drivers/hv/hv_fcopy.c

   1 /*
   2  * An implementation of file copy service.
   3  *
   4  * Copyright (C) 2014, Microsoft, Inc.
   5  *
   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  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/nls.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/hyperv.h>
  25 #include <linux/sched.h>
  26
  27 #include "hyperv_vmbus.h"
  28 #include "hv_utils_transport.h"
  29
  30 #define WIN8_SRV_MAJOR          1
  31 #define WIN8_SRV_MINOR          1
  32 #define WIN8_SRV_VERSION        (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
  33
  34 /*
  35  * Global state maintained for transaction that is being processed.
  36  * For a class of integration services, including the "file copy service",
  37  * the specified protocol is a "request/response" protocol which means that
  38  * there can only be single outstanding transaction from the host at any
  39  * given point in time. We use this to simplify memory management in this
  40  * driver - we cache and process only one message at a time.
  41  *
  42  * While the request/response protocol is guaranteed by the host, we further
  43  * ensure this by serializing packet processing in this driver - we do not
  44  * read additional packets from the VMBUs until the current packet is fully
  45  * handled.
  46  */
  47
  48 static struct {
  49         int state;   /* hvutil_device_state */
  50         int recv_len; /* number of bytes received. */
  51         struct hv_fcopy_hdr  *fcopy_msg; /* current message */
  52         struct vmbus_channel *recv_channel; /* chn we got the request */
  53         u64 recv_req_id; /* request ID. */
  54 } fcopy_transaction;
  55
  56 static void fcopy_respond_to_host(int error);
  57 static void fcopy_send_data(struct work_struct *dummy);
  58 static void fcopy_timeout_func(struct work_struct *dummy);
  59 static DECLARE_DELAYED_WORK(fcopy_timeout_work, fcopy_timeout_func);
  60 static DECLARE_WORK(fcopy_send_work, fcopy_send_data);
  61 static const char fcopy_devname[] = "vmbus/hv_fcopy";
  62 static u8 *recv_buffer;
  63 static struct hvutil_transport *hvt;
  64 /*
  65  * This state maintains the version number registered by the daemon.
  66  */
  67 static int dm_reg_value;
  68
  69 static void fcopy_poll_wrapper(void *channel)
  70 {
  71         /* Transaction is finished, reset the state here to avoid races. */
  72         fcopy_transaction.state = HVUTIL_READY;
  73         hv_fcopy_onchannelcallback(channel);
  74 }
  75
  76 static void fcopy_timeout_func(struct work_struct *dummy)
  77 {
  78         /*
  79          * If the timer fires, the user-mode component has not responded;
  80          * process the pending transaction.
  81          */
  82         fcopy_respond_to_host(HV_E_FAIL);
  83         hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
  84 }
  85
  86 static void fcopy_register_done(void)
  87 {
  88         pr_debug("FCP: userspace daemon registered\n");
  89         hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
  90 }
  91
  92 static int fcopy_handle_handshake(u32 version)
  93 {
  94         u32 our_ver = FCOPY_CURRENT_VERSION;
  95
  96         switch (version) {
  97         case FCOPY_VERSION_0:
  98                 /* Daemon doesn't expect us to reply */
  99                 dm_reg_value = version;
 100                 break;
 101         case FCOPY_VERSION_1:
 102                 /* Daemon expects us to reply with our own version */
 103                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
 104                     fcopy_register_done))
 105                         return -EFAULT;
 106                 dm_reg_value = version;
 107                 break;
 108         default:
 109                 /*
 110                  * For now we will fail the registration.
 111                  * If and when we have multiple versions to
 112                  * deal with, we will be backward compatible.
 113                  * We will add this code when needed.
 114                  */
 115                 return -EINVAL;
 116         }
 117         pr_debug("FCP: userspace daemon ver. %d connected\n", version);
 118         return 0;
 119 }
 120
 121 static void fcopy_send_data(struct work_struct *dummy)
 122 {
 123         struct hv_start_fcopy *smsg_out = NULL;
 124         int operation = fcopy_transaction.fcopy_msg->operation;
 125         struct hv_start_fcopy *smsg_in;
 126         void *out_src;
 127         int rc, out_len;
 128
 129         /*
 130          * The  strings sent from the host are encoded in
 131          * in utf16; convert it to utf8 strings.
 132          * The host assures us that the utf16 strings will not exceed
 133          * the max lengths specified. We will however, reserve room
 134          * for the string terminating character - in the utf16s_utf8s()
 135          * function we limit the size of the buffer where the converted
 136          * string is placed to W_MAX_PATH -1 to guarantee
 137          * that the strings can be properly terminated!
 138          */
 139
 140         switch (operation) {
 141         case START_FILE_COPY:
 142                 out_len = sizeof(struct hv_start_fcopy);
 143                 smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
 144                 if (!smsg_out)
 145                         return;
 146
 147                 smsg_out->hdr.operation = operation;
 148                 smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 149
 150                 utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 151                                 UTF16_LITTLE_ENDIAN,
 152                                 (__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
 153
 154                 utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 155                                 UTF16_LITTLE_ENDIAN,
 156                                 (__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
 157
 158                 smsg_out->copy_flags = smsg_in->copy_flags;
 159                 smsg_out->file_size = smsg_in->file_size;
 160                 out_src = smsg_out;
 161                 break;
 162
 163         default:
 164                 out_src = fcopy_transaction.fcopy_msg;
 165                 out_len = fcopy_transaction.recv_len;
 166                 break;
 167         }
 168
 169         fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
 170         rc = hvutil_transport_send(hvt, out_src, out_len, NULL);
 171         if (rc) {
 172                 pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
 173                 if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 174                         fcopy_respond_to_host(HV_E_FAIL);
 175                         fcopy_transaction.state = HVUTIL_READY;
 176                 }
 177         }
 178         kfree(smsg_out);
 179
 180         return;
 181 }
 182
 183 /*
 184  * Send a response back to the host.
