1 files changed, 618 insertions, 304 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 6b62c3eb8e1..76665405c5a 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -37,6 +37,7 @@
 #include <linux/kthread.h>
 #include <linux/if_vlan.h>
 #include <linux/udp.h>
+#include <linux/highmem.h>
 
 #include <net/tcp.h>
 
@@ -54,6 +55,13 @@
 bool separate_tx_rx_irq = 1;
 module_param(separate_tx_rx_irq, bool, 0644);
 
+/* When guest ring is filled up, qdisc queues the packets for us, but we have
+ * to timeout them, otherwise other guests' packets can get stuck there
+ */
+unsigned int rx_drain_timeout_msecs = 10000;
+module_param(rx_drain_timeout_msecs, uint, 0444);
+unsigned int rx_drain_timeout_jiffies;
+
 /*
  * This is the maximum slots a skb can have. If a guest sends a skb
  * which exceeds this limit it is considered malicious.
@@ -62,24 +70,6 @@ module_param(separate_tx_rx_irq, bool, 0644);
 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
 module_param(fatal_skb_slots, uint, 0444);
 
-/*
- * To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
- * the maximum slots a valid packet can use. Now this value is defined
- * to be XEN_NETIF_NR_SLOTS_MIN, which is supposed to be supported by
- * all backend.
- */
-#define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN
-
-/*
- * If head != INVALID_PENDING_RING_IDX, it means this tx request is head of
- * one or more merged tx requests, otherwise it is the continuation of
- * previous tx request.
- */
-static inline int pending_tx_is_head(struct xenvif *vif, RING_IDX idx)
-{
-	return vif->pending_tx_info[idx].head != INVALID_PENDING_RING_IDX;
-}
-
 static void xenvif_idx_release(struct xenvif *vif, u16 pending_idx,
 			       u8 status);
 
@@ -109,6 +99,21 @@ static inline unsigned long idx_to_kaddr(struct xenvif *vif,
 	return (unsigned long)pfn_to_kaddr(idx_to_pfn(vif, idx));
 }
 
+#define callback_param(vif, pending_idx) \
+	(vif->pending_tx_info[pending_idx].callback_struct)
+
+/* Find the containing VIF's structure from a pointer in pending_tx_info array
+ */
+static inline struct xenvif* ubuf_to_vif(struct ubuf_info *ubuf)
+{
+	u16 pending_idx = ubuf->desc;
+	struct pending_tx_info *temp =
+		container_of(ubuf, struct pending_tx_info, callback_struct);
+	return container_of(temp - pending_idx,
+			    struct xenvif,
+			    pending_tx_info[0]);
+}
+
 /* This is a miniumum size for the linear area to avoid lots of
  * calls to __pskb_pull_tail() as we set up checksum offsets. The
  * value 128 was chosen as it covers all IPv4 and most likely
@@ -131,12 +136,6 @@ static inline pending_ring_idx_t pending_index(unsigned i)
 	return i & (MAX_PENDING_REQS-1);
 }
 
-static inline pending_ring_idx_t nr_pending_reqs(struct xenvif *vif)
-{
-	return MAX_PENDING_REQS -
-		vif->pending_prod + vif->pending_cons;
-}
-
 bool xenvif_rx_ring_slots_available(struct xenvif *vif, int needed)
 {
 	RING_IDX prod, cons;
@@ -192,8 +191,8 @@ static bool start_new_rx_buffer(int offset, unsigned long size, int head)
 	 * into multiple copies tend to give large frags their
 	 * own buffers as before.
 	 */
-	if ((offset + size > MAX_BUFFER_OFFSET) &&
-	    (size <= MAX_BUFFER_OFFSET) && offset && !head)
+	BUG_ON(size > MAX_BUFFER_OFFSET);
+	if ((offset + size > MAX_BUFFER_OFFSET) && offset && !head)
 		return true;
 
 	return false;
@@ -235,12 +234,14 @@ static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif *vif,
 static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 				 struct netrx_pending_operations *npo,
 				 struct page *page, unsigned long size,
-				 unsigned long offset, int *head)
+				 unsigned long offset, int *head,
+				 struct xenvif *foreign_vif,
+				 grant_ref_t foreign_gref)
 {
 	struct gnttab_copy *copy_gop;
 	struct xenvif_rx_meta *meta;
 	unsigned long bytes;
-	int gso_type;
+	int gso_type = XEN_NETIF_GSO_TYPE_NONE;
 
 	/* Data must not cross a page boundary. */
 	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
@@ -277,8 +278,15 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 		copy_gop->flags = GNTCOPY_dest_gref;
 		copy_gop->len = bytes;
 
-		copy_gop->source.domid = DOMID_SELF;
-		copy_gop->source.u.gmfn = virt_to_mfn(page_address(page));
+		if (foreign_vif) {
+			copy_gop->source.domid = foreign_vif->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 =
+				virt_to_mfn(page_address(page));
+		}
 		copy_gop->source.offset = offset;
 
 		copy_gop->dest.domid = vif->domid;
@@ -299,12 +307,12 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 		}
 
 		/* Leave a gap for the GSO descriptor. */
-		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;
-		else
-			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;
+		}
 
 		if (*head && ((1 << gso_type) & vif->gso_mask))
 			vif->rx.req_cons++;
@@ -338,19 +346,18 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 	int head = 1;
 	int old_meta_prod;
 	int gso_type;
-	int gso_size;
+	struct ubuf_info *ubuf = skb_shinfo(skb)->destructor_arg;
+	grant_ref_t foreign_grefs[MAX_SKB_FRAGS];
+	struct xenvif *foreign_vif = NULL;
 
 	old_meta_prod = npo->meta_prod;
 
-	if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
-		gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
-		gso_size = skb_shinfo(skb)->gso_size;
-	} else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6) {
-		gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
-		gso_size = skb_shinfo(skb)->gso_size;
-	} else {
-		gso_type = XEN_NETIF_GSO_TYPE_NONE;
-		gso_size = 0;
+	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 */
@@ -358,7 +365,7 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 		req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 		meta = npo->meta + npo->meta_prod++;
 		meta->gso_type = gso_type;
-		meta->gso_size = gso_size;
+		meta->gso_size = skb_shinfo(skb)->gso_size;
 		meta->size = 0;
 		meta->id = req->id;
 	}
@@ -368,7 +375,7 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 
 	if ((1 << gso_type) & vif->gso_mask) {
 		meta->gso_type = gso_type;
-		meta->gso_size = gso_size;
+		meta->gso_size = skb_shinfo(skb)->gso_size;
 	} else {
 		meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 		meta->gso_size = 0;
@@ -379,6 +386,19 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 	npo->copy_off = 0;
 	npo->copy_gref = req->gref;
 
