text: /*
   * Hyper-V transport for vsock
   *
   * Hyper-V Sockets supplies a byte-stream based communication mechanism
   * between the host and the VM. This driver implements the necessary
   * support in the VM by introducing the new vsock transport.
   *
   * Copyright (c) 2017, Microsoft Corporation.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   */
  #include <linux/module.h>
  #include <linux/vmalloc.h>
  #include <linux/hyperv.h>
  #include <net/sock.h>
  #include <net/af_vsock.h>
  
  /* The host side's design of the feature requires 6 exact 4KB pages for
   * recv/send rings respectively -- this is suboptimal considering memory
   * consumption, however unluckily we have to live with it, before the
   * host comes up with a better design in the future.
   */
  #define PAGE_SIZE_4K		4096
  #define RINGBUFFER_HVS_RCV_SIZE (PAGE_SIZE_4K * 6)
  #define RINGBUFFER_HVS_SND_SIZE (PAGE_SIZE_4K * 6)
  
  /* The MTU is 16KB per the host side's design */
  #define HVS_MTU_SIZE		(1024 * 16)
  
  struct vmpipe_proto_header {
  	u32 pkt_type;
  	u32 data_size;
  };
  
  /* For recv, we use the VMBus in-place packet iterator APIs to directly copy
   * data from the ringbuffer into the userspace buffer.
   */
  struct hvs_recv_buf {
  	/* The header before the payload data */
  	struct vmpipe_proto_header hdr;
  
  	/* The payload */
  	u8 data[HVS_MTU_SIZE];
  };
  
  /* We can send up to HVS_MTU_SIZE bytes of payload to the host, but let's use
   * a small size, i.e. HVS_SEND_BUF_SIZE, to minimize the dynamically-allocated
   * buffer, because tests show there is no significant performance difference.
   *
   * Note: the buffer can be eliminated in the future when we add new VMBus
   * ringbuffer APIs that allow us to directly copy data from userspace buffer
   * to VMBus ringbuffer.
   */
  #define HVS_SEND_BUF_SIZE (PAGE_SIZE_4K - sizeof(struct vmpipe_proto_header))
  
  struct hvs_send_buf {
  	/* The header before the payload data */
  	struct vmpipe_proto_header hdr;
  
  	/* The payload */
  	u8 data[HVS_SEND_BUF_SIZE];
  };
  
  #define HVS_HEADER_LEN	(sizeof(struct vmpacket_descriptor) + \
  			 sizeof(struct vmpipe_proto_header))
  
  /* See 'prev_indices' in hv_ringbuffer_read(), hv_ringbuffer_write(), and
   * __hv_pkt_iter_next().
   */
  #define VMBUS_PKT_TRAILER_SIZE	(sizeof(u64))
  
  #define HVS_PKT_LEN(payload_len)	(HVS_HEADER_LEN + \
  					 ALIGN((payload_len), 8) + \
  					 VMBUS_PKT_TRAILER_SIZE)
  
  union hvs_service_id {
  	uuid_le	srv_id;
  
  	struct {
  		unsigned int svm_port;
  		unsigned char b[sizeof(uuid_le) - sizeof(unsigned int)];
  	};
  };
  
  /* Per-socket state (accessed via vsk->trans) */
  struct hvsock {
  	struct vsock_sock *vsk;
  
  	uuid_le vm_srv_id;
  	uuid_le host_srv_id;
  
  	struct vmbus_channel *chan;
  	struct vmpacket_descriptor *recv_desc;
  
  	/* The length of the payload not delivered to userland yet */
  	u32 recv_data_len;
  	/* The offset of the payload */
  	u32 recv_data_off;
  
  	/* Have we sent the zero-length packet (FIN)? */
  	bool fin_sent;
  };
  
