1 files changed, 521 insertions, 256 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f616cefc95b..8dae2f724a3 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -12,54 +12,235 @@
 #include <linux/virtio_net.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
-#include <linux/rcupdate.h>
 #include <linux/file.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 
 #include <linux/net.h>
 #include <linux/if_packet.h>
 #include <linux/if_arp.h>
 #include <linux/if_tun.h>
 #include <linux/if_macvlan.h>
+#include <linux/if_vlan.h>
 
 #include <net/sock.h>
 
 #include "vhost.h"
 
+static int experimental_zcopytx = 1;
+module_param(experimental_zcopytx, int, 0444);
+MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
+		                       " 1 -Enable; 0 - Disable");
+
 /* Max number of bytes transferred before requeueing the job.
  * Using this limit prevents one virtqueue from starving others. */
 #define VHOST_NET_WEIGHT 0x80000
 
+/* MAX number of TX used buffers for outstanding zerocopy */
+#define VHOST_MAX_PEND 128
+#define VHOST_GOODCOPY_LEN 256
+
+/*
+ * For transmit, used buffer len is unused; we override it to track buffer
+ * status internally; used for zerocopy tx only.
+ */
+/* Lower device DMA failed */
+#define VHOST_DMA_FAILED_LEN	3
+/* Lower device DMA done */
+#define VHOST_DMA_DONE_LEN	2
+/* Lower device DMA in progress */
+#define VHOST_DMA_IN_PROGRESS	1
+/* Buffer unused */
+#define VHOST_DMA_CLEAR_LEN	0
+
+#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
+
+enum {
+	VHOST_NET_FEATURES = VHOST_FEATURES |
+			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
+			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
+};
+
 enum {
 	VHOST_NET_VQ_RX = 0,
 	VHOST_NET_VQ_TX = 1,
 	VHOST_NET_VQ_MAX = 2,
 };
 
-enum vhost_net_poll_state {
-	VHOST_NET_POLL_DISABLED = 0,
-	VHOST_NET_POLL_STARTED = 1,
-	VHOST_NET_POLL_STOPPED = 2,
+struct vhost_net_ubuf_ref {
+	/* refcount follows semantics similar to kref:
+	 *  0: object is released
+	 *  1: no outstanding ubufs
+	 * >1: outstanding ubufs
+	 */
+	atomic_t refcount;
+	wait_queue_head_t wait;
+	struct vhost_virtqueue *vq;
+};
+
+struct vhost_net_virtqueue {
+	struct vhost_virtqueue vq;
+	/* hdr is used to store the virtio header.
+	 * Since each iovec has >= 1 byte length, we never need more than
+	 * header length entries to store the header. */
+	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
+	size_t vhost_hlen;
+	size_t sock_hlen;
+	/* vhost zerocopy support fields below: */
+	/* last used idx for outstanding DMA zerocopy buffers */
+	int upend_idx;
+	/* first used idx for DMA done zerocopy buffers */
+	int done_idx;
+	/* an array of userspace buffers info */
+	struct ubuf_info *ubuf_info;
+	/* Reference counting for outstanding ubufs.
+	 * Protected by vq mutex. Writers must also take device mutex. */
+	struct vhost_net_ubuf_ref *ubufs;
 };
 
 struct vhost_net {
 	struct vhost_dev dev;
-	struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
+	struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 	struct vhost_poll poll[VHOST_NET_VQ_MAX];
-	/* Tells us whether we are polling a socket for TX.
-	 * We only do this when socket buffer fills up.
+	/* Number of TX recently submitted.
 	 * Protected by tx vq lock. */
-	enum vhost_net_poll_state tx_poll_state;
+	unsigned tx_packets;
+	/* Number of times zerocopy TX recently failed.
+	 * Protected by tx vq lock. */
+	unsigned tx_zcopy_err;
+	/* Flush in progress. Protected by tx vq lock. */
+	bool tx_flush;
 };
 
