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 } 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 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         hv_poll_channel(fcopy_transaction.recv_channel, fcopy_poll_wrapper);
 112         return 0;
 113 }
 114
 115 static void fcopy_send_data(struct work_struct *dummy)
 116 {
 117         struct hv_start_fcopy *smsg_out = NULL;
 118         int operation = fcopy_transaction.fcopy_msg->operation;
 119         struct hv_start_fcopy *smsg_in;
 120         void *out_src;
 121         int rc, out_len;
 122
 123         /*
 124          * The  strings sent from the host are encoded in
 125          * in utf16; convert it to utf8 strings.
 126          * The host assures us that the utf16 strings will not exceed
 127          * the max lengths specified. We will however, reserve room
 128          * for the string terminating character - in the utf16s_utf8s()
 129          * function we limit the size of the buffer where the converted
 130          * string is placed to W_MAX_PATH -1 to guarantee
 131          * that the strings can be properly terminated!
 132          */
 133
 134         switch (operation) {
 135         case START_FILE_COPY:
 136                 out_len = sizeof(struct hv_start_fcopy);
 137                 smsg_out = kzalloc(sizeof(*smsg_out), GFP_KERNEL);
 138                 if (!smsg_out)
 139                         return;
 140
 141                 smsg_out->hdr.operation = operation;
 142                 smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 143
 144                 utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 145                                 UTF16_LITTLE_ENDIAN,
 146                                 (__u8 *)&smsg_out->file_name, W_MAX_PATH - 1);
 147
 148                 utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 149                                 UTF16_LITTLE_ENDIAN,
 150                                 (__u8 *)&smsg_out->path_name, W_MAX_PATH - 1);
 151
 152                 smsg_out->copy_flags = smsg_in->copy_flags;
 153                 smsg_out->file_size = smsg_in->file_size;
 154                 out_src = smsg_out;
 155                 break;
 156
 157         default:
 158                 out_src = fcopy_transaction.fcopy_msg;
 159                 out_len = fcopy_transaction.recv_len;
 160                 break;
 161         }
 162
 163         fcopy_transaction.state = HVUTIL_USERSPACE_REQ;
 164         rc = hvutil_transport_send(hvt, out_src, out_len);
 165         if (rc) {
 166                 pr_debug("FCP: failed to communicate to the daemon: %d\n", rc);
 167                 if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 168                         fcopy_respond_to_host(HV_E_FAIL);
 169                         fcopy_transaction.state = HVUTIL_READY;
 170                 }
 171         }
 172         kfree(smsg_out);
 173
 174         return;
 175 }
 176
 177 /*
 178  * Send a response back to the host.
 179  */
 180
 181 static void
 182 fcopy_respond_to_host(int error)
 183 {
 184         struct icmsg_hdr *icmsghdr;
 185         u32 buf_len;
 186         struct vmbus_channel *channel;
 187         u64 req_id;
 188
 189         /*
 190          * Copy the global state for completing the transaction. Note that
 191          * only one transaction can be active at a time. This is guaranteed
 192          * by the file copy protocol implemented by the host. Furthermore,
 193          * the "transaction active" state we maintain ensures that there can
 194          * only be one active transaction at a time.
 195          */
 196
 197         buf_len = fcopy_transaction.recv_len;
 198         channel = fcopy_transaction.recv_channel;
 199         req_id = fcopy_transaction.recv_req_id;
 200
 201         icmsghdr = (struct icmsg_hdr *)
 202                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 203
 204         if (channel->onchannel_callback == NULL)
 205                 /*
 206                  * We have raced with util driver being unloaded;
 207                  * silently return.
