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 static struct completion release_event;
  65 /*
  66  * This state maintains the version number registered by the daemon.
  67  */
  68 static int dm_reg_value;
  69
  70 static void fcopy_poll_wrapper(void *channel)
  71 {
  72         /* Transaction is finished, reset the state here to avoid races. */
  73         fcopy_transaction.state = HVUTIL_READY;
  74         hv_fcopy_onchannelcallback(channel);
  75 }
  76
  77 static void fcopy_timeout_func(struct work_struct *dummy)
  78 {
  79         /*
  80          * If the timer fires, the user-mode component has not responded;
  81          * process the pending transaction.
  82          */
  83         fcopy_respond_to_host(HV_E_FAIL);
  84         hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
  85 }
  86
  87 static int fcopy_handle_handshake(u32 version)
  88 {
  89         u32 our_ver = FCOPY_CURRENT_VERSION;
  90
  91         switch (version) {
  92         case FCOPY_VERSION_0:
  93                 /* Daemon doesn't expect us to reply */
  94                 dm_reg_value = version;
  95                 break;
  96         case FCOPY_VERSION_1:
  97                 /* Daemon expects us to reply with our own version */
  98                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
  99                         return -EFAULT;
 100                 dm_reg_value = version;
 101                 break;
 102         default:
 103                 /*
 104                  * For now we will fail the registration.
 105                  * If and when we have multiple versions to
 106                  * deal with, we will be backward compatible.
 107                  * We will add this code when needed.
 108                  */
 109                 return -EINVAL;
 110         }
 111         pr_debug("FCP: userspace daemon ver. %d registered\n", version);
 112         hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
 113         return 0;
 114 }
 115
 116 static void fcopy_send_data(struct work_struct *dummy)
 117 {
 118         struct hv_start_fcopy *smsg_out = NULL;
 119         int operation = fcopy_transaction.fcopy_msg->operation;
 120         struct hv_start_fcopy *smsg_in;
 121         void *out_src;
 122         int rc, out_len;
 123
 124         /*
 125          * The  strings sent from the host are encoded in
 126          * in utf16; convert it to utf8 strings.
 127          * The host assures us that the utf16 strings will not exceed
 128          * the max lengths specified. We will however, reserve room
 129          * for the string terminating character - in the utf16s_utf8s()
 130          * function we limit the size of the buffer where the converted
 131          * string is placed to W_MAX_PATH -1 to guarantee
 132          * that the strings can be properly terminated!
 133          */
 134
 135         switch (operation) {
 136         case START_FILE_COPY:
 137                 out_len = sizeof(struct hv_start_fcopy);
 138                 smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
 139                 if (!smsg_out)
 140                         return;
 141
 142                 smsg_out->hdr.operation = operation;
 143                 smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 144
 145                 utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 146                                 UTF16_LITTLE_ENDIAN,
 147                                 (__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
 148
 149                 utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 150                                 UTF16_LITTLE_ENDIAN,
 151                                 (__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
 152
 153                 smsg_out->copy_flags = smsg_in->copy_flags;
 154                 smsg_out->file_size = smsg_in->file_size;
 155                 out_src = smsg_out;
 156                 break;
 157
 158         case WRITE_TO_FILE:
 159                 out_src = fcopy_transaction.fcopy_msg;
 160                 out_len = sizeof(struct hv_do_fcopy);
 161                 break;
 162         default:
 163                 out_src = fcopy_transaction.fcopy_msg;
 164                 out_len = fcopy_transaction.recv_len;
 165                 break;
 166         }
 167
 168         fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
 169         rc = hvutil_transport_send(hvt, out_src, out_len);
 170         if (rc) {
 171                 pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
 172                 if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 173                         fcopy_respond_to_host(HV_E_FAIL);
 174                         fcopy_transaction.state = HVUTIL_READY;
 175                 }
 176         }
 177         kfree(smsg_out);
 178
 179         return;
 180 }
 181
 182 /*
 183  * Send a response back to the host.
 184  */
 185
 186 static void
 187 fcopy_respond_to_host(int error)
 188 {
 189         struct icmsg_hdr *icmsghdr;
 190         u32 buf_len;
 191         struct vmbus_channel *channel;
 192         u64 req_id;
 193
 194         /*
 195          * Copy the global state for completing the transaction. Note that
 196          * only one transaction can be active at a time. This is guaranteed
 197          * by the file copy protocol implemented by the host. Furthermore,
 198          * the "transaction active" state we maintain ensures that there can
 199          * only be one active transaction at a time.
 200          */
 201
 202         buf_len = fcopy_transaction.recv_len;
 203         channel = fcopy_transaction.recv_channel;
 204         req_id = fcopy_transaction.recv_req_id;
 205
 206         icmsghdr = (struct icmsg_hdr *)
 207                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 208
 209         if (channel->onchannel_callback == NULL)
 210                 /*
 211                  * We have raced with util driver being unloaded;
 212                  * silently return.
 213                  */
 214                 return;
 215
 216         icmsghdr->status = error;
 217         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 218         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 219                                 VM_PKT_DATA_INBAND, 0);
 220 }
 221
 222 void hv_fcopy_onchannelcallback(void *context)
 223 {
 224         struct vmbus_channel *channel = context;
 225         u32 recvlen;
 226         u64 requestid;
 227         struct hv_fcopy_hdr *fcopy_msg;
 228         struct icmsg_hdr *icmsghdr;
 229         struct icmsg_negotiate *negop = NULL;
 230         int util_fw_version;
 231         int fcopy_srv_version;
 232
 233         if (fcopy_transaction.state > HVUTIL_READY)
 234                 return;
 235
 236         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 237                          &requestid);
 238         if (recvlen <= 0)
 239                 return;
 240
 241         icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 242                         sizeof(struct vmbuspipe_hdr)];
 243         if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 244                 util_fw_version = UTIL_FW_VERSION;
 245                 fcopy_srv_version = WIN8_SRV_VERSION;
 246                 vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 247                                 util_fw_version, fcopy_srv_version);
 248         } else {
 249                 fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 250                                 sizeof(struct vmbuspipe_hdr) +
 251                                 sizeof(struct icmsg_hdr)];
 252
 253                 /*
 254                  * Stash away this global state for completing the
 255                  * transaction; note transactions are serialized.
 256                  */
 257
 258                 fcopy_transaction.recv_len = recvlen;
 259                 fcopy_transaction.recv_channel = channel;
 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         complete(&release_event);
 321 }
 322
 323 int hv_fcopy_init(struct hv_util_service *srv)
 324 {
 325         recv_buffer = srv->recv_buffer;
 326
 327         init_completion(&release_event);
 328         /*
 329          * When this driver loads, the user level daemon that
 330          * processes the host requests may not yet be running.
 331          * Defer processing channel callbacks until the daemon
 332          * has registered.
 333          */
 334         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 335
 336         hvt = hvutil_transport_init(fcopy_devname, 0, 0,
 337                                     fcopy_on_msg, fcopy_on_reset);
 338         if (!hvt)
 339                 return -EFAULT;
 340
 341         return 0;
 342 }
 343
 344 void hv_fcopy_deinit(void)
 345 {
 346         fcopy_transaction.state = HVUTIL_DEVICE_DYING;
 347         cancel_delayed_work_sync(&fcopy_timeout_work);
 348         hvutil_transport_destroy(hvt);
 349         wait_for_completion(&release_event);
 350 }