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Subject[PATCH 2/3] Provides multiple submits and asynchronous notifications.
Date
The vhost-net backend now only supports synchronous send/recv
operations. The patch provides multiple submits and asynchronous
notifications. This is needed for zero-copy case.

Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>
---
drivers/vhost/net.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++--
drivers/vhost/vhost.h | 23 ++++++++
2 files changed, 164 insertions(+), 4 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 22d5fef..8a85227 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -22,6 +22,7 @@
#include <linux/if_packet.h>
#include <linux/if_arp.h>
#include <linux/if_tun.h>
+#include <linux/mpassthru.h>

#include <net/sock.h>

@@ -91,6 +92,10 @@ static void tx_poll_start(struct vhost_net *net, struct socket *sock)
net->tx_poll_state = VHOST_NET_POLL_STARTED;
}

+static void handle_async_rx_events_notify(struct vhost_net *net,
+ struct vhost_virtqueue *vq);
+static void handle_async_tx_events_notify(struct vhost_net *net,
+ struct vhost_virtqueue *vq);
/* 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)
@@ -124,6 +129,8 @@ static void handle_tx(struct vhost_net *net)
tx_poll_stop(net);
hdr_size = vq->hdr_size;

+ handle_async_tx_events_notify(net, vq);
+
for (;;) {
head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
ARRAY_SIZE(vq->iov),
@@ -151,6 +158,12 @@ static void handle_tx(struct vhost_net *net)
/* Skip header. TODO: support TSO. */
s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
msg.msg_iovlen = out;
+
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC) {
+ vq->head = head;
+ msg.msg_control = (void *)vq;
+ }
+
len = iov_length(vq->iov, out);
/* Sanity check */
if (!len) {
@@ -166,6 +179,10 @@ static void handle_tx(struct vhost_net *net)
tx_poll_start(net, sock);
break;
}
+
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC)
+ continue;
+
if (err != len)
pr_err("Truncated TX packet: "
" len %d != %zd\n", err, len);
@@ -177,6 +194,8 @@ static void handle_tx(struct vhost_net *net)
}
}

+ handle_async_tx_events_notify(net, vq);
+
mutex_unlock(&vq->mutex);
unuse_mm(net->dev.mm);
}
@@ -206,7 +225,8 @@ static void handle_rx(struct vhost_net *net)
int err;
size_t hdr_size;
struct socket *sock = rcu_dereference(vq->private_data);
- if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
+ if (!sock || (skb_queue_empty(&sock->sk->sk_receive_queue) &&
+ vq->link_state == VHOST_VQ_LINK_SYNC))
return;

use_mm(net->dev.mm);
@@ -217,6 +237,8 @@ static void handle_rx(struct vhost_net *net)
vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
vq->log : NULL;

+ handle_async_rx_events_notify(net, vq);
+
for (;;) {
head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
ARRAY_SIZE(vq->iov),
@@ -245,6 +267,11 @@ static void handle_rx(struct vhost_net *net)
s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
msg.msg_iovlen = in;
len = iov_length(vq->iov, in);
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC) {
+ vq->head = head;
+ vq->_log = log;
+ msg.msg_control = (void *)vq;
+ }
/* Sanity check */
if (!len) {
vq_err(vq, "Unexpected header len for RX: "
@@ -259,6 +286,10 @@ static void handle_rx(struct vhost_net *net)
vhost_discard_vq_desc(vq);
break;
}
+
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC)
+ continue;
+
/* TODO: Should check and handle checksum. */
if (err > len) {
pr_err("Discarded truncated rx packet: "
@@ -284,10 +315,83 @@ static void handle_rx(struct vhost_net *net)
}
}

+ handle_async_rx_events_notify(net, vq);
+
mutex_unlock(&vq->mutex);
unuse_mm(net->dev.mm);
}

