drivers/input/serio/hyperv-keyboard.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Copyright (c) 2013, Microsoft Corporation.
   4  */
   5
   6 #include <linux/init.h>
   7 #include <linux/module.h>
   8 #include <linux/device.h>
   9 #include <linux/completion.h>
  10 #include <linux/hyperv.h>
  11 #include <linux/serio.h>
  12 #include <linux/slab.h>
  13
  14 /*
  15  * Current version 1.0
  16  *
  17  */
  18 #define SYNTH_KBD_VERSION_MAJOR 1
  19 #define SYNTH_KBD_VERSION_MINOR 0
  20 #define SYNTH_KBD_VERSION               (SYNTH_KBD_VERSION_MINOR | \
  21                                          (SYNTH_KBD_VERSION_MAJOR << 16))
  22
  23
  24 /*
  25  * Message types in the synthetic input protocol
  26  */
  27 enum synth_kbd_msg_type {
  28         SYNTH_KBD_PROTOCOL_REQUEST = 1,
  29         SYNTH_KBD_PROTOCOL_RESPONSE = 2,
  30         SYNTH_KBD_EVENT = 3,
  31         SYNTH_KBD_LED_INDICATORS = 4,
  32 };
  33
  34 /*
  35  * Basic message structures.
  36  */
  37 struct synth_kbd_msg_hdr {
  38         __le32 type;
  39 };
  40
  41 struct synth_kbd_msg {
  42         struct synth_kbd_msg_hdr header;
  43         char data[]; /* Enclosed message */
  44 };
  45
  46 union synth_kbd_version {
  47         __le32 version;
  48 };
  49
  50 /*
  51  * Protocol messages
  52  */
  53 struct synth_kbd_protocol_request {
  54         struct synth_kbd_msg_hdr header;
  55         union synth_kbd_version version_requested;
  56 };
  57
  58 #define PROTOCOL_ACCEPTED       BIT(0)
  59 struct synth_kbd_protocol_response {
  60         struct synth_kbd_msg_hdr header;
  61         __le32 proto_status;
  62 };
  63
  64 #define IS_UNICODE      BIT(0)
  65 #define IS_BREAK        BIT(1)
  66 #define IS_E0           BIT(2)
  67 #define IS_E1           BIT(3)
  68 struct synth_kbd_keystroke {
  69         struct synth_kbd_msg_hdr header;
  70         __le16 make_code;
  71         __le16 reserved0;
  72         __le32 info; /* Additional information */
  73 };
  74
  75
  76 #define HK_MAXIMUM_MESSAGE_SIZE 256
  77
  78 #define KBD_VSC_SEND_RING_BUFFER_SIZE           (10 * PAGE_SIZE)
  79 #define KBD_VSC_RECV_RING_BUFFER_SIZE           (10 * PAGE_SIZE)
  80
  81 #define XTKBD_EMUL0     0xe0
  82 #define XTKBD_EMUL1     0xe1
  83 #define XTKBD_RELEASE   0x80
  84
  85
  86 /*
  87  * Represents a keyboard device
  88  */
  89 struct hv_kbd_dev {
  90         struct hv_device *hv_dev;
  91         struct serio *hv_serio;
  92         struct synth_kbd_protocol_request protocol_req;
  93         struct synth_kbd_protocol_response protocol_resp;
  94         /* Synchronize the request/response if needed */
  95         struct completion wait_event;
  96         spinlock_t lock; /* protects 'started' field */
  97         bool started;
  98 };
  99
 100 static void hv_kbd_on_receive(struct hv_device *hv_dev,
 101                               struct synth_kbd_msg *msg, u32 msg_length)
 102 {
 103         struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
 104         struct synth_kbd_keystroke *ks_msg;
 105         unsigned long flags;
 106         u32 msg_type = __le32_to_cpu(msg->header.type);
 107         u32 info;
 108         u16 scan_code;
 109
 110         switch (msg_type) {
 111         case SYNTH_KBD_PROTOCOL_RESPONSE:
 112                 /*
 113                  * Validate the information provided by the host.
