Merge branch 'xen-netback-rx-refactor'

Paul Durrant says:

====================
xen-netback: guest rx side refactor

This series refactors the guest rx side of xen-netback:

- The code is moved into its own source module.

- The prefix variant of GSO handling is retired (since it is no longer
  in common use, and alternatives exist).

- The code is then simplified and modifications made to improve
  performance.

v2:
- Rebased onto refreshed net-next
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 644 insertions, 793 deletions

diff --git a/drivers/net/xen-netback/Makefile b/drivers/net/xen-netback/Makefile
index 11e02be9db1a..d49798a46b51 100644
--- a/drivers/net/xen-netback/Makefile
+++ b/drivers/net/xen-netback/Makefile
@@ -1,3 +1,3 @@
 obj-$(CONFIG_XEN_NETDEV_BACKEND) := xen-netback.o
 
-xen-netback-y := netback.o xenbus.o interface.o hash.o
+xen-netback-y := netback.o xenbus.o interface.o hash.o rx.o
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index b38fb2cf3364..cf68149cbb55 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -91,13 +91,6 @@ struct xenvif_rx_meta {
  */
 #define MAX_XEN_SKB_FRAGS (65536 / XEN_PAGE_SIZE + 1)
 
-/* It's possible for an skb to have a maximal number of frags
- * but still be less than MAX_BUFFER_OFFSET in size. Thus the
- * worst-case number of copy operations is MAX_XEN_SKB_FRAGS per
- * ring slot.
- */
-#define MAX_GRANT_COPY_OPS (MAX_XEN_SKB_FRAGS * XEN_NETIF_RX_RING_SIZE)
-
 #define NETBACK_INVALID_HANDLE -1
 
 /* To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
@@ -133,6 +126,15 @@ struct xenvif_stats {
 	unsigned long tx_frag_overflow;
 };
 
+#define COPY_BATCH_SIZE 64
+
+struct xenvif_copy_state {
+	struct gnttab_copy op[COPY_BATCH_SIZE];
+	RING_IDX idx[COPY_BATCH_SIZE];
+	unsigned int num;
+	struct sk_buff_head *completed;
+};
+
 struct xenvif_queue { /* Per-queue data for xenvif */
 	unsigned int id; /* Queue ID, 0-based */
 	char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
@@ -189,12 +191,7 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	unsigned long last_rx_time;
 	bool stalled;
 
-	struct gnttab_copy grant_copy_op[MAX_GRANT_COPY_OPS];
-
-	/* We create one meta structure per ring request we consume, so
-	 * the maximum number is the same as the ring size.
-	 */
-	struct xenvif_rx_meta meta[XEN_NETIF_RX_RING_SIZE];
+	struct xenvif_copy_state rx_copy;
 
 	/* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
 	unsigned long   credit_bytes;
@@ -260,7 +257,6 @@ struct xenvif {
 
 	/* Frontend feature information. */
 	int gso_mask;
-	int gso_prefix_mask;
 
 	u8 can_sg:1;
 	u8 ip_csum:1;
@@ -359,6 +355,7 @@ int xenvif_dealloc_kthread(void *data);
 
 irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);
 
+void xenvif_rx_action(struct xenvif_queue *queue);
 void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
 
 void xenvif_carrier_on(struct xenvif *vif);
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index fb50c6d5f6c3..4af532a67d95 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -319,9 +319,9 @@ static netdev_features_t xenvif_fix_features(struct net_device *dev,
 
 	if (!vif->can_sg)
 		features &= ~NETIF_F_SG;
-	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
+	if (~(vif->gso_mask) & GSO_BIT(TCPV4))
 		features &= ~NETIF_F_TSO;
-	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
+	if (~(vif->gso_mask) & GSO_BIT(TCPV6))
 		features &= ~NETIF_F_TSO6;
 	if (!vif->ip_csum)
 		features &= ~NETIF_F_IP_CSUM;
@@ -467,7 +467,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 	dev->netdev_ops	= &xenvif_netdev_ops;
 	dev->hw_features = NETIF_F_SG |
 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
-		NETIF_F_TSO | NETIF_F_TSO6;
+		NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_FRAGLIST;
 	dev->features = dev->hw_features | NETIF_F_RXCSUM;
 	dev->ethtool_ops = &xenvif_ethtool_ops;
 
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 3d0c989384b5..47b481095d77 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -106,13 +106,6 @@ static void push_tx_responses(struct xenvif_queue *queue);
 
 static inline int tx_work_todo(struct xenvif_queue *queue);
 
-static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
-					     u16      id,
-					     s8       st,
-					     u16      offset,
-					     u16      size,
-					     u16      flags);
-
 static inline unsigned long idx_to_pfn(struct xenvif_queue *queue,
 				       u16 idx)
 {
@@ -155,571 +148,11 @@ static inline pending_ring_idx_t pending_index(unsigned i)
 	return i & (MAX_PENDING_REQS-1);
 }
 