  /* In the VM, we support Hyper-V Sockets with AF_VSOCK, and the endpoint is
   * <cid, port> (see struct sockaddr_vm). Note: cid is not really used here:
   * when we write apps to connect to the host, we can only use VMADDR_CID_ANY
   * or VMADDR_CID_HOST (both are equivalent) as the remote cid, and when we
   * write apps to bind() & listen() in the VM, we can only use VMADDR_CID_ANY
   * as the local cid.
   *
   * On the host, Hyper-V Sockets are supported by Winsock AF_HYPERV:
   * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-
   * guide/make-integration-service, and the endpoint is <VmID, ServiceId> with
   * the below sockaddr:
   *
   * struct SOCKADDR_HV
   * {
   *    ADDRESS_FAMILY Family;
   *    USHORT Reserved;
   *    GUID VmId;
   *    GUID ServiceId;
   * };
   * Note: VmID is not used by Linux VM and actually it isn't transmitted via
   * VMBus, because here it's obvious the host and the VM can easily identify
   * each other. Though the VmID is useful on the host, especially in the case
   * of Windows container, Linux VM doesn't need it at all.
   *
   * To make use of the AF_VSOCK infrastructure in Linux VM, we have to limit
   * the available GUID space of SOCKADDR_HV so that we can create a mapping
   * between AF_VSOCK port and SOCKADDR_HV Service GUID. The rule of writing
   * Hyper-V Sockets apps on the host and in Linux VM is:
   *
   ****************************************************************************
   * The only valid Service GUIDs, from the perspectives of both the host and *
   * Linux VM, that can be connected by the other end, must conform to this   *
   * format: <port>-facb-11e6-bd58-64006a7986d3, and the "port" must be in    *
   * this range [0, 0x7FFFFFFF].                                              *
   ****************************************************************************
   *
   * When we write apps on the host to connect(), the GUID ServiceID is used.
   * When we write apps in Linux VM to connect(), we only need to specify the
   * port and the driver will form the GUID and use that to request the host.
   *
   * From the perspective of Linux VM:
   * 1. the local ephemeral port (i.e. the local auto-bound port when we call
   * connect() without explicit bind()) is generated by __vsock_bind_stream(),
   * and the range is [1024, 0xFFFFFFFF).
   * 2. the remote ephemeral port (i.e. the auto-generated remote port for
   * a connect request initiated by the host's connect()) is generated by
   * hvs_remote_addr_init() and the range is [0x80000000, 0xFFFFFFFF).
   */
  
  #define MAX_LISTEN_PORT			((u32)0x7FFFFFFF)
  #define MAX_VM_LISTEN_PORT		MAX_LISTEN_PORT
  #define MAX_HOST_LISTEN_PORT		MAX_LISTEN_PORT
  #define MIN_HOST_EPHEMERAL_PORT		(MAX_HOST_LISTEN_PORT + 1)
  
  /* 00000000-facb-11e6-bd58-64006a7986d3 */
  static const uuid_le srv_id_template =
  	UUID_LE(0x00000000, 0xfacb, 0x11e6, 0xbd, 0x58,
  		0x64, 0x00, 0x6a, 0x79, 0x86, 0xd3);
  
  static bool is_valid_srv_id(const uuid_le *id)
  {
  	return !memcmp(&id->b[4], &srv_id_template.b[4], sizeof(uuid_le) - 4);
  }
  
  static unsigned int get_port_by_srv_id(const uuid_le *svr_id)
  {
  	return *((unsigned int *)svr_id);
  }
  
  static void hvs_addr_init(struct sockaddr_vm *addr, const uuid_le *svr_id)
  {
  	unsigned int port = get_port_by_srv_id(svr_id);
  
  	vsock_addr_init(addr, VMADDR_CID_ANY, port);
  }
  
  static void hvs_remote_addr_init(struct sockaddr_vm *remote,
  				 struct sockaddr_vm *local)
  {
  	static u32 host_ephemeral_port = MIN_HOST_EPHEMERAL_PORT;
  	struct sock *sk;
  
  	vsock_addr_init(remote, VMADDR_CID_ANY, VMADDR_PORT_ANY);
  
  	while (1) {
  		/* Wrap around ? */
  		if (host_ephemeral_port < MIN_HOST_EPHEMERAL_PORT ||
  		    host_ephemeral_port == VMADDR_PORT_ANY)
  			host_ephemeral_port = MIN_HOST_EPHEMERAL_PORT;
  
  		remote->svm_port = host_ephemeral_port++;
  
  		sk = vsock_find_connected_socket(remote, local);
  		if (!sk) {
  			/* Found an available ephemeral port */
  			return;
  		}
  
  		/* Release refcnt got in vsock_find_connected_socket */
  		sock_put(sk);
  	}
  }
  
  static void hvs_set_channel_pending_send_size(struct vmbus_channel *chan)
  {
  	set_channel_pending_send_size(chan,
  				      HVS_PKT_LEN(HVS_SEND_BUF_SIZE));
  
