linux/drivers/hv/hv_kvp.c
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   1/*
   2 * An implementation of key value pair (KVP) functionality for Linux.
   3 *
   4 *
   5 * Copyright (C) 2010, Novell, Inc.
   6 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms of the GNU General Public License version 2 as published
  10 * by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope that it will be useful, but
  13 * WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  15 * NON INFRINGEMENT.  See the GNU General Public License for more
  16 * details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  21 *
  22 */
  23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25#include <linux/net.h>
  26#include <linux/nls.h>
  27#include <linux/connector.h>
  28#include <linux/workqueue.h>
  29#include <linux/hyperv.h>
  30
  31
  32
  33/*
  34 * Global state maintained for transaction that is being processed.
  35 * Note that only one transaction can be active at any point in time.
  36 *
  37 * This state is set when we receive a request from the host; we
  38 * cleanup this state when the transaction is completed - when we respond
  39 * to the host with the key value.
  40 */
  41
  42static struct {
  43        bool active; /* transaction status - active or not */
  44        int recv_len; /* number of bytes received. */
  45        struct hv_kvp_msg  *kvp_msg; /* current message */
  46        struct vmbus_channel *recv_channel; /* chn we got the request */
  47        u64 recv_req_id; /* request ID. */
  48        void *kvp_context; /* for the channel callback */
  49} kvp_transaction;
  50
  51static void kvp_send_key(struct work_struct *dummy);
  52
  53#define TIMEOUT_FIRED 1
  54
  55static void kvp_respond_to_host(char *key, char *value, int error);
  56static void kvp_work_func(struct work_struct *dummy);
  57static void kvp_register(void);
  58
  59static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
  60static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);
  61
  62static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
  63static const char kvp_name[] = "kvp_kernel_module";
  64static u8 *recv_buffer;
  65/*
  66 * Register the kernel component with the user-level daemon.
  67 * As part of this registration, pass the LIC version number.
  68 */
  69
  70static void
  71kvp_register(void)
  72{
  73
  74        struct cn_msg *msg;
  75        struct hv_kvp_msg *kvp_msg;
  76        char *version;
  77
  78        msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg), GFP_ATOMIC);
  79
  80        if (msg) {
  81                kvp_msg = (struct hv_kvp_msg *)msg->data;
  82                version = kvp_msg->body.kvp_register.version;
  83                msg->id.idx =  CN_KVP_IDX;
  84                msg->id.val = CN_KVP_VAL;
  85
  86                kvp_msg->kvp_hdr.operation = KVP_OP_REGISTER;
  87                strcpy(version, HV_DRV_VERSION);
  88                msg->len = sizeof(struct hv_kvp_msg);
  89                cn_netlink_send(msg, 0, GFP_ATOMIC);
  90                kfree(msg);
  91        }
  92}
  93static void
  94kvp_work_func(struct work_struct *dummy)
  95{
  96        /*
  97         * If the timer fires, the user-mode component has not responded;
  98         * process the pending transaction.
  99         */
 100        kvp_respond_to_host("Unknown key", "Guest timed out", TIMEOUT_FIRED);
 101}
 102
 103/*
 104 * Callback when data is received from user mode.
 105 */
 106
 107static void
 108kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 109{
 110        struct hv_kvp_msg *message;
 111        struct hv_kvp_msg_enumerate *data;
 112
 113        message = (struct hv_kvp_msg *)msg->data;
 114        switch (message->kvp_hdr.operation) {
 115        case KVP_OP_REGISTER:
 116                pr_info("KVP: user-mode registering done.\n");
 117                kvp_register();
 118                kvp_transaction.active = false;
 119                hv_kvp_onchannelcallback(kvp_transaction.kvp_context);
 120                break;
 121
 122        default:
 123                data = &message->body.kvp_enum_data;
 124                /*
 125                 * Complete the transaction by forwarding the key value
 126                 * to the host. But first, cancel the timeout.
 127                 */
 128                if (cancel_delayed_work_sync(&kvp_work))
 129                        kvp_respond_to_host(data->data.key,
 130                                         data->data.value,
 131                                        !strlen(data->data.key));
 132        }
 133}
 134
 135static void
 136kvp_send_key(struct work_struct *dummy)
 137{
 138        struct cn_msg *msg;
 139        struct hv_kvp_msg *message;
 140        struct hv_kvp_msg *in_msg;
 141        __u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
 142        __u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
 143        __u32 val32;
 144        __u64 val64;
 145
 146        msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
 147        if (!msg)
 148                return;
 149
 150        msg->id.idx =  CN_KVP_IDX;
 151        msg->id.val = CN_KVP_VAL;
 152
 153        message = (struct hv_kvp_msg *)msg->data;
 154        message->kvp_hdr.operation = operation;
 155        message->kvp_hdr.pool = pool;
 156        in_msg = kvp_transaction.kvp_msg;
 157
 158        /*
 159         * The key/value strings sent from the host are encoded in
 160         * in utf16; convert it to utf8 strings.
