linux/net/vmw_vsock/hyperv_transport.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Hyper-V transport for vsock
   4 *
   5 * Hyper-V Sockets supplies a byte-stream based communication mechanism
   6 * between the host and the VM. This driver implements the necessary
   7 * support in the VM by introducing the new vsock transport.
   8 *
   9 * Copyright (c) 2017, Microsoft Corporation.
  10 */
  11#include <linux/module.h>
  12#include <linux/vmalloc.h>
  13#include <linux/hyperv.h>
  14#include <net/sock.h>
  15#include <net/af_vsock.h>
  16#include <asm/hyperv-tlfs.h>
  17
  18/* Older (VMBUS version 'VERSION_WIN10' or before) Windows hosts have some
  19 * stricter requirements on the hv_sock ring buffer size of six 4K pages.
  20 * hyperv-tlfs defines HV_HYP_PAGE_SIZE as 4K. Newer hosts don't have this
  21 * limitation; but, keep the defaults the same for compat.
  22 */
  23#define RINGBUFFER_HVS_RCV_SIZE (HV_HYP_PAGE_SIZE * 6)
  24#define RINGBUFFER_HVS_SND_SIZE (HV_HYP_PAGE_SIZE * 6)
  25#define RINGBUFFER_HVS_MAX_SIZE (HV_HYP_PAGE_SIZE * 64)
  26
  27/* The MTU is 16KB per the host side's design */
  28#define HVS_MTU_SIZE            (1024 * 16)
  29
  30/* How long to wait for graceful shutdown of a connection */
  31#define HVS_CLOSE_TIMEOUT (8 * HZ)
  32
  33struct vmpipe_proto_header {
  34        u32 pkt_type;
  35        u32 data_size;
  36};
  37
  38/* For recv, we use the VMBus in-place packet iterator APIs to directly copy
  39 * data from the ringbuffer into the userspace buffer.
  40 */
  41struct hvs_recv_buf {
  42        /* The header before the payload data */
  43        struct vmpipe_proto_header hdr;
  44
  45        /* The payload */
  46        u8 data[HVS_MTU_SIZE];
  47};
  48
  49/* We can send up to HVS_MTU_SIZE bytes of payload to the host, but let's use
  50 * a smaller size, i.e. HVS_SEND_BUF_SIZE, to maximize concurrency between the
  51 * guest and the host processing as one VMBUS packet is the smallest processing
  52 * unit.
  53 *
  54 * Note: the buffer can be eliminated in the future when we add new VMBus
  55 * ringbuffer APIs that allow us to directly copy data from userspace buffer
  56 * to VMBus ringbuffer.
  57 */
  58#define HVS_SEND_BUF_SIZE \
  59                (HV_HYP_PAGE_SIZE - sizeof(struct vmpipe_proto_header))
  60
  61struct hvs_send_buf {
  62        /* The header before the payload data */
  63        struct vmpipe_proto_header hdr;
  64
  65        /* The payload */
  66        u8 data[HVS_SEND_BUF_SIZE];
  67};
  68
  69#define HVS_HEADER_LEN  (sizeof(struct vmpacket_descriptor) + \
  70                         sizeof(struct vmpipe_proto_header))
  71
  72/* See 'prev_indices' in hv_ringbuffer_read(), hv_ringbuffer_write(), and
  73 * __hv_pkt_iter_next().
  74 */
  75#define VMBUS_PKT_TRAILER_SIZE  (sizeof(u64))
  76
  77#define HVS_PKT_LEN(payload_len)        (HVS_HEADER_LEN + \
  78                                         ALIGN((payload_len), 8) + \
  79                                         VMBUS_PKT_TRAILER_SIZE)
  80
  81union hvs_service_id {
  82        guid_t  srv_id;
  83
  84        struct {
  85                unsigned int svm_port;
  86                unsigned char b[sizeof(guid_t) - sizeof(unsigned int)];
  87        };
  88};
  89
  90/* Per-socket state (accessed via vsk->trans) */
  91struct hvsock {
  92        struct vsock_sock *vsk;
  93
  94        guid_t vm_srv_id;
  95        guid_t host_srv_id;
  96
  97        struct vmbus_channel *chan;
  98        struct vmpacket_descriptor *recv_desc;
  99
 100        /* The length of the payload not delivered to userland yet */
 101        u32 recv_data_len;
 102        /* The offset of the payload */
 103        u32 recv_data_off;
 104
 105        /* Have we sent the zero-length packet (FIN)? */
 106        bool fin_sent;
 107};
 108
 109/* In the VM, we support Hyper-V Sockets with AF_VSOCK, and the endpoint is
 110 * <cid, port> (see struct sockaddr_vm). Note: cid is not really used here:
 111 * when we write apps to connect to the host, we can only use VMADDR_CID_ANY
 112 * or VMADDR_CID_HOST (both are equivalent) as the remote cid, and when we
 113 * write apps to bind() & listen() in the VM, we can only use VMADDR_CID_ANY
 114 * as the local cid.