+	if ((skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) &&
+		 (ubuf->callback == &xenvif_zerocopy_callback)) {
+		int i = 0;
+		foreign_vif = ubuf_to_vif(ubuf);
+
+		do {
+			u16 pending_idx = ubuf->desc;
+			foreign_grefs[i++] =
+				foreign_vif->pending_tx_info[pending_idx].req.gref;
+			ubuf = (struct ubuf_info *) ubuf->ctx;
+		} while (ubuf);
+	}
+
 	data = skb->data;
 	while (data < skb_tail_pointer(skb)) {
 		unsigned int offset = offset_in_page(data);
@@ -388,7 +408,9 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 			len = skb_tail_pointer(skb) - data;
 
 		xenvif_gop_frag_copy(vif, skb, npo,
-				     virt_to_page(data), len, offset, &head);
+				     virt_to_page(data), len, offset, &head,
+				     NULL,
+				     0);
 		data += len;
 	}
 
@@ -397,7 +419,9 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 				     skb_frag_page(&skb_shinfo(skb)->frags[i]),
 				     skb_frag_size(&skb_shinfo(skb)->frags[i]),
 				     skb_shinfo(skb)->frags[i].page_offset,
-				     &head);
+				     &head,
+				     foreign_vif,
+				     foreign_grefs[i]);
 	}
 
 	return npo->meta_prod - old_meta_prod;
@@ -455,10 +479,12 @@ static void xenvif_add_frag_responses(struct xenvif *vif, int status,
 	}
 }
 
-struct skb_cb_overlay {
+struct xenvif_rx_cb {
 	int meta_slots_used;
 };
 
+#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)
+
 void xenvif_kick_thread(struct xenvif *vif)
 {
 	wake_up(&vif->wq);
@@ -474,9 +500,7 @@ static void xenvif_rx_action(struct xenvif *vif)
 	LIST_HEAD(notify);
 	int ret;
 	unsigned long offset;
-	struct skb_cb_overlay *sco;
 	bool need_to_notify = false;
-	bool ring_full = false;
 
 	struct netrx_pending_operations npo = {
 		.copy  = vif->grant_copy_op,
@@ -486,7 +510,9 @@ static void xenvif_rx_action(struct xenvif *vif)
 	skb_queue_head_init(&rxq);
 
 	while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) {
-		int max_slots_needed;
+		RING_IDX max_slots_needed;
+		RING_IDX old_req_cons;
+		RING_IDX ring_slots_used;
 		int i;
 
 		/* We need a cheap worse case estimate for the number of
@@ -498,32 +524,53 @@ static void xenvif_rx_action(struct xenvif *vif)
 						PAGE_SIZE);
 		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 			unsigned int size;
+			unsigned int offset;
+
 			size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
-			max_slots_needed += DIV_ROUND_UP(size, PAGE_SIZE);
+			offset = skb_shinfo(skb)->frags[i].page_offset;
+
+			/* For a worse-case estimate we need to factor in
+			 * the fragment page offset as this will affect the
+			 * number of times xenvif_gop_frag_copy() will
+			 * call start_new_rx_buffer().
+			 */
+			max_slots_needed += DIV_ROUND_UP(offset + size,
+							 PAGE_SIZE);
 		}
-		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
-		    skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+
+		/* To avoid the estimate becoming too pessimal for some
+		 * frontends that limit posted rx requests, cap the estimate
+		 * at MAX_SKB_FRAGS.
+		 */
+		if (max_slots_needed > MAX_SKB_FRAGS)
+			max_slots_needed = MAX_SKB_FRAGS;
+
+		/* We may need one more slot for GSO metadata */
+		if (skb_is_gso(skb) &&
+		   (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4 ||
+		    skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
 			max_slots_needed++;
 
 		/* If the skb may not fit then bail out now */
 		if (!xenvif_rx_ring_slots_available(vif, max_slots_needed)) {
 			skb_queue_head(&vif->rx_queue, skb);
 			need_to_notify = true;
-			ring_full = true;
+			vif->rx_last_skb_slots = max_slots_needed;
 			break;
-		}
+		} else
+			vif->rx_last_skb_slots = 0;
+
+		old_req_cons = vif->rx.req_cons;
+		XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo);
+		ring_slots_used = vif->rx.req_cons - old_req_cons;
 
-		sco = (struct skb_cb_overlay *)skb->cb;
-		sco->meta_slots_used = xenvif_gop_skb(skb, &npo);
-		BUG_ON(sco->meta_slots_used > max_slots_needed);
+		BUG_ON(ring_slots_used > max_slots_needed);
 
 		__skb_queue_tail(&rxq, skb);
 	}
 
 	BUG_ON(npo.meta_prod > ARRAY_SIZE(vif->meta));
 
-	vif->rx_queue_stopped = !npo.copy_prod && ring_full;
-
 	if (!npo.copy_prod)
 		goto done;
 
@@ -531,7 +578,6 @@ static void xenvif_rx_action(struct xenvif *vif)
 	gnttab_batch_copy(vif->grant_copy_op, npo.copy_prod);
 
 	while ((skb = __skb_dequeue(&rxq)) != NULL) {
-		sco = (struct skb_cb_overlay *)skb->cb;
 
 		if ((1 << vif->meta[npo.meta_cons].gso_type) &
 		    vif->gso_prefix_mask) {
@@ -542,19 +588,21 @@ static void xenvif_rx_action(struct xenvif *vif)
 
 			resp->offset = vif->meta[npo.meta_cons].gso_size;
 			resp->id = vif->meta[npo.meta_cons].id;
-			resp->status = sco->meta_slots_used;
+			resp->status = XENVIF_RX_CB(skb)->meta_slots_used;
 
 			npo.meta_cons++;
-			sco->meta_slots_used--;
+			XENVIF_RX_CB(skb)->meta_slots_used--;
 		}
 
 
 		vif->dev->stats.tx_bytes += skb->len;
 		vif->dev->stats.tx_packets++;
 