  	/* See hvs_stream_has_space(): we must make sure the host has seen
  	 * the new pending send size, before we can re-check the writable
  	 * bytes.
  	 */
  	virt_mb();
  }
  
  static void hvs_clear_channel_pending_send_size(struct vmbus_channel *chan)
  {
  	set_channel_pending_send_size(chan, 0);
  
  	/* Ditto */
  	virt_mb();
  }
  
  static bool hvs_channel_readable(struct vmbus_channel *chan)
  {
  	u32 readable = hv_get_bytes_to_read(&chan->inbound);
  
  	/* 0-size payload means FIN */
  	return readable >= HVS_PKT_LEN(0);
  }
  
  static int hvs_channel_readable_payload(struct vmbus_channel *chan)
  {
  	u32 readable = hv_get_bytes_to_read(&chan->inbound);
  
  	if (readable > HVS_PKT_LEN(0)) {
  		/* At least we have 1 byte to read. We don't need to return
  		 * the exact readable bytes: see vsock_stream_recvmsg() ->
  		 * vsock_stream_has_data().
  		 */
  		return 1;
  	}
  
  	if (readable == HVS_PKT_LEN(0)) {
  		/* 0-size payload means FIN */
  		return 0;
  	}
  
  	/* No payload or FIN */
  	return -1;
  }
  
  static size_t hvs_channel_writable_bytes(struct vmbus_channel *chan)
  {
  	u32 writeable = hv_get_bytes_to_write(&chan->outbound);
  	size_t ret;
  
  	/* The ringbuffer mustn't be 100% full, and we should reserve a
  	 * zero-length-payload packet for the FIN: see hv_ringbuffer_write()
  	 * and hvs_shutdown().
  	 */
  	if (writeable <= HVS_PKT_LEN(1) + HVS_PKT_LEN(0))
  		return 0;
  
  	ret = writeable - HVS_PKT_LEN(1) - HVS_PKT_LEN(0);
  
  	return round_down(ret, 8);
  }
  
  static int hvs_send_data(struct vmbus_channel *chan,
  			 struct hvs_send_buf *send_buf, size_t to_write)
  {
  	send_buf->hdr.pkt_type = 1;
  	send_buf->hdr.data_size = to_write;
  	return vmbus_sendpacket(chan, &send_buf->hdr,
  				sizeof(send_buf->hdr) + to_write,
  				0, VM_PKT_DATA_INBAND, 0);
  }
  
  static void hvs_channel_cb(void *ctx)
  {
  	struct sock *sk = (struct sock *)ctx;
  	struct vsock_sock *vsk = vsock_sk(sk);
  	struct hvsock *hvs = vsk->trans;
  	struct vmbus_channel *chan = hvs->chan;
  
  	if (hvs_channel_readable(chan))
  		sk->sk_data_ready(sk);
  
  	/* See hvs_stream_has_space(): when we reach here, the writable bytes
  	 * may be already less than HVS_PKT_LEN(HVS_SEND_BUF_SIZE).
  	 */
  	if (hv_get_bytes_to_write(&chan->outbound) > 0)
  		sk->sk_write_space(sk);
  }
  
  static void hvs_close_connection(struct vmbus_channel *chan)
  {
  	struct sock *sk = get_per_channel_state(chan);
  	struct vsock_sock *vsk = vsock_sk(sk);
  
  	lock_sock(sk);
  
  	sk->sk_state = TCP_CLOSE;
  	sock_set_flag(sk, SOCK_DONE);
  	vsk->peer_shutdown |= SEND_SHUTDOWN | RCV_SHUTDOWN;
  
  	sk->sk_state_change(sk);
  
  	release_sock(sk);
  }
  
  static void hvs_open_connection(struct vmbus_channel *chan)
  {
  	uuid_le *if_instance, *if_type;
  	unsigned char conn_from_host;
  
  	struct sockaddr_vm addr;
  	struct sock *sk, *new = NULL;
  	struct vsock_sock *vnew;
  	struct hvsock *hvs, *hvs_new;
  	int ret;
  
  	if_type = &chan->offermsg.offer.if_type;
  	if_instance = &chan->offermsg.offer.if_instance;
  	conn_from_host = chan->offermsg.offer.u.pipe.user_def[0];
  