-static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
-{
-	RING_IDX prod, cons;
-	struct sk_buff *skb;
-	int needed;
-
-	skb = skb_peek(&queue->rx_queue);
-	if (!skb)
-		return false;
-
-	needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
-	if (skb_is_gso(skb))
-		needed++;
-	if (skb->sw_hash)
-		needed++;
-
-	do {
-		prod = queue->rx.sring->req_prod;
-		cons = queue->rx.req_cons;
-
-		if (prod - cons >= needed)
-			return true;
-
-		queue->rx.sring->req_event = prod + 1;
-
-		/* Make sure event is visible before we check prod
-		 * again.
-		 */
-		mb();
-	} while (queue->rx.sring->req_prod != prod);
-
-	return false;
-}
-
-void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&queue->rx_queue.lock, flags);
-
-	__skb_queue_tail(&queue->rx_queue, skb);
-
-	queue->rx_queue_len += skb->len;
-	if (queue->rx_queue_len > queue->rx_queue_max)
-		netif_tx_stop_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
-
-	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
-}
-
-static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
-{
-	struct sk_buff *skb;
-
-	spin_lock_irq(&queue->rx_queue.lock);
-
-	skb = __skb_dequeue(&queue->rx_queue);
-	if (skb)
-		queue->rx_queue_len -= skb->len;
-
-	spin_unlock_irq(&queue->rx_queue.lock);
-
-	return skb;
-}
-
-static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue)
-{
-	spin_lock_irq(&queue->rx_queue.lock);
-
-	if (queue->rx_queue_len < queue->rx_queue_max)
-		netif_tx_wake_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
-
-	spin_unlock_irq(&queue->rx_queue.lock);
-}
-
-
-static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
-{
-	struct sk_buff *skb;
-	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
-		kfree_skb(skb);
-}
-
-static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
-{
-	struct sk_buff *skb;
-
-	for(;;) {
-		skb = skb_peek(&queue->rx_queue);
-		if (!skb)
-			break;
-		if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
-			break;
-		xenvif_rx_dequeue(queue);
-		kfree_skb(skb);
-	}
-}
-
-struct netrx_pending_operations {
-	unsigned copy_prod, copy_cons;
-	unsigned meta_prod, meta_cons;
-	struct gnttab_copy *copy;
-	struct xenvif_rx_meta *meta;
-	int copy_off;
-	grant_ref_t copy_gref;
-};
-
-static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif_queue *queue,
-						 struct netrx_pending_operations *npo)
-{
-	struct xenvif_rx_meta *meta;
-	struct xen_netif_rx_request req;
-
-	RING_COPY_REQUEST(&queue->rx, queue->rx.req_cons++, &req);
-
-	meta = npo->meta + npo->meta_prod++;
-	meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
-	meta->gso_size = 0;
-	meta->size = 0;
-	meta->id = req.id;
-
-	npo->copy_off = 0;
-	npo->copy_gref = req.gref;
-
-	return meta;
-}
-
-struct gop_frag_copy {
-	struct xenvif_queue *queue;
-	struct netrx_pending_operations *npo;
-	struct xenvif_rx_meta *meta;
-	int head;
-	int gso_type;
-	int protocol;
-	int hash_present;
-
-	struct page *page;
-};
-
-static void xenvif_setup_copy_gop(unsigned long gfn,
-				  unsigned int offset,
-				  unsigned int *len,
-				  struct gop_frag_copy *info)
-{
-	struct gnttab_copy *copy_gop;
-	struct xen_page_foreign *foreign;
-	/* Convenient aliases */
-	struct xenvif_queue *queue = info->queue;
-	struct netrx_pending_operations *npo = info->npo;
-	struct page *page = info->page;
-
-	BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
-
-	if (npo->copy_off == MAX_BUFFER_OFFSET)
-		info->meta = get_next_rx_buffer(queue, npo);
-
-	if (npo->copy_off + *len > MAX_BUFFER_OFFSET)
-		*len = MAX_BUFFER_OFFSET - npo->copy_off;
-
-	copy_gop = npo->copy + npo->copy_prod++;
-	copy_gop->flags = GNTCOPY_dest_gref;
-	copy_gop->len = *len;
-
-	foreign = xen_page_foreign(page);
-	if (foreign) {
-		copy_gop->source.domid = foreign->domid;
-		copy_gop->source.u.ref = foreign->gref;
-		copy_gop->flags |= GNTCOPY_source_gref;
-	} else {
-		copy_gop->source.domid = DOMID_SELF;
-		copy_gop->source.u.gmfn = gfn;
-	}
-	copy_gop->source.offset = offset;
-
-	copy_gop->dest.domid = queue->vif->domid;
-	copy_gop->dest.offset = npo->copy_off;
-	copy_gop->dest.u.ref = npo->copy_gref;
-
-	npo->copy_off += *len;
-	info->meta->size += *len;
-
-	if (!info->head)
-		return;
-
-	/* Leave a gap for the GSO descriptor. */
-	if ((1 << info->gso_type) & queue->vif->gso_mask)
-		queue->rx.req_cons++;
-
-	/* Leave a gap for the hash extra segment. */
-	if (info->hash_present)
-		queue->rx.req_cons++;
-
-	info->head = 0; /* There must be something in this buffer now */
-}
-
-static void xenvif_gop_frag_copy_grant(unsigned long gfn,
-				       unsigned offset,
-				       unsigned int len,
-				       void *data)
-{
-	unsigned int bytes;
-
-	while (len) {
-		bytes = len;
-		xenvif_setup_copy_gop(gfn, offset, &bytes, data);
-		offset += bytes;
-		len -= bytes;
-	}
-}
-
-/*
- * Set up the grant operations for this fragment. If it's a flipping
- * interface, we also set up the unmap request from here.
- */
-static void xenvif_gop_frag_copy(struct xenvif_queue *queue, struct sk_buff *skb,
-				 struct netrx_pending_operations *npo,
-				 struct page *page, unsigned long size,
-				 unsigned long offset, int *head)
