drivers/hv/hv_kvp.c

   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 #include "hv_kvp.h"
  32
  33
  34
  35 /*
  36  * Global state maintained for transaction that is being processed.
  37  * Note that only one transaction can be active at any point in time.
  38  *
  39  * This state is set when we receive a request from the host; we
  40  * cleanup this state when the transaction is completed - when we respond
  41  * to the host with the key value.
  42  */
  43
  44 static struct {
  45         bool active; /* transaction status - active or not */
  46         int recv_len; /* number of bytes received. */
  47         int index; /* current index */
  48         struct vmbus_channel *recv_channel; /* chn we got the request */
  49         u64 recv_req_id; /* request ID. */
  50 } kvp_transaction;
  51
  52 static void kvp_send_key(struct work_struct *dummy);
  53
  54 #define TIMEOUT_FIRED 1
  55
  56 static void kvp_respond_to_host(char *key, char *value, int error);
  57 static void kvp_work_func(struct work_struct *dummy);
  58 static void kvp_register(void);
  59
  60 static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
  61 static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);
  62
  63 static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
  64 static const char kvp_name[] = "kvp_kernel_module";
  65 static u8 *recv_buffer;
  66 /*
  67  * Register the kernel component with the user-level daemon.
  68  * As part of this registration, pass the LIC version number.
  69  */
  70
  71 static void
  72 kvp_register(void)
  73 {
  74
  75         struct cn_msg *msg;
  76
  77         msg = kzalloc(sizeof(*msg) + strlen(HV_DRV_VERSION) + 1 , GFP_ATOMIC);
  78
  79         if (msg) {
  80                 msg->id.idx =  CN_KVP_IDX;
  81                 msg->id.val = CN_KVP_VAL;
  82                 msg->seq = KVP_REGISTER;
  83                 strcpy(msg->data, HV_DRV_VERSION);
  84                 msg->len = strlen(HV_DRV_VERSION) + 1;
  85                 cn_netlink_send(msg, 0, GFP_ATOMIC);
  86                 kfree(msg);
  87         }
  88 }
  89 static void
  90 kvp_work_func(struct work_struct *dummy)
  91 {
  92         /*
  93          * If the timer fires, the user-mode component has not responded;
  94          * process the pending transaction.
  95          */
  96         kvp_respond_to_host("Unknown key", "Guest timed out", TIMEOUT_FIRED);
  97 }
  98
  99 /*
 100  * Callback when data is received from user mode.
 101  */
 102
 103 static void
 104 kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 105 {
 106         struct hv_ku_msg *message;
 107
 108         message = (struct hv_ku_msg *)msg->data;
 109         if (msg->seq == KVP_REGISTER) {
 110                 pr_info("KVP: user-mode registering done.\n");
 111                 kvp_register();
 112         }
 113
 114         if (msg->seq == KVP_USER_SET) {
 115                 /*
 116                  * Complete the transaction by forwarding the key value
 117                  * to the host. But first, cancel the timeout.
 118                  */
 119                 if (cancel_delayed_work_sync(&kvp_work))
 120                         kvp_respond_to_host(message->kvp_key,
 121                                                 message->kvp_value,
 122                                                 !strlen(message->kvp_key));
 123         }
 124 }
 125
 126 static void
 127 kvp_send_key(struct work_struct *dummy)
 128 {
 129         struct cn_msg *msg;
 130         int index = kvp_transaction.index;
 131
 132         msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
 133
 134         if (msg) {
 135                 msg->id.idx =  CN_KVP_IDX;
 136                 msg->id.val = CN_KVP_VAL;
 137                 msg->seq = KVP_KERNEL_GET;
 138                 ((struct hv_ku_msg *)msg->data)->kvp_index = index;
 139                 msg->len = sizeof(struct hv_ku_msg);
 140                 cn_netlink_send(msg, 0, GFP_ATOMIC);
 141                 kfree(msg);
 142         }
 143         return;
 144 }
 145
 146 /*
 147  * Send a response back to the host.
 148  */
 149
 150 static void
 151 kvp_respond_to_host(char *key, char *value, int error)
 152 {
 153         struct hv_kvp_msg  *kvp_msg;
 154         struct hv_kvp_msg_enumerate  *kvp_data;
 155         char    *key_name;
 156         struct icmsg_hdr *icmsghdrp;
 157         int     keylen, valuelen;
 158         u32     buf_len;
 159         struct vmbus_channel *channel;
 160         u64     req_id;
 161
 162         /*
 163          * If a transaction is not active; log and return.
 164          */
 165
 166         if (!kvp_transaction.active) {
 167                 /*
 168                  * This is a spurious call!
 169                  */
 170                 pr_warn("KVP: Transaction not active\n");
 171                 return;
 172         }
 173         /*
 174          * Copy the global state for completing the transaction. Note that
 175          * only one transaction can be active at a time.
 176          */
 177
 178         buf_len = kvp_transaction.recv_len;
 179         channel = kvp_transaction.recv_channel;
 180         req_id = kvp_transaction.recv_req_id;
 181
 182         kvp_transaction.active = false;
 183
 184         if (channel->onchannel_callback == NULL)
 185                 /*
 186                  * We have raced with util driver being unloaded;
 187                  * silently return.