  	/* The host or the VM should only listen on a port in
  	 * [0, MAX_LISTEN_PORT]
  	 */
  	if (!is_valid_srv_id(if_type) ||
  	    get_port_by_srv_id(if_type) > MAX_LISTEN_PORT)
  		return;
  
  	hvs_addr_init(&addr, conn_from_host ? if_type : if_instance);
  	sk = vsock_find_bound_socket(&addr);
  	if (!sk)
  		return;
  
  	lock_sock(sk);
  	if ((conn_from_host && sk->sk_state != TCP_LISTEN) ||
  	    (!conn_from_host && sk->sk_state != TCP_SYN_SENT))
  		goto out;
  
  	if (conn_from_host) {
  		if (sk->sk_ack_backlog >= sk->sk_max_ack_backlog)
  			goto out;
  
  		new = __vsock_create(sock_net(sk), NULL, sk, GFP_KERNEL,
  				     sk->sk_type, 0);
  		if (!new)
  			goto out;
  
  		new->sk_state = TCP_SYN_SENT;
  		vnew = vsock_sk(new);
  		hvs_new = vnew->trans;
  		hvs_new->chan = chan;
  	} else {
  		hvs = vsock_sk(sk)->trans;
  		hvs->chan = chan;
  	}
  
  	set_channel_read_mode(chan, HV_CALL_DIRECT);
  	ret = vmbus_open(chan, RINGBUFFER_HVS_SND_SIZE,
  			 RINGBUFFER_HVS_RCV_SIZE, NULL, 0,
  			 hvs_channel_cb, conn_from_host ? new : sk);
  	if (ret != 0) {
  		if (conn_from_host) {
  			hvs_new->chan = NULL;
  			sock_put(new);
  		} else {
  			hvs->chan = NULL;
  		}
  		goto out;
  	}
  
  	set_per_channel_state(chan, conn_from_host ? new : sk);
  	vmbus_set_chn_rescind_callback(chan, hvs_close_connection);
  
  	if (conn_from_host) {
  		new->sk_state = TCP_ESTABLISHED;
  		sk->sk_ack_backlog++;
  
  		hvs_addr_init(&vnew->local_addr, if_type);
  		hvs_remote_addr_init(&vnew->remote_addr, &vnew->local_addr);
  
  		hvs_new->vm_srv_id = *if_type;
  		hvs_new->host_srv_id = *if_instance;
  
  		vsock_insert_connected(vnew);
  
  		vsock_enqueue_accept(sk, new);
  	} else {
  		sk->sk_state = TCP_ESTABLISHED;
  		sk->sk_socket->state = SS_CONNECTED;
  
  		vsock_insert_connected(vsock_sk(sk));
  	}
  
  	sk->sk_state_change(sk);
  
  out:
  	/* Release refcnt obtained when we called vsock_find_bound_socket() */
  	sock_put(sk);
  
  	release_sock(sk);
  }
  
  static u32 hvs_get_local_cid(void)
  {
  	return VMADDR_CID_ANY;
  }
  
  static int hvs_sock_init(struct vsock_sock *vsk, struct vsock_sock *psk)
  {
  	struct hvsock *hvs;
  
  	hvs = kzalloc(sizeof(*hvs), GFP_KERNEL);
  	if (!hvs)
  		return -ENOMEM;
  
  	vsk->trans = hvs;
  	hvs->vsk = vsk;
  
  	return 0;
  }
  
  static int hvs_connect(struct vsock_sock *vsk)
  {
  	union hvs_service_id vm, host;
  	struct hvsock *h = vsk->trans;
  
  	vm.srv_id = srv_id_template;
  	vm.svm_port = vsk->local_addr.svm_port;
  	h->vm_srv_id = vm.srv_id;
  
  	host.srv_id = srv_id_template;
  	host.svm_port = vsk->remote_addr.svm_port;
  	h->host_srv_id = host.srv_id;
  
  	return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id);
  }
  
  static int hvs_shutdown(struct vsock_sock *vsk, int mode)
  {
  	struct sock *sk = sk_vsock(vsk);
  	struct vmpipe_proto_header hdr;
  	struct hvs_send_buf *send_buf;
  	struct hvsock *hvs;
  
  	if (!(mode & SEND_SHUTDOWN))
  		return 0;
  
  	lock_sock(sk);
  
  	hvs = vsk->trans;
  	if (hvs->fin_sent)
  		goto out;
  
  	send_buf = (struct hvs_send_buf *)&hdr;
  