+static unsigned vhost_net_zcopy_mask __read_mostly;
+
+static void vhost_net_enable_zcopy(int vq)
+{
+	vhost_net_zcopy_mask |= 0x1 << vq;
+}
+
+static struct vhost_net_ubuf_ref *
+vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
+{
+	struct vhost_net_ubuf_ref *ubufs;
+	/* No zero copy backend? Nothing to count. */
+	if (!zcopy)
+		return NULL;
+	ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
+	if (!ubufs)
+		return ERR_PTR(-ENOMEM);
+	atomic_set(&ubufs->refcount, 1);
+	init_waitqueue_head(&ubufs->wait);
+	ubufs->vq = vq;
+	return ubufs;
+}
+
+static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
+{
+	int r = atomic_sub_return(1, &ubufs->refcount);
+	if (unlikely(!r))
+		wake_up(&ubufs->wait);
+	return r;
+}
+
+static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put(ubufs);
+	wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
+}
+
+static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
+{
+	vhost_net_ubuf_put_and_wait(ubufs);
+	kfree(ubufs);
+}
+
+static void vhost_net_clear_ubuf_info(struct vhost_net *n)
+{
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		kfree(n->vqs[i].ubuf_info);
+		n->vqs[i].ubuf_info = NULL;
+	}
+}
+
+static int vhost_net_set_ubuf_info(struct vhost_net *n)
+{
+	bool zcopy;
+	int i;
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
+		zcopy = vhost_net_zcopy_mask & (0x1 << i);
+		if (!zcopy)
+			continue;
+		n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
+					      UIO_MAXIOV, GFP_KERNEL);
+		if  (!n->vqs[i].ubuf_info)
+			goto err;
+	}
+	return 0;
+
+err:
+	vhost_net_clear_ubuf_info(n);
+	return -ENOMEM;
+}
+
+static void vhost_net_vq_reset(struct vhost_net *n)
+{
+	int i;
+
+	vhost_net_clear_ubuf_info(n);
+
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
+	}
+
+}
+
+static void vhost_net_tx_packet(struct vhost_net *net)
+{
+	++net->tx_packets;
+	if (net->tx_packets < 1024)
+		return;
+	net->tx_packets = 0;
+	net->tx_zcopy_err = 0;
+}
+
+static void vhost_net_tx_err(struct vhost_net *net)
+{
+	++net->tx_zcopy_err;
+}
+
+static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
+{
+	/* TX flush waits for outstanding DMAs to be done.
+	 * Don't start new DMAs.
+	 */
+	return !net->tx_flush &&
+		net->tx_packets / 64 >= net->tx_zcopy_err;
+}
+
+static bool vhost_sock_zcopy(struct socket *sock)
+{
+	return unlikely(experimental_zcopytx) &&
+		sock_flag(sock->sk, SOCK_ZEROCOPY);
+}
+
 /* Pop first len bytes from iovec. Return number of segments used. */
 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
 			  size_t len, int iov_count)
 {
 	int seg = 0;
 	size_t size;
+
 	while (len && seg < iov_count) {
 		size = min(from->iov_len, len);
 		to->iov_base = from->iov_base;
@@ -79,6 +260,7 @@ static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
 {
 	int seg = 0;
 	size_t size;
+
 	while (len && seg < iovcount) {
 		size = min(from->iov_len, len);
 		to->iov_base = from->iov_base;
@@ -90,29 +272,69 @@ static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
 	}
 }
 
-/* Caller must have TX VQ lock */
-static void tx_poll_stop(struct vhost_net *net)
+/* In case of DMA done not in order in lower device driver for some reason.
+ * upend_idx is used to track end of used idx, done_idx is used to track head
+ * of used idx. Once lower device DMA done contiguously, we will signal KVM
+ * guest used idx.
+ */
+static void vhost_zerocopy_signal_used(struct vhost_net *net,
+				       struct vhost_virtqueue *vq)
 {
-	if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
-		return;
-	vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
-	net->tx_poll_state = VHOST_NET_POLL_STOPPED;
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	int i, add;
+	int j = 0;
+
+	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
+		if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
+			vhost_net_tx_err(net);
+		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
+			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
+			++j;
+		} else
+			break;
+	}
+	while (j) {
+		add = min(UIO_MAXIOV - nvq->done_idx, j);
+		vhost_add_used_and_signal_n(vq->dev, vq,
+					    &vq->heads[nvq->done_idx], add);
+		nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
+		j -= add;
+	}
 }
 
-/* Caller must have TX VQ lock */
-static void tx_poll_start(struct vhost_net *net, struct socket *sock)
+static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 {
-	if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
-		return;
-	vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
-	net->tx_poll_state = VHOST_NET_POLL_STARTED;
+	struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
+	struct vhost_virtqueue *vq = ubufs->vq;
+	int cnt;
+
+	rcu_read_lock_bh();
+
+	/* set len to mark this desc buffers done DMA */
+	vq->heads[ubuf->desc].len = success ?
+		VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
+	cnt = vhost_net_ubuf_put(ubufs);
+
+	/*
+	 * Trigger polling thread if guest stopped submitting new buffers:
+	 * in this case, the refcount after decrement will eventually reach 1.
+	 * We also trigger polling periodically after each 16 packets
+	 * (the value 16 here is more or less arbitrary, it's tuned to trigger
+	 * less than 10% of times).
+	 */
+	if (cnt <= 1 || !(cnt % 16))
+		vhost_poll_queue(&vq->poll);
+
+	rcu_read_unlock_bh();
 }
 