-		status = xenvif_check_gop(vif, sco->meta_slots_used, &npo);
+		status = xenvif_check_gop(vif,
+					  XENVIF_RX_CB(skb)->meta_slots_used,
+					  &npo);
 
-		if (sco->meta_slots_used == 1)
+		if (XENVIF_RX_CB(skb)->meta_slots_used == 1)
 			flags = 0;
 		else
 			flags = XEN_NETRXF_more_data;
@@ -591,13 +639,13 @@ static void xenvif_rx_action(struct xenvif *vif)
 
 		xenvif_add_frag_responses(vif, status,
 					  vif->meta + npo.meta_cons + 1,
-					  sco->meta_slots_used);
+					  XENVIF_RX_CB(skb)->meta_slots_used);
 
 		RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
 
 		need_to_notify |= !!ret;
 
-		npo.meta_cons += sco->meta_slots_used;
+		npo.meta_cons += XENVIF_RX_CB(skb)->meta_slots_used;
 		dev_kfree_skb(skb);
 	}
 
@@ -647,9 +695,12 @@ static void xenvif_tx_err(struct xenvif *vif,
 			  struct xen_netif_tx_request *txp, RING_IDX end)
 {
 	RING_IDX cons = vif->tx.req_cons;
+	unsigned long flags;
 
 	do {
+		spin_lock_irqsave(&vif->response_lock, flags);
 		make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
+		spin_unlock_irqrestore(&vif->response_lock, flags);
 		if (cons == end)
 			break;
 		txp = RING_GET_REQUEST(&vif->tx, cons++);
@@ -660,7 +711,8 @@ static void xenvif_tx_err(struct xenvif *vif,
 static void xenvif_fatal_tx_err(struct xenvif *vif)
 {
 	netdev_err(vif->dev, "fatal error; disabling device\n");
-	xenvif_carrier_off(vif);
+	vif->disabled = true;
+	xenvif_kick_thread(vif);
 }
 
 static int xenvif_count_requests(struct xenvif *vif,
@@ -761,204 +813,220 @@ static int xenvif_count_requests(struct xenvif *vif,
 	return slots;
 }
 
-static struct page *xenvif_alloc_page(struct xenvif *vif,
-				      u16 pending_idx)
+
+struct xenvif_tx_cb {
+	u16 pending_idx;
+};
+
+#define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
+
+static inline void xenvif_tx_create_map_op(struct xenvif *vif,
+					  u16 pending_idx,
+					  struct xen_netif_tx_request *txp,
+					  struct gnttab_map_grant_ref *mop)
 {
-	struct page *page;
+	vif->pages_to_map[mop-vif->tx_map_ops] = vif->mmap_pages[pending_idx];
+	gnttab_set_map_op(mop, idx_to_kaddr(vif, pending_idx),
+			  GNTMAP_host_map | GNTMAP_readonly,
+			  txp->gref, vif->domid);
+
+	memcpy(&vif->pending_tx_info[pending_idx].req, txp,
+	       sizeof(*txp));
+}
 
-	page = alloc_page(GFP_ATOMIC|__GFP_COLD);
-	if (!page)
+static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
+{
+	struct sk_buff *skb =
+		alloc_skb(size + NET_SKB_PAD + NET_IP_ALIGN,
+			  GFP_ATOMIC | __GFP_NOWARN);
+	if (unlikely(skb == NULL))
 		return NULL;
-	vif->mmap_pages[pending_idx] = page;
 
-	return page;
+	/* Packets passed to netif_rx() must have some headroom. */
+	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
+
+	/* Initialize it here to avoid later surprises */
+	skb_shinfo(skb)->destructor_arg = NULL;
+
+	return skb;
 }
 
-static struct gnttab_copy *xenvif_get_requests(struct xenvif *vif,
-					       struct sk_buff *skb,
-					       struct xen_netif_tx_request *txp,
-					       struct gnttab_copy *gop)
+static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif *vif,
+							struct sk_buff *skb,
+							struct xen_netif_tx_request *txp,
+							struct gnttab_map_grant_ref *gop)
 {
 	struct skb_shared_info *shinfo = skb_shinfo(skb);
 	skb_frag_t *frags = shinfo->frags;
-	u16 pending_idx = *((u16 *)skb->data);
-	u16 head_idx = 0;
-	int slot, start;
-	struct page *page;
-	pending_ring_idx_t index, start_idx = 0;
-	uint16_t dst_offset;
-	unsigned int nr_slots;
-	struct pending_tx_info *first = NULL;
+	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
+	int start;
+	pending_ring_idx_t index;
+	unsigned int nr_slots, frag_overflow = 0;
 
 	/* At this point shinfo->nr_frags is in fact the number of
 	 * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
 	 */
+	if (shinfo->nr_frags > MAX_SKB_FRAGS) {
+		frag_overflow = shinfo->nr_frags - MAX_SKB_FRAGS;
+		BUG_ON(frag_overflow > MAX_SKB_FRAGS);
+		shinfo->nr_frags = MAX_SKB_FRAGS;
+	}
 	nr_slots = shinfo->nr_frags;
 
 	/* Skip first skb fragment if it is on same page as header fragment. */
 	start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
 
-	/* Coalesce tx requests, at this point the packet passed in
-	 * should be <= 64K. Any packets larger than 64K have been
-	 * handled in xenvif_count_requests().
-	 */
-	for (shinfo->nr_frags = slot = start; slot < nr_slots;
-	     shinfo->nr_frags++) {
-		struct pending_tx_info *pending_tx_info =
-			vif->pending_tx_info;
+	for (shinfo->nr_frags = start; shinfo->nr_frags < nr_slots;
+	     shinfo->nr_frags++, txp++, gop++) {
+		index = pending_index(vif->pending_cons++);
+		pending_idx = vif->pending_ring[index];
+		xenvif_tx_create_map_op(vif, pending_idx, txp, gop);
+		frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
+	}
 
