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SubjectRe:[RFC][PATCH v3 2/3] Provides multiple submits and asynchronous notifications.
Date
From: Xin Xiaohui <xiaohui.xin@intel.com>

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>
---
Michael,

>Can't vhost supply a kiocb completion callback that will handle the list?

Yes, thanks. And with it I also remove the vq->receiver finally.

Thanks
Xiaohui

drivers/vhost/net.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++--
drivers/vhost/vhost.c | 115 ++++++++++++++-----------
drivers/vhost/vhost.h | 14 +++
3 files changed, 301 insertions(+), 55 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 22d5fef..4a70f66 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -17,11 +17,13 @@
#include <linux/workqueue.h>
#include <linux/rcupdate.h>
#include <linux/file.h>
+#include <linux/aio.h>

#include <linux/net.h>
#include <linux/if_packet.h>
#include <linux/if_arp.h>
#include <linux/if_tun.h>
+#include <linux/mpassthru.h>

#include <net/sock.h>

@@ -47,6 +49,7 @@ struct vhost_net {
struct vhost_dev dev;
struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
struct vhost_poll poll[VHOST_NET_VQ_MAX];
+ struct kmem_cache *cache;
/* Tells us whether we are polling a socket for TX.
* We only do this when socket buffer fills up.
* Protected by tx vq lock. */
@@ -91,11 +94,132 @@ static void tx_poll_start(struct vhost_net *net, struct socket *sock)
net->tx_poll_state = VHOST_NET_POLL_STARTED;
}

+struct kiocb *notify_dequeue(struct vhost_virtqueue *vq)
+{
+ struct kiocb *iocb = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vq->notify_lock, flags);
+ if (!list_empty(&vq->notifier)) {
+ iocb = list_first_entry(&vq->notifier,
+ struct kiocb, ki_list);
+ list_del(&iocb->ki_list);
+ }
+ spin_unlock_irqrestore(&vq->notify_lock, flags);
+ return iocb;
+}
+
+static void handle_iocb(struct kiocb *iocb)
+{
+ struct vhost_virtqueue *vq = iocb->private;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vq->notify_lock, flags);
+ list_add_tail(&iocb->ki_list, &vq->notifier);
+ spin_unlock_irqrestore(&vq->notify_lock, flags);
+}
+
+static void handle_async_rx_events_notify(struct vhost_net *net,
+ struct vhost_virtqueue *vq,
+ struct socket *sock)
+{
+ struct kiocb *iocb = NULL;
+ struct vhost_log *vq_log = NULL;
+ int rx_total_len = 0;
+ unsigned int head, log, in, out;
+ int size;
+
+ if (vq->link_state != VHOST_VQ_LINK_ASYNC)
+ return;
+
+ if (sock->sk->sk_data_ready)
+ sock->sk->sk_data_ready(sock->sk, 0);
+
+ vq_log = unlikely(vhost_has_feature(
+ &net->dev, VHOST_F_LOG_ALL)) ? vq->log : NULL;
+ while ((iocb = notify_dequeue(vq)) != NULL) {
+ vhost_add_used_and_signal(&net->dev, vq,
+ iocb->ki_pos, iocb->ki_nbytes);
+ log = (int)(iocb->ki_user_data >> 32);
+ size = iocb->ki_nbytes;
+ head = iocb->ki_pos;
+ rx_total_len += iocb->ki_nbytes;
+
+ if (iocb->ki_dtor)
+ iocb->ki_dtor(iocb);
+ kmem_cache_free(net->cache, iocb);
+
+ /* when log is enabled, recomputing the log info is needed,
+ * since these buffers are in async queue, and may not get
+ * the log info before.
+ */
+ if (unlikely(vq_log)) {
+ if (!log)
+ __vhost_get_vq_desc(&net->dev, vq, vq->iov,
+ ARRAY_SIZE(vq->iov),
+ &out, &in, vq_log,
+ &log, head);
+ 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 kiocb *iocb = NULL;
+ int tx_total_len = 0;
+
+ if (vq->link_state != VHOST_VQ_LINK_ASYNC)
+ return;
+
+ while ((iocb = notify_dequeue(vq)) != NULL) {
+ vhost_add_used_and_signal(&net->dev, vq,
+ iocb->ki_pos, 0);
+ tx_total_len += iocb->ki_nbytes;
+
+ if (iocb->ki_dtor)
+ iocb->ki_dtor(iocb);
+
+ kmem_cache_free(net->cache, iocb);
+ if (unlikely(tx_total_len >= VHOST_NET_WEIGHT)) {
+ vhost_poll_queue(&vq->poll);
+ break;
+ }
+ }
+}
+
+static struct kiocb *create_iocb(struct vhost_net *net,
+ struct vhost_virtqueue *vq,
+ unsigned head, unsigned log)
+{
+ struct kiocb *iocb = NULL;
+
+ if (vq->link_state != VHOST_VQ_LINK_ASYNC)
+ return NULL;
+ iocb = kmem_cache_zalloc(net->cache, GFP_KERNEL);
+ if (!iocb)
+ return NULL;
+ iocb->private = vq;
+ iocb->ki_pos = head;
+ iocb->ki_dtor = handle_iocb;
+ if (vq == &net->dev.vqs[VHOST_NET_VQ_RX]) {
+ iocb->ki_user_data = ((unsigned long)log << 32 | vq->num);
+ iocb->ki_iovec = vq->hdr;
+ }
+ return iocb;
+}
+
/* 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 kiocb *iocb = NULL;
unsigned head, out, in, s;
struct msghdr msg = {
.msg_name = NULL,
@@ -124,6 +248,8 @@ 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 +277,11 @@ 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;
+
+ iocb = create_iocb(net, vq, head, 0);
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC && !iocb)
+ break;
+
len = iov_length(vq->iov, out);
/* Sanity check */
if (!len) {
@@ -160,12 +291,18 @@ static void handle_tx(struct vhost_net *net)
break;
}
/* TODO: Check specific error and bomb out unless ENOBUFS? */
- err = sock->ops->sendmsg(NULL, sock, &msg, len);
+ err = sock->ops->sendmsg(iocb, sock, &msg, len);
if (unlikely(err < 0)) {
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC)
+ kmem_cache_free(net->cache, iocb);
vhost_discard_vq_desc(vq);
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 +314,8 @@ static void handle_tx(struct vhost_net *net)
}
}