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
 static void handle_tx(struct vhost_net *net)
 {
-	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
+	struct vhost_virtqueue *vq = &nvq->vq;
 	unsigned out, in, s;
 	int head;
 	struct msghdr msg = {
@@ -124,32 +346,35 @@ static void handle_tx(struct vhost_net *net)
 		.msg_flags = MSG_DONTWAIT,
 	};
 	size_t len, total_len = 0;
-	int err, wmem;
+	int err;
 	size_t hdr_size;
 	struct socket *sock;
+	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
+	bool zcopy, zcopy_used;
 
-	/* TODO: check that we are running from vhost_worker? */
-	sock = rcu_dereference_check(vq->private_data, 1);
+	mutex_lock(&vq->mutex);
+	sock = vq->private_data;
 	if (!sock)
-		return;
-
-	wmem = atomic_read(&sock->sk->sk_wmem_alloc);
-	if (wmem >= sock->sk->sk_sndbuf) {
-		mutex_lock(&vq->mutex);
-		tx_poll_start(net, sock);
-		mutex_unlock(&vq->mutex);
-		return;
-	}
+		goto out;
 
-	mutex_lock(&vq->mutex);
-	vhost_disable_notify(vq);
+	vhost_disable_notify(&net->dev, vq);
 
-	if (wmem < sock->sk->sk_sndbuf / 2)
-		tx_poll_stop(net);
-	hdr_size = vq->vhost_hlen;
+	hdr_size = nvq->vhost_hlen;
+	zcopy = nvq->ubufs;
 
 	for (;;) {
-		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
+		/* Release DMAs done buffers first */
+		if (zcopy)
+			vhost_zerocopy_signal_used(net, vq);
+
+		/* If more outstanding DMAs, queue the work.
+		 * Handle upend_idx wrap around
+		 */
+		if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
+			      % UIO_MAXIOV == nvq->done_idx))
+			break;
+
+		head = vhost_get_vq_desc(vq, vq->iov,
 					 ARRAY_SIZE(vq->iov),
 					 &out, &in,
 					 NULL, NULL);
@@ -158,14 +383,8 @@ static void handle_tx(struct vhost_net *net)
 			break;
 		/* Nothing new?  Wait for eventfd to tell us they refilled. */
 		if (head == vq->num) {
-			wmem = atomic_read(&sock->sk->sk_wmem_alloc);
-			if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
-				tx_poll_start(net, sock);
-				set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
-				break;
-			}
-			if (unlikely(vhost_enable_notify(vq))) {
-				vhost_disable_notify(vq);
+			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+				vhost_disable_notify(&net->dev, vq);
 				continue;
 			}
 			break;
@@ -176,34 +395,67 @@ static void handle_tx(struct vhost_net *net)
 			break;
 		}
 		/* Skip header. TODO: support TSO. */
-		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
+		s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
 		msg.msg_iovlen = out;
 		len = iov_length(vq->iov, out);
 		/* Sanity check */
 		if (!len) {
 			vq_err(vq, "Unexpected header len for TX: "
 			       "%zd expected %zd\n",
-			       iov_length(vq->hdr, s), hdr_size);
+			       iov_length(nvq->hdr, s), hdr_size);
 			break;
 		}
+
+		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
+				   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
+				      nvq->done_idx
+				   && vhost_net_tx_select_zcopy(net);
+
+		/* use msg_control to pass vhost zerocopy ubuf info to skb */
+		if (zcopy_used) {
+			struct ubuf_info *ubuf;
+			ubuf = nvq->ubuf_info + nvq->upend_idx;
+
+			vq->heads[nvq->upend_idx].id = head;
+			vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
+			ubuf->callback = vhost_zerocopy_callback;
+			ubuf->ctx = nvq->ubufs;
+			ubuf->desc = nvq->upend_idx;
+			msg.msg_control = ubuf;
+			msg.msg_controllen = sizeof(ubuf);
+			ubufs = nvq->ubufs;
+			atomic_inc(&ubufs->refcount);
+			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
+		} else {
+			msg.msg_control = NULL;
+			ubufs = NULL;
+		}
 		/* TODO: Check specific error and bomb out unless ENOBUFS? */
 		err = sock->ops->sendmsg(NULL, sock, &msg, len);
 		if (unlikely(err < 0)) {
+			if (zcopy_used) {
+				vhost_net_ubuf_put(ubufs);
+				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
+					% UIO_MAXIOV;
+			}
 			vhost_discard_vq_desc(vq, 1);
-			tx_poll_start(net, sock);
 			break;
 		}
 		if (err != len)
 			pr_debug("Truncated TX packet: "
 				 " len %d != %zd\n", err, len);
-		vhost_add_used_and_signal(&net->dev, vq, head, 0);
+		if (!zcopy_used)
+			vhost_add_used_and_signal(&net->dev, vq, head, 0);
+		else
+			vhost_zerocopy_signal_used(net, vq);
 		total_len += len;
+		vhost_net_tx_packet(net);
 		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 			vhost_poll_queue(&vq->poll);
 			break;
 		}
 	}
-
+out:
 	mutex_unlock(&vq->mutex);
 }
 
