3 files changed, 315 insertions, 18 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index d395b59289ae..f13e56babe4b 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -74,6 +74,22 @@ static int move_iovec_hdr(struct iovec *from, struct iovec *to,
         }
         return seg;
 }
+/* Copy iovec entries for len bytes from iovec. */
+static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
+                           size_t len, int iovcount)
+{
+        int seg = 0;
+        size_t size;
+        while (len && seg < iovcount) {
+                size = min(from->iov_len, len);
+                to->iov_base = from->iov_base;
+                to->iov_len = size;
+                len -= size;
+                ++from;
+                ++to;
+                ++seg;
+        }
+}
 
 /* Caller must have TX VQ lock */
 static void tx_poll_stop(struct vhost_net *net)
@@ -129,7 +145,7 @@ static void handle_tx(struct vhost_net *net)
 
         if (wmem < sock->sk->sk_sndbuf / 2)
                 tx_poll_stop(net);
-        hdr_size = vq->hdr_size;
+        hdr_size = vq->vhost_hlen;
 
         for (;;) {
                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
@@ -172,7 +188,7 @@ static void handle_tx(struct vhost_net *net)
                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
                 if (unlikely(err < 0)) {
-                        vhost_discard_vq_desc(vq);
+                        vhost_discard_vq_desc(vq, 1);
                         tx_poll_start(net, sock);
                         break;
                 }
@@ -191,9 +207,82 @@ static void handle_tx(struct vhost_net *net)
         unuse_mm(net->dev.mm);
 }
 
+static int peek_head_len(struct sock *sk)
+{
+        struct sk_buff *head;
+        int len = 0;
+
+        lock_sock(sk);
+        head = skb_peek(&sk->sk_receive_queue);
+        if (head)
+                len = head->len;
+        release_sock(sk);
+        return len;
+}
+
+/* This is a multi-buffer version of vhost_get_desc, that works if
+ *      vq has read descriptors only.
+ * @vq          - the relevant virtqueue
+ * @datalen     - data length we'll be reading
+ * @iovcount    - returned count of io vectors we fill
+ * @log         - vhost log
+ * @log_num     - log offset
+ *      returns number of buffer heads allocated, negative on error
+ */
+static int get_rx_bufs(struct vhost_virtqueue *vq,
+                       struct vring_used_elem *heads,
+                       int datalen,
+                       unsigned *iovcount,
+                       struct vhost_log *log,
+                       unsigned *log_num)
+{
+        unsigned int out, in;
+        int seg = 0;
+        int headcount = 0;
+        unsigned d;
+        int r, nlogs = 0;
+
+        while (datalen > 0) {
+                if (unlikely(headcount >= VHOST_NET_MAX_SG)) {
+                        r = -ENOBUFS;
+                        goto err;
+                }
+                d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
+                                      ARRAY_SIZE(vq->iov) - seg, &out,
+                                      &in, log, log_num);
+                if (d == vq->num) {
+                        r = 0;
+                        goto err;
+                }
+                if (unlikely(out || in <= 0)) {
+                        vq_err(vq, "unexpected descriptor format for RX: "
+                                "out %d, in %d\n", out, in);
+                        r = -EINVAL;
+                        goto err;
+                }
+                if (unlikely(log)) {
+                        nlogs += *log_num;
+                        log += *log_num;
+                }
+                heads[headcount].id = d;
+                heads[headcount].len = iov_length(vq->iov + seg, in);
+                datalen -= heads[headcount].len;
+                ++headcount;
+                seg += in;
+        }
+        heads[headcount - 1].len += datalen;
+        *iovcount = seg;
+        if (unlikely(log))
+                *log_num = nlogs;
+        return headcount;
+err:
+        vhost_discard_vq_desc(vq, headcount);
+        return r;
+}
+
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
-static void handle_rx(struct vhost_net *net)
+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;
@@ -223,7 +312,7 @@ static void handle_rx(struct vhost_net *net)
         use_mm(net->dev.mm);
         mutex_lock(&vq->mutex);
         vhost_disable_notify(vq);
-        hdr_size = vq->hdr_size;
+        hdr_size = vq->vhost_hlen;
 
         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
                 vq->log : NULL;
@@ -270,14 +359,14 @@ static void handle_rx(struct vhost_net *net)
                                          len, MSG_DONTWAIT | MSG_TRUNC);
                 /* TODO: Check specific error and bomb out unless EAGAIN? */
                 if (err < 0) {
-                        vhost_discard_vq_desc(vq);
+                        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);
+                        vhost_discard_vq_desc(vq, 1);
                         continue;
                 }
                 len = err;
@@ -302,6 +391,123 @@ static void handle_rx(struct vhost_net *net)
         unuse_mm(net->dev.mm);
 }
 