-{
-	struct gop_frag_copy info = {
-		.queue = queue,
-		.npo = npo,
-		.head = *head,
-		.gso_type = XEN_NETIF_GSO_TYPE_NONE,
-		/* xenvif_set_skb_hash() will have either set a s/w
-		 * hash or cleared the hash depending on
-		 * whether the the frontend wants a hash for this skb.
-		 */
-		.hash_present = skb->sw_hash,
-	};
-	unsigned long bytes;
-
-	if (skb_is_gso(skb)) {
-		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-			info.gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-			info.gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-	}
-
-	/* Data must not cross a page boundary. */
-	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
-
-	info.meta = npo->meta + npo->meta_prod - 1;
-
-	/* Skip unused frames from start of page */
-	page += offset >> PAGE_SHIFT;
-	offset &= ~PAGE_MASK;
-
-	while (size > 0) {
-		BUG_ON(offset >= PAGE_SIZE);
-
-		bytes = PAGE_SIZE - offset;
-		if (bytes > size)
-			bytes = size;
-
-		info.page = page;
-		gnttab_foreach_grant_in_range(page, offset, bytes,
-					      xenvif_gop_frag_copy_grant,
-					      &info);
-		size -= bytes;
-		offset = 0;
-
-		/* Next page */
-		if (size) {
-			BUG_ON(!PageCompound(page));
-			page++;
-		}
-	}
-
-	*head = info.head;
-}
-
-/*
- * Prepare an SKB to be transmitted to the frontend.
- *
- * This function is responsible for allocating grant operations, meta
- * structures, etc.
- *
- * It returns the number of meta structures consumed. The number of
- * ring slots used is always equal to the number of meta slots used
- * plus the number of GSO descriptors used. Currently, we use either
- * zero GSO descriptors (for non-GSO packets) or one descriptor (for
- * frontend-side LRO).
- */
-static int xenvif_gop_skb(struct sk_buff *skb,
-			  struct netrx_pending_operations *npo,
-			  struct xenvif_queue *queue)
-{
-	struct xenvif *vif = netdev_priv(skb->dev);
-	int nr_frags = skb_shinfo(skb)->nr_frags;
-	int i;
-	struct xen_netif_rx_request req;
-	struct xenvif_rx_meta *meta;
-	unsigned char *data;
-	int head = 1;
-	int old_meta_prod;
-	int gso_type;
-
-	old_meta_prod = npo->meta_prod;
-
-	gso_type = XEN_NETIF_GSO_TYPE_NONE;
-	if (skb_is_gso(skb)) {
-		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-			gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-			gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-	}
-
-	/* Set up a GSO prefix descriptor, if necessary */
-	if ((1 << gso_type) & vif->gso_prefix_mask) {
-		RING_COPY_REQUEST(&queue->rx, queue->rx.req_cons++, &req);
-		meta = npo->meta + npo->meta_prod++;
-		meta->gso_type = gso_type;
-		meta->gso_size = skb_shinfo(skb)->gso_size;
-		meta->size = 0;
-		meta->id = req.id;
-	}
-
-	RING_COPY_REQUEST(&queue->rx, queue->rx.req_cons++, &req);
-	meta = npo->meta + npo->meta_prod++;
-
-	if ((1 << gso_type) & vif->gso_mask) {
-		meta->gso_type = gso_type;
-		meta->gso_size = skb_shinfo(skb)->gso_size;
-	} else {
-		meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
-		meta->gso_size = 0;
-	}
-
-	meta->size = 0;
-	meta->id = req.id;
-	npo->copy_off = 0;
-	npo->copy_gref = req.gref;
-
-	data = skb->data;
-	while (data < skb_tail_pointer(skb)) {
-		unsigned int offset = offset_in_page(data);
-		unsigned int len = PAGE_SIZE - offset;
-
-		if (data + len > skb_tail_pointer(skb))
-			len = skb_tail_pointer(skb) - data;
-
-		xenvif_gop_frag_copy(queue, skb, npo,
-				     virt_to_page(data), len, offset, &head);
-		data += len;
-	}
-
-	for (i = 0; i < nr_frags; i++) {
-		xenvif_gop_frag_copy(queue, skb, npo,
-				     skb_frag_page(&skb_shinfo(skb)->frags[i]),
-				     skb_frag_size(&skb_shinfo(skb)->frags[i]),
-				     skb_shinfo(skb)->frags[i].page_offset,
-				     &head);
-	}
-
-	return npo->meta_prod - old_meta_prod;
-}
-
-/*
- * This is a twin to xenvif_gop_skb.  Assume that xenvif_gop_skb was
- * used to set up the operations on the top of
- * netrx_pending_operations, which have since been done.  Check that
- * they didn't give any errors and advance over them.
- */
-static int xenvif_check_gop(struct xenvif *vif, int nr_meta_slots,
-			    struct netrx_pending_operations *npo)
-{
-	struct gnttab_copy     *copy_op;
-	int status = XEN_NETIF_RSP_OKAY;
-	int i;
-
-	for (i = 0; i < nr_meta_slots; i++) {
-		copy_op = npo->copy + npo->copy_cons++;
-		if (copy_op->status != GNTST_okay) {
-			netdev_dbg(vif->dev,
-				   "Bad status %d from copy to DOM%d.\n",
-				   copy_op->status, vif->domid);
-			status = XEN_NETIF_RSP_ERROR;
-		}
-	}
-
-	return status;
-}
-
-static void xenvif_add_frag_responses(struct xenvif_queue *queue, int status,
-				      struct xenvif_rx_meta *meta,
-				      int nr_meta_slots)
-{
-	int i;
-	unsigned long offset;
-
-	/* No fragments used */
-	if (nr_meta_slots <= 1)
-		return;
-
-	nr_meta_slots--;
-
-	for (i = 0; i < nr_meta_slots; i++) {
-		int flags;
-		if (i == nr_meta_slots - 1)
-			flags = 0;
-		else
-			flags = XEN_NETRXF_more_data;
-
-		offset = 0;
-		make_rx_response(queue, meta[i].id, status, offset,
-				 meta[i].size, flags);
-	}
-}
-
 void xenvif_kick_thread(struct xenvif_queue *queue)
 {
 	wake_up(&queue->wq);
 }
 