@@ -211,12 +463,17 @@ static int peek_head_len(struct sock *sk)
 {
 	struct sk_buff *head;
 	int len = 0;
+	unsigned long flags;
 
-	lock_sock(sk);
+	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 	head = skb_peek(&sk->sk_receive_queue);
-	if (head)
+	if (likely(head)) {
 		len = head->len;
-	release_sock(sk);
+		if (vlan_tx_tag_present(head))
+			len += VLAN_HLEN;
+	}
+
+	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 	return len;
 }
 
@@ -227,6 +484,7 @@ static int peek_head_len(struct sock *sk)
  * @iovcount	- returned count of io vectors we fill
  * @log		- vhost log
  * @log_num	- log offset
+ * @quota       - headcount quota, 1 for big buffer
  *	returns number of buffer heads allocated, negative on error
  */
 static int get_rx_bufs(struct vhost_virtqueue *vq,
@@ -234,7 +492,8 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 		       int datalen,
 		       unsigned *iovcount,
 		       struct vhost_log *log,
-		       unsigned *log_num)
+		       unsigned *log_num,
+		       unsigned int quota)
 {
 	unsigned int out, in;
 	int seg = 0;
@@ -242,14 +501,18 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 	unsigned d;
 	int r, nlogs = 0;
 
-	while (datalen > 0) {
+	while (datalen > 0 && headcount < quota) {
 		if (unlikely(seg >= UIO_MAXIOV)) {
 			r = -ENOBUFS;
 			goto err;
 		}
-		d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
+		r = vhost_get_vq_desc(vq, vq->iov + seg,
 				      ARRAY_SIZE(vq->iov) - seg, &out,
 				      &in, log, log_num);
+		if (unlikely(r < 0))
+			goto err;
+
+		d = r;
 		if (d == vq->num) {
 			r = 0;
 			goto err;
@@ -274,6 +537,12 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
 	*iovcount = seg;
 	if (unlikely(log))
 		*log_num = nlogs;
+
+	/* Detect overrun */
+	if (unlikely(datalen > 0)) {
+		r = UIO_MAXIOV + 1;
+		goto err;
+	}
 	return headcount;
 err:
 	vhost_discard_vq_desc(vq, headcount);
@@ -282,119 +551,10 @@ err:
 
