Date:   Wed, 17 Aug 2022 05:01:00 +0000
From:   Arseniy Krasnov <AVKrasnov@...rdevices.ru>
To:     Bobby Eshleman <bobbyeshleman@...il.com>,
        Bobby Eshleman <bobby.eshleman@...il.com>
CC:     "virtio-dev@...ts.oasis-open.org" <virtio-dev@...ts.oasis-open.org>,
        "Bobby Eshleman" <bobby.eshleman@...edance.com>,
        Cong Wang <cong.wang@...edance.com>,
        Jiang Wang <jiang.wang@...edance.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [virtio-dev] Re: [PATCH 5/6] virtio/vsock: add support for dgram

On 16.08.2022 05:32, Bobby Eshleman wrote:
> CC'ing virtio-dev@...ts.oasis-open.org
> 
> On Mon, Aug 15, 2022 at 10:56:08AM -0700, Bobby Eshleman wrote:
>> This patch supports dgram in virtio and on the vhost side.
Hello,

sorry, i don't understand, how this maintains message boundaries? Or it
is unnecessary for SOCK_DGRAM?

Thanks
>>
>> Signed-off-by: Jiang Wang <jiang.wang@...edance.com>
>> Signed-off-by: Bobby Eshleman <bobby.eshleman@...edance.com>
>> ---
>>  drivers/vhost/vsock.c                   |   2 +-
>>  include/net/af_vsock.h                  |   2 +
>>  include/uapi/linux/virtio_vsock.h       |   1 +
>>  net/vmw_vsock/af_vsock.c                |  26 +++-
>>  net/vmw_vsock/virtio_transport.c        |   2 +-
>>  net/vmw_vsock/virtio_transport_common.c | 173 ++++++++++++++++++++++--
>>  6 files changed, 186 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>> index a5d1bdb786fe..3dc72a5647ca 100644
>> --- a/drivers/vhost/vsock.c
>> +++ b/drivers/vhost/vsock.c
>> @@ -925,7 +925,7 @@ static int __init vhost_vsock_init(void)
>>  	int ret;
>>  
>>  	ret = vsock_core_register(&vhost_transport.transport,
>> -				  VSOCK_TRANSPORT_F_H2G);
>> +				  VSOCK_TRANSPORT_F_H2G | VSOCK_TRANSPORT_F_DGRAM);
>>  	if (ret < 0)
>>  		return ret;
>>  
>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>> index 1c53c4c4d88f..37e55c81e4df 100644
>> --- a/include/net/af_vsock.h
>> +++ b/include/net/af_vsock.h
>> @@ -78,6 +78,8 @@ struct vsock_sock {
>>  s64 vsock_stream_has_data(struct vsock_sock *vsk);
>>  s64 vsock_stream_has_space(struct vsock_sock *vsk);
>>  struct sock *vsock_create_connected(struct sock *parent);
>> +int vsock_bind_stream(struct vsock_sock *vsk,
>> +		      struct sockaddr_vm *addr);
>>  
>>  /**** TRANSPORT ****/
>>  
>> diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
>> index 857df3a3a70d..0975b9c88292 100644
>> --- a/include/uapi/linux/virtio_vsock.h
>> +++ b/include/uapi/linux/virtio_vsock.h
>> @@ -70,6 +70,7 @@ struct virtio_vsock_hdr {
>>  enum virtio_vsock_type {
>>  	VIRTIO_VSOCK_TYPE_STREAM = 1,
>>  	VIRTIO_VSOCK_TYPE_SEQPACKET = 2,
>> +	VIRTIO_VSOCK_TYPE_DGRAM = 3,
>>  };
>>  
>>  enum virtio_vsock_op {
>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>> index 1893f8aafa48..87e4ae1866d3 100644
>> --- a/net/vmw_vsock/af_vsock.c
>> +++ b/net/vmw_vsock/af_vsock.c
>> @@ -675,6 +675,19 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
>>  	return 0;
>>  }
>>  
>> +int vsock_bind_stream(struct vsock_sock *vsk,
>> +		      struct sockaddr_vm *addr)
>> +{
>> +	int retval;
>> +