 185  */
 186
 187 static void
 188 fcopy_respond_to_host(int error)
 189 {
 190         struct icmsg_hdr *icmsghdr;
 191         u32 buf_len;
 192         struct vmbus_channel *channel;
 193         u64 req_id;
 194
 195         /*
 196          * Copy the global state for completing the transaction. Note that
 197          * only one transaction can be active at a time. This is guaranteed
 198          * by the file copy protocol implemented by the host. Furthermore,
 199          * the "transaction active" state we maintain ensures that there can
 200          * only be one active transaction at a time.
 201          */
 202
 203         buf_len = fcopy_transaction.recv_len;
 204         channel = fcopy_transaction.recv_channel;
 205         req_id = fcopy_transaction.recv_req_id;
 206
 207         icmsghdr = (struct icmsg_hdr *)
 208                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 209
 210         if (channel->onchannel_callback == NULL)
 211                 /*
 212                  * We have raced with util driver being unloaded;
 213                  * silently return.
 214                  */
 215                 return;
 216
 217         icmsghdr->status = error;
 218         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 219         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 220                                 VM_PKT_DATA_INBAND, 0);
 221 }
 222
 223 void hv_fcopy_onchannelcallback(void *context)
 224 {
 225         struct vmbus_channel *channel = context;
 226         u32 recvlen;
 227         u64 requestid;
 228         struct hv_fcopy_hdr *fcopy_msg;
 229         struct icmsg_hdr *icmsghdr;
 230         struct icmsg_negotiate *negop = NULL;
 231         int util_fw_version;
 232         int fcopy_srv_version;
 233
 234         if (fcopy_transaction.state > HVUTIL_READY)
 235                 return;
 236
 237         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 238                          &requestid);
 239         if (recvlen <= 0)
 240                 return;
 241
 242         icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 243                         sizeof(struct vmbuspipe_hdr)];
 244         if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 245                 util_fw_version = UTIL_FW_VERSION;
 246                 fcopy_srv_version = WIN8_SRV_VERSION;
 247                 vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 248                                 util_fw_version, fcopy_srv_version);
 249         } else {
 250                 fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 251                                 sizeof(struct vmbuspipe_hdr) +
 252                                 sizeof(struct icmsg_hdr)];
 253
 254                 /*
 255                  * Stash away this global state for completing the
 256                  * transaction; note transactions are serialized.
 257                  */
 258
 259                 fcopy_transaction.recv_len = recvlen;
 260                 fcopy_transaction.recv_req_id = requestid;
 261                 fcopy_transaction.fcopy_msg = fcopy_msg;
 262
 263                 if (fcopy_transaction.state < HVUTIL_READY) {
 264                         /* Userspace is not registered yet */
 265                         fcopy_respond_to_host(HV_E_FAIL);
 266                         return;
 267                 }
 268                 fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 269
 270                 /*
 271                  * Send the information to the user-level daemon.
 272                  */
 273                 schedule_work(&fcopy_send_work);
 274                 schedule_delayed_work(&fcopy_timeout_work,
 275                                       HV_UTIL_TIMEOUT * HZ);
 276                 return;
 277         }
 278         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 279         vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
 280                         VM_PKT_DATA_INBAND, 0);
 281 }
 282
 283 /* Callback when data is received from userspace */
 284 static int fcopy_on_msg(void *msg, int len)
 285 {
 286         int *val = (int *)msg;
 287
 288         if (len != sizeof(int))
 289                 return -EINVAL;
 290
 291         if (fcopy_transaction.state == HVUTIL_DEVICE_INIT)
 292                 return fcopy_handle_handshake(*val);
 293
 294         if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)
 295                 return -EINVAL;
 296
 297         /*
 298          * Complete the transaction by forwarding the result
 299          * to the host. But first, cancel the timeout.
 300          */
 301         if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 302                 fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
 303                 fcopy_respond_to_host(*val);
 304                 hv_poll_channel(fcopy_transaction.recv_channel,
 305                                 fcopy_poll_wrapper);
 306         }
 307
 308         return 0;
 309 }
 310
 311 static void fcopy_on_reset(void)
 312 {
 313         /*
 314          * The daemon has exited; reset the state.
 315          */
 316         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 317
 318         if (cancel_delayed_work_sync(&fcopy_timeout_work))
 319                 fcopy_respond_to_host(HV_E_FAIL);
 320 }
 321
 322 int hv_fcopy_init(struct hv_util_service *srv)
 323 {
 324         recv_buffer = srv->recv_buffer;
 325         fcopy_transaction.recv_channel = srv->channel;
 326
 327         /*
 328          * When this driver loads, the user level daemon that
 329          * processes the host requests may not yet be running.
 330          * Defer processing channel callbacks until the daemon
 331          * has registered.
 332          */
 333         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 334
 335         hvt = hvutil_transport_init(fcopy_devname, 0, 0,
 336                                     fcopy_on_msg, fcopy_on_reset);
 337         if (!hvt)
 338                 return -EFAULT;
 339
 340         return 0;
 341 }
 342
 343 void hv_fcopy_deinit(void)
 344 {
 345         fcopy_transaction.state = HVUTIL_DEVICE_DYING;
 346         cancel_delayed_work_sync(&fcopy_timeout_work);
 347         hvutil_transport_destroy(hvt);
 348 }