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
-static void handle_rx_big(struct vhost_net *net)
-{
-	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
-	unsigned out, in, log, s;
-	int head;
-	struct vhost_log *vq_log;
-	struct msghdr msg = {
-		.msg_name = NULL,
-		.msg_namelen = 0,
-		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
-		.msg_controllen = 0,
-		.msg_iov = vq->iov,
-		.msg_flags = MSG_DONTWAIT,
-	};
-
-	struct virtio_net_hdr hdr = {
-		.flags = 0,
-		.gso_type = VIRTIO_NET_HDR_GSO_NONE
-	};
-
-	size_t len, total_len = 0;
-	int err;
-	size_t hdr_size;
-	/* TODO: check that we are running from vhost_worker? */
-	struct socket *sock = rcu_dereference_check(vq->private_data, 1);
-	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
-		return;
-
-	mutex_lock(&vq->mutex);
-	vhost_disable_notify(vq);
-	hdr_size = vq->vhost_hlen;
-
-	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
-		vq->log : NULL;
-
-	for (;;) {
-		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
-					 ARRAY_SIZE(vq->iov),
-					 &out, &in,
-					 vq_log, &log);
-		/* On error, stop handling until the next kick. */
-		if (unlikely(head < 0))
-			break;
-		/* OK, now we need to know about added descriptors. */
-		if (head == vq->num) {
-			if (unlikely(vhost_enable_notify(vq))) {
-				/* They have slipped one in as we were
-				 * doing that: check again. */
-				vhost_disable_notify(vq);
-				continue;
-			}
-			/* Nothing new?  Wait for eventfd to tell us
-			 * they refilled. */
-			break;
-		}
-		/* We don't need to be notified again. */
-		if (out) {
-			vq_err(vq, "Unexpected descriptor format for RX: "
-			       "out %d, int %d\n",
-			       out, in);
-			break;
-		}
-		/* Skip header. TODO: support TSO/mergeable rx buffers. */
-		s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
-		msg.msg_iovlen = in;
-		len = iov_length(vq->iov, in);
-		/* Sanity check */
-		if (!len) {
-			vq_err(vq, "Unexpected header len for RX: "
-			       "%zd expected %zd\n",
-			       iov_length(vq->hdr, s), hdr_size);
-			break;
-		}
-		err = sock->ops->recvmsg(NULL, sock, &msg,
-					 len, MSG_DONTWAIT | MSG_TRUNC);
-		/* TODO: Check specific error and bomb out unless EAGAIN? */
-		if (err < 0) {
-			vhost_discard_vq_desc(vq, 1);
-			break;
-		}
-		/* TODO: Should check and handle checksum. */
-		if (err > len) {
-			pr_debug("Discarded truncated rx packet: "
-				 " len %d > %zd\n", err, len);
-			vhost_discard_vq_desc(vq, 1);
-			continue;
-		}
-		len = err;
-		err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
-		if (err) {
-			vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
-			       vq->iov->iov_base, err);
-			break;
-		}
-		len += hdr_size;
-		vhost_add_used_and_signal(&net->dev, vq, head, len);
-		if (unlikely(vq_log))
-			vhost_log_write(vq, vq_log, log, len);
-		total_len += len;
-		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
-			vhost_poll_queue(&vq->poll);
-			break;
-		}
-	}
-
-	mutex_unlock(&vq->mutex);
-}
-
-/* Expects to be always run from workqueue - which acts as
- * read-size critical section for our kind of RCU. */
-static void handle_rx_mergeable(struct vhost_net *net)
+static void handle_rx(struct vhost_net *net)
 {
-	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
+	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
+	struct vhost_virtqueue *vq = &nvq->vq;
 	unsigned uninitialized_var(in), log;
 	struct vhost_log *vq_log;
 	struct msghdr msg = {
@@ -405,43 +565,53 @@ static void handle_rx_mergeable(struct vhost_net *net)
 		.msg_iov = vq->iov,
 		.msg_flags = MSG_DONTWAIT,
 	};
-
 	struct virtio_net_hdr_mrg_rxbuf hdr = {
 		.hdr.flags = 0,
 		.hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 	};
-
 	size_t total_len = 0;
-	int err, headcount;
+	int err, mergeable;
+	s16 headcount;
 	size_t vhost_hlen, sock_hlen;
 	size_t vhost_len, sock_len;
-	/* TODO: check that we are running from vhost_worker? */
-	struct socket *sock = rcu_dereference_check(vq->private_data, 1);
-	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
-		return;
+	struct socket *sock;
 
 	mutex_lock(&vq->mutex);
-	vhost_disable_notify(vq);
-	vhost_hlen = vq->vhost_hlen;
-	sock_hlen = vq->sock_hlen;
+	sock = vq->private_data;
+	if (!sock)
+		goto out;
+	vhost_disable_notify(&net->dev, vq);
 
-	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
+	vhost_hlen = nvq->vhost_hlen;
+	sock_hlen = nvq->sock_hlen;
+
+	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 		vq->log : NULL;
+	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
 
 	while ((sock_len = peek_head_len(sock->sk))) {
 		sock_len += sock_hlen;
 		vhost_len = sock_len + vhost_hlen;
 		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
-					&in, vq_log, &log);
+					&in, vq_log, &log,
+					likely(mergeable) ? UIO_MAXIOV : 1);
 		/* On error, stop handling until the next kick. */
 		if (unlikely(headcount < 0))
 			break;
+		/* On overrun, truncate and discard */
+		if (unlikely(headcount > UIO_MAXIOV)) {
+			msg.msg_iovlen = 1;
+			err = sock->ops->recvmsg(NULL, sock, &msg,
+						 1, MSG_DONTWAIT | MSG_TRUNC);
+			pr_debug("Discarded rx packet: len %zd\n", sock_len);
+			continue;
+		}
 		/* OK, now we need to know about added descriptors. */
 		if (!headcount) {
-			if (unlikely(vhost_enable_notify(vq))) {
+			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 				/* They have slipped one in as we were
 				 * doing that: check again. */
-				vhost_disable_notify(vq);
+				vhost_disable_notify(&net->dev, vq);
 				continue;
 			}
 			/* Nothing new?  Wait for eventfd to tell us
@@ -451,11 +621,11 @@ static void handle_rx_mergeable(struct vhost_net *net)
 		/* We don't need to be notified again. */
 		if (unlikely((vhost_hlen)))
 			/* Skip header. TODO: support TSO. */
-			move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
+			move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
 		else
 			/* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 			 * needed because recvmsg can modify msg_iov. */
-			copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
+			copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
 		msg.msg_iovlen = in;
 		err = sock->ops->recvmsg(NULL, sock, &msg,
 					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
@@ -469,15 +639,15 @@ static void handle_rx_mergeable(struct vhost_net *net)
 			continue;
 		}
 		if (unlikely(vhost_hlen) &&
-		    memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
+		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
 				      vhost_hlen)) {
 			vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 			       vq->iov->iov_base);
 			break;
 		}
 		/* TODO: Should check and handle checksum. */
-		if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF) &&
-		    memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
+		if (likely(mergeable) &&
+		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
 				      offsetof(typeof(hdr), num_buffers),
 				      sizeof hdr.num_buffers)) {
 			vq_err(vq, "Failed num_buffers write");
@@ -494,18 +664,10 @@ static void handle_rx_mergeable(struct vhost_net *net)
 			break;
 		}
 	}
-
+out:
 	mutex_unlock(&vq->mutex);
 }
 