+ handle_async_tx_events_notify(net, vq);
+
mutex_unlock(&vq->mutex);
unuse_mm(net->dev.mm);
}
@@ -186,6 +325,7 @@ static void handle_tx(struct vhost_net *net)
static void handle_rx(struct vhost_net *net)
{
struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
+ struct kiocb *iocb = NULL;
unsigned head, out, in, log, s;
struct vhost_log *vq_log;
struct msghdr msg = {
@@ -206,7 +346,8 @@ 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);
@@ -214,9 +355,17 @@ static void handle_rx(struct vhost_net *net)
vhost_disable_notify(vq);
hdr_size = vq->hdr_size;

+ /* In async cases, when write log is enabled, in case the submitted
+ * buffers did not get log info before the log enabling, so we'd
+ * better recompute the log info when needed. We do this in
+ * handle_async_rx_events_notify().
+ */
+
vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
vq->log : NULL;

+ handle_async_rx_events_notify(net, vq, sock);
+
for (;;) {
head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
ARRAY_SIZE(vq->iov),
@@ -245,6 +394,11 @@ 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);
+
+ iocb = create_iocb(net, vq, head, log);
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC && !iocb)
+ break;
+
/* Sanity check */
if (!len) {
vq_err(vq, "Unexpected header len for RX: "
@@ -252,13 +406,20 @@ static void handle_rx(struct vhost_net *net)
iov_length(vq->hdr, s), hdr_size);
break;
}
- err = sock->ops->recvmsg(NULL, sock, &msg,
+
+ err = sock->ops->recvmsg(iocb, sock, &msg,
len, MSG_DONTWAIT | MSG_TRUNC);
/* TODO: Check specific error and bomb out unless EAGAIN? */
if (err < 0) {
+ if (vq->link_state == VHOST_VQ_LINK_ASYNC)
+ kmem_cache_free(net->cache, iocb);
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 +445,13 @@ static void handle_rx(struct vhost_net *net)
}
}

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

+
static void handle_tx_kick(struct work_struct *work)
{
struct vhost_virtqueue *vq;
@@ -338,6 +502,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT);
vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN);
n->tx_poll_state = VHOST_NET_POLL_DISABLED;
+ n->cache = NULL;
return 0;
}

@@ -398,6 +563,18 @@ static void vhost_net_flush(struct vhost_net *n)
vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
}

+static void vhost_async_cleanup(struct vhost_net *n)
+{
+ /* clean the notifier */
+ struct vhost_virtqueue *vq = &n->dev.vqs[VHOST_NET_VQ_RX];
+ struct kiocb *iocb = NULL;
+ if (n->cache) {
+ while ((iocb = notify_dequeue(vq)) != NULL)
+ kmem_cache_free(n->cache, iocb);
+ kmem_cache_destroy(n->cache);
+ }
+}
+
static int vhost_net_release(struct inode *inode, struct file *f)
{
struct vhost_net *n = f->private_data;
@@ -414,6 +591,7 @@ static int vhost_net_release(struct inode *inode, struct file *f)
/* We do an extra flush before freeing memory,
* since jobs can re-queue themselves. */
vhost_net_flush(n);
+ vhost_async_cleanup(n);
kfree(n);
return 0;
}
@@ -462,7 +640,19 @@ 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 +663,30 @@ 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) {
+ INIT_LIST_HEAD(&vq->notifier);
+ spin_lock_init(&vq->notify_lock);
+ if (!n->cache) {
+ n->cache = kmem_cache_create("vhost_kiocb",
+ sizeof(struct kiocb), 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ }
+ }
+}
+
static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
{
struct socket *sock, *oldsock;
@@ -493,12 +704,15 @@ 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 +721,8 @@ 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 +730,7 @@ done:
}
return r;
err:
+ mutex_unlock(&vq->mutex);
mutex_unlock(&n->dev.mutex);
return r;
}
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 97233d5..53dab80 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -715,66 +715,21 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
return 0;
}

