kernel/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         void *fcopy_context; /* for the channel callback */
  55 } fcopy_transaction;
  56
  57 static void fcopy_respond_to_host(int error);
  58 static void fcopy_send_data(struct work_struct *dummy);
  59 static void fcopy_timeout_func(struct work_struct *dummy);
  60 static DECLARE_DELAYED_WORK(fcopy_timeout_work, fcopy_timeout_func);
  61 static DECLARE_WORK(fcopy_send_work, fcopy_send_data);
  62 static const char fcopy_devname[] = "vmbus/hv_fcopy";
  63 static u8 *recv_buffer;
  64 static struct hvutil_transport *hvt;
  65 /*
  66  * This state maintains the version number registered by the daemon.
  67  */
  68 static int dm_reg_value;
  69
  70 static void fcopy_timeout_func(struct work_struct *dummy)
  71 {
  72         /*
  73          * If the timer fires, the user-mode component has not responded;
  74          * process the pending transaction.
  75          */
  76         fcopy_respond_to_host(HV_E_FAIL);
  77
  78         /* Transaction is finished, reset the state. */
  79         if (fcopy_transaction.state > HVUTIL_READY)
  80                 fcopy_transaction.state = HVUTIL_READY;
  81
  82         hv_poll_channel(fcopy_transaction.fcopy_context,
  83                         hv_fcopy_onchannelcallback);
  84 }
  85
  86 static int fcopy_handle_handshake(u32 version)
  87 {
  88         u32 our_ver = FCOPY_CURRENT_VERSION;
  89
  90         switch (version) {
  91         case FCOPY_VERSION_0:
  92                 /* Daemon doesn't expect us to reply */
  93                 dm_reg_value = version;
  94                 break;
  95         case FCOPY_VERSION_1:
  96                 /* Daemon expects us to reply with our own version */
  97                 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver)))
  98                         return -EFAULT;
  99                 dm_reg_value = version;
 100                 break;
 101         default:
 102                 /*
 103                  * For now we will fail the registration.
 104                  * If and when we have multiple versions to
 105                  * deal with, we will be backward compatible.
 106                  * We will add this code when needed.
 107                  */
 108                 return -EINVAL;
 109         }
 110         pr_debug("FCP: userspace daemon ver. %d registered\n", version);
 111         fcopy_transaction.state = HVUTIL_READY;
 112         hv_poll_channel(fcopy_transaction.fcopy_context,
 113                         hv_fcopy_onchannelcallback);
 114         return 0;
 115 }
 116
 117 static void fcopy_send_data(struct work_struct *dummy)
 118 {
 119         struct hv_start_fcopy *smsg_out = NULL;
 120         int operation = fcopy_transaction.fcopy_msg->operation;
 121         struct hv_start_fcopy *smsg_in;
 122         void *out_src;
 123         int rc, out_len;
 124
 125         /*
 126          * The  strings sent from the host are encoded in
 127          * in utf16; convert it to utf8 strings.
 128          * The host assures us that the utf16 strings will not exceed
 129          * the max lengths specified. We will however, reserve room
 130          * for the string terminating character - in the utf16s_utf8s()
 131          * function we limit the size of the buffer where the converted
 132          * string is placed to W_MAX_PATH -1 to guarantee
 133          * that the strings can be properly terminated!
 134          */
 135
 136         switch (operation) {
 137         case START_FILE_COPY:
 138                 out_len = sizeof(struct hv_start_fcopy);
 139                 smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
 140                 if (!smsg_out)
 141                         return;
 142
 143                 smsg_out->hdr.operation = operation;
 144                 smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 145
 146                 utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 147                                 UTF16_LITTLE_ENDIAN,
 148                                 (__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
 149
 150                 utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 151                                 UTF16_LITTLE_ENDIAN,
 152                                 (__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
 153
 154                 smsg_out->copy_flags = smsg_in->copy_flags;
 155                 smsg_out->file_size = smsg_in->file_size;
 156                 out_src = smsg_out;
 157                 break;
 158
 159         default:
 160                 out_src = fcopy_transaction.fcopy_msg;
 161                 out_len = fcopy_transaction.recv_len;
 162                 break;
 163         }
 164
 165         fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
 166         rc = hvutil_transport_send(hvt, out_src, out_len);
 167         if (rc) {
 168                 pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
 169                 if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 170                         fcopy_respond_to_host(HV_E_FAIL);
 171                         fcopy_transaction.state = HVUTIL_READY;
 172                 }
 173         }
 174         kfree(smsg_out);
 175
 176         return;
 177 }
 178
 179 /*
 180  * Send a response back to the host.
 181  */
 182
 183 static void
 184 fcopy_respond_to_host(int error)
 185 {
 186         struct icmsg_hdr *icmsghdr;
 187         u32 buf_len;
 188         struct vmbus_channel *channel;
 189         u64 req_id;
 190
 191         /*
 192          * Copy the global state for completing the transaction. Note that
 193          * only one transaction can be active at a time. This is guaranteed
 194          * by the file copy protocol implemented by the host. Furthermore,
 195          * the "transaction active" state we maintain ensures that there can
 196          * only be one active transaction at a time.