-static void handle_rx(struct vhost_net *net)
-{
-	if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
-		handle_rx_mergeable(net);
-	else
-		handle_rx_big(net);
-}
-
 static void handle_tx_kick(struct vhost_work *work)
 {
 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
@@ -540,25 +702,40 @@ static void handle_rx_net(struct vhost_work *work)
 
 static int vhost_net_open(struct inode *inode, struct file *f)
 {
-	struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
+	struct vhost_net *n;
 	struct vhost_dev *dev;
-	int r;
+	struct vhost_virtqueue **vqs;
+	int i;
 
-	if (!n)
+	n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
+	if (!n) {
+		n = vmalloc(sizeof *n);
+		if (!n)
+			return -ENOMEM;
+	}
+	vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		kvfree(n);
 		return -ENOMEM;
+	}
 
 	dev = &n->dev;
-	n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
-	n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
-	r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
-	if (r < 0) {
-		kfree(n);
-		return r;
+	vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
+	vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
+	n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
+	n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
+	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
+		n->vqs[i].ubufs = NULL;
+		n->vqs[i].ubuf_info = NULL;
+		n->vqs[i].upend_idx = 0;
+		n->vqs[i].done_idx = 0;
+		n->vqs[i].vhost_hlen = 0;
+		n->vqs[i].sock_hlen = 0;
 	}
+	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 
 	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
-	n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 
 	f->private_data = n;
 
@@ -568,29 +745,27 @@ static int vhost_net_open(struct inode *inode, struct file *f)
 static void vhost_net_disable_vq(struct vhost_net *n,
 				 struct vhost_virtqueue *vq)
 {
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 	if (!vq->private_data)
 		return;
-	if (vq == n->vqs + VHOST_NET_VQ_TX) {
-		tx_poll_stop(n);
-		n->tx_poll_state = VHOST_NET_POLL_DISABLED;
-	} else
-		vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
+	vhost_poll_stop(poll);
 }
 
-static void vhost_net_enable_vq(struct vhost_net *n,
+static int vhost_net_enable_vq(struct vhost_net *n,
 				struct vhost_virtqueue *vq)
 {
+	struct vhost_net_virtqueue *nvq =
+		container_of(vq, struct vhost_net_virtqueue, vq);
+	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 	struct socket *sock;
 
-	sock = rcu_dereference_protected(vq->private_data,
-					 lockdep_is_held(&vq->mutex));
+	sock = vq->private_data;
 	if (!sock)
-		return;
-	if (vq == n->vqs + VHOST_NET_VQ_TX) {
-		n->tx_poll_state = VHOST_NET_POLL_STOPPED;
-		tx_poll_start(n, sock);
-	} else
-		vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
+		return 0;
+
+	return vhost_poll_start(poll, sock->file);
 }
 
 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
@@ -599,10 +774,9 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 	struct socket *sock;
 
 	mutex_lock(&vq->mutex);
-	sock = rcu_dereference_protected(vq->private_data,
-					 lockdep_is_held(&vq->mutex));
+	sock = vq->private_data;
 	vhost_net_disable_vq(n, vq);
-	rcu_assign_pointer(vq->private_data, NULL);
+	vq->private_data = NULL;
 	mutex_unlock(&vq->mutex);
 	return sock;
 }
@@ -610,20 +784,31 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 			   struct socket **rx_sock)
 {
-	*tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
-	*rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
+	*tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
+	*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 }
 