-static void xenvif_rx_action(struct xenvif_queue *queue)
-{
-	struct xenvif *vif = queue->vif;
-	s8 status;
-	u16 flags;
-	struct xen_netif_rx_response *resp;
-	struct sk_buff_head rxq;
-	struct sk_buff *skb;
-	LIST_HEAD(notify);
-	int ret;
-	unsigned long offset;
-	bool need_to_notify = false;
-
-	struct netrx_pending_operations npo = {
-		.copy  = queue->grant_copy_op,
-		.meta  = queue->meta,
-	};
-
-	skb_queue_head_init(&rxq);
-
-	while (xenvif_rx_ring_slots_available(queue)
-	       && (skb = xenvif_rx_dequeue(queue)) != NULL) {
-		queue->last_rx_time = jiffies;
-
-		XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue);
-
-		__skb_queue_tail(&rxq, skb);
-	}
-
-	BUG_ON(npo.meta_prod > ARRAY_SIZE(queue->meta));
-
-	if (!npo.copy_prod)
-		goto done;
-
-	BUG_ON(npo.copy_prod > MAX_GRANT_COPY_OPS);
-	gnttab_batch_copy(queue->grant_copy_op, npo.copy_prod);
-
-	while ((skb = __skb_dequeue(&rxq)) != NULL) {
-		struct xen_netif_extra_info *extra = NULL;
-
-		if ((1 << queue->meta[npo.meta_cons].gso_type) &
-		    vif->gso_prefix_mask) {
-			resp = RING_GET_RESPONSE(&queue->rx,
-						 queue->rx.rsp_prod_pvt++);
-
-			resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
-
-			resp->offset = queue->meta[npo.meta_cons].gso_size;
-			resp->id = queue->meta[npo.meta_cons].id;
-			resp->status = XENVIF_RX_CB(skb)->meta_slots_used;
-
-			npo.meta_cons++;
-			XENVIF_RX_CB(skb)->meta_slots_used--;
-		}
-
-
-		queue->stats.tx_bytes += skb->len;
-		queue->stats.tx_packets++;
-
-		status = xenvif_check_gop(vif,
-					  XENVIF_RX_CB(skb)->meta_slots_used,
-					  &npo);
-
-		if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
-			flags = 0;
-		else
-			flags = XEN_NETRXF_more_data;
-
-		if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
-			flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
-		else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
-			/* remote but checksummed. */
-			flags |= XEN_NETRXF_data_validated;
-
-		offset = 0;
-		resp = make_rx_response(queue, queue->meta[npo.meta_cons].id,
-					status, offset,
-					queue->meta[npo.meta_cons].size,
-					flags);
-
-		if ((1 << queue->meta[npo.meta_cons].gso_type) &
-		    vif->gso_mask) {
-			extra = (struct xen_netif_extra_info *)
-				RING_GET_RESPONSE(&queue->rx,
-						  queue->rx.rsp_prod_pvt++);
-
-			resp->flags |= XEN_NETRXF_extra_info;
-
-			extra->u.gso.type = queue->meta[npo.meta_cons].gso_type;
-			extra->u.gso.size = queue->meta[npo.meta_cons].gso_size;
-			extra->u.gso.pad = 0;
-			extra->u.gso.features = 0;
-
-			extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
-			extra->flags = 0;
-		}
-
-		if (skb->sw_hash) {
-			/* Since the skb got here via xenvif_select_queue()
-			 * we know that the hash has been re-calculated
-			 * according to a configuration set by the frontend
-			 * and therefore we know that it is legitimate to
-			 * pass it to the frontend.
-			 */
-			if (resp->flags & XEN_NETRXF_extra_info)
-				extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;
-			else
-				resp->flags |= XEN_NETRXF_extra_info;
-
-			extra = (struct xen_netif_extra_info *)
-				RING_GET_RESPONSE(&queue->rx,
-						  queue->rx.rsp_prod_pvt++);
-
-			extra->u.hash.algorithm =
-				XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;
-
-			if (skb->l4_hash)
-				extra->u.hash.type =
-					skb->protocol == htons(ETH_P_IP) ?
-					_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
-					_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
-			else
-				extra->u.hash.type =
-					skb->protocol == htons(ETH_P_IP) ?
-					_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
-					_XEN_NETIF_CTRL_HASH_TYPE_IPV6;
-
-			*(uint32_t *)extra->u.hash.value =
-				skb_get_hash_raw(skb);
-
-			extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
-			extra->flags = 0;
-		}
-
-		xenvif_add_frag_responses(queue, status,
-					  queue->meta + npo.meta_cons + 1,
-					  XENVIF_RX_CB(skb)->meta_slots_used);
-
-		RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, ret);
-
-		need_to_notify |= !!ret;
-
-		npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
-		dev_kfree_skb(skb);
-	}
-
-done:
-	if (need_to_notify)
-		notify_remote_via_irq(queue->rx_irq);
-}
-
 void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
 {
 	int more_to_do;
@@ -1951,29 +1384,6 @@ static void push_tx_responses(struct xenvif_queue *queue)
 		notify_remote_via_irq(queue->tx_irq);
 }
 