-		page = alloc_page(GFP_ATOMIC|__GFP_COLD);
-		if (!page)
-			goto err;
-
-		dst_offset = 0;
-		first = NULL;
-		while (dst_offset < PAGE_SIZE && slot < nr_slots) {
-			gop->flags = GNTCOPY_source_gref;
-
-			gop->source.u.ref = txp->gref;
-			gop->source.domid = vif->domid;
-			gop->source.offset = txp->offset;
-
-			gop->dest.domid = DOMID_SELF;
-
-			gop->dest.offset = dst_offset;
-			gop->dest.u.gmfn = virt_to_mfn(page_address(page));
-
-			if (dst_offset + txp->size > PAGE_SIZE) {
-				/* This page can only merge a portion
-				 * of tx request. Do not increment any
-				 * pointer / counter here. The txp
-				 * will be dealt with in future
-				 * rounds, eventually hitting the
-				 * `else` branch.
-				 */
-				gop->len = PAGE_SIZE - dst_offset;
-				txp->offset += gop->len;
-				txp->size -= gop->len;
-				dst_offset += gop->len; /* quit loop */
-			} else {
-				/* This tx request can be merged in the page */
-				gop->len = txp->size;
-				dst_offset += gop->len;
-
-				index = pending_index(vif->pending_cons++);
-
-				pending_idx = vif->pending_ring[index];
-
-				memcpy(&pending_tx_info[pending_idx].req, txp,
-				       sizeof(*txp));
-
-				/* Poison these fields, corresponding
-				 * fields for head tx req will be set
-				 * to correct values after the loop.
-				 */
-				vif->mmap_pages[pending_idx] = (void *)(~0UL);
-				pending_tx_info[pending_idx].head =
-					INVALID_PENDING_RING_IDX;
-
-				if (!first) {
-					first = &pending_tx_info[pending_idx];
-					start_idx = index;
-					head_idx = pending_idx;
-				}
-
-				txp++;
-				slot++;
-			}
+	if (frag_overflow) {
+		struct sk_buff *nskb = xenvif_alloc_skb(0);
+		if (unlikely(nskb == NULL)) {
+			if (net_ratelimit())
+				netdev_err(vif->dev,
+					   "Can't allocate the frag_list skb.\n");
+			return NULL;
+		}
 
-			gop++;
+		shinfo = skb_shinfo(nskb);
+		frags = shinfo->frags;
+
+		for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
+		     shinfo->nr_frags++, txp++, gop++) {
+			index = pending_index(vif->pending_cons++);
+			pending_idx = vif->pending_ring[index];
+			xenvif_tx_create_map_op(vif, pending_idx, txp, gop);
+			frag_set_pending_idx(&frags[shinfo->nr_frags],
+					     pending_idx);
 		}
 
-		first->req.offset = 0;
-		first->req.size = dst_offset;
-		first->head = start_idx;
-		vif->mmap_pages[head_idx] = page;
-		frag_set_pending_idx(&frags[shinfo->nr_frags], head_idx);
+		skb_shinfo(skb)->frag_list = nskb;
 	}
 
-	BUG_ON(shinfo->nr_frags > MAX_SKB_FRAGS);
-
 	return gop;
-err:
-	/* Unwind, freeing all pages and sending error responses. */
-	while (shinfo->nr_frags-- > start) {
-		xenvif_idx_release(vif,
-				frag_get_pending_idx(&frags[shinfo->nr_frags]),
-				XEN_NETIF_RSP_ERROR);
+}
+
+static inline void xenvif_grant_handle_set(struct xenvif *vif,
+					   u16 pending_idx,
+					   grant_handle_t handle)
+{
+	if (unlikely(vif->grant_tx_handle[pending_idx] !=
+		     NETBACK_INVALID_HANDLE)) {
+		netdev_err(vif->dev,
+			   "Trying to overwrite active handle! pending_idx: %x\n",
+			   pending_idx);
+		BUG();
 	}
-	/* The head too, if necessary. */
-	if (start)
-		xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_ERROR);
+	vif->grant_tx_handle[pending_idx] = handle;
+}
 
-	return NULL;
+static inline void xenvif_grant_handle_reset(struct xenvif *vif,
+					     u16 pending_idx)
+{
+	if (unlikely(vif->grant_tx_handle[pending_idx] ==
+		     NETBACK_INVALID_HANDLE)) {
+		netdev_err(vif->dev,
+			   "Trying to unmap invalid handle! pending_idx: %x\n",
+			   pending_idx);
+		BUG();
+	}
+	vif->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
 }
 
 static int xenvif_tx_check_gop(struct xenvif *vif,
 			       struct sk_buff *skb,
-			       struct gnttab_copy **gopp)
+			       struct gnttab_map_grant_ref **gopp_map,
+			       struct gnttab_copy **gopp_copy)
 {
-	struct gnttab_copy *gop = *gopp;
-	u16 pending_idx = *((u16 *)skb->data);
+	struct gnttab_map_grant_ref *gop_map = *gopp_map;
+	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
 	struct skb_shared_info *shinfo = skb_shinfo(skb);
-	struct pending_tx_info *tx_info;
 	int nr_frags = shinfo->nr_frags;
-	int i, err, start;
-	u16 peek; /* peek into next tx request */
+	int i, err;
+	struct sk_buff *first_skb = NULL;
 
 	/* Check status of header. */
-	err = gop->status;
-	if (unlikely(err))
+	err = (*gopp_copy)->status;
+	(*gopp_copy)++;
+	if (unlikely(err)) {
+		if (net_ratelimit())
+			netdev_dbg(vif->dev,
+				   "Grant copy of header failed! status: %d pending_idx: %u ref: %u\n",
+				   (*gopp_copy)->status,
+				   pending_idx,
+				   (*gopp_copy)->source.u.ref);
 		xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_ERROR);
+	}
 
-	/* Skip first skb fragment if it is on same page as header fragment. */
-	start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
-
-	for (i = start; i < nr_frags; i++) {
+check_frags:
+	for (i = 0; i < nr_frags; i++, gop_map++) {
 		int j, newerr;
-		pending_ring_idx_t head;
 
 		pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
-		tx_info = &vif->pending_tx_info[pending_idx];
-		head = tx_info->head;
 
 		/* Check error status: if okay then remember grant handle. */
-		do {
-			newerr = (++gop)->status;
-			if (newerr)
-				break;
-			peek = vif->pending_ring[pending_index(++head)];
-		} while (!pending_tx_is_head(vif, peek));
+		newerr = gop_map->status;
 
 		if (likely(!newerr)) {
+			xenvif_grant_handle_set(vif,
+						pending_idx,
+						gop_map->handle);
 			/* Had a previous error? Invalidate this fragment. */
 			if (unlikely(err))
-				xenvif_idx_release(vif, pending_idx,
-						   XEN_NETIF_RSP_OKAY);
+				xenvif_idx_unmap(vif, pending_idx);
 			continue;
 		}
 