 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 {
 	vhost_poll_flush(n->poll + index);
-	vhost_poll_flush(&n->dev.vqs[index].poll);
+	vhost_poll_flush(&n->vqs[index].vq.poll);
 }
 
 static void vhost_net_flush(struct vhost_net *n)
 {
 	vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 	vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
+	if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = true;
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		/* Wait for all lower device DMAs done. */
+		vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
+		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+		n->tx_flush = false;
+		atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
+		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
+	}
 }
 
 static int vhost_net_release(struct inode *inode, struct file *f)
@@ -634,15 +819,20 @@ static int vhost_net_release(struct inode *inode, struct file *f)
 
 	vhost_net_stop(n, &tx_sock, &rx_sock);
 	vhost_net_flush(n);
-	vhost_dev_cleanup(&n->dev);
+	vhost_dev_stop(&n->dev);
+	vhost_dev_cleanup(&n->dev, false);
+	vhost_net_vq_reset(n);
 	if (tx_sock)
-		fput(tx_sock->file);
+		sockfd_put(tx_sock);
 	if (rx_sock)
-		fput(rx_sock->file);
+		sockfd_put(rx_sock);
+	/* Make sure no callbacks are outstanding */
+	synchronize_rcu_bh();
 	/* We do an extra flush before freeing memory,
 	 * since jobs can re-queue themselves. */
 	vhost_net_flush(n);
-	kfree(n);
+	kfree(n->dev.vqs);
+	kvfree(n);
 	return 0;
 }
 
@@ -654,6 +844,7 @@ static struct socket *get_raw_socket(int fd)
 	} uaddr;
 	int uaddr_len = sizeof uaddr, r;
 	struct socket *sock = sockfd_lookup(fd, &r);
+
 	if (!sock)
 		return ERR_PTR(-ENOTSOCK);
 
@@ -674,7 +865,7 @@ static struct socket *get_raw_socket(int fd)
 	}
 	return sock;
 err:
-	fput(sock->file);
+	sockfd_put(sock);
 	return ERR_PTR(r);
 }
 
@@ -682,6 +873,7 @@ static struct socket *get_tap_socket(int fd)
 {
 	struct file *file = fget(fd);
 	struct socket *sock;
+
 	if (!file)
 		return ERR_PTR(-EBADF);
 	sock = tun_get_socket(file);
@@ -696,6 +888,7 @@ static struct socket *get_tap_socket(int fd)
 static struct socket *get_socket(int fd)
 {
 	struct socket *sock;
+
 	/* special case to disable backend */
 	if (fd == -1)
 		return NULL;
@@ -712,6 +905,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 {
 	struct socket *sock, *oldsock;
 	struct vhost_virtqueue *vq;
+	struct vhost_net_virtqueue *nvq;
+	struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 	int r;
 
 	mutex_lock(&n->dev.mutex);
@@ -723,7 +918,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 		r = -ENOBUFS;
 		goto err;
 	}
-	vq = n->vqs + index;
+	vq = &n->vqs[index].vq;
+	nvq = &n->vqs[index];
 	mutex_lock(&vq->mutex);
 
 	/* Verify that ring has been setup correctly. */
@@ -738,24 +934,56 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 	}
 
 	/* start polling new socket */
-	oldsock = rcu_dereference_protected(vq->private_data,
-					    lockdep_is_held(&vq->mutex));
+	oldsock = vq->private_data;
 	if (sock != oldsock) {
-                vhost_net_disable_vq(n, vq);
-                rcu_assign_pointer(vq->private_data, sock);
-                vhost_net_enable_vq(n, vq);
+		ubufs = vhost_net_ubuf_alloc(vq,
+					     sock && vhost_sock_zcopy(sock));
+		if (IS_ERR(ubufs)) {
+			r = PTR_ERR(ubufs);
+			goto err_ubufs;
+		}
+
+		vhost_net_disable_vq(n, vq);
+		vq->private_data = sock;
+		r = vhost_init_used(vq);
+		if (r)
+			goto err_used;
+		r = vhost_net_enable_vq(n, vq);
+		if (r)
+			goto err_used;
+
+		oldubufs = nvq->ubufs;
+		nvq->ubufs = ubufs;
+
+		n->tx_packets = 0;
+		n->tx_zcopy_err = 0;
+		n->tx_flush = false;
 	}
 
 	mutex_unlock(&vq->mutex);
 
+	if (oldubufs) {
+		vhost_net_ubuf_put_wait_and_free(oldubufs);
+		mutex_lock(&vq->mutex);
+		vhost_zerocopy_signal_used(n, vq);
+		mutex_unlock(&vq->mutex);
+	}
+
 	if (oldsock) {
 		vhost_net_flush_vq(n, index);
-		fput(oldsock->file);
+		sockfd_put(oldsock);
 	}
 
 	mutex_unlock(&n->dev.mutex);
 	return 0;
 