>> +	spin_lock_bh(&vsock_table_lock);
>> +	retval = __vsock_bind_connectible(vsk, addr);
>> +	spin_unlock_bh(&vsock_table_lock);
>> +
>> +	return retval;
>> +}
>> +EXPORT_SYMBOL(vsock_bind_stream);
>> +
>>  static int __vsock_bind_dgram(struct vsock_sock *vsk,
>>  			      struct sockaddr_vm *addr)
>>  {
>> @@ -2363,11 +2376,16 @@ int vsock_core_register(const struct vsock_transport *t, int features)
>>  	}
>>  
>>  	if (features & VSOCK_TRANSPORT_F_DGRAM) {
>> -		if (t_dgram) {
>> -			err = -EBUSY;
>> -			goto err_busy;
>> +		/* TODO: always chose the G2H variant over others, support nesting later */
>> +		if (features & VSOCK_TRANSPORT_F_G2H) {
>> +			if (t_dgram)
>> +				pr_warn("virtio_vsock: t_dgram already set\n");
>> +			t_dgram = t;
>> +		}
>> +
>> +		if (!t_dgram) {
>> +			t_dgram = t;
>>  		}
>> -		t_dgram = t;
>>  	}
>>  
>>  	if (features & VSOCK_TRANSPORT_F_LOCAL) {
>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>> index 073314312683..d4526ca462d2 100644
>> --- a/net/vmw_vsock/virtio_transport.c
>> +++ b/net/vmw_vsock/virtio_transport.c
>> @@ -850,7 +850,7 @@ static int __init virtio_vsock_init(void)
>>  		return -ENOMEM;
>>  
>>  	ret = vsock_core_register(&virtio_transport.transport,
>> -				  VSOCK_TRANSPORT_F_G2H);
>> +				  VSOCK_TRANSPORT_F_G2H | VSOCK_TRANSPORT_F_DGRAM);
>>  	if (ret)
>>  		goto out_wq;
>>  
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index bdf16fff054f..aedb48728677 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -229,7 +229,9 @@ EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
>>  
>>  static u16 virtio_transport_get_type(struct sock *sk)
>>  {
>> -	if (sk->sk_type == SOCK_STREAM)
>> +	if (sk->sk_type == SOCK_DGRAM)
>> +		return VIRTIO_VSOCK_TYPE_DGRAM;
>> +	else if (sk->sk_type == SOCK_STREAM)
>>  		return VIRTIO_VSOCK_TYPE_STREAM;
>>  	else
>>  		return VIRTIO_VSOCK_TYPE_SEQPACKET;
>> @@ -287,22 +289,29 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>>  	vvs = vsk->trans;
>>  
>>  	/* we can send less than pkt_len bytes */
>> -	if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
>> -		pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>> +	if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
>> +		if (info->type != VIRTIO_VSOCK_TYPE_DGRAM)
>> +			pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
>> +		else
>> +			return 0;
>> +	}
>>  
>> -	/* virtio_transport_get_credit might return less than pkt_len credit */
>> -	pkt_len = virtio_transport_get_credit(vvs, pkt_len);
>> +	if (info->type != VIRTIO_VSOCK_TYPE_DGRAM) {
>> +		/* virtio_transport_get_credit might return less than pkt_len credit */
>> +		pkt_len = virtio_transport_get_credit(vvs, pkt_len);
>>  
>> -	/* Do not send zero length OP_RW pkt */
>> -	if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
>> -		return pkt_len;
>> +		/* Do not send zero length OP_RW pkt */
>> +		if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
>> +			return pkt_len;
>> +	}
>>  
>>  	skb = virtio_transport_alloc_skb(info, pkt_len,
>>  					 src_cid, src_port,
>>  					 dst_cid, dst_port,
>>  					 &err);
>>  	if (!skb) {