  	/* It can't fail: see hvs_channel_writable_bytes(). */
  	(void)hvs_send_data(hvs->chan, send_buf, 0);
  
  	hvs->fin_sent = true;
  out:
  	release_sock(sk);
  	return 0;
  }
  
  static void hvs_release(struct vsock_sock *vsk)
  {
  	struct sock *sk = sk_vsock(vsk);
  	struct hvsock *hvs = vsk->trans;
  	struct vmbus_channel *chan;
  
  	lock_sock(sk);
  
  	sk->sk_state = TCP_CLOSING;
  	vsock_remove_sock(vsk);
  
  	release_sock(sk);
  
  	chan = hvs->chan;
  	if (chan)
  		hvs_shutdown(vsk, RCV_SHUTDOWN | SEND_SHUTDOWN);
  
  }
  
  static void hvs_destruct(struct vsock_sock *vsk)
  {
  	struct hvsock *hvs = vsk->trans;
  	struct vmbus_channel *chan = hvs->chan;
  
  	if (chan)
  		vmbus_hvsock_device_unregister(chan);
  
  	kfree(hvs);
  }
  
  static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
  {
  	return -EOPNOTSUPP;
  }
  
  static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
  			     size_t len, int flags)
  {
  	return -EOPNOTSUPP;
  }
  
  static int hvs_dgram_enqueue(struct vsock_sock *vsk,
  			     struct sockaddr_vm *remote, struct msghdr *msg,
  			     size_t dgram_len)
  {
  	return -EOPNOTSUPP;
  }
  
  static bool hvs_dgram_allow(u32 cid, u32 port)
  {
  	return false;
  }
  
  static int hvs_update_recv_data(struct hvsock *hvs)
  {
  	struct hvs_recv_buf *recv_buf;
  	u32 payload_len;
  
  	recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
  	payload_len = recv_buf->hdr.data_size;
  
  	if (payload_len > HVS_MTU_SIZE)
  		return -EIO;
  
  	if (payload_len == 0)
  		hvs->vsk->peer_shutdown |= SEND_SHUTDOWN;
  
  	hvs->recv_data_len = payload_len;
  	hvs->recv_data_off = 0;
  
  	return 0;
  }
  
  static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
  				  size_t len, int flags)
  {
  	struct hvsock *hvs = vsk->trans;
  	bool need_refill = !hvs->recv_desc;
  	struct hvs_recv_buf *recv_buf;
  	u32 to_read;
  	int ret;
  
  	if (flags & MSG_PEEK)
  		return -EOPNOTSUPP;
  
  	if (need_refill) {
  		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
  		ret = hvs_update_recv_data(hvs);
  		if (ret)
  			return ret;
  	}
  
  	recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
  	to_read = min_t(u32, len, hvs->recv_data_len);
  	ret = memcpy_to_msg(msg, recv_buf->data + hvs->recv_data_off, to_read);
  	if (ret != 0)
  		return ret;
  
  	hvs->recv_data_len -= to_read;
  	if (hvs->recv_data_len == 0) {
  		hvs->recv_desc = hv_pkt_iter_next(hvs->chan, hvs->recv_desc);
  		if (hvs->recv_desc) {
  			ret = hvs_update_recv_data(hvs);
  			if (ret)
  				return ret;
  		}
  	} else {
  		hvs->recv_data_off += to_read;
  	}
  
  	return to_read;
  }
  
  static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
  				  size_t len)
  {
  	struct hvsock *hvs = vsk->trans;
  	struct vmbus_channel *chan = hvs->chan;
  	struct hvs_send_buf *send_buf;
  	ssize_t to_write, max_writable, ret;
  
  	BUILD_BUG_ON(sizeof(*send_buf) != PAGE_SIZE_4K);
  
  	send_buf = kmalloc(sizeof(*send_buf), GFP_KERNEL);
  	if (!send_buf)
  		return -ENOMEM;
  
  	max_writable = hvs_channel_writable_bytes(chan);
  	to_write = min_t(ssize_t, len, max_writable);
  	to_write = min_t(ssize_t, to_write, HVS_SEND_BUF_SIZE);
  
  	ret = memcpy_from_msg(send_buf->data, msg, to_write);
  	if (ret < 0)
  		goto out;
  
  	ret = hvs_send_data(hvs->chan, send_buf, to_write);
  	if (ret < 0)
  		goto out;
  