+err_used:
+	vq->private_data = oldsock;
+	vhost_net_enable_vq(n, vq);
+	if (ubufs)
+		vhost_net_ubuf_put_wait_and_free(ubufs);
+err_ubufs:
+	sockfd_put(sock);
 err_vq:
 	mutex_unlock(&vq->mutex);
 err:
@@ -768,19 +996,27 @@ static long vhost_net_reset_owner(struct vhost_net *n)
 	struct socket *tx_sock = NULL;
 	struct socket *rx_sock = NULL;
 	long err;
+	struct vhost_memory *memory;
+
 	mutex_lock(&n->dev.mutex);
 	err = vhost_dev_check_owner(&n->dev);
 	if (err)
 		goto done;
+	memory = vhost_dev_reset_owner_prepare();
+	if (!memory) {
+		err = -ENOMEM;
+		goto done;
+	}
 	vhost_net_stop(n, &tx_sock, &rx_sock);
 	vhost_net_flush(n);
-	err = vhost_dev_reset_owner(&n->dev);
+	vhost_dev_reset_owner(&n->dev, memory);
+	vhost_net_vq_reset(n);
 done:
 	mutex_unlock(&n->dev.mutex);
 	if (tx_sock)
-		fput(tx_sock->file);
+		sockfd_put(tx_sock);
 	if (rx_sock)
-		fput(rx_sock->file);
+		sockfd_put(rx_sock);
 	return err;
 }
 
@@ -807,19 +1043,38 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
 		mutex_unlock(&n->dev.mutex);
 		return -EFAULT;
 	}
-	n->dev.acked_features = features;
-	smp_wmb();
 	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
-		mutex_lock(&n->vqs[i].mutex);
+		mutex_lock(&n->vqs[i].vq.mutex);
+		n->vqs[i].vq.acked_features = features;
 		n->vqs[i].vhost_hlen = vhost_hlen;
 		n->vqs[i].sock_hlen = sock_hlen;
-		mutex_unlock(&n->vqs[i].mutex);
+		mutex_unlock(&n->vqs[i].vq.mutex);
 	}
-	vhost_net_flush(n);
 	mutex_unlock(&n->dev.mutex);
 	return 0;
 }
 
+static long vhost_net_set_owner(struct vhost_net *n)
+{
+	int r;
+
+	mutex_lock(&n->dev.mutex);
+	if (vhost_dev_has_owner(&n->dev)) {
+		r = -EBUSY;
+		goto out;
+	}
+	r = vhost_net_set_ubuf_info(n);
+	if (r)
+		goto out;
+	r = vhost_dev_set_owner(&n->dev);
+	if (r)
+		vhost_net_clear_ubuf_info(n);
+	vhost_net_flush(n);
+out:
+	mutex_unlock(&n->dev.mutex);
+	return r;
+}
+
 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 			    unsigned long arg)
 {
@@ -829,28 +1084,34 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 	struct vhost_vring_file backend;
 	u64 features;
 	int r;
+
 	switch (ioctl) {
 	case VHOST_NET_SET_BACKEND:
 		if (copy_from_user(&backend, argp, sizeof backend))
 			return -EFAULT;
 		return vhost_net_set_backend(n, backend.index, backend.fd);
 	case VHOST_GET_FEATURES:
-		features = VHOST_FEATURES;
+		features = VHOST_NET_FEATURES;
 		if (copy_to_user(featurep, &features, sizeof features))
 			return -EFAULT;
 		return 0;
 	case VHOST_SET_FEATURES:
 		if (copy_from_user(&features, featurep, sizeof features))
 			return -EFAULT;
-		if (features & ~VHOST_FEATURES)
+		if (features & ~VHOST_NET_FEATURES)
 			return -EOPNOTSUPP;
 		return vhost_net_set_features(n, features);
 	case VHOST_RESET_OWNER:
 		return vhost_net_reset_owner(n);
+	case VHOST_SET_OWNER:
+		return vhost_net_set_owner(n);
 	default:
 		mutex_lock(&n->dev.mutex);
-		r = vhost_dev_ioctl(&n->dev, ioctl, arg);
-		vhost_net_flush(n);
+		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
+		else
+			vhost_net_flush(n);
 		mutex_unlock(&n->dev.mutex);
 		return r;
 	}
@@ -876,13 +1137,15 @@ static const struct file_operations vhost_net_fops = {
 };
 
 static struct miscdevice vhost_net_misc = {
-	MISC_DYNAMIC_MINOR,
-	"vhost-net",
-	&vhost_net_fops,
+	.minor = VHOST_NET_MINOR,
+	.name = "vhost-net",
+	.fops = &vhost_net_fops,
 };
 
 static int vhost_net_init(void)
 {
+	if (experimental_zcopytx)
+		vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
 	return misc_register(&vhost_net_misc);
 }
 module_init(vhost_net_init);
@@ -897,3 +1160,5 @@ MODULE_VERSION("0.0.1");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Michael S. Tsirkin");
 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
+MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
+MODULE_ALIAS("devname:vhost-net");