 115 *
 116 * On the host, Hyper-V Sockets are supported by Winsock AF_HYPERV:
 117 * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-
 118 * guide/make-integration-service, and the endpoint is <VmID, ServiceId> with
 119 * the below sockaddr:
 120 *
 121 * struct SOCKADDR_HV
 122 * {
 123 *    ADDRESS_FAMILY Family;
 124 *    USHORT Reserved;
 125 *    GUID VmId;
 126 *    GUID ServiceId;
 127 * };
 128 * Note: VmID is not used by Linux VM and actually it isn't transmitted via
 129 * VMBus, because here it's obvious the host and the VM can easily identify
 130 * each other. Though the VmID is useful on the host, especially in the case
 131 * of Windows container, Linux VM doesn't need it at all.
 132 *
 133 * To make use of the AF_VSOCK infrastructure in Linux VM, we have to limit
 134 * the available GUID space of SOCKADDR_HV so that we can create a mapping
 135 * between AF_VSOCK port and SOCKADDR_HV Service GUID. The rule of writing
 136 * Hyper-V Sockets apps on the host and in Linux VM is:
 137 *
 138 ****************************************************************************
 139 * The only valid Service GUIDs, from the perspectives of both the host and *
 140 * Linux VM, that can be connected by the other end, must conform to this   *
 141 * format: <port>-facb-11e6-bd58-64006a7986d3.                              *
 142 ****************************************************************************
 143 *
 144 * When we write apps on the host to connect(), the GUID ServiceID is used.
 145 * When we write apps in Linux VM to connect(), we only need to specify the
 146 * port and the driver will form the GUID and use that to request the host.
 147 *
 148 */
 149
 150/* 00000000-facb-11e6-bd58-64006a7986d3 */
 151static const guid_t srv_id_template =
 152        GUID_INIT(0x00000000, 0xfacb, 0x11e6, 0xbd, 0x58,
 153                  0x64, 0x00, 0x6a, 0x79, 0x86, 0xd3);
 154
 155static bool hvs_check_transport(struct vsock_sock *vsk);
 156
 157static bool is_valid_srv_id(const guid_t *id)
 158{
 159        return !memcmp(&id->b[4], &srv_id_template.b[4], sizeof(guid_t) - 4);
 160}
 161
 162static unsigned int get_port_by_srv_id(const guid_t *svr_id)
 163{
 164        return *((unsigned int *)svr_id);
 165}
 166
 167static void hvs_addr_init(struct sockaddr_vm *addr, const guid_t *svr_id)
 168{
 169        unsigned int port = get_port_by_srv_id(svr_id);
 170
 171        vsock_addr_init(addr, VMADDR_CID_ANY, port);
 172}
 173
 174static void hvs_set_channel_pending_send_size(struct vmbus_channel *chan)
 175{
 176        set_channel_pending_send_size(chan,
 177                                      HVS_PKT_LEN(HVS_SEND_BUF_SIZE));
 178
 179        virt_mb();
 180}
 181
 182static bool hvs_channel_readable(struct vmbus_channel *chan)
 183{
 184        u32 readable = hv_get_bytes_to_read(&chan->inbound);
 185
 186        /* 0-size payload means FIN */
 187        return readable >= HVS_PKT_LEN(0);
 188}
 189
 190static int hvs_channel_readable_payload(struct vmbus_channel *chan)
 191{
 192        u32 readable = hv_get_bytes_to_read(&chan->inbound);
 193
 194        if (readable > HVS_PKT_LEN(0)) {
 195                /* At least we have 1 byte to read. We don't need to return
 196                 * the exact readable bytes: see vsock_stream_recvmsg() ->
 197                 * vsock_stream_has_data().