 114                  * If the host is giving us a bogus packet,
 115                  * drop the packet (hoping the problem
 116                  * goes away).
 117                  */
 118                 if (msg_length < sizeof(struct synth_kbd_protocol_response)) {
 119                         dev_err(&hv_dev->device,
 120                                 "Illegal protocol response packet (len: %d)\n",
 121                                 msg_length);
 122                         break;
 123                 }
 124
 125                 memcpy(&kbd_dev->protocol_resp, msg,
 126                         sizeof(struct synth_kbd_protocol_response));
 127                 complete(&kbd_dev->wait_event);
 128                 break;
 129
 130         case SYNTH_KBD_EVENT:
 131                 /*
 132                  * Validate the information provided by the host.
 133                  * If the host is giving us a bogus packet,
 134                  * drop the packet (hoping the problem
 135                  * goes away).
 136                  */
 137                 if (msg_length < sizeof(struct  synth_kbd_keystroke)) {
 138                         dev_err(&hv_dev->device,
 139                                 "Illegal keyboard event packet (len: %d)\n",
 140                                 msg_length);
 141                         break;
 142                 }
 143
 144                 ks_msg = (struct synth_kbd_keystroke *)msg;
 145                 info = __le32_to_cpu(ks_msg->info);
 146
 147                 /*
 148                  * Inject the information through the serio interrupt.
 149                  */
 150                 spin_lock_irqsave(&kbd_dev->lock, flags);
 151                 if (kbd_dev->started) {
 152                         if (info & IS_E0)
 153                                 serio_interrupt(kbd_dev->hv_serio,
 154                                                 XTKBD_EMUL0, 0);
 155                         if (info & IS_E1)
 156                                 serio_interrupt(kbd_dev->hv_serio,
 157                                                 XTKBD_EMUL1, 0);
 158                         scan_code = __le16_to_cpu(ks_msg->make_code);
 159                         if (info & IS_BREAK)
 160                                 scan_code |= XTKBD_RELEASE;
 161
 162                         serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
 163                 }
 164                 spin_unlock_irqrestore(&kbd_dev->lock, flags);
 165
 166                 /*
 167                  * Only trigger a wakeup on key down, otherwise
 168                  * "echo freeze > /sys/power/state" can't really enter the
 169                  * state because the Enter-UP can trigger a wakeup at once.
 170                  */
 171                 if (!(info & IS_BREAK))
 172                         pm_wakeup_hard_event(&hv_dev->device);
 173
 174                 break;
 175
 176         default:
 177                 dev_err(&hv_dev->device,
 178                         "unhandled message type %d\n", msg_type);
 179         }
 180 }
 181
 182 static void hv_kbd_handle_received_packet(struct hv_device *hv_dev,
 183                                           struct vmpacket_descriptor *desc,
 184                                           u32 bytes_recvd,
 185                                           u64 req_id)
 186 {
 187         struct synth_kbd_msg *msg;
 188         u32 msg_sz;
 189
 190         switch (desc->type) {
 191         case VM_PKT_COMP:
 192                 break;
 193
 194         case VM_PKT_DATA_INBAND:
 195                 /*
 196                  * We have a packet that has "inband" data. The API used
 197                  * for retrieving the packet guarantees that the complete
 198                  * packet is read. So, minimally, we should be able to
 199                  * parse the payload header safely (assuming that the host
 200                  * can be trusted.  Trusting the host seems to be a
 201                  * reasonable assumption because in a virtualized
 202                  * environment there is not whole lot you can do if you
 203                  * don't trust the host.
 204                  *
 205                  * Nonetheless, let us validate if the host can be trusted
 206                  * (in a trivial way).  The interesting aspect of this
 207                  * validation is how do you recover if we discover that the
 208                  * host is not to be trusted? Simply dropping the packet, I
 209                  * don't think is an appropriate recovery.  In the interest
 210                  * of failing fast, it may be better to crash the guest.
 211                  * For now, I will just drop the packet!