 161         * The host assures us that the utf16 strings will not exceed
 162         * the max lengths specified. We will however, reserve room
 163         * for the string terminating character - in the utf16s_utf8s()
 164         * function we limit the size of the buffer where the converted
 165         * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to gaurantee
 166         * that the strings can be properly terminated!
 167         */
 168
 169        switch (message->kvp_hdr.operation) {
 170        case KVP_OP_SET:
 171                switch (in_msg->body.kvp_set.data.value_type) {
 172                case REG_SZ:
 173                        /*
 174                         * The value is a string - utf16 encoding.
 175                         */
 176                        message->body.kvp_set.data.value_size =
 177                                utf16s_to_utf8s(
 178                                (wchar_t *)in_msg->body.kvp_set.data.value,
 179                                in_msg->body.kvp_set.data.value_size,
 180                                UTF16_LITTLE_ENDIAN,
 181                                message->body.kvp_set.data.value,
 182                                HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
 183                                break;
 184
 185                case REG_U32:
 186                        /*
 187                         * The value is a 32 bit scalar.
 188                         * We save this as a utf8 string.
 189                         */
 190                        val32 = in_msg->body.kvp_set.data.value_u32;
 191                        message->body.kvp_set.data.value_size =
 192                                sprintf(message->body.kvp_set.data.value,
 193                                        "%d", val32) + 1;
 194                        break;
 195
 196                case REG_U64:
 197                        /*
 198                         * The value is a 64 bit scalar.
 199                         * We save this as a utf8 string.
 200                         */
 201                        val64 = in_msg->body.kvp_set.data.value_u64;
 202                        message->body.kvp_set.data.value_size =
 203                                sprintf(message->body.kvp_set.data.value,
 204                                        "%llu", val64) + 1;
 205                        break;
 206
 207                }
 208        case KVP_OP_GET:
 209                message->body.kvp_set.data.key_size =
 210                        utf16s_to_utf8s(
 211                        (wchar_t *)in_msg->body.kvp_set.data.key,
 212                        in_msg->body.kvp_set.data.key_size,
 213                        UTF16_LITTLE_ENDIAN,
 214                        message->body.kvp_set.data.key,
 215                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
 216                        break;
 217
 218        case KVP_OP_DELETE:
 219                message->body.kvp_delete.key_size =
 220                        utf16s_to_utf8s(
 221                        (wchar_t *)in_msg->body.kvp_delete.key,
 222                        in_msg->body.kvp_delete.key_size,
 223                        UTF16_LITTLE_ENDIAN,
 224                        message->body.kvp_delete.key,
 225                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
 226                        break;
 227
 228        case KVP_OP_ENUMERATE:
 229                message->body.kvp_enum_data.index =
 230                        in_msg->body.kvp_enum_data.index;
 231                        break;
 232        }
 233
 234        msg->len = sizeof(struct hv_kvp_msg);
 235        cn_netlink_send(msg, 0, GFP_ATOMIC);
 236        kfree(msg);
 237
 238        return;
 239}
 240
 241/*
 242 * Send a response back to the host.
 243 */
 244
 245static void
 246kvp_respond_to_host(char *key, char *value, int error)
 247{
 248        struct hv_kvp_msg  *kvp_msg;
 249        struct hv_kvp_exchg_msg_value  *kvp_data;
 250        char    *key_name;
 251        struct icmsg_hdr *icmsghdrp;
 252        int     keylen = 0;
 253        int     valuelen = 0;
 254        u32     buf_len;
 255        struct vmbus_channel *channel;
 256        u64     req_id;
 257
 258        /*
 259         * If a transaction is not active; log and return.
 260         */
 261
 262        if (!kvp_transaction.active) {
 263                /*
 264                 * This is a spurious call!
 265                 */
 266                pr_warn("KVP: Transaction not active\n");
 267                return;
 268        }
 269        /*
 270         * Copy the global state for completing the transaction. Note that
 271         * only one transaction can be active at a time.
 272         */
 273
 274        buf_len = kvp_transaction.recv_len;
 275        channel = kvp_transaction.recv_channel;
 276        req_id = kvp_transaction.recv_req_id;
 277
 278        kvp_transaction.active = false;
 279
 280        icmsghdrp = (struct icmsg_hdr *)
 281                        &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 282
 283        if (channel->onchannel_callback == NULL)
 284                /*
 285                 * We have raced with util driver being unloaded;
 286                 * silently return.
 287                 */
 288                return;
 289
 290
 291        /*
 292         * If the error parameter is set, terminate the host's enumeration
 293         * on this pool.
 294         */
 295        if (error) {
 296                /*
 297                 * Something failed or the we have timedout;
 298                 * terminate the current  host-side iteration.