 198                 */
 199                return 1;
 200        }
 201
 202        if (readable == HVS_PKT_LEN(0)) {
 203                /* 0-size payload means FIN */
 204                return 0;
 205        }
 206
 207        /* No payload or FIN */
 208        return -1;
 209}
 210
 211static size_t hvs_channel_writable_bytes(struct vmbus_channel *chan)
 212{
 213        u32 writeable = hv_get_bytes_to_write(&chan->outbound);
 214        size_t ret;
 215
 216        /* The ringbuffer mustn't be 100% full, and we should reserve a
 217         * zero-length-payload packet for the FIN: see hv_ringbuffer_write()
 218         * and hvs_shutdown().
 219         */
 220        if (writeable <= HVS_PKT_LEN(1) + HVS_PKT_LEN(0))
 221                return 0;
 222
 223        ret = writeable - HVS_PKT_LEN(1) - HVS_PKT_LEN(0);
 224
 225        return round_down(ret, 8);
 226}
 227
 228static int hvs_send_data(struct vmbus_channel *chan,
 229                         struct hvs_send_buf *send_buf, size_t to_write)
 230{
 231        send_buf->hdr.pkt_type = 1;
 232        send_buf->hdr.data_size = to_write;
 233        return vmbus_sendpacket(chan, &send_buf->hdr,
 234                                sizeof(send_buf->hdr) + to_write,
 235                                0, VM_PKT_DATA_INBAND, 0);
 236}
 237
 238static void hvs_channel_cb(void *ctx)
 239{
 240        struct sock *sk = (struct sock *)ctx;
 241        struct vsock_sock *vsk = vsock_sk(sk);
 242        struct hvsock *hvs = vsk->trans;
 243        struct vmbus_channel *chan = hvs->chan;
 244
 245        if (hvs_channel_readable(chan))
 246                sk->sk_data_ready(sk);
 247
 248        if (hv_get_bytes_to_write(&chan->outbound) > 0)
 249                sk->sk_write_space(sk);
 250}
 251
 252static void hvs_do_close_lock_held(struct vsock_sock *vsk,
 253                                   bool cancel_timeout)
 254{
 255        struct sock *sk = sk_vsock(vsk);
 256
 257        sock_set_flag(sk, SOCK_DONE);
 258        vsk->peer_shutdown = SHUTDOWN_MASK;
 259        if (vsock_stream_has_data(vsk) <= 0)
 260                sk->sk_state = TCP_CLOSING;
 261        sk->sk_state_change(sk);
 262        if (vsk->close_work_scheduled &&
 263            (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
 264                vsk->close_work_scheduled = false;
 265                vsock_remove_sock(vsk);
 266
 267                /* Release the reference taken while scheduling the timeout */
 268                sock_put(sk);
 269        }
 270}
 271
 272static void hvs_close_connection(struct vmbus_channel *chan)
 273{
 274        struct sock *sk = get_per_channel_state(chan);
 275
 276        lock_sock(sk);
 277        hvs_do_close_lock_held(vsock_sk(sk), true);
 278        release_sock(sk);
 279
 280        /* Release the refcnt for the channel that's opened in
 281         * hvs_open_connection().
 282         */
 283        sock_put(sk);
 284}
 285
 286static void hvs_open_connection(struct vmbus_channel *chan)
 287{
 288        guid_t *if_instance, *if_type;
 289        unsigned char conn_from_host;
 290
 291        struct sockaddr_vm addr;
 292        struct sock *sk, *new = NULL;
 293        struct vsock_sock *vnew = NULL;
 294        struct hvsock *hvs = NULL;
 295        struct hvsock *hvs_new = NULL;
 296        int rcvbuf;
 297        int ret;
 298        int sndbuf;
 299
 300        if_type = &chan->offermsg.offer.if_type;
 301        if_instance = &chan->offermsg.offer.if_instance;
 302        conn_from_host = chan->offermsg.offer.u.pipe.user_def[0];
 303        if (!is_valid_srv_id(if_type))
 304                return;
 305
 306        hvs_addr_init(&addr, conn_from_host ? if_type : if_instance);
 307        sk = vsock_find_bound_socket(&addr);
 308        if (!sk)
 309                return;
 310
 311        lock_sock(sk);
 312        if ((conn_from_host && sk->sk_state != TCP_LISTEN) ||
 313            (!conn_from_host && sk->sk_state != TCP_SYN_SENT))
 314                goto out;
 315
 316        if (conn_from_host) {
 317                if (sk->sk_ack_backlog >= sk->sk_max_ack_backlog)
 318                        goto out;
 319
 320                new = vsock_create_connected(sk);
 321                if (!new)
 322                        goto out;
 323
 324                new->sk_state = TCP_SYN_SENT;
 325                vnew = vsock_sk(new);
 326
 327                hvs_addr_init(&vnew->local_addr, if_type);
 328
 329                /* Remote peer is always the host */
 330                vsock_addr_init(&vnew->remote_addr,
 331                                VMADDR_CID_HOST, VMADDR_PORT_ANY);
 332                vnew->remote_addr.svm_port = get_port_by_srv_id(if_instance);
 333                ret = vsock_assign_transport(vnew, vsock_sk(sk));
 334                /* Transport assigned (looking at remote_addr) must be the
 335                 * same where we received the request.