+/* 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)
+{
+        struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
+        unsigned uninitialized_var(in), log;
+        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_mrg_rxbuf hdr = {
+                .hdr.flags = 0,
+                .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
+        };
+
+        size_t total_len = 0;
+        int err, headcount;
+        size_t vhost_hlen, sock_hlen;
+        size_t vhost_len, sock_len;
+        struct socket *sock = rcu_dereference(vq->private_data);
+        if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
+                return;
+
+        use_mm(net->dev.mm);
+        mutex_lock(&vq->mutex);
+        vhost_disable_notify(vq);
+        vhost_hlen = vq->vhost_hlen;
+        sock_hlen = vq->sock_hlen;
+
+        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
+                vq->log : NULL;
+
+        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);
+                /* On error, stop handling until the next kick. */
+                if (unlikely(headcount < 0))
+                        break;
+                /* OK, now we need to know about added descriptors. */
+                if (!headcount) {
+                        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 (unlikely((vhost_hlen)))
+                        /* Skip header. TODO: support TSO. */
+                        move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
+                else
+                        /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
+                         * needed because sendmsg can modify msg_iov. */
+                        copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
+                msg.msg_iovlen = in;
+                err = sock->ops->recvmsg(NULL, sock, &msg,
+                                         sock_len, MSG_DONTWAIT | MSG_TRUNC);
+                /* Userspace might have consumed the packet meanwhile:
+                 * it's not supposed to do this usually, but might be hard
+                 * to prevent. Discard data we got (if any) and keep going. */
+                if (unlikely(err != sock_len)) {
+                        pr_debug("Discarded rx packet: "
+                                 " len %d, expected %zd\n", err, sock_len);
+                        vhost_discard_vq_desc(vq, headcount);
+                        continue;
+                }
+                if (unlikely(vhost_hlen) &&
+                    memcpy_toiovecend(vq->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,
+                                      offsetof(typeof(hdr), num_buffers),
+                                      sizeof hdr.num_buffers)) {
+                        vq_err(vq, "Failed num_buffers write");
+                        vhost_discard_vq_desc(vq, headcount);
+                        break;
+                }
+                vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
+                                            headcount);
+                if (unlikely(vq_log))
+                        vhost_log_write(vq, vq_log, log, vhost_len);
+                total_len += vhost_len;
+                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
+                        vhost_poll_queue(&vq->poll);
+                        break;
+                }
+        }
+
+        mutex_unlock(&vq->mutex);
+        unuse_mm(net->dev.mm);
+}
+
+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,
@@ -577,9 +783,21 @@ done:
 
 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 {
-        size_t hdr_size = features & (1 << VHOST_NET_F_VIRTIO_NET_HDR) ?
-                sizeof(struct virtio_net_hdr) : 0;
+        size_t vhost_hlen, sock_hlen, hdr_len;
         int i;
+
+        hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
+                        sizeof(struct virtio_net_hdr_mrg_rxbuf) :
+                        sizeof(struct virtio_net_hdr);
+        if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
+                /* vhost provides vnet_hdr */
+                vhost_hlen = hdr_len;
+                sock_hlen = 0;
+        } else {
+                /* socket provides vnet_hdr */
+                vhost_hlen = 0;
+                sock_hlen = hdr_len;
+        }
         mutex_lock(&n->dev.mutex);
         if ((features & (1 << VHOST_F_LOG_ALL)) &&
             !vhost_log_access_ok(&n->dev)) {
@@ -590,7 +808,8 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
         smp_wmb();
         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
                 mutex_lock(&n->vqs[i].mutex);
-                n->vqs[i].hdr_size = hdr_size;
+                n->vqs[i].vhost_hlen = vhost_hlen;
+                n->vqs[i].sock_hlen = sock_hlen;
                 mutex_unlock(&n->vqs[i].mutex);
         }
         vhost_net_flush(n);
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index dd2d019b889f..e05557d52999 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -149,7 +149,8 @@ static void vhost_vq_reset(struct vhost_dev *dev,
         vq->used_flags = 0;
         vq->log_used = false;
         vq->log_addr = -1ull;
-        vq->hdr_size = 0;
+        vq->vhost_hlen = 0;
+        vq->sock_hlen = 0;
         vq->private_data = NULL;
         vq->log_base = NULL;
         vq->error_ctx = NULL;
@@ -1101,9 +1102,9 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 }
 
 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
-void vhost_discard_vq_desc(struct vhost_virtqueue *vq)
+void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
 {
-        vq->last_avail_idx--;
+        vq->last_avail_idx -= n;
 }
 
 /* After we've used one of their buffers, we tell them about it.  We'll then
@@ -1148,6 +1149,67 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
         return 0;
 }
 