 208                  */
 209                 return;
 210
 211         icmsghdr->status = error;
 212         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 213         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 214                                 VM_PKT_DATA_INBAND, 0);
 215 }
 216
 217 void hv_fcopy_onchannelcallback(void *context)
 218 {
 219         struct vmbus_channel *channel = context;
 220         u32 recvlen;
 221         u64 requestid;
 222         struct hv_fcopy_hdr *fcopy_msg;
 223         struct icmsg_hdr *icmsghdr;
 224         struct icmsg_negotiate *negop = NULL;
 225         int util_fw_version;
 226         int fcopy_srv_version;
 227
 228         if (fcopy_transaction.state > HVUTIL_READY)
 229                 return;
 230
 231         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 232                          &requestid);
 233         if (recvlen <= 0)
 234                 return;
 235
 236         icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 237                         sizeof(struct vmbuspipe_hdr)];
 238         if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 239                 util_fw_version = UTIL_FW_VERSION;
 240                 fcopy_srv_version = WIN8_SRV_VERSION;
 241                 vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 242                                 util_fw_version, fcopy_srv_version);
 243         } else {
 244                 fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 245                                 sizeof(struct vmbuspipe_hdr) +
 246                                 sizeof(struct icmsg_hdr)];
 247
 248                 /*
 249                  * Stash away this global state for completing the
 250                  * transaction; note transactions are serialized.
 251                  */
 252
 253                 fcopy_transaction.recv_len = recvlen;
 254                 fcopy_transaction.recv_channel = channel;
 255                 fcopy_transaction.recv_req_id = requestid;
 256                 fcopy_transaction.fcopy_msg = fcopy_msg;
 257
 258                 if (fcopy_transaction.state < HVUTIL_READY) {
 259                         /* Userspace is not registered yet */
 260                         fcopy_respond_to_host(HV_E_FAIL);
 261                         return;
 262                 }
 263                 fcopy_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 264
 265                 /*
 266                  * Send the information to the user-level daemon.
 267                  */
 268                 schedule_work(&fcopy_send_work);
 269                 schedule_delayed_work(&fcopy_timeout_work,
 270                                       HV_UTIL_TIMEOUT * HZ);
 271                 return;
 272         }
 273         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 274         vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
 275                         VM_PKT_DATA_INBAND, 0);
 276 }
 277
 278 /* Callback when data is received from userspace */
 279 static int fcopy_on_msg(void *msg, int len)
 280 {
 281         int *val = (int *)msg;
 282
 283         if (len != sizeof(int))
 284                 return -EINVAL;
 285
 286         if (fcopy_transaction.state == HVUTIL_DEVICE_INIT)
 287                 return fcopy_handle_handshake(*val);
 288
 289         if (fcopy_transaction.state != HVUTIL_USERSPACE_REQ)
 290                 return -EINVAL;
 291
 292         /*
 293          * Complete the transaction by forwarding the result
 294          * to the host. But first, cancel the timeout.
 295          */
 296         if (cancel_delayed_work_sync(&fcopy_timeout_work)) {
 297                 fcopy_transaction.state = HVUTIL_USERSPACE_RECV;
 298                 fcopy_respond_to_host(*val);
 299                 hv_poll_channel(fcopy_transaction.recv_channel,
 300                                 fcopy_poll_wrapper);
 301         }
 302
 303         return 0;
 304 }
 305
 306 static void fcopy_on_reset(void)
 307 {
 308         /*
 309          * The daemon has exited; reset the state.
 310          */
 311         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 312
 313         if (cancel_delayed_work_sync(&fcopy_timeout_work))
 314                 fcopy_respond_to_host(HV_E_FAIL);
 315 }
 316
 317 int hv_fcopy_init(struct hv_util_service *srv)
 318 {
 319         recv_buffer = srv->recv_buffer;
 320
 321         /*
 322          * When this driver loads, the user level daemon that
 323          * processes the host requests may not yet be running.
 324          * Defer processing channel callbacks until the daemon
 325          * has registered.
 326          */
 327         fcopy_transaction.state = HVUTIL_DEVICE_INIT;
 328
 329         hvt = hvutil_transport_init(fcopy_devname, 0, 0,
 330                                     fcopy_on_msg, fcopy_on_reset);
 331         if (!hvt)
 332                 return -EFAULT;
 333
 334         return 0;
 335 }
 336
 337 void hv_fcopy_deinit(void)
 338 {
 339         fcopy_transaction.state = HVUTIL_DEVICE_DYING;
 340         cancel_delayed_work_sync(&fcopy_timeout_work);
 341         hvutil_transport_destroy(hvt);
 342 }