-static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
-					     u16      id,
-					     s8       st,
-					     u16      offset,
-					     u16      size,
-					     u16      flags)
-{
-	RING_IDX i = queue->rx.rsp_prod_pvt;
-	struct xen_netif_rx_response *resp;
-
-	resp = RING_GET_RESPONSE(&queue->rx, i);
-	resp->offset     = offset;
-	resp->flags      = flags;
-	resp->id         = id;
-	resp->status     = (s16)size;
-	if (st < 0)
-		resp->status = (s16)st;
-
-	queue->rx.rsp_prod_pvt = ++i;
-
-	return resp;
-}
-
 void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx)
 {
 	int ret;
@@ -2055,170 +1465,6 @@ err:
 	return err;
 }
 
-static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
-{
-	struct xenvif *vif = queue->vif;
-
-	queue->stalled = true;
-
-	/* At least one queue has stalled? Disable the carrier. */
-	spin_lock(&vif->lock);
-	if (vif->stalled_queues++ == 0) {
-		netdev_info(vif->dev, "Guest Rx stalled");
-		netif_carrier_off(vif->dev);
-	}
-	spin_unlock(&vif->lock);
-}
-
-static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
-{
-	struct xenvif *vif = queue->vif;
-
-	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
-	queue->stalled = false;
-
-	/* All queues are ready? Enable the carrier. */
-	spin_lock(&vif->lock);
-	if (--vif->stalled_queues == 0) {
-		netdev_info(vif->dev, "Guest Rx ready");
-		netif_carrier_on(vif->dev);
-	}
-	spin_unlock(&vif->lock);
-}
-
-static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
-{
-	RING_IDX prod, cons;
-
-	prod = queue->rx.sring->req_prod;
-	cons = queue->rx.req_cons;
-
-	return !queue->stalled && prod - cons < 1
-		&& time_after(jiffies,
-			      queue->last_rx_time + queue->vif->stall_timeout);
-}
-
-static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
-{
-	RING_IDX prod, cons;
-
-	prod = queue->rx.sring->req_prod;
-	cons = queue->rx.req_cons;
-
-	return queue->stalled && prod - cons >= 1;
-}
-
-static bool xenvif_have_rx_work(struct xenvif_queue *queue)
-{
-	return xenvif_rx_ring_slots_available(queue)
-		|| (queue->vif->stall_timeout &&
-		    (xenvif_rx_queue_stalled(queue)
-		     || xenvif_rx_queue_ready(queue)))
-		|| kthread_should_stop()
-		|| queue->vif->disabled;
-}
-
-static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
-{
-	struct sk_buff *skb;
-	long timeout;
-
-	skb = skb_peek(&queue->rx_queue);
-	if (!skb)
-		return MAX_SCHEDULE_TIMEOUT;
-
-	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
-	return timeout < 0 ? 0 : timeout;
-}
-
-/* Wait until the guest Rx thread has work.
- *
- * The timeout needs to be adjusted based on the current head of the
- * queue (and not just the head at the beginning).  In particular, if
- * the queue is initially empty an infinite timeout is used and this
- * needs to be reduced when a skb is queued.
- *
- * This cannot be done with wait_event_timeout() because it only
- * calculates the timeout once.
- */
-static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
-{
-	DEFINE_WAIT(wait);
-
-	if (xenvif_have_rx_work(queue))
-		return;
-
-	for (;;) {
-		long ret;
-
-		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
-		if (xenvif_have_rx_work(queue))
-			break;
-		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
-		if (!ret)
-			break;
-	}
-	finish_wait(&queue->wq, &wait);
-}
-
-int xenvif_kthread_guest_rx(void *data)
-{
-	struct xenvif_queue *queue = data;
-	struct xenvif *vif = queue->vif;
-
-	if (!vif->stall_timeout)
-		xenvif_queue_carrier_on(queue);
-
-	for (;;) {
-		xenvif_wait_for_rx_work(queue);
-
-		if (kthread_should_stop())
-			break;
-
-		/* This frontend is found to be rogue, disable it in
-		 * kthread context. Currently this is only set when
-		 * netback finds out frontend sends malformed packet,
-		 * but we cannot disable the interface in softirq
-		 * context so we defer it here, if this thread is
-		 * associated with queue 0.
-		 */
-		if (unlikely(vif->disabled && queue->id == 0)) {
-			xenvif_carrier_off(vif);
-			break;
-		}
-
-		if (!skb_queue_empty(&queue->rx_queue))
-			xenvif_rx_action(queue);
-
-		/* If the guest hasn't provided any Rx slots for a
-		 * while it's probably not responsive, drop the
-		 * carrier so packets are dropped earlier.
-		 */
-		if (vif->stall_timeout) {
-			if (xenvif_rx_queue_stalled(queue))
-				xenvif_queue_carrier_off(queue);
-			else if (xenvif_rx_queue_ready(queue))
-				xenvif_queue_carrier_on(queue);
-		}
-
-		/* Queued packets may have foreign pages from other
-		 * domains.  These cannot be queued indefinitely as
-		 * this would starve guests of grant refs and transmit
-		 * slots.
-		 */
-		xenvif_rx_queue_drop_expired(queue);
-
-		xenvif_rx_queue_maybe_wake(queue);
-
-		cond_resched();
-	}
-
-	/* Bin any remaining skbs */
-	xenvif_rx_queue_purge(queue);
-
-	return 0;
-}
-
 static bool xenvif_dealloc_kthread_should_stop(struct xenvif_queue *queue)
 {
 	/* Dealloc thread must remain running until all inflight
diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
new file mode 100644
index 000000000000..8e9ade6ccf18
--- /dev/null
+++ b/drivers/net/xen-netback/rx.c
@@ -0,0 +1,629 @@
+/*
+ * Copyright (c) 2016 Citrix Systems Inc.
