root/drivers/input/serio/hyperv-keyboard.c

DEFINITIONS

1. hv_kbd_on_receive
2. hv_kbd_handle_received_packet
3. hv_kbd_on_channel_callback
4. hv_kbd_connect_to_vsp
5. hv_kbd_start
6. hv_kbd_stop
7. hv_kbd_probe
8. hv_kbd_remove
9. hv_kbd_init
10. hv_kbd_exit

   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           (40 * 1024)
  79 #define KBD_VSC_RECV_RING_BUFFER_SIZE           (40 * 1024)
  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 vmpacket_descriptor *desc;
 241         struct hv_device *hv_dev = context;
 242         u32 bytes_recvd;
 243         u64 req_id;
 244 
 245         foreach_vmbus_pkt(desc, hv_dev->channel) {
 246                 bytes_recvd = desc->len8 * 8;
 247                 req_id = desc->trans_id;
 248 
 249                 hv_kbd_handle_received_packet(hv_dev, desc, bytes_recvd,
 250                                               req_id);
 251         }
 252 }
 253 
 254 static int hv_kbd_connect_to_vsp(struct hv_device *hv_dev)
 255 {
 256         struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
 257         struct synth_kbd_protocol_request *request;
 258         struct synth_kbd_protocol_response *response;
 259         u32 proto_status;
 260         int error;
 261 
 262         request = &kbd_dev->protocol_req;
 263         memset(request, 0, sizeof(struct synth_kbd_protocol_request));
 264         request->header.type = __cpu_to_le32(SYNTH_KBD_PROTOCOL_REQUEST);
 265         request->version_requested.version = __cpu_to_le32(SYNTH_KBD_VERSION);
 266 
 267         error = vmbus_sendpacket(hv_dev->channel, request,
 268                                  sizeof(struct synth_kbd_protocol_request),
 269                                  (unsigned long)request,
 270                                  VM_PKT_DATA_INBAND,
 271                                  VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 272         if (error)
 273                 return error;
 274 
 275         if (!wait_for_completion_timeout(&kbd_dev->wait_event, 10 * HZ))
 276                 return -ETIMEDOUT;
 277 
 278         response = &kbd_dev->protocol_resp;
 279         proto_status = __le32_to_cpu(response->proto_status);
 280         if (!(proto_status & PROTOCOL_ACCEPTED)) {
 281                 dev_err(&hv_dev->device,
 282                         "synth_kbd protocol request failed (version %d)\n",
 283                         SYNTH_KBD_VERSION);
 284                 return -ENODEV;
 285         }
 286 
 287         return 0;
 288 }
 289 
 290 static int hv_kbd_start(struct serio *serio)
 291 {
 292         struct hv_kbd_dev *kbd_dev = serio->port_data;
 293         unsigned long flags;
 294 
 295         spin_lock_irqsave(&kbd_dev->lock, flags);
 296         kbd_dev->started = true;
 297         spin_unlock_irqrestore(&kbd_dev->lock, flags);
 298 
 299         return 0;
 300 }
 301 
 302 static void hv_kbd_stop(struct serio *serio)
 303 {
 304         struct hv_kbd_dev *kbd_dev = serio->port_data;
 305         unsigned long flags;
 306 
 307         spin_lock_irqsave(&kbd_dev->lock, flags);
 308         kbd_dev->started = false;
 309         spin_unlock_irqrestore(&kbd_dev->lock, flags);
 310 }
 311 
 312 static int hv_kbd_probe(struct hv_device *hv_dev,
 313                         const struct hv_vmbus_device_id *dev_id)
 314 {
 315         struct hv_kbd_dev *kbd_dev;
 316         struct serio *hv_serio;
 317         int error;
 318 
 319         kbd_dev = kzalloc(sizeof(struct hv_kbd_dev), GFP_KERNEL);
 320         hv_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 321         if (!kbd_dev || !hv_serio) {
 322                 error = -ENOMEM;
 323                 goto err_free_mem;
 324         }
 325 
 326         kbd_dev->hv_dev = hv_dev;
 327         kbd_dev->hv_serio = hv_serio;
 328         spin_lock_init(&kbd_dev->lock);
 329         init_completion(&kbd_dev->wait_event);
 330         hv_set_drvdata(hv_dev, kbd_dev);
 331 
 332         hv_serio->dev.parent  = &hv_dev->device;
 333         hv_serio->id.type = SERIO_8042_XL;
 334         hv_serio->port_data = kbd_dev;
 335         strlcpy(hv_serio->name, dev_name(&hv_dev->device),
 336                 sizeof(hv_serio->name));
 337         strlcpy(hv_serio->phys, dev_name(&hv_dev->device),
 338                 sizeof(hv_serio->phys));
 339 
 340         hv_serio->start = hv_kbd_start;
 341         hv_serio->stop = hv_kbd_stop;
 342 
 343         error = vmbus_open(hv_dev->channel,
 344                            KBD_VSC_SEND_RING_BUFFER_SIZE,
 345                            KBD_VSC_RECV_RING_BUFFER_SIZE,
 346                            NULL, 0,
 347                            hv_kbd_on_channel_callback,
 348                            hv_dev);
 349         if (error)
 350                 goto err_free_mem;
 351 
 352         error = hv_kbd_connect_to_vsp(hv_dev);
 353         if (error)
 354                 goto err_close_vmbus;
 355 
 356         serio_register_port(kbd_dev->hv_serio);
 357 
 358         device_init_wakeup(&hv_dev->device, true);
 359 
 360         return 0;
 361 
 362 err_close_vmbus:
 363         vmbus_close(hv_dev->channel);
 364 err_free_mem:
 365         kfree(hv_serio);
 366         kfree(kbd_dev);
 367         return error;
 368 }
 369 
 370 static int hv_kbd_remove(struct hv_device *hv_dev)
 371 {
 372         struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
 373 
 374         serio_unregister_port(kbd_dev->hv_serio);
 375         vmbus_close(hv_dev->channel);
 376         kfree(kbd_dev);
 377 
 378         hv_set_drvdata(hv_dev, NULL);
 379 
 380         return 0;
 381 }
 382 
 383 static const struct hv_vmbus_device_id id_table[] = {
 384         /* Keyboard guid */
 385         { HV_KBD_GUID, },
 386         { },
 387 };
 388 
 389 MODULE_DEVICE_TABLE(vmbus, id_table);
 390 
 391 static struct  hv_driver hv_kbd_drv = {
 392         .name = KBUILD_MODNAME,
 393         .id_table = id_table,
 394         .probe = hv_kbd_probe,
 395         .remove = hv_kbd_remove,
 396         .driver = {
 397                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 398         },
 399 };
 400 
 401 static int __init hv_kbd_init(void)
 402 {
 403         return vmbus_driver_register(&hv_kbd_drv);
 404 }
 405 
 406 static void __exit hv_kbd_exit(void)
 407 {
 408         vmbus_driver_unregister(&hv_kbd_drv);
 409 }
 410 
 411 MODULE_LICENSE("GPL");
 412 MODULE_DESCRIPTION("Microsoft Hyper-V Synthetic Keyboard Driver");
 413 
 414 module_init(hv_kbd_init);
 415 module_exit(hv_kbd_exit);