 212                  */
 213
 214                 msg_sz = bytes_recvd - (desc->offset8 << 3);
 215                 if (msg_sz <= sizeof(struct synth_kbd_msg_hdr)) {
 216                         /*
 217                          * Drop the packet and hope
 218                          * the problem magically goes away.
 219                          */
 220                         dev_err(&hv_dev->device,
 221                                 "Illegal packet (type: %d, tid: %llx, size: %d)\n",
 222                                 desc->type, req_id, msg_sz);
 223                         break;
 224                 }
 225
 226                 msg = (void *)desc + (desc->offset8 << 3);
 227                 hv_kbd_on_receive(hv_dev, msg, msg_sz);
 228                 break;
 229
 230         default:
 231                 dev_err(&hv_dev->device,
 232                         "unhandled packet type %d, tid %llx len %d\n",
 233                         desc->type, req_id, bytes_recvd);
 234                 break;
 235         }
 236 }
 237
 238 static void hv_kbd_on_channel_callback(void *context)
 239 {
 240         struct hv_device *hv_dev = context;
 241         void *buffer;
 242         int bufferlen = 0x100; /* Start with sensible size */
 243         u32 bytes_recvd;
 244         u64 req_id;
 245         int error;
 246
 247         buffer = kmalloc(bufferlen, GFP_ATOMIC);
 248         if (!buffer)
 249                 return;
 250
 251         while (1) {
 252                 error = vmbus_recvpacket_raw(hv_dev->channel, buffer, bufferlen,
 253                                              &bytes_recvd, &req_id);
 254                 switch (error) {
 255                 case 0:
 256                         if (bytes_recvd == 0) {
 257                                 kfree(buffer);
 258                                 return;
 259                         }
 260
 261                         hv_kbd_handle_received_packet(hv_dev, buffer,
 262                                                       bytes_recvd, req_id);
 263                         break;
 264
 265                 case -ENOBUFS:
 266                         kfree(buffer);
 267                         /* Handle large packet */
 268                         bufferlen = bytes_recvd;
 269                         buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
 270                         if (!buffer)
 271                                 return;
 272                         break;
 273                 }
 274         }
 275 }
 276
 277 static int hv_kbd_connect_to_vsp(struct hv_device *hv_dev)
 278 {
 279         struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
 280         struct synth_kbd_protocol_request *request;
 281         struct synth_kbd_protocol_response *response;
 282         u32 proto_status;
 283         int error;
 284
 285         request = &kbd_dev->protocol_req;
 286         memset(request, 0, sizeof(struct synth_kbd_protocol_request));
 287         request->header.type = __cpu_to_le32(SYNTH_KBD_PROTOCOL_REQUEST);
 288         request->version_requested.version = __cpu_to_le32(SYNTH_KBD_VERSION);
 289
 290         error = vmbus_sendpacket(hv_dev->channel, request,
 291                                  sizeof(struct synth_kbd_protocol_request),
 292                                  (unsigned long)request,
 293                                  VM_PKT_DATA_INBAND,
 294                                  VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 295         if (error)
 296                 return error;
 297
 298         if (!wait_for_completion_timeout(&kbd_dev->wait_event, 10 * HZ))
 299                 return -ETIMEDOUT;
 300
 301         response = &kbd_dev->protocol_resp;
 302         proto_status = __le32_to_cpu(response->proto_status);
 303         if (!(proto_status & PROTOCOL_ACCEPTED)) {
 304                 dev_err(&hv_dev->device,
 305                         "synth_kbd protocol request failed (version %d)\n",
 306                         SYNTH_KBD_VERSION);
 307                 return -ENODEV;