+ * Copyright (c) 2002-2005, K A Fraser
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+#include "common.h"
+
+#include <linux/kthread.h>
+
+#include <xen/xen.h>
+#include <xen/events.h>
+
+static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue)
+{
+	RING_IDX prod, cons;
+	struct sk_buff *skb;
+	int needed;
+
+	skb = skb_peek(&queue->rx_queue);
+	if (!skb)
+		return false;
+
+	needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE);
+	if (skb_is_gso(skb))
+		needed++;
+	if (skb->sw_hash)
+		needed++;
+
+	do {
+		prod = queue->rx.sring->req_prod;
+		cons = queue->rx.req_cons;
+
+		if (prod - cons >= needed)
+			return true;
+
+		queue->rx.sring->req_event = prod + 1;
+
+		/* Make sure event is visible before we check prod
+		 * again.
+		 */
+		mb();
+	} while (queue->rx.sring->req_prod != prod);
+
+	return false;
+}
+
+void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->rx_queue.lock, flags);
+
+	__skb_queue_tail(&queue->rx_queue, skb);
+
+	queue->rx_queue_len += skb->len;
+	if (queue->rx_queue_len > queue->rx_queue_max) {
+		struct net_device *dev = queue->vif->dev;
+
+		netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id));
+	}
+
+	spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
+}
+
+static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+
+	spin_lock_irq(&queue->rx_queue.lock);
+
+	skb = __skb_dequeue(&queue->rx_queue);
+	if (skb) {
+		queue->rx_queue_len -= skb->len;
+		if (queue->rx_queue_len < queue->rx_queue_max) {
+			struct netdev_queue *txq;
+
+			txq = netdev_get_tx_queue(queue->vif->dev, queue->id);
+			netif_tx_wake_queue(txq);
+		}
+	}
+
+	spin_unlock_irq(&queue->rx_queue.lock);
+
+	return skb;
+}
+
+static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+
+	while ((skb = xenvif_rx_dequeue(queue)) != NULL)
+		kfree_skb(skb);
+}
+
+static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+
+	for (;;) {
+		skb = skb_peek(&queue->rx_queue);
+		if (!skb)
+			break;
+		if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
+			break;
+		xenvif_rx_dequeue(queue);
+		kfree_skb(skb);
+	}
+}
+
+static void xenvif_rx_copy_flush(struct xenvif_queue *queue)
+{
+	unsigned int i;
+	int notify;
+
+	gnttab_batch_copy(queue->rx_copy.op, queue->rx_copy.num);
+
+	for (i = 0; i < queue->rx_copy.num; i++) {
+		struct gnttab_copy *op;
+
+		op = &queue->rx_copy.op[i];
+
+		/* If the copy failed, overwrite the status field in
+		 * the corresponding response.
+		 */
+		if (unlikely(op->status != GNTST_okay)) {
+			struct xen_netif_rx_response *rsp;
+
+			rsp = RING_GET_RESPONSE(&queue->rx,
+						queue->rx_copy.idx[i]);
+			rsp->status = op->status;
+		}
+	}
+
+	queue->rx_copy.num = 0;
+
+	/* Push responses for all completed packets. */
+	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->rx, notify);
+	if (notify)
+		notify_remote_via_irq(queue->rx_irq);
+
+	__skb_queue_purge(queue->rx_copy.completed);
+}
+
+static void xenvif_rx_copy_add(struct xenvif_queue *queue,
+			       struct xen_netif_rx_request *req,
+			       unsigned int offset, void *data, size_t len)
+{
+	struct gnttab_copy *op;
+	struct page *page;
+	struct xen_page_foreign *foreign;
+
+	if (queue->rx_copy.num == COPY_BATCH_SIZE)
+		xenvif_rx_copy_flush(queue);
+
+	op = &queue->rx_copy.op[queue->rx_copy.num];
+
+	page = virt_to_page(data);
+
+	op->flags = GNTCOPY_dest_gref;
+
+	foreign = xen_page_foreign(page);
+	if (foreign) {
+		op->source.domid = foreign->domid;
+		op->source.u.ref = foreign->gref;
+		op->flags |= GNTCOPY_source_gref;
+	} else {
+		op->source.u.gmfn = virt_to_gfn(data);
+		op->source.domid  = DOMID_SELF;
+	}
+
+	op->source.offset = xen_offset_in_page(data);
+	op->dest.u.ref    = req->gref;
+	op->dest.domid    = queue->vif->domid;
+	op->dest.offset   = offset;
+	op->len           = len;
+
+	queue->rx_copy.idx[queue->rx_copy.num] = queue->rx.req_cons;
+	queue->rx_copy.num++;
+}
+
+static unsigned int xenvif_gso_type(struct sk_buff *skb)
+{
+	if (skb_is_gso(skb)) {
+		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+			return XEN_NETIF_GSO_TYPE_TCPV4;
+		else
+			return XEN_NETIF_GSO_TYPE_TCPV6;
+	}
+	return XEN_NETIF_GSO_TYPE_NONE;
+}
+
+struct xenvif_pkt_state {
+	struct sk_buff *skb;
+	size_t remaining_len;
+	struct sk_buff *frag_iter;
+	int frag; /* frag == -1 => frag_iter->head */
+	unsigned int frag_offset;
+	struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
+	unsigned int extra_count;
+	unsigned int slot;
+};
+
+static void xenvif_rx_next_skb(struct xenvif_queue *queue,
+			       struct xenvif_pkt_state *pkt)
+{
+	struct sk_buff *skb;
+	unsigned int gso_type;
+
+	skb = xenvif_rx_dequeue(queue);
+
+	queue->stats.tx_bytes += skb->len;
+	queue->stats.tx_packets++;
+
+	/* Reset packet state. */
+	memset(pkt, 0, sizeof(struct xenvif_pkt_state));
+
+	pkt->skb = skb;
+	pkt->frag_iter = skb;
+	pkt->remaining_len = skb->len;
+	pkt->frag = -1;
+
+	gso_type = xenvif_gso_type(skb);
+	if ((1 << gso_type) & queue->vif->gso_mask) {
+		struct xen_netif_extra_info *extra;
+
+		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
+
+		extra->u.gso.type = gso_type;