 197          */
 198
 199         buf_len = fcopy_transaction.recv_len;
 200         channel = fcopy_transaction.recv_channel;
 201         req_id = fcopy_transaction.recv_req_id;
 202
 203         icmsghdr = (struct icmsg_hdr *)
 204                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 205
 206         if (channel->onchannel_callback == NULL)
 207                 /*
 208                  * We have raced with util driver being unloaded;
 209                  * silently return.
 210                  */
 211                 return;
 212
 213         icmsghdr->status = error;
 214         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 215         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 216                                 VM_PKT_DATA_INBAND, 0);
 217 }
 218
 219 void hv_fcopy_onchannelcallback(void *context)
 220 {
 221         struct vmbus_channel *channel = context;
 222         u32 recvlen;
 223         u64 requestid;
 224         struct hv_fcopy_hdr *fcopy_msg;
 225         struct icmsg_hdr *icmsghdr;
 226         struct icmsg_negotiate *negop = NULL;
 227         int util_fw_version;
 228         int fcopy_srv_version;
 229
 230         if (fcopy_transaction.state > HVUTIL_READY) {
 231                 /*
 232                  * We will defer processing this callback once
 233                  * the current transaction is complete.
 234                  */
 235                 fcopy_transaction.fcopy_context = context;
 236                 return;
 237         }
 238         fcopy_transaction.fcopy_context = NULL;
 239
 240         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 241                          &requestid);
 242         if (recvlen <= 0)
 243                 return;
 244
 245         icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 246                         sizeof(struct vmbuspipe_hdr)];
 247         if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 248                 util_fw_version = UTIL_FW_VERSION;
 249                 fcopy_srv_version = WIN8_SRV_VERSION;
 250                 vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 251                                 util_fw_version, fcopy_srv_version);
 252         } else {
 253                 fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 254                                 sizeof(struct vmbuspipe_hdr) +
 255                                 sizeof(struct icmsg_hdr)];
 256
 257                 /*
 258                  * Stash away this global state for completing the
 259                  * transaction; note transactions are serialized.
 260                  */
 261
 262                 fcopy_transaction.recv_len = recvlen;
 263                 fcopy_transaction.recv_channel = channel;
 264                 fcopy_transaction.recv_req_id = requestid;
 265                 fcopy_transaction.fcopy_msg = fcopy_msg;
 266
 267                 if (fcopy_transaction.state < HVUTIL_READY) {
 268                         /* Userspace is not registered yet */
 269                         fcopy_respond_to_host(HV_E_FAIL);
 270                         return;
 271                 }
 272                 fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 273
 274                 /*
 275                  * Send the information to the user-level daemon.
 276                  */
 277                 schedule_work(&fcopy_send_work);
 278                 schedule_delayed_work(&fcopy_timeout_work, 5*HZ);
 279                 return;
 280         }
 281         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 282         vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
 283                         VM_PKT_DATA_INBAND, 0);
 284 }
 285
 286 /* Callback when data is received from userspace */
 287 static int fcopy_on_msg(void *msg, int len)
 288 {
 289         int *val = (int *)msg;
 290
 291         if (len != sizeof(int))
 292                 return -EINVAL;
 293
 294         if (fcopy_transaction.state == HVUTIL_DEVICE_INIT)
 295                 return fcopy_handle_handshake(*val);
 296
 297         if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)
 298                 return -EINVAL;
 299
 300         /*
 301          * Complete the transaction by forwarding the result
 302          * to the host. But first, cancel the timeout.
 303          */
 304         if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 305                 fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
 306                 fcopy_respond_to_host(*val);
 307                 fcopy_transaction.state = HVUTIL_READY;
 308                 hv_poll_channel(fcopy_transaction.fcopy_context,
 309                                 hv_fcopy_onchannelcallback);
 310         }
 311
 312         return 0;
 313 }
 314
 315 static void fcopy_on_reset(void)
 316 {
 317         /*
 318          * The daemon has exited; reset the state.
 319          */
 320         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 321
 322         if (cancel_delayed_work_sync(&fcopy_timeout_work))
 323                 fcopy_respond_to_host(HV_E_FAIL);
 324 }
 325
 326 int hv_fcopy_init(struct hv_util_service *srv)
 327 {
 328         recv_buffer = srv->recv_buffer;
 329
 330         /*
 331          * When this driver loads, the user level daemon that
 332          * processes the host requests may not yet be running.
 333          * Defer processing channel callbacks until the daemon
 334          * has registered.
 335          */
 336         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 337
 338         hvt = hvutil_transport_init(fcopy_devname, 0, 0,
 339                                     fcopy_on_msg, fcopy_on_reset);
 340         if (!hvt)
 341                 return -EFAULT;
 342
 343         return 0;
 344 }
 345
 346 void hv_fcopy_deinit(void)
 347 {
 348         fcopy_transaction.state = HVUTIL_DEVICE_DYING;
 349         cancel_delayed_work_sync(&fcopy_timeout_work);
 350         hvutil_transport_destroy(hvt);
 351 }