 336                 */
 337                if (ret || !hvs_check_transport(vnew)) {
 338                        sock_put(new);
 339                        goto out;
 340                }
 341                hvs_new = vnew->trans;
 342                hvs_new->chan = chan;
 343        } else {
 344                hvs = vsock_sk(sk)->trans;
 345                hvs->chan = chan;
 346        }
 347
 348        set_channel_read_mode(chan, HV_CALL_DIRECT);
 349
 350        /* Use the socket buffer sizes as hints for the VMBUS ring size. For
 351         * server side sockets, 'sk' is the parent socket and thus, this will
 352         * allow the child sockets to inherit the size from the parent. Keep
 353         * the mins to the default value and align to page size as per VMBUS
 354         * requirements.
 355         * For the max, the socket core library will limit the socket buffer
 356         * size that can be set by the user, but, since currently, the hv_sock
 357         * VMBUS ring buffer is physically contiguous allocation, restrict it
 358         * further.
 359         * Older versions of hv_sock host side code cannot handle bigger VMBUS
 360         * ring buffer size. Use the version number to limit the change to newer
 361         * versions.
 362         */
 363        if (vmbus_proto_version < VERSION_WIN10_V5) {
 364                sndbuf = RINGBUFFER_HVS_SND_SIZE;
 365                rcvbuf = RINGBUFFER_HVS_RCV_SIZE;
 366        } else {
 367                sndbuf = max_t(int, sk->sk_sndbuf, RINGBUFFER_HVS_SND_SIZE);
 368                sndbuf = min_t(int, sndbuf, RINGBUFFER_HVS_MAX_SIZE);
 369                sndbuf = ALIGN(sndbuf, HV_HYP_PAGE_SIZE);
 370                rcvbuf = max_t(int, sk->sk_rcvbuf, RINGBUFFER_HVS_RCV_SIZE);
 371                rcvbuf = min_t(int, rcvbuf, RINGBUFFER_HVS_MAX_SIZE);
 372                rcvbuf = ALIGN(rcvbuf, HV_HYP_PAGE_SIZE);
 373        }
 374
 375        ret = vmbus_open(chan, sndbuf, rcvbuf, NULL, 0, hvs_channel_cb,
 376                         conn_from_host ? new : sk);
 377        if (ret != 0) {
 378                if (conn_from_host) {
 379                        hvs_new->chan = NULL;
 380                        sock_put(new);
 381                } else {
 382                        hvs->chan = NULL;
 383                }
 384                goto out;
 385        }
 386
 387        set_per_channel_state(chan, conn_from_host ? new : sk);
 388
 389        /* This reference will be dropped by hvs_close_connection(). */
 390        sock_hold(conn_from_host ? new : sk);
 391        vmbus_set_chn_rescind_callback(chan, hvs_close_connection);
 392
 393        /* Set the pending send size to max packet size to always get
 394         * notifications from the host when there is enough writable space.
 395         * The host is optimized to send notifications only when the pending
 396         * size boundary is crossed, and not always.