 308         }
 309
 310         return 0;
 311 }
 312
 313 static int hv_kbd_start(struct serio *serio)
 314 {
 315         struct hv_kbd_dev *kbd_dev = serio->port_data;
 316         unsigned long flags;
 317
 318         spin_lock_irqsave(&kbd_dev->lock, flags);
 319         kbd_dev->started = true;
 320         spin_unlock_irqrestore(&kbd_dev->lock, flags);
 321
 322         return 0;
 323 }
 324
 325 static void hv_kbd_stop(struct serio *serio)
 326 {
 327         struct hv_kbd_dev *kbd_dev = serio->port_data;
 328         unsigned long flags;
 329
 330         spin_lock_irqsave(&kbd_dev->lock, flags);
 331         kbd_dev->started = false;
 332         spin_unlock_irqrestore(&kbd_dev->lock, flags);
 333 }
 334
 335 static int hv_kbd_probe(struct hv_device *hv_dev,
 336                         const struct hv_vmbus_device_id *dev_id)
 337 {
 338         struct hv_kbd_dev *kbd_dev;
 339         struct serio *hv_serio;
 340         int error;
 341
 342         kbd_dev = kzalloc(sizeof(struct hv_kbd_dev), GFP_KERNEL);
 343         hv_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 344         if (!kbd_dev || !hv_serio) {
 345                 error = -ENOMEM;
 346                 goto err_free_mem;
 347         }
 348
 349         kbd_dev->hv_dev = hv_dev;
 350         kbd_dev->hv_serio = hv_serio;
 351         spin_lock_init(&kbd_dev->lock);
 352         init_completion(&kbd_dev->wait_event);
 353         hv_set_drvdata(hv_dev, kbd_dev);
 354
 355         hv_serio->dev.parent  = &hv_dev->device;
 356         hv_serio->id.type = SERIO_8042_XL;
 357         hv_serio->port_data = kbd_dev;
 358         strlcpy(hv_serio->name, dev_name(&hv_dev->device),
 359                 sizeof(hv_serio->name));
 360         strlcpy(hv_serio->phys, dev_name(&hv_dev->device),
 361                 sizeof(hv_serio->phys));
 362
 363         hv_serio->start = hv_kbd_start;
 364         hv_serio->stop = hv_kbd_stop;
 365
 366         error = vmbus_open(hv_dev->channel,
 367                            KBD_VSC_SEND_RING_BUFFER_SIZE,
 368                            KBD_VSC_RECV_RING_BUFFER_SIZE,
 369                            NULL, 0,
 370                            hv_kbd_on_channel_callback,
 371                            hv_dev);
 372         if (error)
 373                 goto err_free_mem;
 374
 375         error = hv_kbd_connect_to_vsp(hv_dev);
 376         if (error)
 377                 goto err_close_vmbus;
 378
 379         serio_register_port(kbd_dev->hv_serio);
 380
 381         device_init_wakeup(&hv_dev->device, true);
 382
 383         return 0;
 384
 385 err_close_vmbus:
 386         vmbus_close(hv_dev->channel);
 387 err_free_mem:
 388         kfree(hv_serio);
 389         kfree(kbd_dev);
 390         return error;
 391 }
 392
 393 static int hv_kbd_remove(struct hv_device *hv_dev)
 394 {
 395         struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
 396
 397         serio_unregister_port(kbd_dev->hv_serio);
 398         vmbus_close(hv_dev->channel);
 399         kfree(kbd_dev);
 400
 401         hv_set_drvdata(hv_dev, NULL);
 402
 403         return 0;
 404 }
 405
 406 static const struct hv_vmbus_device_id id_table[] = {
 407         /* Keyboard guid */
 408         { HV_KBD_GUID, },
 409         { },
 410 };
 411
 412 MODULE_DEVICE_TABLE(vmbus, id_table);
 413
 414 static struct  hv_driver hv_kbd_drv = {
 415         .name = KBUILD_MODNAME,
 416         .id_table = id_table,
 417         .probe = hv_kbd_probe,
 418         .remove = hv_kbd_remove,
 419         .driver = {
 420                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 421         },
 422 };
 423
 424 static int __init hv_kbd_init(void)
 425 {
 426         return vmbus_driver_register(&hv_kbd_drv);
 427 }
 428
 429 static void __exit hv_kbd_exit(void)
 430 {
 431         vmbus_driver_unregister(&hv_kbd_drv);
 432 }
 433
 434 MODULE_LICENSE("GPL");
 435 MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Keyboard Driver");
 436
 437 module_init(hv_kbd_init);
 438 module_exit(hv_kbd_exit);