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