+		extra->u.gso.size = skb_shinfo(skb)->gso_size;
+		extra->u.gso.pad = 0;
+		extra->u.gso.features = 0;
+		extra->type = XEN_NETIF_EXTRA_TYPE_GSO;
+		extra->flags = 0;
+
+		pkt->extra_count++;
+	}
+
+	if (skb->sw_hash) {
+		struct xen_netif_extra_info *extra;
+
+		extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];
+
+		extra->u.hash.algorithm =
+			XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ;
+
+		if (skb->l4_hash)
+			extra->u.hash.type =
+				skb->protocol == htons(ETH_P_IP) ?
+				_XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP :
+				_XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
+		else
+			extra->u.hash.type =
+				skb->protocol == htons(ETH_P_IP) ?
+				_XEN_NETIF_CTRL_HASH_TYPE_IPV4 :
+				_XEN_NETIF_CTRL_HASH_TYPE_IPV6;
+
+		*(uint32_t *)extra->u.hash.value = skb_get_hash_raw(skb);
+
+		extra->type = XEN_NETIF_EXTRA_TYPE_HASH;
+		extra->flags = 0;
+
+		pkt->extra_count++;
+	}
+}
+
+static void xenvif_rx_complete(struct xenvif_queue *queue,
+			       struct xenvif_pkt_state *pkt)
+{
+	/* All responses are ready to be pushed. */
+	queue->rx.rsp_prod_pvt = queue->rx.req_cons;
+
+	__skb_queue_tail(queue->rx_copy.completed, pkt->skb);
+}
+
+static void xenvif_rx_next_frag(struct xenvif_pkt_state *pkt)
+{
+	struct sk_buff *frag_iter = pkt->frag_iter;
+	unsigned int nr_frags = skb_shinfo(frag_iter)->nr_frags;
+
+	pkt->frag++;
+	pkt->frag_offset = 0;
+
+	if (pkt->frag >= nr_frags) {
+		if (frag_iter == pkt->skb)
+			pkt->frag_iter = skb_shinfo(frag_iter)->frag_list;
+		else
+			pkt->frag_iter = frag_iter->next;
+
+		pkt->frag = -1;
+	}
+}
+
+static void xenvif_rx_next_chunk(struct xenvif_queue *queue,
+				 struct xenvif_pkt_state *pkt,
+				 unsigned int offset, void **data,
+				 size_t *len)
+{
+	struct sk_buff *frag_iter = pkt->frag_iter;
+	void *frag_data;
+	size_t frag_len, chunk_len;
+
+	BUG_ON(!frag_iter);
+
+	if (pkt->frag == -1) {
+		frag_data = frag_iter->data;
+		frag_len = skb_headlen(frag_iter);
+	} else {
+		skb_frag_t *frag = &skb_shinfo(frag_iter)->frags[pkt->frag];
+
+		frag_data = skb_frag_address(frag);
+		frag_len = skb_frag_size(frag);
+	}
+
+	frag_data += pkt->frag_offset;
+	frag_len -= pkt->frag_offset;
+
+	chunk_len = min(frag_len, XEN_PAGE_SIZE - offset);
+	chunk_len = min(chunk_len,
+			XEN_PAGE_SIZE -	xen_offset_in_page(frag_data));
+
+	pkt->frag_offset += chunk_len;
+
+	/* Advance to next frag? */
+	if (frag_len == chunk_len)
+		xenvif_rx_next_frag(pkt);
+
+	*data = frag_data;
+	*len = chunk_len;
+}
+
+static void xenvif_rx_data_slot(struct xenvif_queue *queue,
+				struct xenvif_pkt_state *pkt,
+				struct xen_netif_rx_request *req,
+				struct xen_netif_rx_response *rsp)
+{
+	unsigned int offset = 0;
+	unsigned int flags;
+
+	do {
+		size_t len;
+		void *data;
+
+		xenvif_rx_next_chunk(queue, pkt, offset, &data, &len);
+		xenvif_rx_copy_add(queue, req, offset, data, len);
+
+		offset += len;
+		pkt->remaining_len -= len;
+
+	} while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0);
+
+	if (pkt->remaining_len > 0)
+		flags = XEN_NETRXF_more_data;
+	else
+		flags = 0;
+
+	if (pkt->slot == 0) {
+		struct sk_buff *skb = pkt->skb;
+
+		if (skb->ip_summed == CHECKSUM_PARTIAL)
+			flags |= XEN_NETRXF_csum_blank |
+				 XEN_NETRXF_data_validated;
+		else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
+			flags |= XEN_NETRXF_data_validated;
+
+		if (pkt->extra_count != 0)
+			flags |= XEN_NETRXF_extra_info;
+	}
+
+	rsp->offset = 0;
+	rsp->flags = flags;
+	rsp->id = req->id;
+	rsp->status = (s16)offset;
+}
+
+static void xenvif_rx_extra_slot(struct xenvif_queue *queue,
+				 struct xenvif_pkt_state *pkt,
+				 struct xen_netif_rx_request *req,
+				 struct xen_netif_rx_response *rsp)
+{
+	struct xen_netif_extra_info *extra = (void *)rsp;
+	unsigned int i;
+
+	pkt->extra_count--;
+
+	for (i = 0; i < ARRAY_SIZE(pkt->extras); i++) {
+		if (pkt->extras[i].type) {
+			*extra = pkt->extras[i];
+
+			if (pkt->extra_count != 0)
+				extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;
+
+			pkt->extras[i].type = 0;
+			return;
+		}
+	}
+	BUG();
+}
+
+void xenvif_rx_skb(struct xenvif_queue *queue)
+{
+	struct xenvif_pkt_state pkt;
+
+	xenvif_rx_next_skb(queue, &pkt);
+
+	do {
+		struct xen_netif_rx_request *req;
+		struct xen_netif_rx_response *rsp;
+
+		req = RING_GET_REQUEST(&queue->rx, queue->rx.req_cons);
+		rsp = RING_GET_RESPONSE(&queue->rx, queue->rx.req_cons);
+
+		/* Extras must go after the first data slot */
+		if (pkt.slot != 0 && pkt.extra_count != 0)
+			xenvif_rx_extra_slot(queue, &pkt, req, rsp);
+		else
+			xenvif_rx_data_slot(queue, &pkt, req, rsp);
+
+		queue->rx.req_cons++;
+		pkt.slot++;
+	} while (pkt.remaining_len > 0 || pkt.extra_count != 0);
+
+	xenvif_rx_complete(queue, &pkt);
+}
+
+#define RX_BATCH_SIZE 64
+
+void xenvif_rx_action(struct xenvif_queue *queue)
+{
+	struct sk_buff_head completed_skbs;
+	unsigned int work_done = 0;
+
+	__skb_queue_head_init(&completed_skbs);
+	queue->rx_copy.completed = &completed_skbs;
+
+	while (xenvif_rx_ring_slots_available(queue) &&
+	       work_done < RX_BATCH_SIZE) {
+		xenvif_rx_skb(queue);
+		work_done++;
+	}
+