 397         */
 398        hvs_set_channel_pending_send_size(chan);
 399
 400        if (conn_from_host) {
 401                new->sk_state = TCP_ESTABLISHED;
 402                sk_acceptq_added(sk);
 403
 404                hvs_new->vm_srv_id = *if_type;
 405                hvs_new->host_srv_id = *if_instance;
 406
 407                vsock_insert_connected(vnew);
 408
 409                vsock_enqueue_accept(sk, new);
 410        } else {
 411                sk->sk_state = TCP_ESTABLISHED;
 412                sk->sk_socket->state = SS_CONNECTED;
 413
 414                vsock_insert_connected(vsock_sk(sk));
 415        }
 416
 417        sk->sk_state_change(sk);
 418
 419out:
 420        /* Release refcnt obtained when we called vsock_find_bound_socket() */
 421        sock_put(sk);
 422
 423        release_sock(sk);
 424}
 425
 426static u32 hvs_get_local_cid(void)
 427{
 428        return VMADDR_CID_ANY;
 429}
 430
 431static int hvs_sock_init(struct vsock_sock *vsk, struct vsock_sock *psk)
 432{
 433        struct hvsock *hvs;
 434        struct sock *sk = sk_vsock(vsk);
 435
 436        hvs = kzalloc(sizeof(*hvs), GFP_KERNEL);
 437        if (!hvs)
 438                return -ENOMEM;
 439
 440        vsk->trans = hvs;
 441        hvs->vsk = vsk;
 442        sk->sk_sndbuf = RINGBUFFER_HVS_SND_SIZE;
 443        sk->sk_rcvbuf = RINGBUFFER_HVS_RCV_SIZE;
 444        return 0;
 445}
 446
 447static int hvs_connect(struct vsock_sock *vsk)
 448{
 449        union hvs_service_id vm, host;
 450        struct hvsock *h = vsk->trans;
 451
 452        vm.srv_id = srv_id_template;
 453        vm.svm_port = vsk->local_addr.svm_port;
 454        h->vm_srv_id = vm.srv_id;
 455
 456        host.srv_id = srv_id_template;
 457        host.svm_port = vsk->remote_addr.svm_port;
 458        h->host_srv_id = host.srv_id;
 459
 460        return vmbus_send_tl_connect_request(&h->vm_srv_id, &h->host_srv_id);
 461}
 462
 463static void hvs_shutdown_lock_held(struct hvsock *hvs, int mode)
 464{
 465        struct vmpipe_proto_header hdr;
 466
 467        if (hvs->fin_sent || !hvs->chan)
 468                return;
 469
 470        /* It can't fail: see hvs_channel_writable_bytes(). */
 471        (void)hvs_send_data(hvs->chan, (struct hvs_send_buf *)&hdr, 0);
 472        hvs->fin_sent = true;
 473}
 474
 475static int hvs_shutdown(struct vsock_sock *vsk, int mode)
 476{
 477        if (!(mode & SEND_SHUTDOWN))
 478                return 0;
 479
 480        hvs_shutdown_lock_held(vsk->trans, mode);
 481        return 0;
 482}
 483
 484static void hvs_close_timeout(struct work_struct *work)
 485{
 486        struct vsock_sock *vsk =
 487                container_of(work, struct vsock_sock, close_work.work);
 488        struct sock *sk = sk_vsock(vsk);
 489
 490        sock_hold(sk);
 491        lock_sock(sk);
 492        if (!sock_flag(sk, SOCK_DONE))
 493                hvs_do_close_lock_held(vsk, false);
 494
 495        vsk->close_work_scheduled = false;
 496        release_sock(sk);
 497        sock_put(sk);
 498}
 499
 500/* Returns true, if it is safe to remove socket; false otherwise */
 501static bool hvs_close_lock_held(struct vsock_sock *vsk)
 502{
 503        struct sock *sk = sk_vsock(vsk);
 504
 505        if (!(sk->sk_state == TCP_ESTABLISHED ||
 506              sk->sk_state == TCP_CLOSING))
 507                return true;
 508
 509        if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
 510                hvs_shutdown_lock_held(vsk->trans, SHUTDOWN_MASK);
 511
 512        if (sock_flag(sk, SOCK_DONE))
 513                return true;
 514
 515        /* This reference will be dropped by the delayed close routine */
 516        sock_hold(sk);
 517        INIT_DELAYED_WORK(&vsk->close_work, hvs_close_timeout);
 518        vsk->close_work_scheduled = true;
 519        schedule_delayed_work(&vsk->close_work, HVS_CLOSE_TIMEOUT);
 520        return false;
 521}
 522
 523static void hvs_release(struct vsock_sock *vsk)
 524{
 525        bool remove_sock;
 526
 527        remove_sock = hvs_close_lock_held(vsk);
 528        if (remove_sock)
 529                vsock_remove_sock(vsk);