  	ret = to_write;
  out:
  	kfree(send_buf);
  	return ret;
  }
  
  static s64 hvs_stream_has_data(struct vsock_sock *vsk)
  {
  	struct hvsock *hvs = vsk->trans;
  	s64 ret;
  
  	if (hvs->recv_data_len > 0)
  		return 1;
  
  	switch (hvs_channel_readable_payload(hvs->chan)) {
  	case 1:
  		ret = 1;
  		break;
  	case 0:
  		vsk->peer_shutdown |= SEND_SHUTDOWN;
  		ret = 0;
  		break;
  	default: /* -1 */
  		ret = 0;
  		break;
  	}
  
  	return ret;
  }
  
  static s64 hvs_stream_has_space(struct vsock_sock *vsk)
  {
  	struct hvsock *hvs = vsk->trans;
  	struct vmbus_channel *chan = hvs->chan;
  	s64 ret;
  
  	ret = hvs_channel_writable_bytes(chan);
  	if (ret > 0)  {
  		hvs_clear_channel_pending_send_size(chan);
  	} else {
  		/* See hvs_channel_cb() */
  		hvs_set_channel_pending_send_size(chan);
  
  		/* Re-check the writable bytes to avoid race */
  		ret = hvs_channel_writable_bytes(chan);
  		if (ret > 0)
  			hvs_clear_channel_pending_send_size(chan);
  	}
  
  	return ret;
  }
  
  static u64 hvs_stream_rcvhiwat(struct vsock_sock *vsk)
  {
  	return HVS_MTU_SIZE + 1;
  }
  
  static bool hvs_stream_is_active(struct vsock_sock *vsk)
  {
  	struct hvsock *hvs = vsk->trans;
  
  	return hvs->chan != NULL;
  }
  
  static bool hvs_stream_allow(u32 cid, u32 port)
  {
  	/* The host's port range [MIN_HOST_EPHEMERAL_PORT, 0xFFFFFFFF) is
  	 * reserved as ephemeral ports, which are used as the host's ports
  	 * when the host initiates connections.
  	 *
  	 * Perform this check in the guest so an immediate error is produced
  	 * instead of a timeout.
  	 */
  	if (port > MAX_HOST_LISTEN_PORT)
  		return false;
  
  	if (cid == VMADDR_CID_HOST)
  		return true;
  
  	return false;
  }
  
  static
  int hvs_notify_poll_in(struct vsock_sock *vsk, size_t target, bool *readable)
  {
  	struct hvsock *hvs = vsk->trans;
  
  	*readable = hvs_channel_readable(hvs->chan);
  	return 0;
  }
  
  static
  int hvs_notify_poll_out(struct vsock_sock *vsk, size_t target, bool *writable)
  {
  	*writable = hvs_stream_has_space(vsk) > 0;
  
  	return 0;
  }
  
  static
  int hvs_notify_recv_init(struct vsock_sock *vsk, size_t target,
  			 struct vsock_transport_recv_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_recv_pre_block(struct vsock_sock *vsk, size_t target,
  			      struct vsock_transport_recv_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_recv_pre_dequeue(struct vsock_sock *vsk, size_t target,
  				struct vsock_transport_recv_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_recv_post_dequeue(struct vsock_sock *vsk, size_t target,
  				 ssize_t copied, bool data_read,
  				 struct vsock_transport_recv_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_send_init(struct vsock_sock *vsk,
  			 struct vsock_transport_send_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_send_pre_block(struct vsock_sock *vsk,
  			      struct vsock_transport_send_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_send_pre_enqueue(struct vsock_sock *vsk,
  				struct vsock_transport_send_notify_data *d)
  {
  	return 0;
  }
  
  static
  int hvs_notify_send_post_enqueue(struct vsock_sock *vsk, ssize_t written,
  				 struct vsock_transport_send_notify_data *d)
  {
  	return 0;
  }
  
  static void hvs_set_buffer_size(struct vsock_sock *vsk, u64 val)
  {
  	/* Ignored. */
  }
  
  static void hvs_set_min_buffer_size(struct vsock_sock *vsk, u64 val)
  {
  	/* Ignored. */
  }
  
  static void hvs_set_max_buffer_size(struct vsock_sock *vsk, u64 val)
  {
  	/* Ignored. */
  }
  
  static u64 hvs_get_buffer_size(struct vsock_sock *vsk)
  {
  	return -ENOPROTOOPT;
  }
  
  static u64 hvs_get_min_buffer_size(struct vsock_sock *vsk)
  {
  	return -ENOPROTOOPT;
  }
  
  static u64 hvs_get_max_buffer_size(struct vsock_sock *vsk)
  {
  	return -ENOPROTOOPT;
  }
  
  static struct vsock_transport hvs_transport = {
  	.get_local_cid            = hvs_get_local_cid,
  
