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Date:   Tue, 16 Aug 2022 02:32:10 +0000
From:   Bobby Eshleman <bobbyeshleman@gmail.com>
To:     Bobby Eshleman <bobby.eshleman@gmail.com>
Cc:     virtio-dev@lists.oasis-open.org,
        Bobby Eshleman <bobby.eshleman@bytedance.com>,
        Cong Wang <cong.wang@bytedance.com>,
        Jiang Wang <jiang.wang@bytedance.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] virtio/vsock: add support for dgram
Message-ID: <YvsBqpEoq1tbgj8A@bullseye>
References: <cover.1660362668.git.bobby.eshleman@bytedance.com>
 <3cb082f1c88f3f2ef1fc250dbc0745fb79c745c7.1660362668.git.bobby.eshleman@bytedance.com>
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CC'ing virtio-dev@lists.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.
> 
> Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
> Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.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
>