 530}
 531
 532static void hvs_destruct(struct vsock_sock *vsk)
 533{
 534        struct hvsock *hvs = vsk->trans;
 535        struct vmbus_channel *chan = hvs->chan;
 536
 537        if (chan)
 538                vmbus_hvsock_device_unregister(chan);
 539
 540        kfree(hvs);
 541}
 542
 543static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
 544{
 545        return -EOPNOTSUPP;
 546}
 547
 548static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 549                             size_t len, int flags)
 550{
 551        return -EOPNOTSUPP;
 552}
 553
 554static int hvs_dgram_enqueue(struct vsock_sock *vsk,
 555                             struct sockaddr_vm *remote, struct msghdr *msg,
 556                             size_t dgram_len)
 557{
 558        return -EOPNOTSUPP;
 559}
 560
 561static bool hvs_dgram_allow(u32 cid, u32 port)
 562{
 563        return false;
 564}
 565
 566static int hvs_update_recv_data(struct hvsock *hvs)
 567{
 568        struct hvs_recv_buf *recv_buf;
 569        u32 payload_len;
 570
 571        recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
 572        payload_len = recv_buf->hdr.data_size;
 573
 574        if (payload_len > HVS_MTU_SIZE)
 575                return -EIO;
 576
 577        if (payload_len == 0)
 578                hvs->vsk->peer_shutdown |= SEND_SHUTDOWN;
 579
 580        hvs->recv_data_len = payload_len;
 581        hvs->recv_data_off = 0;
 582
 583        return 0;
 584}
 585
 586static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 587                                  size_t len, int flags)
 588{
 589        struct hvsock *hvs = vsk->trans;
 590        bool need_refill = !hvs->recv_desc;
 591        struct hvs_recv_buf *recv_buf;
 592        u32 to_read;
 593        int ret;
 594
 595        if (flags & MSG_PEEK)
 596                return -EOPNOTSUPP;
 597
 598        if (need_refill) {
 599                hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan);
 600                ret = hvs_update_recv_data(hvs);
 601                if (ret)
 602                        return ret;
 603        }
 604
 605        recv_buf = (struct hvs_recv_buf *)(hvs->recv_desc + 1);
 606        to_read = min_t(u32, len, hvs->recv_data_len);
 607        ret = memcpy_to_msg(msg, recv_buf->data + hvs->recv_data_off, to_read);
 608        if (ret != 0)
 609                return ret;
 610
 611        hvs->recv_data_len -= to_read;
 612        if (hvs->recv_data_len == 0) {
 613                hvs->recv_desc = hv_pkt_iter_next_raw(hvs->chan, hvs->recv_desc);
 614                if (hvs->recv_desc) {
 615                        ret = hvs_update_recv_data(hvs);
 616                        if (ret)
 617                                return ret;
 618                }
 619        } else {
 620                hvs->recv_data_off += to_read;
 621        }
 622
 623        return to_read;
 624}
 625
 626static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
 627                                  size_t len)
 628{
 629        struct hvsock *hvs = vsk->trans;
 630        struct vmbus_channel *chan = hvs->chan;
 631        struct hvs_send_buf *send_buf;
 632        ssize_t to_write, max_writable;
 633        ssize_t ret = 0;
 634        ssize_t bytes_written = 0;
 635
 636        BUILD_BUG_ON(sizeof(*send_buf) != HV_HYP_PAGE_SIZE);
 637
 638        send_buf = kmalloc(sizeof(*send_buf), GFP_KERNEL);
 639        if (!send_buf)
 640                return -ENOMEM;
 641
 642        /* Reader(s) could be draining data from the channel as we write.
 643         * Maximize bandwidth, by iterating until the channel is found to be
 644         * full.
 645         */
 646        while (len) {
 647                max_writable = hvs_channel_writable_bytes(chan);
 648                if (!max_writable)
 649                        break;
 650                to_write = min_t(ssize_t, len, max_writable);
 651                to_write = min_t(ssize_t, to_write, HVS_SEND_BUF_SIZE);
 652                /* memcpy_from_msg is safe for loop as it advances the offsets
 653                 * within the message iterator.