+static int __vhost_add_used_n(struct vhost_virtqueue *vq,
+                            struct vring_used_elem *heads,
+                            unsigned count)
+{
+        struct vring_used_elem __user *used;
+        int start;
+
+        start = vq->last_used_idx % vq->num;
+        used = vq->used->ring + start;
+        if (copy_to_user(used, heads, count * sizeof *used)) {
+                vq_err(vq, "Failed to write used");
+                return -EFAULT;
+        }
+        if (unlikely(vq->log_used)) {
+                /* Make sure data is seen before log. */
+                smp_wmb();
+                /* Log used ring entry write. */
+                log_write(vq->log_base,
+                          vq->log_addr +
+                           ((void __user *)used - (void __user *)vq->used),
+                          count * sizeof *used);
+        }
+        vq->last_used_idx += count;
+        return 0;
+}
+
+/* After we've used one of their buffers, we tell them about it.  We'll then
+ * want to notify the guest, using eventfd. */
+int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
+                     unsigned count)
+{
+        int start, n, r;
+
+        start = vq->last_used_idx % vq->num;
+        n = vq->num - start;
+        if (n < count) {
+                r = __vhost_add_used_n(vq, heads, n);
+                if (r < 0)
+                        return r;
+                heads += n;
+                count -= n;
+        }
+        r = __vhost_add_used_n(vq, heads, count);
+
+        /* Make sure buffer is written before we update index. */
+        smp_wmb();
+        if (put_user(vq->last_used_idx, &vq->used->idx)) {
+                vq_err(vq, "Failed to increment used idx");
+                return -EFAULT;
+        }
+        if (unlikely(vq->log_used)) {
+                /* Log used index update. */
+                log_write(vq->log_base,
+                          vq->log_addr + offsetof(struct vring_used, idx),
+                          sizeof vq->used->idx);
+                if (vq->log_ctx)
+                        eventfd_signal(vq->log_ctx, 1);
+        }
+        return r;
+}
+
 /* This actually signals the guest, using eventfd. */
 void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 {
@@ -1182,6 +1244,15 @@ void vhost_add_used_and_signal(struct vhost_dev *dev,
         vhost_signal(dev, vq);
 }
 
+/* multi-buffer version of vhost_add_used_and_signal */
+void vhost_add_used_and_signal_n(struct vhost_dev *dev,
+                                 struct vhost_virtqueue *vq,
+                                 struct vring_used_elem *heads, unsigned count)
+{
+        vhost_add_used_n(vq, heads, count);
+        vhost_signal(dev, vq);
+}
+
 /* OK, now we need to know about added descriptors. */
 bool vhost_enable_notify(struct vhost_virtqueue *vq)
 {
@@ -1206,7 +1277,7 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
                 return false;
         }
 
-        return avail_idx != vq->last_avail_idx;
+        return avail_idx != vq->avail_idx;
 }
 
 /* We don't need to be notified again. */
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 3693327549b3..afd77295971c 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -96,7 +96,9 @@ struct vhost_virtqueue {
         struct iovec indirect[VHOST_NET_MAX_SG];
         struct iovec iov[VHOST_NET_MAX_SG];
         struct iovec hdr[VHOST_NET_MAX_SG];
-        size_t hdr_size;
+        size_t vhost_hlen;
+        size_t sock_hlen;
+        struct vring_used_elem heads[VHOST_NET_MAX_SG];
         /* We use a kind of RCU to access private pointer.
          * All readers access it from worker, which makes it possible to
          * flush the vhost_work instead of synchronize_rcu. Therefore readers do
@@ -139,12 +141,16 @@ int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
                       struct iovec iov[], unsigned int iov_count,
                       unsigned int *out_num, unsigned int *in_num,
                       struct vhost_log *log, unsigned int *log_num);
-void vhost_discard_vq_desc(struct vhost_virtqueue *);
+void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 
 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
-void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
+int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
+                     unsigned count);
 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
-                               unsigned int head, int len);
+                               unsigned int id, int len);
+void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
+                               struct vring_used_elem *heads, unsigned count);
+void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 void vhost_disable_notify(struct vhost_virtqueue *);
 bool vhost_enable_notify(struct vhost_virtqueue *);
 
@@ -161,7 +167,8 @@ enum {
         VHOST_FEATURES = (1 << VIRTIO_F_NOTIFY_ON_EMPTY) |
                          (1 << VIRTIO_RING_F_INDIRECT_DESC) |
                          (1 << VHOST_F_LOG_ALL) |
-                         (1 << VHOST_NET_F_VIRTIO_NET_HDR),
+                         (1 << VHOST_NET_F_VIRTIO_NET_HDR) |
+                         (1 << VIRTIO_NET_F_MRG_RXBUF),
 };
 
 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)