 		/* Error on this fragment: respond to client with an error. */
+		if (net_ratelimit())
+			netdev_dbg(vif->dev,
+				   "Grant map of %d. frag failed! status: %d pending_idx: %u ref: %u\n",
+				   i,
+				   gop_map->status,
+				   pending_idx,
+				   gop_map->ref);
 		xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_ERROR);
 
 		/* Not the first error? Preceding frags already invalidated. */
 		if (err)
 			continue;
-
-		/* First error: invalidate header and preceding fragments. */
-		pending_idx = *((u16 *)skb->data);
-		xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
-		for (j = start; j < i; j++) {
+		/* First error: invalidate preceding fragments. */
+		for (j = 0; j < i; j++) {
 			pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
-			xenvif_idx_release(vif, pending_idx,
-					   XEN_NETIF_RSP_OKAY);
+			xenvif_idx_unmap(vif, pending_idx);
 		}
 
 		/* Remember the error: invalidate all subsequent fragments. */
 		err = newerr;
 	}
 
-	*gopp = gop + 1;
+	if (skb_has_frag_list(skb)) {
+		first_skb = skb;
+		skb = shinfo->frag_list;
+		shinfo = skb_shinfo(skb);
+		nr_frags = shinfo->nr_frags;
+
+		goto check_frags;
+	}
+
+	/* There was a mapping error in the frag_list skb. We have to unmap
+	 * the first skb's frags
+	 */
+	if (first_skb && err) {
+		int j;
+		shinfo = skb_shinfo(first_skb);
+		for (j = 0; j < shinfo->nr_frags; j++) {
+			pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
+			xenvif_idx_unmap(vif, pending_idx);
+		}
+	}
+
+	*gopp_map = gop_map;
 	return err;
 }
 
@@ -967,6 +1035,7 @@ static void xenvif_fill_frags(struct xenvif *vif, struct sk_buff *skb)
 	struct skb_shared_info *shinfo = skb_shinfo(skb);
 	int nr_frags = shinfo->nr_frags;
 	int i;
+	u16 prev_pending_idx = INVALID_PENDING_IDX;
 
 	for (i = 0; i < nr_frags; i++) {
 		skb_frag_t *frag = shinfo->frags + i;
@@ -976,6 +1045,17 @@ static void xenvif_fill_frags(struct xenvif *vif, struct sk_buff *skb)
 
 		pending_idx = frag_get_pending_idx(frag);
 
+		/* If this is not the first frag, chain it to the previous*/
+		if (prev_pending_idx == INVALID_PENDING_IDX)
+			skb_shinfo(skb)->destructor_arg =
+				&callback_param(vif, pending_idx);
+		else
+			callback_param(vif, prev_pending_idx).ctx =
+				&callback_param(vif, pending_idx);
+
+		callback_param(vif, pending_idx).ctx = NULL;
+		prev_pending_idx = pending_idx;
+
 		txp = &vif->pending_tx_info[pending_idx].req;
 		page = virt_to_page(idx_to_kaddr(vif, pending_idx));
 		__skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
@@ -983,10 +1063,15 @@ static void xenvif_fill_frags(struct xenvif *vif, struct sk_buff *skb)
 		skb->data_len += txp->size;
 		skb->truesize += txp->size;
 
-		/* Take an extra reference to offset xenvif_idx_release */
+		/* Take an extra reference to offset network stack's put_page */
 		get_page(vif->mmap_pages[pending_idx]);
-		xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
 	}
+	/* FIXME: __skb_fill_page_desc set this to true because page->pfmemalloc
+	 * overlaps with "index", and "mapping" is not set. I think mapping
+	 * should be set. If delivered to local stack, it would drop this
+	 * skb in sk_filter unless the socket has the right to use it.
+	 */
+	skb->pfmemalloc	= false;
 }
 
 static int xenvif_get_extras(struct xenvif *vif,
@@ -1104,18 +1189,18 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
 	return false;
 }
 
-static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
+static void xenvif_tx_build_gops(struct xenvif *vif,
+				     int budget,
+				     unsigned *copy_ops,
+				     unsigned *map_ops)
 {
-	struct gnttab_copy *gop = vif->tx_copy_ops, *request_gop;
+	struct gnttab_map_grant_ref *gop = vif->tx_map_ops, *request_gop;
 	struct sk_buff *skb;
 	int ret;
 
-	while ((nr_pending_reqs(vif) + XEN_NETBK_LEGACY_SLOTS_MAX
-		< MAX_PENDING_REQS) &&
-	       (skb_queue_len(&vif->tx_queue) < budget)) {
+	while (skb_queue_len(&vif->tx_queue) < budget) {
 		struct xen_netif_tx_request txreq;
 		struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
-		struct page *page;
 		struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
 		u16 pending_idx;
 		RING_IDX idx;
@@ -1131,7 +1216,7 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
 				   vif->tx.sring->req_prod, vif->tx.req_cons,
 				   XEN_NETIF_TX_RING_SIZE);
 			xenvif_fatal_tx_err(vif);
-			continue;
+			break;
 		}
 
 		work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&vif->tx);
@@ -1191,8 +1276,7 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
 			    ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
 			PKT_PROT_LEN : txreq.size;
 
-		skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
-				GFP_ATOMIC | __GFP_NOWARN);
+		skb = xenvif_alloc_skb(data_len);
 		if (unlikely(skb == NULL)) {
 			netdev_dbg(vif->dev,
 				   "Can't allocate a skb in start_xmit.\n");
@@ -1200,9 +1284,6 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
 			break;
 		}
 
-		/* Packets passed to netif_rx() must have some headroom. */
-		skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
-
 		if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
 			struct xen_netif_extra_info *gso;
 			gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
@@ -1214,42 +1295,36 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
 			}
 		}
 
-		/* XXX could copy straight to head */
-		page = xenvif_alloc_page(vif, pending_idx);
-		if (!page) {
-			kfree_skb(skb);
-			xenvif_tx_err(vif, &txreq, idx);
-			break;
-		}
+		XENVIF_TX_CB(skb)->pending_idx = pending_idx;
 
-		gop->source.u.ref = txreq.gref;
-		gop->source.domid = vif->domid;
-		gop->source.offset = txreq.offset;
-
-		gop->dest.u.gmfn = virt_to_mfn(page_address(page));
-		gop->dest.domid = DOMID_SELF;
-		gop->dest.offset = txreq.offset;
+		__skb_put(skb, data_len);
+		vif->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref;
+		vif->tx_copy_ops[*copy_ops].source.domid = vif->domid;
+		vif->tx_copy_ops[*copy_ops].source.offset = txreq.offset;
 