 654                 */
 655                ret = memcpy_from_msg(send_buf->data, msg, to_write);
 656                if (ret < 0)
 657                        goto out;
 658
 659                ret = hvs_send_data(hvs->chan, send_buf, to_write);
 660                if (ret < 0)
 661                        goto out;
 662
 663                bytes_written += to_write;
 664                len -= to_write;
 665        }
 666out:
 667        /* If any data has been sent, return that */
 668        if (bytes_written)
 669                ret = bytes_written;
 670        kfree(send_buf);
 671        return ret;
 672}
 673
 674static s64 hvs_stream_has_data(struct vsock_sock *vsk)
 675{
 676        struct hvsock *hvs = vsk->trans;
 677        s64 ret;
 678
 679        if (hvs->recv_data_len > 0)
 680                return 1;
 681
 682        switch (hvs_channel_readable_payload(hvs->chan)) {
 683        case 1:
 684                ret = 1;
 685                break;
 686        case 0:
 687                vsk->peer_shutdown |= SEND_SHUTDOWN;
 688                ret = 0;
 689                break;
 690        default: /* -1 */
 691                ret = 0;
 692                break;
 693        }
 694
 695        return ret;
 696}
 697
 698static s64 hvs_stream_has_space(struct vsock_sock *vsk)
 699{
 700        struct hvsock *hvs = vsk->trans;
 701
 702        return hvs_channel_writable_bytes(hvs->chan);
 703}
 704
 705static u64 hvs_stream_rcvhiwat(struct vsock_sock *vsk)
 706{
 707        return HVS_MTU_SIZE + 1;
 708}
 709
 710static bool hvs_stream_is_active(struct vsock_sock *vsk)
 711{
 712        struct hvsock *hvs = vsk->trans;
 713
 714        return hvs->chan != NULL;
 715}
 716
 717static bool hvs_stream_allow(u32 cid, u32 port)
 718{
 719        if (cid == VMADDR_CID_HOST)
 720                return true;
 721
 722        return false;
 723}
 724
 725static
 726int hvs_notify_poll_in(struct vsock_sock *vsk, size_t target, bool *readable)
 727{
 728        struct hvsock *hvs = vsk->trans;
 729
 730        *readable = hvs_channel_readable(hvs->chan);
 731        return 0;
 732}
 733
 734static
 735int hvs_notify_poll_out(struct vsock_sock *vsk, size_t target, bool *writable)
 736{
 737        *writable = hvs_stream_has_space(vsk) > 0;
 738
 739        return 0;
 740}
 741
 742static
 743int hvs_notify_recv_init(struct vsock_sock *vsk, size_t target,
 744                         struct vsock_transport_recv_notify_data *d)
 745{
 746        return 0;
 747}
 748
 749static
 750int hvs_notify_recv_pre_block(struct vsock_sock *vsk, size_t target,
 751                              struct vsock_transport_recv_notify_data *d)
 752{
 753        return 0;
 754}
 755
 756static
 757int hvs_notify_recv_pre_dequeue(struct vsock_sock *vsk, size_t target,
 758                                struct vsock_transport_recv_notify_data *d)
 759{
 760        return 0;
 761}
 762
 763static
 764int hvs_notify_recv_post_dequeue(struct vsock_sock *vsk, size_t target,
 765                                 ssize_t copied, bool data_read,
 766                                 struct vsock_transport_recv_notify_data *d)
 767{
 768        return 0;
 769}
 770
 771static
 772int hvs_notify_send_init(struct vsock_sock *vsk,
 773                         struct vsock_transport_send_notify_data *d)
 774{
 775        return 0;
 776}
 777
 778static
 779int hvs_notify_send_pre_block(struct vsock_sock *vsk,
 780                              struct vsock_transport_send_notify_data *d)
 781{
 782        return 0;
 783}
 784
 785static
 786int hvs_notify_send_pre_enqueue(struct vsock_sock *vsk,
 787                                struct vsock_transport_send_notify_data *d)
 788{
 789        return 0;
 790}
 791
 792static
 793int hvs_notify_send_post_enqueue(struct vsock_sock *vsk, ssize_t written,
 794                                 struct vsock_transport_send_notify_data *d)
 795{
 796        return 0;
 797}
 798
 799static struct vsock_transport hvs_transport = {
 800        .module                   = THIS_MODULE,
 801
 802        .get_local_cid            = hvs_get_local_cid,
 803
 804        .init                     = hvs_sock_init,
 805        .destruct                 = hvs_destruct,
 806        .release                  = hvs_release,
