net/macvtap: add vhost support

This adds support for passing a macvtap file descriptor into
vhost-net, much like we already do for tun/tap.

Most of the new code is taken from the respective patch
in the tun driver and may get consolidated in the future.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 97 insertions, 24 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 705099749766..e354501ab297 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -58,6 +58,8 @@ static unsigned int macvtap_major;
 static struct class *macvtap_class;
 static struct cdev macvtap_cdev;
 
+static const struct proto_ops macvtap_socket_ops;
+
 /*
  * RCU usage:
  * The macvtap_queue and the macvlan_dev are loosely coupled, the
@@ -176,7 +178,7 @@ static int macvtap_forward(struct net_device *dev, struct sk_buff *skb)
                 return -ENOLINK;
 
         skb_queue_tail(&q->sk.sk_receive_queue, skb);
-        wake_up(q->sk.sk_sleep);
+        wake_up_interruptible_poll(q->sk.sk_sleep, POLLIN | POLLRDNORM | POLLRDBAND);
         return 0;
 }
 
@@ -242,7 +244,7 @@ static void macvtap_sock_write_space(struct sock *sk)
                 return;
 
         if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
-                wake_up_interruptible_sync(sk->sk_sleep);
+                wake_up_interruptible_poll(sk->sk_sleep, POLLOUT | POLLWRNORM | POLLWRBAND);
 }
 
 static int macvtap_open(struct inode *inode, struct file *file)
@@ -270,6 +272,8 @@ static int macvtap_open(struct inode *inode, struct file *file)
         init_waitqueue_head(&q->sock.wait);
         q->sock.type = SOCK_RAW;
         q->sock.state = SS_CONNECTED;
+        q->sock.file = file;
+        q->sock.ops = &macvtap_socket_ops;
         sock_init_data(&q->sock, &q->sk);
         q->sk.sk_write_space = macvtap_sock_write_space;
 
@@ -387,32 +391,20 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
 
         rcu_read_lock_bh();
         vlan = rcu_dereference(q->vlan);
-        macvlan_count_rx(vlan, len, ret == 0, 0);
+        if (vlan)
+                macvlan_count_rx(vlan, len, ret == 0, 0);
         rcu_read_unlock_bh();
 
         return ret ? ret : len;
 }
 
-static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
-                                unsigned long count, loff_t pos)
+static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
+                               const struct iovec *iv, unsigned long len,
+                               int noblock)
 {
-        struct file *file = iocb->ki_filp;
-        struct macvtap_queue *q = file->private_data;
-
         DECLARE_WAITQUEUE(wait, current);
         struct sk_buff *skb;
-        ssize_t len, ret = 0;
-
-        if (!q) {
-                ret = -ENOLINK;
-                goto out;
-        }
-
-        len = iov_length(iv, count);
-        if (len < 0) {
-                ret = -EINVAL;
-                goto out;
-        }
+        ssize_t ret = 0;
 
         add_wait_queue(q->sk.sk_sleep, &wait);
         while (len) {
@@ -421,7 +413,7 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
                 /* Read frames from the queue */
                 skb = skb_dequeue(&q->sk.sk_receive_queue);
                 if (!skb) {
-                        if (file->f_flags & O_NONBLOCK) {
+                        if (noblock) {
                                 ret = -EAGAIN;
                                 break;
                         }
@@ -440,7 +432,24 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
 
         current->state = TASK_RUNNING;
         remove_wait_queue(q->sk.sk_sleep, &wait);
+        return ret;
+}
+
+static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
+                                unsigned long count, loff_t pos)
+{
+        struct file *file = iocb->ki_filp;
+        struct macvtap_queue *q = file->private_data;
+        ssize_t len, ret = 0;
 
+        len = iov_length(iv, count);
+        if (len < 0) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        ret = macvtap_do_read(q, iocb, iv, len, file->f_flags & O_NONBLOCK);
+        ret = min_t(ssize_t, ret, len); /* XXX copied from tun.c. Why? */
 out:
         return ret;
 }
@@ -538,6 +547,53 @@ static const struct file_operations macvtap_fops = {
 #endif
 };
 
+static int macvtap_sendmsg(struct kiocb *iocb, struct socket *sock,
+                           struct msghdr *m, size_t total_len)
+{
+        struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
+        return macvtap_get_user(q, m->msg_iov, total_len,
+                            m->msg_flags & MSG_DONTWAIT);
+}
+
+static int macvtap_recvmsg(struct kiocb *iocb, struct socket *sock,
+                           struct msghdr *m, size_t total_len,
+                           int flags)
+{
+        struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
+        int ret;
+        if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
+                return -EINVAL;
+        ret = macvtap_do_read(q, iocb, m->msg_iov, total_len,
+                          flags & MSG_DONTWAIT);
+        if (ret > total_len) {
+                m->msg_flags |= MSG_TRUNC;
+                ret = flags & MSG_TRUNC ? ret : total_len;
+        }
+        return ret;
+}
+
+/* Ops structure to mimic raw sockets with tun */
+static const struct proto_ops macvtap_socket_ops = {
+        .sendmsg = macvtap_sendmsg,
+        .recvmsg = macvtap_recvmsg,
+};
+
+/* Get an underlying socket object from tun file.  Returns error unless file is
+ * attached to a device.  The returned object works like a packet socket, it
+ * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
+ * holding a reference to the file for as long as the socket is in use. */
+struct socket *macvtap_get_socket(struct file *file)
+{
+        struct macvtap_queue *q;
+        if (file->f_op != &macvtap_fops)
+                return ERR_PTR(-EINVAL);
+        q = file->private_data;
+        if (!q)
+                return ERR_PTR(-EBADFD);
+        return &q->sock;
+}
+EXPORT_SYMBOL_GPL(macvtap_get_socket);
+
 static int macvtap_init(void)
 {
         int err;
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index 9e9355367bb3..e4e2fd1b5107 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -1,6 +1,6 @@
 config VHOST_NET
         tristate "Host kernel accelerator for virtio net (EXPERIMENTAL)"
-        depends on NET && EVENTFD && (TUN || !TUN) && EXPERIMENTAL
+        depends on NET && EVENTFD && (TUN || !TUN) && (MACVTAP || !MACVTAP) && EXPERIMENTAL