  	.init                     = hvs_sock_init,
  	.destruct                 = hvs_destruct,
  	.release                  = hvs_release,
  	.connect                  = hvs_connect,
  	.shutdown                 = hvs_shutdown,
  
  	.dgram_bind               = hvs_dgram_bind,
  	.dgram_dequeue            = hvs_dgram_dequeue,
  	.dgram_enqueue            = hvs_dgram_enqueue,
  	.dgram_allow              = hvs_dgram_allow,
  
  	.stream_dequeue           = hvs_stream_dequeue,
  	.stream_enqueue           = hvs_stream_enqueue,
  	.stream_has_data          = hvs_stream_has_data,
  	.stream_has_space         = hvs_stream_has_space,
  	.stream_rcvhiwat          = hvs_stream_rcvhiwat,
  	.stream_is_active         = hvs_stream_is_active,
  	.stream_allow             = hvs_stream_allow,
  
  	.notify_poll_in           = hvs_notify_poll_in,
  	.notify_poll_out          = hvs_notify_poll_out,
  	.notify_recv_init         = hvs_notify_recv_init,
  	.notify_recv_pre_block    = hvs_notify_recv_pre_block,
  	.notify_recv_pre_dequeue  = hvs_notify_recv_pre_dequeue,
  	.notify_recv_post_dequeue = hvs_notify_recv_post_dequeue,
  	.notify_send_init         = hvs_notify_send_init,
  	.notify_send_pre_block    = hvs_notify_send_pre_block,
  	.notify_send_pre_enqueue  = hvs_notify_send_pre_enqueue,
  	.notify_send_post_enqueue = hvs_notify_send_post_enqueue,
  
  	.set_buffer_size          = hvs_set_buffer_size,
  	.set_min_buffer_size      = hvs_set_min_buffer_size,
  	.set_max_buffer_size      = hvs_set_max_buffer_size,
  	.get_buffer_size          = hvs_get_buffer_size,
  	.get_min_buffer_size      = hvs_get_min_buffer_size,
  	.get_max_buffer_size      = hvs_get_max_buffer_size,
  };
  
  static int hvs_probe(struct hv_device *hdev,
  		     const struct hv_vmbus_device_id *dev_id)
  {
  	struct vmbus_channel *chan = hdev->channel;
  
  	hvs_open_connection(chan);
  
  	/* Always return success to suppress the unnecessary error message
  	 * in vmbus_probe(): on error the host will rescind the device in
  	 * 30 seconds and we can do cleanup at that time in
  	 * vmbus_onoffer_rescind().
  	 */
  	return 0;
  }
  
  static int hvs_remove(struct hv_device *hdev)
  {
  	struct vmbus_channel *chan = hdev->channel;
  
  	vmbus_close(chan);
  
  	return 0;
  }
  
  /* This isn't really used. See vmbus_match() and vmbus_probe() */
  static const struct hv_vmbus_device_id id_table[] = {
  	{},
  };
  
  static struct hv_driver hvs_drv = {
  	.name		= "hv_sock",
  	.hvsock		= true,
  	.id_table	= id_table,
  	.probe		= hvs_probe,
  	.remove		= hvs_remove,
  };
  
  static int __init hvs_init(void)
  {
  	int ret;
  
  	if (vmbus_proto_version < VERSION_WIN10)
  		return -ENODEV;
  
  	ret = vmbus_driver_register(&hvs_drv);
  	if (ret != 0)
  		return ret;
  
  	ret = vsock_core_init(&hvs_transport);
  	if (ret) {
  		vmbus_driver_unregister(&hvs_drv);
  		return ret;
  	}
  
  	return 0;
  }
  
  static void __exit hvs_exit(void)
  {
  	vsock_core_exit();
  	vmbus_driver_unregister(&hvs_drv);
  }
  
  module_init(hvs_init);
  module_exit(hvs_exit);
  
  MODULE_DESCRIPTION("Hyper-V Sockets");
  MODULE_VERSION("1.0.0");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_NETPROTO(PF_VSOCK);
  