i = 0; i < vif->num_queues; ++i) {
+			char filename[sizeof("io_ring_q") + 4];
+
+			snprintf(filename, sizeof(filename), "io_ring_q%d", i);
+			pfile = debugfs_create_file(filename,
+						    S_IRUSR | S_IWUSR,
+						    vif->xenvif_dbg_root,
+						    &vif->queues[i],
+						    &xenvif_dbg_io_ring_ops_fops);
+			if (IS_ERR_OR_NULL(pfile))
+				pr_warn("Creation of io_ring file returned %ld!\n",
+					PTR_ERR(pfile));
+		}
+	} else
+		netdev_warn(vif->dev,
+			    "Creation of vif debugfs dir returned %ld!\n",
+			    PTR_ERR(vif->xenvif_dbg_root));
+}
+
+static void xenvif_debugfs_delif(struct xenvif *vif)
+{
+	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
+		return;
+
+	if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root))
+		debugfs_remove_recursive(vif->xenvif_dbg_root);
+	vif->xenvif_dbg_root = NULL;
+}
+#endif /* CONFIG_DEBUG_FS */
+
 static int netback_remove(struct xenbus_device *dev)
 {
 	struct backend_info *be = dev_get_drvdata(&dev->dev);
@@ -53,6 +235,7 @@
 	unregister_hotplug_status_watch(be);
 	if (be->vif) {
 		kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
+		xen_unregister_watchers(be->vif);
 		xenbus_rm(XBT_NIL, dev->nodename, "hotplug-status");
 		xenvif_free(be->vif);
 		be->vif = NULL;
@@ -109,6 +292,22 @@
 			goto abort_transaction;
 		}
 
+		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
+				    "%d", sg);
+		if (err) {
+			message = "writing feature-gso-tcpv6";
+			goto abort_transaction;
+		}
+
+		/* We support partial checksum setup for IPv6 packets */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-ipv6-csum-offload",
+				    "%d", 1);
+		if (err) {
+			message = "writing feature-ipv6-csum-offload";
+			goto abort_transaction;
+		}
+
 		/* We support rx-copy path. */
 		err = xenbus_printf(xbt, dev->nodename,
 				    "feature-rx-copy", "%d", 1);
@@ -128,6 +327,14 @@
 			goto abort_transaction;
 		}
 
+		/* We support multicast-control. */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-multicast-control", "%d", 1);
+		if (err) {
+			message = "writing feature-multicast-control";
+			goto abort_transaction;
+		}
+
 		err = xenbus_transaction_end(xbt, 0);
 	} while (err == -EAGAIN);
 
@@ -136,6 +343,22 @@
 		goto fail;
 	}
 
+	/*
+	 * Split event channels support, this is optional so it is not
+	 * put inside the above loop.
+	 */
+	err = xenbus_printf(XBT_NIL, dev->nodename,
+			    "feature-split-event-channels",
+			    "%u", separate_tx_rx_irq);
+	if (err)
+		pr_debug("Error writing feature-split-event-channels\n");
+
+	/* Multi-queue support: This is an optional feature. */
+	err = xenbus_printf(XBT_NIL, dev->nodename,
+			    "multi-queue-max-queues", "%u", xenvif_max_queues);
+	if (err)
+		pr_debug("Error writing multi-queue-max-queues\n");
+
 	script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
 	if (IS_ERR(script)) {
 		err = PTR_ERR(script);
@@ -152,7 +375,9 @@
 	be->state = XenbusStateInitWait;
 
 	/* This kicks hotplug scripts, so do it immediately. */
-	backend_create_xenvif(be);
+	err = backend_create_xenvif(be);
+	if (err)
+		goto fail;
 
 	return 0;
 
@@ -160,7 +385,7 @@
 	xenbus_transaction_end(xbt, 1);
 	xenbus_dev_fatal(dev, err, "%s", message);
 fail:
-	pr_debug("failed");
+	pr_debug("failed\n");
 	netback_remove(dev);
 	return err;
 }
@@ -189,36 +414,43 @@
 }
 
 
-static void backend_create_xenvif(struct backend_info *be)
+static int backend_create_xenvif(struct backend_info *be)
 {
 	int err;
 	long handle;
 	struct xenbus_device *dev = be->dev;
+	struct xenvif *vif;
 
 	if (be->vif != NULL)
-		return;
+		return 0;
 
 	err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
 	if (err != 1) {
 		xenbus_dev_fatal(dev, err, "reading handle");
-		return;
+		return (err < 0) ? err : -EINVAL;
 	}
 