>> -		virtio_transport_put_credit(vvs, pkt_len);
>> +		if (info->type != VIRTIO_VSOCK_TYPE_DGRAM)
>> +			virtio_transport_put_credit(vvs, pkt_len);
>>  		return err;
>>  	}
>>  
>> @@ -586,6 +595,61 @@ virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
>>  }
>>  EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
>>  
>> +static ssize_t
>> +virtio_transport_dgram_do_dequeue(struct vsock_sock *vsk,
>> +				  struct msghdr *msg, size_t len)
>> +{
>> +	struct virtio_vsock_sock *vvs = vsk->trans;
>> +	struct sk_buff *skb;
>> +	size_t total = 0;
>> +	u32 free_space;
>> +	int err = -EFAULT;
>> +
>> +	spin_lock_bh(&vvs->rx_lock);
>> +	if (total < len && !skb_queue_empty_lockless(&vvs->rx_queue)) {
>> +		skb = __skb_dequeue(&vvs->rx_queue);
>> +
>> +		total = len;
>> +		if (total > skb->len - vsock_metadata(skb)->off)
>> +			total = skb->len - vsock_metadata(skb)->off;
>> +		else if (total < skb->len - vsock_metadata(skb)->off)
>> +			msg->msg_flags |= MSG_TRUNC;
>> +
>> +		/* sk_lock is held by caller so no one else can dequeue.
>> +		 * Unlock rx_lock since memcpy_to_msg() may sleep.
>> +		 */
>> +		spin_unlock_bh(&vvs->rx_lock);
>> +
>> +		err = memcpy_to_msg(msg, skb->data + vsock_metadata(skb)->off, total);
>> +		if (err)
>> +			return err;
>> +
>> +		spin_lock_bh(&vvs->rx_lock);
>> +
>> +		virtio_transport_dec_rx_pkt(vvs, skb);
>> +		consume_skb(skb);
>> +	}
>> +
>> +	free_space = vvs->buf_alloc - (vvs->fwd_cnt - vvs->last_fwd_cnt);
>> +
>> +	spin_unlock_bh(&vvs->rx_lock);
>> +
>> +	if (total > 0 && msg->msg_name) {
>> +		/* Provide the address of the sender. */
>> +		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
>> +
>> +		vsock_addr_init(vm_addr, le64_to_cpu(vsock_hdr(skb)->src_cid),
>> +				le32_to_cpu(vsock_hdr(skb)->src_port));
>> +		msg->msg_namelen = sizeof(*vm_addr);
>> +	}
>> +	return total;
>> +}
>> +
>> +static s64 virtio_transport_dgram_has_data(struct vsock_sock *vsk)
>> +{
>> +	return virtio_transport_stream_has_data(vsk);
>> +}
>> +
>>  int
>>  virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>>  				   struct msghdr *msg,
>> @@ -611,7 +675,66 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
>>  			       struct msghdr *msg,
>>  			       size_t len, int flags)
>>  {
>> -	return -EOPNOTSUPP;
>> +	struct sock *sk;
>> +	size_t err = 0;
>> +	long timeout;
>> +
>> +	DEFINE_WAIT(wait);
>> +
>> +	sk = &vsk->sk;
>> +	err = 0;
>> +
>> +	if (flags & MSG_OOB || flags & MSG_ERRQUEUE || flags & MSG_PEEK)
>> +		return -EOPNOTSUPP;
>> +
>> +	lock_sock(sk);
>> +
>> +	if (!len)
>> +		goto out;
>> +
>> +	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
>> +
>> +	while (1) {
>> +		s64 ready;
>> +
>> +		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
>> +		ready = virtio_transport_dgram_has_data(vsk);
>> +
>> +		if (ready == 0) {
>> +			if (timeout == 0) {
>> +				err = -EAGAIN;
>> +				finish_wait(sk_sleep(sk), &wait);
>> +				break;
>> +			}
>> +
>> +			release_sock(sk);
>> +			timeout = schedule_timeout(timeout);
>> +			lock_sock(sk);
>> +
>> +			if (signal_pending(current)) {
>> +				err = sock_intr_errno(timeout);