-		gop->len = txreq.size;
-		gop->flags = GNTCOPY_source_gref;
+		vif->tx_copy_ops[*copy_ops].dest.u.gmfn =
+			virt_to_mfn(skb->data);
+		vif->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF;
+		vif->tx_copy_ops[*copy_ops].dest.offset =
+			offset_in_page(skb->data);
 
-		gop++;
+		vif->tx_copy_ops[*copy_ops].len = data_len;
+		vif->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;
 
-		memcpy(&vif->pending_tx_info[pending_idx].req,
-		       &txreq, sizeof(txreq));
-		vif->pending_tx_info[pending_idx].head = index;
-		*((u16 *)skb->data) = pending_idx;
-
-		__skb_put(skb, data_len);
+		(*copy_ops)++;
 
 		skb_shinfo(skb)->nr_frags = ret;
 		if (data_len < txreq.size) {
 			skb_shinfo(skb)->nr_frags++;
 			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
 					     pending_idx);
+			xenvif_tx_create_map_op(vif, pending_idx, &txreq, gop);
+			gop++;
 		} else {
 			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
 					     INVALID_PENDING_IDX);
+			memcpy(&vif->pending_tx_info[pending_idx].req, &txreq,
+			       sizeof(txreq));
 		}
 
 		vif->pending_cons++;
@@ -1266,17 +1341,85 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget)
 
 		vif->tx.req_cons = idx;
 
-		if ((gop-vif->tx_copy_ops) >= ARRAY_SIZE(vif->tx_copy_ops))
+		if (((gop-vif->tx_map_ops) >= ARRAY_SIZE(vif->tx_map_ops)) ||
+		    (*copy_ops >= ARRAY_SIZE(vif->tx_copy_ops)))
 			break;
 	}
 
-	return gop - vif->tx_copy_ops;
+	(*map_ops) = gop - vif->tx_map_ops;
+	return;
 }
 
+/* Consolidate skb with a frag_list into a brand new one with local pages on
+ * frags. Returns 0 or -ENOMEM if can't allocate new pages.
+ */
+static int xenvif_handle_frag_list(struct xenvif *vif, struct sk_buff *skb)
+{
+	unsigned int offset = skb_headlen(skb);
+	skb_frag_t frags[MAX_SKB_FRAGS];
+	int i;
+	struct ubuf_info *uarg;
+	struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
+
+	vif->tx_zerocopy_sent += 2;
+	vif->tx_frag_overflow++;
+
+	xenvif_fill_frags(vif, nskb);
+	/* Subtract frags size, we will correct it later */
+	skb->truesize -= skb->data_len;
+	skb->len += nskb->len;
+	skb->data_len += nskb->len;
+
+	/* create a brand new frags array and coalesce there */
+	for (i = 0; offset < skb->len; i++) {
+		struct page *page;
+		unsigned int len;
+
+		BUG_ON(i >= MAX_SKB_FRAGS);
+		page = alloc_page(GFP_ATOMIC|__GFP_COLD);
+		if (!page) {
+			int j;
+			skb->truesize += skb->data_len;
+			for (j = 0; j < i; j++)
+				put_page(frags[j].page.p);
+			return -ENOMEM;
+		}
+
+		if (offset + PAGE_SIZE < skb->len)
+			len = PAGE_SIZE;
+		else
+			len = skb->len - offset;
+		if (skb_copy_bits(skb, offset, page_address(page), len))
+			BUG();
+
+		offset += len;
+		frags[i].page.p = page;
+		frags[i].page_offset = 0;
+		skb_frag_size_set(&frags[i], len);
+	}
+	/* swap out with old one */
+	memcpy(skb_shinfo(skb)->frags,
+	       frags,
+	       i * sizeof(skb_frag_t));
+	skb_shinfo(skb)->nr_frags = i;
+	skb->truesize += i * PAGE_SIZE;
+
+	/* remove traces of mapped pages and frag_list */
+	skb_frag_list_init(skb);
+	uarg = skb_shinfo(skb)->destructor_arg;
+	uarg->callback(uarg, true);
+	skb_shinfo(skb)->destructor_arg = NULL;
+
+	skb_shinfo(nskb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+	kfree_skb(nskb);
+
+	return 0;
+}
 
 static int xenvif_tx_submit(struct xenvif *vif)
 {
-	struct gnttab_copy *gop = vif->tx_copy_ops;
+	struct gnttab_map_grant_ref *gop_map = vif->tx_map_ops;
+	struct gnttab_copy *gop_copy = vif->tx_copy_ops;
 	struct sk_buff *skb;
 	int work_done = 0;
 
@@ -1285,21 +1428,18 @@ static int xenvif_tx_submit(struct xenvif *vif)
 		u16 pending_idx;
 		unsigned data_len;
 
-		pending_idx = *((u16 *)skb->data);
+		pending_idx = XENVIF_TX_CB(skb)->pending_idx;
 		txp = &vif->pending_tx_info[pending_idx].req;
 
 		/* Check the remap error code. */
-		if (unlikely(xenvif_tx_check_gop(vif, skb, &gop))) {
-			netdev_dbg(vif->dev, "netback grant failed.\n");
+		if (unlikely(xenvif_tx_check_gop(vif, skb, &gop_map, &gop_copy))) {
 			skb_shinfo(skb)->nr_frags = 0;
 			kfree_skb(skb);
 			continue;
 		}
 
 		data_len = skb->len;
-		memcpy(skb->data,
-		       (void *)(idx_to_kaddr(vif, pending_idx)|txp->offset),
-		       data_len);
+		callback_param(vif, pending_idx).ctx = NULL;
 		if (data_len < txp->size) {
 			/* Append the packet payload as a fragment. */
 			txp->offset += data_len;
@@ -1317,6 +1457,17 @@ static int xenvif_tx_submit(struct xenvif *vif)
 
 		xenvif_fill_frags(vif, skb);
 