+struct vhost_notifier *notify_dequeue(struct vhost_virtqueue *vq)
+{
+ struct vhost_notifier *vnotify = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vq->notify_lock, flags);
+ if (!list_empty(&vq->notifier)) {
+ vnotify = list_first_entry(&vq->notifier,
+ struct vhost_notifier, list);
+ list_del(&vnotify->list);
+ }
+ spin_unlock_irqrestore(&vq->notify_lock, flags);
+ return vnotify;
+}
+
+static void handle_async_rx_events_notify(struct vhost_net *net,
+ struct vhost_virtqueue *vq)
+{
+ struct vhost_notifier *vnotify = NULL;
+ struct vhost_log *vq_log = NULL;
+ int rx_total_len = 0;
+ int log, size;
+
+ if (vq->link_state != VHOST_VQ_LINK_ASYNC)
+ return;
+ if (vq != &net->dev.vqs[VHOST_NET_VQ_RX])
+ return;
+
+ if (vq->receiver)
+ vq->receiver(vq);
+ vq_log = unlikely(vhost_has_feature(
+ &net->dev, VHOST_F_LOG_ALL)) ? vq->log : NULL;
+ while ((vnotify = notify_dequeue(vq)) != NULL) {
+ vhost_add_used_and_signal(&net->dev, vq,
+ vnotify->head, vnotify->size);
+ log = vnotify->log;
+ size = vnotify->size;
+ rx_total_len += vnotify->size;
+ vnotify->dtor(vnotify);
+ if (unlikely(vq_log))
+ vhost_log_write(vq, vq_log, log, size);
+ if (unlikely(rx_total_len >= VHOST_NET_WEIGHT)) {
+ vhost_poll_queue(&vq->poll);
+ break;
+ }
+ }
+}
+
+static void handle_async_tx_events_notify(struct vhost_net *net,
+ struct vhost_virtqueue *vq)
+{
+ struct vhost_notifier *vnotify = NULL;
+ int tx_total_len = 0;
+
+ if (vq->link_state != VHOST_VQ_LINK_ASYNC)
+ return;
+ if (vq != &net->dev.vqs[VHOST_NET_VQ_TX])
+ return;
+
+ while ((vnotify = notify_dequeue(vq)) != NULL) {
+ vhost_add_used_and_signal(&net->dev, vq,
+ vnotify->head, 0);
+ tx_total_len += vnotify->size;
+ vnotify->dtor(vnotify);
+ if (unlikely(tx_total_len >= VHOST_NET_WEIGHT)) {
+ vhost_poll_queue(&vq->poll);
+ break;
+ }
+ }
+}
+
static void handle_tx_kick(struct work_struct *work)
{
struct vhost_virtqueue *vq;
@@ -462,7 +566,19 @@ static struct socket *get_tun_socket(int fd)
return sock;
}

-static struct socket *get_socket(int fd)
+static struct socket *get_mp_socket(int fd)
+{
+ struct file *file = fget(fd);
+ struct socket *sock;
+ if (!file)
+ return ERR_PTR(-EBADF);
+ sock = mp_get_socket(file);
+ if (IS_ERR(sock))
+ fput(file);
+ return sock;
+}
+
+static struct socket *get_socket(struct vhost_virtqueue *vq, int fd)
{
struct socket *sock;
if (fd == -1)
@@ -473,9 +589,26 @@ static struct socket *get_socket(int fd)
sock = get_tun_socket(fd);
if (!IS_ERR(sock))
return sock;
+ sock = get_mp_socket(fd);
+ if (!IS_ERR(sock)) {
+ vq->link_state = VHOST_VQ_LINK_ASYNC;
+ return sock;
+ }
return ERR_PTR(-ENOTSOCK);
}

+static void vhost_init_link_state(struct vhost_net *n, int index)
+{
+ struct vhost_virtqueue *vq = n->vqs + index;
+
+ WARN_ON(!mutex_is_locked(&vq->mutex));
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC) {
+ vq->receiver = NULL;
+ INIT_LIST_HEAD(&vq->notifier);
+ spin_lock_init(&vq->notify_lock);
+ }
+}
+
static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
{
struct socket *sock, *oldsock;
@@ -493,12 +626,15 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
}
vq = n->vqs + index;
mutex_lock(&vq->mutex);
- sock = get_socket(fd);
+ vq->link_state = VHOST_VQ_LINK_SYNC;
+ sock = get_socket(vq, fd);
if (IS_ERR(sock)) {
r = PTR_ERR(sock);
goto err;
}

+ vhost_init_link_state(n, index);
+
/* start polling new socket */
oldsock = vq->private_data;
if (sock == oldsock)
@@ -507,8 +643,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
vhost_net_disable_vq(n, vq);
rcu_assign_pointer(vq->private_data, sock);
vhost_net_enable_vq(n, vq);
- mutex_unlock(&vq->mutex);
done:
+ mutex_unlock(&vq->mutex);
mutex_unlock(&n->dev.mutex);
if (oldsock) {
vhost_net_flush_vq(n, index);
@@ -516,6 +652,7 @@ done:
}
return r;
err:
+ mutex_unlock(&vq->mutex);
mutex_unlock(&n->dev.mutex);
return r;
}
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index d1f0453..295bffa 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -43,6 +43,22 @@ struct vhost_log {
u64 len;
};

+enum vhost_vq_link_state {
+ VHOST_VQ_LINK_SYNC = 0,
+ VHOST_VQ_LINK_ASYNC = 1,
+};
+
+/* The structure to notify the virtqueue for async socket */
+struct vhost_notifier {
+ struct list_head list;
+ struct vhost_virtqueue *vq;
+ int head;
+ int size;
+ int log;
+ void *ctrl;
+ void (*dtor)(struct vhost_notifier *);
+};
+
/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {
struct vhost_dev *dev;
@@ -96,6 +112,13 @@ struct vhost_virtqueue {
/* Log write descriptors */
void __user *log_base;
struct vhost_log log[VHOST_NET_MAX_SG];
+ /*Differiate async socket for 0-copy from normal*/
+ enum vhost_vq_link_state link_state;
+ int head;
+ int _log;
+ struct list_head notifier;
+ spinlock_t notify_lock;
+ void (*receiver)(struct vhost_virtqueue *);
};

struct vhost_dev {
--
1.5.4.4


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