 299                 */
 300                icmsghdrp->status = HV_S_CONT;
 301                goto response_done;
 302        }
 303
 304        icmsghdrp->status = HV_S_OK;
 305
 306        kvp_msg = (struct hv_kvp_msg *)
 307                        &recv_buffer[sizeof(struct vmbuspipe_hdr) +
 308                        sizeof(struct icmsg_hdr)];
 309
 310        switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
 311        case KVP_OP_GET:
 312                kvp_data = &kvp_msg->body.kvp_get.data;
 313                goto copy_value;
 314
 315        case KVP_OP_SET:
 316        case KVP_OP_DELETE:
 317                goto response_done;
 318
 319        default:
 320                break;
 321        }
 322
 323        kvp_data = &kvp_msg->body.kvp_enum_data.data;
 324        key_name = key;
 325
 326        /*
 327         * The windows host expects the key/value pair to be encoded
 328         * in utf16. Ensure that the key/value size reported to the host
 329         * will be less than or equal to the MAX size (including the
 330         * terminating character).
 331         */
 332        keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
 333                                (wchar_t *) kvp_data->key,
 334                                (HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
 335        kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */
 336
 337copy_value:
 338        valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
 339                                (wchar_t *) kvp_data->value,
 340                                (HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
 341        kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */
 342
 343        /*
 344         * If the utf8s to utf16s conversion failed; notify host
 345         * of the error.
 346         */
 347        if ((keylen < 0) || (valuelen < 0))
 348                icmsghdrp->status = HV_E_FAIL;
 349
 350        kvp_data->value_type = REG_SZ; /* all our values are strings */
 351
 352response_done:
 353        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 354
 355        vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 356                                VM_PKT_DATA_INBAND, 0);
 357
 358}
 359
 360/*
 361 * This callback is invoked when we get a KVP message from the host.
 362 * The host ensures that only one KVP transaction can be active at a time.
 363 * KVP implementation in Linux needs to forward the key to a user-mde
 364 * component to retrive the corresponding value. Consequently, we cannot
 365 * respond to the host in the conext of this callback. Since the host
 366 * guarantees that at most only one transaction can be active at a time,
 367 * we stash away the transaction state in a set of global variables.
 368 */
 369
 370void hv_kvp_onchannelcallback(void *context)
 371{
 372        struct vmbus_channel *channel = context;
 373        u32 recvlen;
 374        u64 requestid;
 375
 376        struct hv_kvp_msg *kvp_msg;
 377
 378        struct icmsg_hdr *icmsghdrp;
 379        struct icmsg_negotiate *negop = NULL;
 380
 381        if (kvp_transaction.active) {
 382                /*
 383                 * We will defer processing this callback once
 384                 * the current transaction is complete.
 385                 */
 386                kvp_transaction.kvp_context = context;
 387                return;
 388        }
 389
 390        vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE, &recvlen, &requestid);
 391
 392        if (recvlen > 0) {
 393                icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 394                        sizeof(struct vmbuspipe_hdr)];
 395
 396                if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 397                        vmbus_prep_negotiate_resp(icmsghdrp, negop,
 398                                 recv_buffer, MAX_SRV_VER, MAX_SRV_VER);
 399                } else {
 400                        kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
 401                                sizeof(struct vmbuspipe_hdr) +
 402                                sizeof(struct icmsg_hdr)];
 403
 404                        /*
 405                         * Stash away this global state for completing the
 406                         * transaction; note transactions are serialized.
 407                         */
 408
 409                        kvp_transaction.recv_len = recvlen;
 410                        kvp_transaction.recv_channel = channel;
 411                        kvp_transaction.recv_req_id = requestid;
 412                        kvp_transaction.active = true;
 413                        kvp_transaction.kvp_msg = kvp_msg;
 414
 415                        /*
 416                         * Get the information from the
 417                         * user-mode component.
 418                         * component. This transaction will be
 419                         * completed when we get the value from
 420                         * the user-mode component.
 421                         * Set a timeout to deal with
 422                         * user-mode not responding.
 423                         */
 424                        schedule_work(&kvp_sendkey_work);
 425                        schedule_delayed_work(&kvp_work, 5*HZ);
 426
 427                        return;
 428
 429                }
 430
 431                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 432                        | ICMSGHDRFLAG_RESPONSE;
 433
 434                vmbus_sendpacket(channel, recv_buffer,
 435                                       recvlen, requestid,
 436                                       VM_PKT_DATA_INBAND, 0);
 437        }
 438
 439}
 440
 441int
 442hv_kvp_init(struct hv_util_service *srv)
 443{
 444        int err;
 445
 446        err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
 447        if (err)
 448                return err;
 449        recv_buffer = srv->recv_buffer;
 450
 451        /*
 452         * When this driver loads, the user level daemon that
 453         * processes the host requests may not yet be running.
 454         * Defer processing channel callbacks until the daemon
 455         * has registered.
 456         */
 457        kvp_transaction.active = true;
 458
 459        return 0;
 460}
 461
 462void hv_kvp_deinit(void)
 463{
 464        cn_del_callback(&kvp_id);
 465        cancel_delayed_work_sync(&kvp_work);
 466        cancel_work_sync(&kvp_sendkey_work);
 467}
 468
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