+		if (unlikely(skb_has_frag_list(skb))) {
+			if (xenvif_handle_frag_list(vif, skb)) {
+				if (net_ratelimit())
+					netdev_err(vif->dev,
+						   "Not enough memory to consolidate frag_list!\n");
+				skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+				kfree_skb(skb);
+				continue;
+			}
+		}
+
 		if (skb_is_nonlinear(skb) && skb_headlen(skb) < PKT_PROT_LEN) {
 			int target = min_t(int, skb->len, PKT_PROT_LEN);
 			__pskb_pull_tail(skb, target - skb_headlen(skb));
@@ -1329,6 +1480,9 @@ static int xenvif_tx_submit(struct xenvif *vif)
 		if (checksum_setup(vif, skb)) {
 			netdev_dbg(vif->dev,
 				   "Can't setup checksum in net_tx_action\n");
+			/* We have to set this flag to trigger the callback */
+			if (skb_shinfo(skb)->destructor_arg)
+				skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
 			kfree_skb(skb);
 			continue;
 		}
@@ -1354,27 +1508,143 @@ static int xenvif_tx_submit(struct xenvif *vif)
 
 		work_done++;
 
+		/* Set this flag right before netif_receive_skb, otherwise
+		 * someone might think this packet already left netback, and
+		 * do a skb_copy_ubufs while we are still in control of the
+		 * skb. E.g. the __pskb_pull_tail earlier can do such thing.
+		 */
+		if (skb_shinfo(skb)->destructor_arg) {
+			skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+			vif->tx_zerocopy_sent++;
+		}
+
 		netif_receive_skb(skb);
 	}
 
 	return work_done;
 }
 
+void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
+{
+	unsigned long flags;
+	pending_ring_idx_t index;
+	struct xenvif *vif = ubuf_to_vif(ubuf);
+
+	/* This is the only place where we grab this lock, to protect callbacks
+	 * from each other.
+	 */
+	spin_lock_irqsave(&vif->callback_lock, flags);
+	do {
+		u16 pending_idx = ubuf->desc;
+		ubuf = (struct ubuf_info *) ubuf->ctx;
+		BUG_ON(vif->dealloc_prod - vif->dealloc_cons >=
+			MAX_PENDING_REQS);
+		index = pending_index(vif->dealloc_prod);
+		vif->dealloc_ring[index] = pending_idx;
+		/* Sync with xenvif_tx_dealloc_action:
+		 * insert idx then incr producer.
+		 */
+		smp_wmb();
+		vif->dealloc_prod++;
+	} while (ubuf);
+	wake_up(&vif->dealloc_wq);
+	spin_unlock_irqrestore(&vif->callback_lock, flags);
+
+	if (likely(zerocopy_success))
+		vif->tx_zerocopy_success++;
+	else
+		vif->tx_zerocopy_fail++;
+}
+
+static inline void xenvif_tx_dealloc_action(struct xenvif *vif)
+{
+	struct gnttab_unmap_grant_ref *gop;
+	pending_ring_idx_t dc, dp;
+	u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
+	unsigned int i = 0;
+
+	dc = vif->dealloc_cons;
+	gop = vif->tx_unmap_ops;
+
+	/* Free up any grants we have finished using */
+	do {
+		dp = vif->dealloc_prod;
+
+		/* Ensure we see all indices enqueued by all
+		 * xenvif_zerocopy_callback().
+		 */
+		smp_rmb();
+
+		while (dc != dp) {
+			BUG_ON(gop - vif->tx_unmap_ops > MAX_PENDING_REQS);
+			pending_idx =
+				vif->dealloc_ring[pending_index(dc++)];
+
+			pending_idx_release[gop-vif->tx_unmap_ops] =
+				pending_idx;
+			vif->pages_to_unmap[gop-vif->tx_unmap_ops] =
+				vif->mmap_pages[pending_idx];
+			gnttab_set_unmap_op(gop,
+					    idx_to_kaddr(vif, pending_idx),
+					    GNTMAP_host_map,
+					    vif->grant_tx_handle[pending_idx]);
+			xenvif_grant_handle_reset(vif, pending_idx);
+			++gop;
+		}
+
+	} while (dp != vif->dealloc_prod);
+
+	vif->dealloc_cons = dc;
+
+	if (gop - vif->tx_unmap_ops > 0) {
+		int ret;
+		ret = gnttab_unmap_refs(vif->tx_unmap_ops,
+					NULL,
+					vif->pages_to_unmap,
+					gop - vif->tx_unmap_ops);
+		if (ret) {
+			netdev_err(vif->dev, "Unmap fail: nr_ops %tx ret %d\n",
+				   gop - vif->tx_unmap_ops, ret);
+			for (i = 0; i < gop - vif->tx_unmap_ops; ++i) {
+				if (gop[i].status != GNTST_okay)
+					netdev_err(vif->dev,
+						   " host_addr: %llx handle: %x status: %d\n",
+						   gop[i].host_addr,
+						   gop[i].handle,
+						   gop[i].status);
+			}
+			BUG();
+		}
+	}
+
+	for (i = 0; i < gop - vif->tx_unmap_ops; ++i)
+		xenvif_idx_release(vif, pending_idx_release[i],
+				   XEN_NETIF_RSP_OKAY);
+}
+
+
 /* Called after netfront has transmitted */
 int xenvif_tx_action(struct xenvif *vif, int budget)
 {
-	unsigned nr_gops;
-	int work_done;
+	unsigned nr_mops, nr_cops = 0;
+	int work_done, ret;
 
 	if (unlikely(!tx_work_todo(vif)))
 		return 0;
 
-	nr_gops = xenvif_tx_build_gops(vif, budget);
+	xenvif_tx_build_gops(vif, budget, &nr_cops, &nr_mops);
 
-	if (nr_gops == 0)
+	if (nr_cops == 0)
 		return 0;
 
-	gnttab_batch_copy(vif->tx_copy_ops, nr_gops);
+	gnttab_batch_copy(vif->tx_copy_ops, nr_cops);
+	if (nr_mops != 0) {
+		ret = gnttab_map_refs(vif->tx_map_ops,
+				      NULL,
+				      vif->pages_to_map,
+				      nr_mops);
+		BUG_ON(ret);
+	}
 
 	work_done = xenvif_tx_submit(vif);
 