-	be->vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
-	if (IS_ERR(be->vif)) {
-		err = PTR_ERR(be->vif);
-		be->vif = NULL;
+	vif = xenvif_alloc(&dev->dev, dev->otherend_id, handle);
+	if (IS_ERR(vif)) {
+		err = PTR_ERR(vif);
 		xenbus_dev_fatal(dev, err, "creating interface");
-		return;
+		return err;
 	}
+	be->vif = vif;
 
 	kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
+	return 0;
 }
 
 static void backend_disconnect(struct backend_info *be)
 {
-	if (be->vif)
+	if (be->vif) {
+		xen_unregister_watchers(be->vif);
+#ifdef CONFIG_DEBUG_FS
+		xenvif_debugfs_delif(be->vif);
+#endif /* CONFIG_DEBUG_FS */
 		xenvif_disconnect(be->vif);
+	}
 }
 
 static void backend_connect(struct backend_info *be)
@@ -429,6 +661,62 @@
 	return 0;
 }
 
+static void xen_net_rate_changed(struct xenbus_watch *watch,
+				const char **vec, unsigned int len)
+{
+	struct xenvif *vif = container_of(watch, struct xenvif, credit_watch);
+	struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
+	unsigned long   credit_bytes;
+	unsigned long   credit_usec;
+	unsigned int queue_index;
+
+	xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+	for (queue_index = 0; queue_index < vif->num_queues; queue_index++) {
+		struct xenvif_queue *queue = &vif->queues[queue_index];
+
+		queue->credit_bytes = credit_bytes;
+		queue->credit_usec = credit_usec;
+		if (!mod_timer_pending(&queue->credit_timeout, jiffies) &&
+			queue->remaining_credit > queue->credit_bytes) {
+			queue->remaining_credit = queue->credit_bytes;
+		}
+	}
+}
+
+static int xen_register_watchers(struct xenbus_device *dev, struct xenvif *vif)
+{
+	int err = 0;
+	char *node;
+	unsigned maxlen = strlen(dev->nodename) + sizeof("/rate");
+
+	if (vif->credit_watch.node)
+		return -EADDRINUSE;
+
+	node = kmalloc(maxlen, GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+	snprintf(node, maxlen, "%s/rate", dev->nodename);
+	vif->credit_watch.node = node;
+	vif->credit_watch.callback = xen_net_rate_changed;
+	err = register_xenbus_watch(&vif->credit_watch);
+	if (err) {
+		pr_err("Failed to set watcher %s\n", vif->credit_watch.node);
+		kfree(node);
+		vif->credit_watch.node = NULL;
+		vif->credit_watch.callback = NULL;
+	}
+	return err;
+}
+
+static void xen_unregister_watchers(struct xenvif *vif)
+{
+	if (vif->credit_watch.node) {
+		unregister_xenbus_watch(&vif->credit_watch);
+		kfree(vif->credit_watch.node);
+		vif->credit_watch.node = NULL;
+	}
+}
+
 static void unregister_hotplug_status_watch(struct backend_info *be)
 {
 	if (be->have_hotplug_status_watch) {
@@ -465,10 +753,26 @@
 {
 	int err;
 	struct xenbus_device *dev = be->dev;
+	unsigned long credit_bytes, credit_usec;
+	unsigned int queue_index;
+	unsigned int requested_num_queues;
+	struct xenvif_queue *queue;
 
-	err = connect_rings(be);
-	if (err)
+	/* Check whether the frontend requested multiple queues
+	 * and read the number requested.
+	 */
+	err = xenbus_scanf(XBT_NIL, dev->otherend,
+			   "multi-queue-num-queues",
+			   "%u", &requested_num_queues);
+	if (err < 0) {
+		requested_num_queues = 1; /* Fall back to single queue */
+	} else if (requested_num_queues > xenvif_max_queues) {
+		/* buggy or malicious guest */
+		xenbus_dev_fatal(dev, err,
+				 "guest requested %u queues, exceeding the maximum of %u.",
+				 requested_num_queues, xenvif_max_queues);
 		return;
+	}
 
 	err = xen_net_read_mac(dev, be->vif->fe_dev_addr);
 	if (err) {
@@ -476,9 +780,71 @@
 		return;
 	}
 
-	xen_net_read_rate(dev, &be->vif->credit_bytes,
-			  &be->vif->credit_usec);
-	be->vif->remaining_credit = be->vif->credit_bytes;
+	xen_net_read_rate(dev, &credit_bytes, &credit_usec);
+	xen_unregister_watchers(be->vif);
+	xen_register_watchers(dev, be->vif);
+	read_xenbus_vif_flags(be);
+
+	/* Use the number of queues requested by the frontend */
+	be->vif->queues = vzalloc(requested_num_queues *
+				  sizeof(struct xenvif_queue));
+	if (!be->vif->queues) {
+		xenbus_dev_fatal(dev, -ENOMEM,
+				 "allocating queues");
+		return;
+	}
+
+	be->vif->num_queues = requested_num_queues;
+	be->vif->stalled_queues = requested_num_queues;
+
+	for (queue_index = 0; queue_index < requested_num_queues; ++queue_index) {
+		queue = &be->vif->queues[queue_index];
+		queue->vif = be->vif;
+		queue->id = queue_index;
+		snprintf(queue->name, sizeof(queue->name), "%s-q%u",
+				be->vif->dev->name, queue->id);
+
+		err = xenvif_init_queue(queue);
+		if (err) {
+			/* xenvif_init_queue() cleans up after itself on
+			 * failure, but we need to clean up any previously
+			 * initialised queues. Set num_queues to i so that
+			 * earlier queues can be destroyed using the regular
+			 * disconnect logic.
+			 */
+			be->vif->num_queues = queue_index;
+			goto err;
+		}
+
+		queue->credit_bytes = credit_bytes;
+		queue->remaining_credit = credit_bytes;
+		queue->credit_usec = credit_usec;
+
+		err = connect_rings(be, queue);
+		if (err) {
+			/* connect_rings() cleans up after itself on failure,
+			 * but we need to clean up after xenvif_init_queue() here,
+			 * and also clean up any previously initialised queues.
+			 */
+			xenvif_deinit_queue(queue);
+			be->vif->num_queues = queue_index;
+			goto err;
+		}
+	}
+
+#ifdef CONFIG_DEBUG_FS
+	xenvif_debugfs_addif(be->vif);
+#endif /* CONFIG_DEBUG_FS */
+
+	/* Initialisation completed, tell core driver the number of
+	 * active queues.
+	 */
+	rtnl_lock();
+	netif_set_real_num_tx_queues(be->vif->dev, requested_num_queues);
+	netif_set_real_num_rx_queues(be->vif->dev, requested_num_queues);
+	rtnl_unlock();
+
+	xenvif_carrier_on(be->vif);
 
 	unregister_hotplug_status_watch(be);
 	err = xenbus_watch_pathfmt(dev, &be->hotplug_status_watch,
@@ -487,30 +853,107 @@
 	if (!err)
 		be->have_hotplug_status_watch = 1;
 
-	netif_wake_queue(be->vif->dev);
+	netif_tx_wake_all_queues(be->vif->dev);
+
+	return;
+
+err:
+	if (be->vif->num_queues > 0)
+		xenvif_disconnect(be->vif); /* Clean up existing queues */
+	vfree(be->vif->queues);
+	be->vif->queues = NULL;
+	be->vif->num_queues = 0;
+	return;
 }
 
 
-static int connect_rings(struct backend_info *be)
+static int connect_rings(struct backend_info *be, struct xenvif_queue *queue)
 {
-	struct xenvif *vif = be->vif;
 	struct xenbus_device *dev = be->dev;
+	unsigned int num_queues = queue->vif->num_queues;
 	unsigned long tx_ring_ref, rx_ring_ref;
-	unsigned int evtchn, rx_copy;
+	unsigned int tx_evtchn, rx_evtchn;
 	int err;
-	int val;
+	char *xspath;
+	size_t xspathsize;
+	const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
+
+	/* If the frontend requested 1 queue, or we have fallen back
+	 * to single queue due to lack of frontend support for multi-
+	 * queue, expect the remaining XenStore keys in the toplevel
+	 * directory. Otherwise, expect them in a subdirectory called
+	 * queue-N.
+	 */
+	if (num_queues == 1) {
+		xspath = kzalloc(strlen(dev->otherend) + 1, GFP_KERNEL);
+		if (!xspath) {
+			xenbus_dev_fatal(dev, -ENOMEM,
+					 "reading ring references");
+			return -ENOMEM;
+		}
+		strcpy(xspath, dev->otherend);
+	} else {
+		xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
+		xspath = kzalloc(xspathsize, GFP_KERNEL);
+		if (!xspath) {
+			xenbus_dev_fatal(dev, -ENOMEM,
+					 "reading ring references");
+			return -ENOMEM;
+		}
+		snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend,
+			 queue->id);
+	}
 
-	err = xenbus_gather(XBT_NIL, dev->otherend,
+	err = xenbus_gather(XBT_NIL, xspath,
 			    "tx-ring-ref", "%lu", &tx_ring_ref,
-			    "rx-ring-ref", "%lu", &rx_ring_ref,
-			    "event-channel", "%u", &evtchn, NULL);
+			    "rx-ring-ref", "%lu", &rx_ring_ref, NULL);
 	if (err) {
 		xenbus_dev_fatal(dev, err,
-				 "reading %s/ring-ref and event-channel",
-				 dev->otherend);
-		return err;
+				 "reading %s/ring-ref",
+				 xspath);
+		goto err;
+	}
+
+	/* Try split event channels first, then single event channel. */
+	err = xenbus_gather(XBT_NIL, xspath,
+			    "event-channel-tx", "%u", &tx_evtchn,
+			    "event-channel-rx", "%u", &rx_evtchn, NULL);
+	if (err < 0) {
+		err = xenbus_scanf(XBT_NIL, xspath,
+				   "event-channel", "%u", &tx_evtchn);
+		if (err < 0) {
+			xenbus_dev_fatal(dev, err,
+					 "reading %s/event-channel(-tx/rx)",
+					 xspath);
+			goto err;
+		}
+		rx_evtchn = tx_evtchn;
 	}
 