 188                  */
 189                 return;
 190
 191         icmsghdrp = (struct icmsg_hdr *)
 192                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 193         kvp_msg = (struct hv_kvp_msg *)
 194                         &recv_buffer[sizeof(struct vmbuspipe_hdr) +
 195                         sizeof(struct icmsg_hdr)];
 196         kvp_data = &kvp_msg->kvp_data;
 197         key_name = key;
 198
 199         /*
 200          * If the error parameter is set, terminate the host's enumeration.
 201          */
 202         if (error) {
 203                 /*
 204                  * We don't support this index or the we have timedout;
 205                  * terminate the host-side iteration by returning an error.
 206                  */
 207                 icmsghdrp->status = HV_E_FAIL;
 208                 goto response_done;
 209         }
 210
 211         /*
 212          * The windows host expects the key/value pair to be encoded
 213          * in utf16.
 214          */
 215         keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
 216                                 (wchar_t *) kvp_data->data.key,
 217                                 HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2);
 218         kvp_data->data.key_size = 2*(keylen + 1); /* utf16 encoding */
 219         valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
 220                                 (wchar_t *) kvp_data->data.value,
 221                                 HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2);
 222         kvp_data->data.value_size = 2*(valuelen + 1); /* utf16 encoding */
 223
 224         kvp_data->data.value_type = REG_SZ; /* all our values are strings */
 225         icmsghdrp->status = HV_S_OK;
 226
 227 response_done:
 228         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 229
 230         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 231                                 VM_PKT_DATA_INBAND, 0);
 232
 233 }
 234
 235 /*
 236  * This callback is invoked when we get a KVP message from the host.
 237  * The host ensures that only one KVP transaction can be active at a time.
 238  * KVP implementation in Linux needs to forward the key to a user-mde
 239  * component to retrive the corresponding value. Consequently, we cannot
 240  * respond to the host in the conext of this callback. Since the host
 241  * guarantees that at most only one transaction can be active at a time,
 242  * we stash away the transaction state in a set of global variables.
 243  */
 244
 245 void hv_kvp_onchannelcallback(void *context)
 246 {
 247         struct vmbus_channel *channel = context;
 248         u32 recvlen;
 249         u64 requestid;
 250
 251         struct hv_kvp_msg *kvp_msg;
 252         struct hv_kvp_msg_enumerate *kvp_data;
 253
 254         struct icmsg_hdr *icmsghdrp;
 255         struct icmsg_negotiate *negop = NULL;
 256
 257
 258         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE, &recvlen, &requestid);
 259
 260         if (recvlen > 0) {
 261                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 262                         sizeof(struct vmbuspipe_hdr)];
 263
 264                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 265                         vmbus_prep_negotiate_resp(icmsghdrp, negop, recv_buffer);
 266                 } else {
 267                         kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
 268                                 sizeof(struct vmbuspipe_hdr) +
 269                                 sizeof(struct icmsg_hdr)];
 270
 271                         kvp_data = &kvp_msg->kvp_data;
 272
 273                         /*
 274                          * We only support the "get" operation on
 275                          * "KVP_POOL_AUTO" pool.
 276                          */
 277
 278                         if ((kvp_msg->kvp_hdr.pool != KVP_POOL_AUTO) ||
 279                                 (kvp_msg->kvp_hdr.operation !=
 280                                 KVP_OP_ENUMERATE)) {
 281                                 icmsghdrp->status = HV_E_FAIL;
 282                                 goto callback_done;
 283                         }
 284
 285                         /*
 286                          * Stash away this global state for completing the
 287                          * transaction; note transactions are serialized.
 288                          */
 289                         kvp_transaction.recv_len = recvlen;
 290                         kvp_transaction.recv_channel = channel;
 291                         kvp_transaction.recv_req_id = requestid;
 292                         kvp_transaction.active = true;
 293                         kvp_transaction.index = kvp_data->index;
 294
 295                         /*
 296                          * Get the information from the
 297                          * user-mode component.
 298                          * component. This transaction will be
 299                          * completed when we get the value from
 300                          * the user-mode component.
 301                          * Set a timeout to deal with
 302                          * user-mode not responding.
 303                          */
 304                         schedule_work(&kvp_sendkey_work);
 305                         schedule_delayed_work(&kvp_work, 5*HZ);
 306
 307                         return;
 308
 309                 }
 310
 311 callback_done:
 312
 313                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 314                         | ICMSGHDRFLAG_RESPONSE;
 315
 316                 vmbus_sendpacket(channel, recv_buffer,
 317                                        recvlen, requestid,
 318                                        VM_PKT_DATA_INBAND, 0);
 319         }
 320
 321 }
 322
 323 int
 324 hv_kvp_init(struct hv_util_service *srv)
 325 {
 326         int err;
 327
 328         err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
 329         if (err)
 330                 return err;
 331         recv_buffer = srv->recv_buffer;
 332
 333         return 0;
 334 }
 335
 336 void hv_kvp_deinit(void)
 337 {
 338         cn_del_callback(&kvp_id);
 339         cancel_delayed_work_sync(&kvp_work);
 340         cancel_work_sync(&kvp_sendkey_work);
 341 }