@@ -1385,45 +1655,18 @@ static void xenvif_idx_release(struct xenvif *vif, u16 pending_idx,
 			       u8 status)
 {
 	struct pending_tx_info *pending_tx_info;
-	pending_ring_idx_t head;
-	u16 peek; /* peek into next tx request */
-
-	BUG_ON(vif->mmap_pages[pending_idx] == (void *)(~0UL));
-
-	/* Already complete? */
-	if (vif->mmap_pages[pending_idx] == NULL)
-		return;
+	pending_ring_idx_t index;
+	unsigned long flags;
 
 	pending_tx_info = &vif->pending_tx_info[pending_idx];
-
-	head = pending_tx_info->head;
-
-	BUG_ON(!pending_tx_is_head(vif, head));
-	BUG_ON(vif->pending_ring[pending_index(head)] != pending_idx);
-
-	do {
-		pending_ring_idx_t index;
-		pending_ring_idx_t idx = pending_index(head);
-		u16 info_idx = vif->pending_ring[idx];
-
-		pending_tx_info = &vif->pending_tx_info[info_idx];
-		make_tx_response(vif, &pending_tx_info->req, status);
-
-		/* Setting any number other than
-		 * INVALID_PENDING_RING_IDX indicates this slot is
-		 * starting a new packet / ending a previous packet.
-		 */
-		pending_tx_info->head = 0;
-
-		index = pending_index(vif->pending_prod++);
-		vif->pending_ring[index] = vif->pending_ring[info_idx];
-
-		peek = vif->pending_ring[pending_index(++head)];
-
-	} while (!pending_tx_is_head(vif, peek));
-
-	put_page(vif->mmap_pages[pending_idx]);
-	vif->mmap_pages[pending_idx] = NULL;
+	spin_lock_irqsave(&vif->response_lock, flags);
+	make_tx_response(vif, &pending_tx_info->req, status);
+	index = pending_index(vif->pending_prod);
+	vif->pending_ring[index] = pending_idx;
+	/* TX shouldn't use the index before we give it back here */
+	mb();
+	vif->pending_prod++;
+	spin_unlock_irqrestore(&vif->response_lock, flags);
 }
 
 
@@ -1471,23 +1714,54 @@ static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
 	return resp;
 }
 
+void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
+{
+	int ret;
+	struct gnttab_unmap_grant_ref tx_unmap_op;
+
+	gnttab_set_unmap_op(&tx_unmap_op,
+			    idx_to_kaddr(vif, pending_idx),
+			    GNTMAP_host_map,
+			    vif->grant_tx_handle[pending_idx]);
+	xenvif_grant_handle_reset(vif, pending_idx);
+
+	ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
+				&vif->mmap_pages[pending_idx], 1);
+	if (ret) {
+		netdev_err(vif->dev,
+			   "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: %x status: %d\n",
+			   ret,
+			   pending_idx,
+			   tx_unmap_op.host_addr,
+			   tx_unmap_op.handle,
+			   tx_unmap_op.status);
+		BUG();
+	}
+
+	xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
+}
+
 static inline int rx_work_todo(struct xenvif *vif)
 {
-	return (!skb_queue_empty(&vif->rx_queue) && !vif->rx_queue_stopped) ||
-		vif->rx_event;
+	return (!skb_queue_empty(&vif->rx_queue) &&
+	       xenvif_rx_ring_slots_available(vif, vif->rx_last_skb_slots)) ||
+	       vif->rx_queue_purge;
 }
 
 static inline int tx_work_todo(struct xenvif *vif)
 {
 
-	if (likely(RING_HAS_UNCONSUMED_REQUESTS(&vif->tx)) &&
-	    (nr_pending_reqs(vif) + XEN_NETBK_LEGACY_SLOTS_MAX
-	     < MAX_PENDING_REQS))
+	if (likely(RING_HAS_UNCONSUMED_REQUESTS(&vif->tx)))
 		return 1;
 
 	return 0;
 }
 
+static inline bool tx_dealloc_work_todo(struct xenvif *vif)
+{
+	return vif->dealloc_cons != vif->dealloc_prod;
+}
+
 void xenvif_unmap_frontend_rings(struct xenvif *vif)
 {
 	if (vif->tx.sring)
@@ -1545,7 +1819,7 @@ static void xenvif_start_queue(struct xenvif *vif)
 		netif_wake_queue(vif->dev);
 }
 
-int xenvif_kthread(void *data)
+int xenvif_kthread_guest_rx(void *data)
 {
 	struct xenvif *vif = data;
 	struct sk_buff *skb;
@@ -1553,18 +1827,34 @@ int xenvif_kthread(void *data)
 	while (!kthread_should_stop()) {
 		wait_event_interruptible(vif->wq,
 					 rx_work_todo(vif) ||
+					 vif->disabled ||
 					 kthread_should_stop());
+
+		/* 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 (unlikely(vif->disabled && netif_carrier_ok(vif->dev)))
+			xenvif_carrier_off(vif);
+
 		if (kthread_should_stop())
 			break;
 
+		if (vif->rx_queue_purge) {
+			skb_queue_purge(&vif->rx_queue);
+			vif->rx_queue_purge = false;
+		}
+
 		if (!skb_queue_empty(&vif->rx_queue))
 			xenvif_rx_action(vif);
 
-		vif->rx_event = false;
-
 		if (skb_queue_empty(&vif->rx_queue) &&
-		    netif_queue_stopped(vif->dev))
+		    netif_queue_stopped(vif->dev)) {
+			del_timer_sync(&vif->wake_queue);
 			xenvif_start_queue(vif);
+		}
 
 		cond_resched();
 	}
@@ -1576,6 +1866,28 @@ int xenvif_kthread(void *data)
 	return 0;
 }
 
+int xenvif_dealloc_kthread(void *data)
+{
+	struct xenvif *vif = data;
+
+	while (!kthread_should_stop()) {
+		wait_event_interruptible(vif->dealloc_wq,
+					 tx_dealloc_work_todo(vif) ||
+					 kthread_should_stop());
+		if (kthread_should_stop())
+			break;
+
+		xenvif_tx_dealloc_action(vif);
+		cond_resched();
+	}
+
+	/* Unmap anything remaining*/
+	if (tx_dealloc_work_todo(vif))
+		xenvif_tx_dealloc_action(vif);
+
+	return 0;
+}
+
 static int __init netback_init(void)
 {
 	int rc = 0;
@@ -1593,6 +1905,8 @@ static int __init netback_init(void)
 	if (rc)
 		goto failed_init;
 
+	rx_drain_timeout_jiffies = msecs_to_jiffies(rx_drain_timeout_msecs);
+
 	return 0;
 
 failed_init: