1 /*
2  *  Copyright (c) 2013, Microsoft Corporation.
3  *
4  *  This program is free software; you can redistribute it and/or modify it
5  *  under the terms and conditions of the GNU General Public License,
6  *  version 2, as published by the Free Software Foundation.
7  *
8  *  This program is distributed in the hope it will be useful, but WITHOUT
9  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  *  more details.
12  */
13 
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/device.h>
17 #include <linux/completion.h>
18 #include <linux/hyperv.h>
19 #include <linux/serio.h>
20 #include <linux/slab.h>
21 
22 /*
23  * Current version 1.0
24  *
25  */
26 #define SYNTH_KBD_VERSION_MAJOR 1
27 #define SYNTH_KBD_VERSION_MINOR	0
28 #define SYNTH_KBD_VERSION		(SYNTH_KBD_VERSION_MINOR | \
29 					 (SYNTH_KBD_VERSION_MAJOR << 16))
30 
31 
32 /*
33  * Message types in the synthetic input protocol
34  */
35 enum synth_kbd_msg_type {
36 	SYNTH_KBD_PROTOCOL_REQUEST = 1,
37 	SYNTH_KBD_PROTOCOL_RESPONSE = 2,
38 	SYNTH_KBD_EVENT = 3,
39 	SYNTH_KBD_LED_INDICATORS = 4,
40 };
41 
42 /*
43  * Basic message structures.
44  */
45 struct synth_kbd_msg_hdr {
46 	__le32 type;
47 };
48 
49 struct synth_kbd_msg {
50 	struct synth_kbd_msg_hdr header;
51 	char data[]; /* Enclosed message */
52 };
53 
54 union synth_kbd_version {
55 	__le32 version;
56 };
57 
58 /*
59  * Protocol messages
60  */
61 struct synth_kbd_protocol_request {
62 	struct synth_kbd_msg_hdr header;
63 	union synth_kbd_version version_requested;
64 };
65 
66 #define PROTOCOL_ACCEPTED	BIT(0)
67 struct synth_kbd_protocol_response {
68 	struct synth_kbd_msg_hdr header;
69 	__le32 proto_status;
70 };
71 
72 #define IS_UNICODE	BIT(0)
73 #define IS_BREAK	BIT(1)
74 #define IS_E0		BIT(2)
75 #define IS_E1		BIT(3)
76 struct synth_kbd_keystroke {
77 	struct synth_kbd_msg_hdr header;
78 	__le16 make_code;
79 	__le16 reserved0;
80 	__le32 info; /* Additional information */
81 };
82 
83 
84 #define HK_MAXIMUM_MESSAGE_SIZE 256
85 
86 #define KBD_VSC_SEND_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
87 #define KBD_VSC_RECV_RING_BUFFER_SIZE		(10 * PAGE_SIZE)
88 
89 #define XTKBD_EMUL0     0xe0
90 #define XTKBD_EMUL1     0xe1
91 #define XTKBD_RELEASE   0x80
92 
93 
94 /*
95  * Represents a keyboard device
96  */
97 struct hv_kbd_dev {
98 	struct hv_device *hv_dev;
99 	struct serio *hv_serio;
100 	struct synth_kbd_protocol_request protocol_req;
101 	struct synth_kbd_protocol_response protocol_resp;
102 	/* Synchronize the request/response if needed */
103 	struct completion wait_event;
104 	spinlock_t lock; /* protects 'started' field */
105 	bool started;
106 };
107 
108 static void hv_kbd_on_receive(struct hv_device *hv_dev,
109 			      struct synth_kbd_msg *msg, u32 msg_length)
110 {
111 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
112 	struct synth_kbd_keystroke *ks_msg;
113 	unsigned long flags;
114 	u32 msg_type = __le32_to_cpu(msg->header.type);
115 	u32 info;
116 	u16 scan_code;
117 
118 	switch (msg_type) {
119 	case SYNTH_KBD_PROTOCOL_RESPONSE:
120 		/*
121 		 * Validate the information provided by the host.
122 		 * If the host is giving us a bogus packet,
123 		 * drop the packet (hoping the problem
124 		 * goes away).
125 		 */
126 		if (msg_length < sizeof(struct synth_kbd_protocol_response)) {
127 			dev_err(&hv_dev->device,
128 				"Illegal protocol response packet (len: %d)\n",
129 				msg_length);
130 			break;
131 		}
132 
133 		memcpy(&kbd_dev->protocol_resp, msg,
134 			sizeof(struct synth_kbd_protocol_response));
135 		complete(&kbd_dev->wait_event);
136 		break;
137 
138 	case SYNTH_KBD_EVENT:
139 		/*
140 		 * Validate the information provided by the host.
141 		 * If the host is giving us a bogus packet,
142 		 * drop the packet (hoping the problem
143 		 * goes away).
144 		 */
145 		if (msg_length < sizeof(struct  synth_kbd_keystroke)) {
146 			dev_err(&hv_dev->device,
147 				"Illegal keyboard event packet (len: %d)\n",
148 				msg_length);
149 			break;
150 		}
151 
152 		ks_msg = (struct synth_kbd_keystroke *)msg;
153 		info = __le32_to_cpu(ks_msg->info);
154 
155 		/*
156 		 * Inject the information through the serio interrupt.
157 		 */
158 		spin_lock_irqsave(&kbd_dev->lock, flags);
159 		if (kbd_dev->started) {
160 			if (info & IS_E0)
161 				serio_interrupt(kbd_dev->hv_serio,
162 						XTKBD_EMUL0, 0);
163 
164 			scan_code = __le16_to_cpu(ks_msg->make_code);
165 			if (info & IS_BREAK)
166 				scan_code |= XTKBD_RELEASE;
167 
168 			serio_interrupt(kbd_dev->hv_serio, scan_code, 0);
169 		}
170 		spin_unlock_irqrestore(&kbd_dev->lock, flags);
171 		break;
172 
173 	default:
174 		dev_err(&hv_dev->device,
175 			"unhandled message type %d\n", msg_type);
176 	}
177 }
178 
179 static void hv_kbd_handle_received_packet(struct hv_device *hv_dev,
180 					  struct vmpacket_descriptor *desc,
181 					  u32 bytes_recvd,
182 					  u64 req_id)
183 {
184 	struct synth_kbd_msg *msg;
185 	u32 msg_sz;
186 
187 	switch (desc->type) {
188 	case VM_PKT_COMP:
189 		break;
190 
191 	case VM_PKT_DATA_INBAND:
192 		/*
193 		 * We have a packet that has "inband" data. The API used
194 		 * for retrieving the packet guarantees that the complete
195 		 * packet is read. So, minimally, we should be able to
196 		 * parse the payload header safely (assuming that the host
197 		 * can be trusted.  Trusting the host seems to be a
198 		 * reasonable assumption because in a virtualized
199 		 * environment there is not whole lot you can do if you
200 		 * don't trust the host.
201 		 *
202 		 * Nonetheless, let us validate if the host can be trusted
203 		 * (in a trivial way).  The interesting aspect of this
204 		 * validation is how do you recover if we discover that the
205 		 * host is not to be trusted? Simply dropping the packet, I
206 		 * don't think is an appropriate recovery.  In the interest
207 		 * of failing fast, it may be better to crash the guest.
208 		 * For now, I will just drop the packet!
209 		 */
210 
211 		msg_sz = bytes_recvd - (desc->offset8 << 3);
212 		if (msg_sz <= sizeof(struct synth_kbd_msg_hdr)) {
213 			/*
214 			 * Drop the packet and hope
215 			 * the problem magically goes away.
216 			 */
217 			dev_err(&hv_dev->device,
218 				"Illegal packet (type: %d, tid: %llx, size: %d)\n",
219 				desc->type, req_id, msg_sz);
220 			break;
221 		}
222 
223 		msg = (void *)desc + (desc->offset8 << 3);
224 		hv_kbd_on_receive(hv_dev, msg, msg_sz);
225 		break;
226 
227 	default:
228 		dev_err(&hv_dev->device,
229 			"unhandled packet type %d, tid %llx len %d\n",
230 			desc->type, req_id, bytes_recvd);
231 		break;
232 	}
233 }
234 
235 static void hv_kbd_on_channel_callback(void *context)
236 {
237 	struct hv_device *hv_dev = context;
238 	void *buffer;
239 	int bufferlen = 0x100; /* Start with sensible size */
240 	u32 bytes_recvd;
241 	u64 req_id;
242 	int error;
243 
244 	buffer = kmalloc(bufferlen, GFP_ATOMIC);
245 	if (!buffer)
246 		return;
247 
248 	while (1) {
249 		error = vmbus_recvpacket_raw(hv_dev->channel, buffer, bufferlen,
250 					     &bytes_recvd, &req_id);
251 		switch (error) {
252 		case 0:
253 			if (bytes_recvd == 0) {
254 				kfree(buffer);
255 				return;
256 			}
257 
258 			hv_kbd_handle_received_packet(hv_dev, buffer,
259 						      bytes_recvd, req_id);
260 			break;
261 
262 		case -ENOBUFS:
263 			kfree(buffer);
264 			/* Handle large packet */
265 			bufferlen = bytes_recvd;
266 			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
267 			if (!buffer)
268 				return;
269 			break;
270 		}
271 	}
272 }
273 
274 static int hv_kbd_connect_to_vsp(struct hv_device *hv_dev)
275 {
276 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
277 	struct synth_kbd_protocol_request *request;
278 	struct synth_kbd_protocol_response *response;
279 	u32 proto_status;
280 	int error;
281 
282 	request = &kbd_dev->protocol_req;
283 	memset(request, 0, sizeof(struct synth_kbd_protocol_request));
284 	request->header.type = __cpu_to_le32(SYNTH_KBD_PROTOCOL_REQUEST);
285 	request->version_requested.version = __cpu_to_le32(SYNTH_KBD_VERSION);
286 
287 	error = vmbus_sendpacket(hv_dev->channel, request,
288 				 sizeof(struct synth_kbd_protocol_request),
289 				 (unsigned long)request,
290 				 VM_PKT_DATA_INBAND,
291 				 VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
292 	if (error)
293 		return error;
294 
295 	if (!wait_for_completion_timeout(&kbd_dev->wait_event, 10 * HZ))
296 		return -ETIMEDOUT;
297 
298 	response = &kbd_dev->protocol_resp;
299 	proto_status = __le32_to_cpu(response->proto_status);
300 	if (!(proto_status & PROTOCOL_ACCEPTED)) {
301 		dev_err(&hv_dev->device,
302 			"synth_kbd protocol request failed (version %d)\n",
303 		        SYNTH_KBD_VERSION);
304 		return -ENODEV;
305 	}
306 
307 	return 0;
308 }
309 
310 static int hv_kbd_start(struct serio *serio)
311 {
312 	struct hv_kbd_dev *kbd_dev = serio->port_data;
313 	unsigned long flags;
314 
315 	spin_lock_irqsave(&kbd_dev->lock, flags);
316 	kbd_dev->started = true;
317 	spin_unlock_irqrestore(&kbd_dev->lock, flags);
318 
319 	return 0;
320 }
321 
322 static void hv_kbd_stop(struct serio *serio)
323 {
324 	struct hv_kbd_dev *kbd_dev = serio->port_data;
325 	unsigned long flags;
326 
327 	spin_lock_irqsave(&kbd_dev->lock, flags);
328 	kbd_dev->started = false;
329 	spin_unlock_irqrestore(&kbd_dev->lock, flags);
330 }
331 
332 static int hv_kbd_probe(struct hv_device *hv_dev,
333 			const struct hv_vmbus_device_id *dev_id)
334 {
335 	struct hv_kbd_dev *kbd_dev;
336 	struct serio *hv_serio;
337 	int error;
338 
339 	kbd_dev = kzalloc(sizeof(struct hv_kbd_dev), GFP_KERNEL);
340 	hv_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
341 	if (!kbd_dev || !hv_serio) {
342 		error = -ENOMEM;
343 		goto err_free_mem;
344 	}
345 
346 	kbd_dev->hv_dev = hv_dev;
347 	kbd_dev->hv_serio = hv_serio;
348 	spin_lock_init(&kbd_dev->lock);
349 	init_completion(&kbd_dev->wait_event);
350 	hv_set_drvdata(hv_dev, kbd_dev);
351 
352 	hv_serio->dev.parent  = &hv_dev->device;
353 	hv_serio->id.type = SERIO_8042_XL;
354 	hv_serio->port_data = kbd_dev;
355 	strlcpy(hv_serio->name, dev_name(&hv_dev->device),
356 		sizeof(hv_serio->name));
357 	strlcpy(hv_serio->phys, dev_name(&hv_dev->device),
358 		sizeof(hv_serio->phys));
359 
360 	hv_serio->start = hv_kbd_start;
361 	hv_serio->stop = hv_kbd_stop;
362 
363 	error = vmbus_open(hv_dev->channel,
364 			   KBD_VSC_SEND_RING_BUFFER_SIZE,
365 			   KBD_VSC_RECV_RING_BUFFER_SIZE,
366 			   NULL, 0,
367 			   hv_kbd_on_channel_callback,
368 			   hv_dev);
369 	if (error)
370 		goto err_free_mem;
371 
372 	error = hv_kbd_connect_to_vsp(hv_dev);
373 	if (error)
374 		goto err_close_vmbus;
375 
376 	serio_register_port(kbd_dev->hv_serio);
377 	return 0;
378 
379 err_close_vmbus:
380 	vmbus_close(hv_dev->channel);
381 err_free_mem:
382 	kfree(hv_serio);
383 	kfree(kbd_dev);
384 	return error;
385 }
386 
387 static int hv_kbd_remove(struct hv_device *hv_dev)
388 {
389 	struct hv_kbd_dev *kbd_dev = hv_get_drvdata(hv_dev);
390 
391 	serio_unregister_port(kbd_dev->hv_serio);
392 	vmbus_close(hv_dev->channel);
393 	kfree(kbd_dev);
394 
395 	hv_set_drvdata(hv_dev, NULL);
396 
397 	return 0;
398 }
399 
400 /*
401  * Keyboard GUID
402  * {f912ad6d-2b17-48ea-bd65-f927a61c7684}
403  */
404 #define HV_KBD_GUID \
405 	.guid = { \
406 			0x6d, 0xad, 0x12, 0xf9, 0x17, 0x2b, 0xea, 0x48, \
407 			0xbd, 0x65, 0xf9, 0x27, 0xa6, 0x1c, 0x76, 0x84 \
408 	}
409 
410 static const struct hv_vmbus_device_id id_table[] = {
411 	/* Keyboard guid */
412 	{ HV_KBD_GUID, },
413 	{ },
414 };
415 
416 MODULE_DEVICE_TABLE(vmbus, id_table);
417 
418 static struct  hv_driver hv_kbd_drv = {
419 	.name = KBUILD_MODNAME,
420 	.id_table = id_table,
421 	.probe = hv_kbd_probe,
422 	.remove = hv_kbd_remove,
423 };
424 
425 static int __init hv_kbd_init(void)
426 {
427 	return vmbus_driver_register(&hv_kbd_drv);
428 }
429 
430 static void __exit hv_kbd_exit(void)
431 {
432 	vmbus_driver_unregister(&hv_kbd_drv);
433 }
434 
435 MODULE_LICENSE("GPL");
436 module_init(hv_kbd_init);
437 module_exit(hv_kbd_exit);
438