+	/* Map the shared frame, irq etc. */
+	err = xenvif_connect(queue, tx_ring_ref, rx_ring_ref,
+			     tx_evtchn, rx_evtchn);
+	if (err) {
+		xenbus_dev_fatal(dev, err,
+				 "mapping shared-frames %lu/%lu port tx %u rx %u",
+				 tx_ring_ref, rx_ring_ref,
+				 tx_evtchn, rx_evtchn);
+		goto err;
+	}
+
+	err = 0;
+err: /* Regular return falls through with err == 0 */
+	kfree(xspath);
+	return err;
+}
+
+static int read_xenbus_vif_flags(struct backend_info *be)
+{
+	struct xenvif *vif = be->vif;
+	struct xenbus_device *dev = be->dev;
+	unsigned int rx_copy;
+	int err, val;
+
 	err = xenbus_scanf(XBT_NIL, dev->otherend, "request-rx-copy", "%u",
 			   &rx_copy);
 	if (err == -ENOENT) {
@@ -525,15 +968,16 @@
 	if (!rx_copy)
 		return -EOPNOTSUPP;
 
-	if (vif->dev->tx_queue_len != 0) {
-		if (xenbus_scanf(XBT_NIL, dev->otherend,
-				 "feature-rx-notify", "%d", &val) < 0)
-			val = 0;
-		if (val)
-			vif->can_queue = 1;
-		else
-			/* Must be non-zero for pfifo_fast to work. */
-			vif->dev->tx_queue_len = 1;
+	if (xenbus_scanf(XBT_NIL, dev->otherend,
+			 "feature-rx-notify", "%d", &val) < 0)
+		val = 0;
+	if (!val) {
+		/* - Reduce drain timeout to poll more frequently for
+		 *   Rx requests.
+		 * - Disable Rx stall detection.
+		 */
+		be->vif->drain_timeout = msecs_to_jiffies(30);
+		be->vif->stall_timeout = 0;
 	}
 
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
@@ -541,50 +985,78 @@
 		val = 0;
 	vif->can_sg = !!val;
 
+	vif->gso_mask = 0;
+	vif->gso_prefix_mask = 0;
+
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->gso = !!val;
+	if (val)
+		vif->gso_mask |= GSO_BIT(TCPV4);
 
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->gso_prefix = !!val;
+	if (val)
+		vif->gso_prefix_mask |= GSO_BIT(TCPV4);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->csum = !val;
+	if (val)
+		vif->gso_mask |= GSO_BIT(TCPV6);
 
-	/* Map the shared frame, irq etc. */
-	err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref, evtchn);
-	if (err) {
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
+			 "%d", &val) < 0)
+		val = 0;
+	if (val)
+		vif->gso_prefix_mask |= GSO_BIT(TCPV6);
+
+	if (vif->gso_mask & vif->gso_prefix_mask) {
 		xenbus_dev_fatal(dev, err,
-				 "mapping shared-frames %lu/%lu port %u",
-				 tx_ring_ref, rx_ring_ref, evtchn);
-		return err;
+				 "%s: gso and gso prefix flags are not "
+				 "mutually exclusive",
+				 dev->otherend);
+		return -EOPNOTSUPP;
 	}
-	return 0;
-}
 
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
+			 "%d", &val) < 0)
+		val = 0;
+	vif->ip_csum = !val;
+
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
+			 "%d", &val) < 0)
+		val = 0;
+	vif->ipv6_csum = !!val;
 
-/* ** Driver Registration ** */
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "request-multicast-control",
+			 "%d", &val) < 0)
+		val = 0;
+	vif->multicast_control = !!val;
 
+	return 0;
+}
 
 static const struct xenbus_device_id netback_ids[] = {
 	{ "vif" },
 	{ "" }
 };
 
-
-static DEFINE_XENBUS_DRIVER(netback, ,
+static struct xenbus_driver netback_driver = {
+	.ids = netback_ids,
 	.probe = netback_probe,
 	.remove = netback_remove,
 	.uevent = netback_uevent,
 	.otherend_changed = frontend_changed,
-);
+};
 
 int xenvif_xenbus_init(void)
 {
 	return xenbus_register_backend(&netback_driver);
 }
+
+void xenvif_xenbus_fini(void)
+{
+	return xenbus_unregister_driver(&netback_driver);
+}