+	/* Flush any pending copies and complete all skbs. */
+	xenvif_rx_copy_flush(queue);
+}
+
+static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
+{
+	RING_IDX prod, cons;
+
+	prod = queue->rx.sring->req_prod;
+	cons = queue->rx.req_cons;
+
+	return !queue->stalled &&
+		prod - cons < 1 &&
+		time_after(jiffies,
+			   queue->last_rx_time + queue->vif->stall_timeout);
+}
+
+static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
+{
+	RING_IDX prod, cons;
+
+	prod = queue->rx.sring->req_prod;
+	cons = queue->rx.req_cons;
+
+	return queue->stalled && prod - cons >= 1;
+}
+
+static bool xenvif_have_rx_work(struct xenvif_queue *queue)
+{
+	return xenvif_rx_ring_slots_available(queue) ||
+		(queue->vif->stall_timeout &&
+		 (xenvif_rx_queue_stalled(queue) ||
+		  xenvif_rx_queue_ready(queue))) ||
+		kthread_should_stop() ||
+		queue->vif->disabled;
+}
+
+static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
+{
+	struct sk_buff *skb;
+	long timeout;
+
+	skb = skb_peek(&queue->rx_queue);
+	if (!skb)
+		return MAX_SCHEDULE_TIMEOUT;
+
+	timeout = XENVIF_RX_CB(skb)->expires - jiffies;
+	return timeout < 0 ? 0 : timeout;
+}
+
+/* Wait until the guest Rx thread has work.
+ *
+ * The timeout needs to be adjusted based on the current head of the
+ * queue (and not just the head at the beginning).  In particular, if
+ * the queue is initially empty an infinite timeout is used and this
+ * needs to be reduced when a skb is queued.
+ *
+ * This cannot be done with wait_event_timeout() because it only
+ * calculates the timeout once.
+ */
+static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
+{
+	DEFINE_WAIT(wait);
+
+	if (xenvif_have_rx_work(queue))
+		return;
+
+	for (;;) {
+		long ret;
+
+		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
+		if (xenvif_have_rx_work(queue))
+			break;
+		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
+		if (!ret)
+			break;
+	}
+	finish_wait(&queue->wq, &wait);
+}
+
+static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
+{
+	struct xenvif *vif = queue->vif;
+
+	queue->stalled = true;
+
+	/* At least one queue has stalled? Disable the carrier. */
+	spin_lock(&vif->lock);
+	if (vif->stalled_queues++ == 0) {
+		netdev_info(vif->dev, "Guest Rx stalled");
+		netif_carrier_off(vif->dev);
+	}
+	spin_unlock(&vif->lock);
+}
+
+static void xenvif_queue_carrier_on(struct xenvif_queue *queue)
+{
+	struct xenvif *vif = queue->vif;
+
+	queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
+	queue->stalled = false;
+
+	/* All queues are ready? Enable the carrier. */
+	spin_lock(&vif->lock);
+	if (--vif->stalled_queues == 0) {
+		netdev_info(vif->dev, "Guest Rx ready");
+		netif_carrier_on(vif->dev);
+	}
+	spin_unlock(&vif->lock);
+}
+
+int xenvif_kthread_guest_rx(void *data)
+{
+	struct xenvif_queue *queue = data;
+	struct xenvif *vif = queue->vif;
+
+	if (!vif->stall_timeout)
+		xenvif_queue_carrier_on(queue);
+
+	for (;;) {
+		xenvif_wait_for_rx_work(queue);
+
+		if (kthread_should_stop())
+			break;
+
+		/* This frontend is found to be rogue, disable it in
+		 * kthread context. Currently this is only set when
+		 * netback finds out frontend sends malformed packet,
+		 * but we cannot disable the interface in softirq
+		 * context so we defer it here, if this thread is
+		 * associated with queue 0.
+		 */
+		if (unlikely(vif->disabled && queue->id == 0)) {
+			xenvif_carrier_off(vif);
+			break;
+		}
+
+		if (!skb_queue_empty(&queue->rx_queue))
+			xenvif_rx_action(queue);
+
+		/* If the guest hasn't provided any Rx slots for a
+		 * while it's probably not responsive, drop the
+		 * carrier so packets are dropped earlier.
+		 */
+		if (vif->stall_timeout) {
+			if (xenvif_rx_queue_stalled(queue))
+				xenvif_queue_carrier_off(queue);
+			else if (xenvif_rx_queue_ready(queue))
+				xenvif_queue_carrier_on(queue);
+		}
+
+		/* Queued packets may have foreign pages from other
+		 * domains.  These cannot be queued indefinitely as
+		 * this would starve guests of grant refs and transmit
+		 * slots.
+		 */
+		xenvif_rx_queue_drop_expired(queue);
+
+		cond_resched();
+	}
+
+	/* Bin any remaining skbs */
+	xenvif_rx_queue_purge(queue);
+
+	return 0;
+}
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index daf4c7867102..7056404e3cb8 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -1135,7 +1135,6 @@ static int read_xenbus_vif_flags(struct backend_info *be)
 	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)
@@ -1143,32 +1142,12 @@ static int read_xenbus_vif_flags(struct backend_info *be)
 	if (val)
 		vif->gso_mask |= GSO_BIT(TCPV4);
 
-	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
-			 "%d", &val) < 0)
-		val = 0;
-	if (val)
-		vif->gso_prefix_mask |= GSO_BIT(TCPV4);
-
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
 			 "%d", &val) < 0)
 		val = 0;
 	if (val)
 		vif->gso_mask |= GSO_BIT(TCPV6);
 
-	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,
-				 "%s: gso and gso prefix flags are not "
-				 "mutually exclusive",
-				 dev->otherend);
-		return -EOPNOTSUPP;
-	}
-
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 			 "%d", &val) < 0)
 		val = 0;