-/* This looks in the virtqueue and for the first available buffer, and converts
- * it to an iovec for convenient access. Since descriptors consist of some
- * number of output then some number of input descriptors, it's actually two
- * iovecs, but we pack them into one and note how many of each there were.
- *
- * This function returns the descriptor number found, or vq->num (which
- * is never a valid descriptor number) if none was found. */
-unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
+unsigned __vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
struct iovec iov[], unsigned int iov_size,
unsigned int *out_num, unsigned int *in_num,
- struct vhost_log *log, unsigned int *log_num)
+ struct vhost_log *log, unsigned int *log_num,
+ unsigned int head)
{
struct vring_desc desc;
- unsigned int i, head, found = 0;
- u16 last_avail_idx;
+ unsigned int i = head, found = 0;
int ret;

- /* Check it isn't doing very strange things with descriptor numbers. */
- last_avail_idx = vq->last_avail_idx;
- if (get_user(vq->avail_idx, &vq->avail->idx)) {
- vq_err(vq, "Failed to access avail idx at %p\n",
- &vq->avail->idx);
- return vq->num;
- }
-
- if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) {
- vq_err(vq, "Guest moved used index from %u to %u",
- last_avail_idx, vq->avail_idx);
- return vq->num;
- }
-
- /* If there's nothing new since last we looked, return invalid. */
- if (vq->avail_idx == last_avail_idx)
- return vq->num;
-
- /* Only get avail ring entries after they have been exposed by guest. */
- rmb();
-
- /* Grab the next descriptor number they're advertising, and increment
- * the index we've seen. */
- if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) {
- vq_err(vq, "Failed to read head: idx %d address %p\n",
- last_avail_idx,
- &vq->avail->ring[last_avail_idx % vq->num]);
- return vq->num;
- }
-
- /* If their number is silly, that's an error. */
- if (head >= vq->num) {
- vq_err(vq, "Guest says index %u > %u is available",
- head, vq->num);
- return vq->num;
- }
-
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
if (unlikely(log))
*log_num = 0;

- i = head;
do {
unsigned iov_count = *in_num + *out_num;
if (i >= vq->num) {
@@ -833,8 +788,70 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
*out_num += ret;
}
} while ((i = next_desc(&desc)) != -1);
+ return head;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which
+ * is never a valid descriptor number) if none was found. */
+unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
+ struct iovec iov[], unsigned int iov_size,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vhost_log *log, unsigned int *log_num)
+{
+ struct vring_desc desc;
+ unsigned int i, head, found = 0;
+ u16 last_avail_idx;
+ unsigned int ret;
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ last_avail_idx = vq->last_avail_idx;
+ if (get_user(vq->avail_idx, &vq->avail->idx)) {
+ vq_err(vq, "Failed to access avail idx at %p\n",
+ &vq->avail->idx);
+ return vq->num;
+ }
+
+ if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) {
+ vq_err(vq, "Guest moved used index from %u to %u",
+ last_avail_idx, vq->avail_idx);
+ return vq->num;
+ }
+
+ /* If there's nothing new since last we looked, return invalid. */
+ if (vq->avail_idx == last_avail_idx)
+ return vq->num;
+
+ /* Only get avail ring entries after they have been exposed by guest. */
+ rmb();
+
+ /* Grab the next descriptor number they're advertising, and increment
+ * the index we've seen. */
+ if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) {
+ vq_err(vq, "Failed to read head: idx %d address %p\n",
+ last_avail_idx,
+ &vq->avail->ring[last_avail_idx % vq->num]);
+ return vq->num;
+ }
+
+ /* If their number is silly, that's an error. */
+ if (head >= vq->num) {
+ vq_err(vq, "Guest says index %u > %u is available",
+ head, vq->num);
+ return vq->num;
+ }
+
+ ret = __vhost_get_vq_desc(dev, vq, iov, iov_size,
+ out_num, in_num,
+ log, log_num, head);

/* On success, increment avail index. */
+ if (ret == vq->num)
+ return ret;
vq->last_avail_idx++;
return head;
}
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index d1f0453..8b95df8 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -43,6 +43,11 @@ struct vhost_log {
u64 len;
};

+enum vhost_vq_link_state {
+ VHOST_VQ_LINK_SYNC = 0,
+ VHOST_VQ_LINK_ASYNC = 1,
+};
+
/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {
struct vhost_dev *dev;
@@ -96,6 +101,10 @@ 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;
+ struct list_head notifier;
+ spinlock_t notify_lock;
};

struct vhost_dev {
@@ -122,6 +131,11 @@ unsigned 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);
+unsigned __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,
+ unsigned int head);
void vhost_discard_vq_desc(struct vhost_virtqueue *);

int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
--
1.5.4.4


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