 807        .connect                  = hvs_connect,
 808        .shutdown                 = hvs_shutdown,
 809
 810        .dgram_bind               = hvs_dgram_bind,
 811        .dgram_dequeue            = hvs_dgram_dequeue,
 812        .dgram_enqueue            = hvs_dgram_enqueue,
 813        .dgram_allow              = hvs_dgram_allow,
 814
 815        .stream_dequeue           = hvs_stream_dequeue,
 816        .stream_enqueue           = hvs_stream_enqueue,
 817        .stream_has_data          = hvs_stream_has_data,
 818        .stream_has_space         = hvs_stream_has_space,
 819        .stream_rcvhiwat          = hvs_stream_rcvhiwat,
 820        .stream_is_active         = hvs_stream_is_active,
 821        .stream_allow             = hvs_stream_allow,
 822
 823        .notify_poll_in           = hvs_notify_poll_in,
 824        .notify_poll_out          = hvs_notify_poll_out,
 825        .notify_recv_init         = hvs_notify_recv_init,
 826        .notify_recv_pre_block    = hvs_notify_recv_pre_block,
 827        .notify_recv_pre_dequeue  = hvs_notify_recv_pre_dequeue,
 828        .notify_recv_post_dequeue = hvs_notify_recv_post_dequeue,
 829        .notify_send_init         = hvs_notify_send_init,
 830        .notify_send_pre_block    = hvs_notify_send_pre_block,
 831        .notify_send_pre_enqueue  = hvs_notify_send_pre_enqueue,
 832        .notify_send_post_enqueue = hvs_notify_send_post_enqueue,
 833
 834};
 835
 836static bool hvs_check_transport(struct vsock_sock *vsk)
 837{
 838        return vsk->transport == &hvs_transport;
 839}
 840
 841static int hvs_probe(struct hv_device *hdev,
 842                     const struct hv_vmbus_device_id *dev_id)
 843{
 844        struct vmbus_channel *chan = hdev->channel;
 845
 846        hvs_open_connection(chan);
 847
 848        /* Always return success to suppress the unnecessary error message
 849         * in vmbus_probe(): on error the host will rescind the device in
 850         * 30 seconds and we can do cleanup at that time in
 851         * vmbus_onoffer_rescind().
 852         */
 853        return 0;
 854}
 855
 856static int hvs_remove(struct hv_device *hdev)
 857{
 858        struct vmbus_channel *chan = hdev->channel;
 859
 860        vmbus_close(chan);
 861
 862        return 0;
 863}
 864
 865/* hv_sock connections can not persist across hibernation, and all the hv_sock
 866 * channels are forced to be rescinded before hibernation: see
 867 * vmbus_bus_suspend(). Here the dummy hvs_suspend() and hvs_resume()
 868 * are only needed because hibernation requires that every vmbus device's
 869 * driver should have a .suspend and .resume callback: see vmbus_suspend().
 870 */
 871static int hvs_suspend(struct hv_device *hv_dev)
 872{
 873        /* Dummy */
 874        return 0;
 875}
 876
 877static int hvs_resume(struct hv_device *dev)
 878{
 879        /* Dummy */
 880        return 0;
 881}
 882
 883/* This isn't really used. See vmbus_match() and vmbus_probe() */
 884static const struct hv_vmbus_device_id id_table[] = {
 885        {},
 886};
 887
 888static struct hv_driver hvs_drv = {
 889        .name           = "hv_sock",
 890        .hvsock         = true,
 891        .id_table       = id_table,
 892        .probe          = hvs_probe,
 893        .remove         = hvs_remove,
 894        .suspend        = hvs_suspend,
 895        .resume         = hvs_resume,
 896};
 897
 898static int __init hvs_init(void)
 899{
 900        int ret;
 901
 902        if (vmbus_proto_version < VERSION_WIN10)
 903                return -ENODEV;
 904
 905        ret = vmbus_driver_register(&hvs_drv);
 906        if (ret != 0)
 907                return ret;
 908
 909        ret = vsock_core_register(&hvs_transport, VSOCK_TRANSPORT_F_G2H);
 910        if (ret) {
 911                vmbus_driver_unregister(&hvs_drv);
 912                return ret;
 913        }
 914
 915        return 0;
 916}
 917
 918static void __exit hvs_exit(void)
 919{
 920        vsock_core_unregister(&hvs_transport);
 921        vmbus_driver_unregister(&hvs_drv);
 922}
 923
 924module_init(hvs_init);
 925module_exit(hvs_exit);
 926
 927MODULE_DESCRIPTION("Hyper-V Sockets");
 928MODULE_VERSION("1.0.0");
 929MODULE_LICENSE("GPL");
 930MODULE_ALIAS_NETPROTO(PF_VSOCK);
 931