>> +				finish_wait(sk_sleep(sk), &wait);
>> +				break;
>> +			} else if (timeout == 0) {
>> +				err = -EAGAIN;
>> +				finish_wait(sk_sleep(sk), &wait);
>> +				break;
>> +			}
>> +		} else {
>> +			finish_wait(sk_sleep(sk), &wait);
>> +
>> +			if (ready < 0) {
>> +				err = -ENOMEM;
>> +				goto out;
>> +			}
>> +
>> +			err = virtio_transport_dgram_do_dequeue(vsk, msg, len);
>> +			break;
>> +		}
>> +	}
>> +out:
>> +	release_sock(sk);
>> +	return err;
>>  }
>>  EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
>>  
>> @@ -819,13 +942,13 @@ EXPORT_SYMBOL_GPL(virtio_transport_stream_allow);
>>  int virtio_transport_dgram_bind(struct vsock_sock *vsk,
>>  				struct sockaddr_vm *addr)
>>  {
>> -	return -EOPNOTSUPP;
>> +	return vsock_bind_stream(vsk, addr);
>>  }
>>  EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind);
>>  
>>  bool virtio_transport_dgram_allow(u32 cid, u32 port)
>>  {
>> -	return false;
>> +	return true;
>>  }
>>  EXPORT_SYMBOL_GPL(virtio_transport_dgram_allow);
>>  
>> @@ -861,7 +984,16 @@ virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
>>  			       struct msghdr *msg,
>>  			       size_t dgram_len)
>>  {
>> -	return -EOPNOTSUPP;
>> +	struct virtio_vsock_pkt_info info = {
>> +		.op = VIRTIO_VSOCK_OP_RW,
>> +		.msg = msg,
>> +		.pkt_len = dgram_len,
>> +		.vsk = vsk,
>> +		.remote_cid = remote_addr->svm_cid,
>> +		.remote_port = remote_addr->svm_port,
>> +	};
>> +
>> +	return virtio_transport_send_pkt_info(vsk, &info);
>>  }
>>  EXPORT_SYMBOL_GPL(virtio_transport_dgram_enqueue);
>>  
>> @@ -1165,6 +1297,12 @@ virtio_transport_recv_connected(struct sock *sk,
>>  	struct virtio_vsock_hdr *hdr = vsock_hdr(skb);
>>  	int err = 0;
>>  
>> +	if (le16_to_cpu(vsock_hdr(skb)->type) == VIRTIO_VSOCK_TYPE_DGRAM) {
>> +		virtio_transport_recv_enqueue(vsk, skb);
>> +		sk->sk_data_ready(sk);
>> +		return err;
>> +	}
>> +
>>  	switch (le16_to_cpu(hdr->op)) {
>>  	case VIRTIO_VSOCK_OP_RW:
>>  		virtio_transport_recv_enqueue(vsk, skb);
>> @@ -1320,7 +1458,8 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
>>  static bool virtio_transport_valid_type(u16 type)
>>  {
>>  	return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
>> -	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
>> +	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET) ||
>> +	       (type == VIRTIO_VSOCK_TYPE_DGRAM);
>>  }
>>  
>>  /* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
>> @@ -1384,6 +1523,11 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
>>  		goto free_pkt;
>>  	}
>>  
>> +	if (sk->sk_type == SOCK_DGRAM) {
>> +		virtio_transport_recv_connected(sk, skb);
>> +		goto out;
>> +	}
>> +
>>  	space_available = virtio_transport_space_update(sk, skb);
>>  
>>  	/* Update CID in case it has changed after a transport reset event */
>> @@ -1415,6 +1559,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
>>  		break;
>>  	}
>>  
>> +out:
>>  	release_sock(sk);
>>  
>>  	/* Release refcnt obtained when we fetched this socket out of the
>> -- 
>> 2.35.1
>>
> 
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