summaryrefslogtreecommitdiff
path: root/drivers/hv/hv_fcopy.c
blob: 23b2ce294c4ca78ea3f961ee102550e4aeb02632 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
/*
 * An implementation of file copy service.
 *
 * Copyright (C) 2014, Microsoft, Inc.
 *
 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/semaphore.h>
#include <linux/fs.h>
#include <linux/nls.h>
#include <linux/workqueue.h>
#include <linux/cdev.h>
#include <linux/hyperv.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/miscdevice.h>

#include "hyperv_vmbus.h"

#define WIN8_SRV_MAJOR		1
#define WIN8_SRV_MINOR		1
#define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)

/*
 * Global state maintained for transaction that is being processed.
 * For a class of integration services, including the "file copy service",
 * the specified protocol is a "request/response" protocol which means that
 * there can only be single outstanding transaction from the host at any
 * given point in time. We use this to simplify memory management in this
 * driver - we cache and process only one message at a time.
 *
 * While the request/response protocol is guaranteed by the host, we further
 * ensure this by serializing packet processing in this driver - we do not
 * read additional packets from the VMBUs until the current packet is fully
 * handled.
 *
 * The transaction "active" state is set when we receive a request from the
 * host and we cleanup this state when the transaction is completed - when we
 * respond to the host with our response. When the transaction active state is
 * set, we defer handling incoming packets.
 */

static struct {
	bool active; /* transaction status - active or not */
	int recv_len; /* number of bytes received. */
	struct hv_fcopy_hdr  *fcopy_msg; /* current message */
	struct hv_start_fcopy  message; /*  sent to daemon */
	struct vmbus_channel *recv_channel; /* chn we got the request */
	u64 recv_req_id; /* request ID. */
	void *fcopy_context; /* for the channel callback */
	struct semaphore read_sema;
} fcopy_transaction;

static bool opened; /* currently device opened */

/*
 * Before we can accept copy messages from the host, we need
 * to handshake with the user level daemon. This state tracks
 * if we are in the handshake phase.
 */
static bool in_hand_shake = true;
static void fcopy_send_data(void);
static void fcopy_respond_to_host(int error);
static void fcopy_work_func(struct work_struct *dummy);
static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
static u8 *recv_buffer;

static void fcopy_work_func(struct work_struct *dummy)
{
	/*
	 * If the timer fires, the user-mode component has not responded;
	 * process the pending transaction.
	 */
	fcopy_respond_to_host(HV_E_FAIL);
}

static int fcopy_handle_handshake(u32 version)
{
	switch (version) {
	case FCOPY_CURRENT_VERSION:
		break;
	default:
		/*
		 * For now we will fail the registration.
		 * If and when we have multiple versions to
		 * deal with, we will be backward compatible.
		 * We will add this code when needed.
		 */
		return -EINVAL;
	}
	pr_info("FCP: user-mode registering done. Daemon version: %d\n",
		version);
	fcopy_transaction.active = false;
	if (fcopy_transaction.fcopy_context)
		hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
	in_hand_shake = false;
	return 0;
}

static void fcopy_send_data(void)
{
	struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
	int operation = fcopy_transaction.fcopy_msg->operation;
	struct hv_start_fcopy *smsg_in;

	/*
	 * The  strings sent from the host are encoded in
	 * in utf16; convert it to utf8 strings.
	 * The host assures us that the utf16 strings will not exceed
	 * the max lengths specified. We will however, reserve room
	 * for the string terminating character - in the utf16s_utf8s()
	 * function we limit the size of the buffer where the converted
	 * string is placed to W_MAX_PATH -1 to guarantee
	 * that the strings can be properly terminated!
	 */

	switch (operation) {
	case START_FILE_COPY:
		memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
		smsg_out->hdr.operation = operation;
		smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;

		utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)smsg_out->file_name, W_MAX_PATH - 1);

		utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)smsg_out->path_name, W_MAX_PATH - 1);

		smsg_out->copy_flags = smsg_in->copy_flags;
		smsg_out->file_size = smsg_in->file_size;
		break;

	default:
		break;
	}
	up(&fcopy_transaction.read_sema);
	return;
}

/*
 * Send a response back to the host.
 */

static void
fcopy_respond_to_host(int error)
{
	struct icmsg_hdr *icmsghdr;
	u32 buf_len;
	struct vmbus_channel *channel;
	u64 req_id;

	/*
	 * Copy the global state for completing the transaction. Note that
	 * only one transaction can be active at a time. This is guaranteed
	 * by the file copy protocol implemented by the host. Furthermore,
	 * the "transaction active" state we maintain ensures that there can
	 * only be one active transaction at a time.
	 */

	buf_len = fcopy_transaction.recv_len;
	channel = fcopy_transaction.recv_channel;
	req_id = fcopy_transaction.recv_req_id;

	fcopy_transaction.active = false;

	icmsghdr = (struct icmsg_hdr *)
			&recv_buffer[sizeof(struct vmbuspipe_hdr)];

	if (channel->onchannel_callback == NULL)
		/*
		 * We have raced with util driver being unloaded;
		 * silently return.
		 */
		return;

	icmsghdr->status = error;
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
	vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
				VM_PKT_DATA_INBAND, 0);
}

void hv_fcopy_onchannelcallback(void *context)
{
	struct vmbus_channel *channel = context;
	u32 recvlen;
	u64 requestid;
	struct hv_fcopy_hdr *fcopy_msg;
	struct icmsg_hdr *icmsghdr;
	struct icmsg_negotiate *negop = NULL;
	int util_fw_version;
	int fcopy_srv_version;

	if (fcopy_transaction.active) {
		/*
		 * We will defer processing this callback once
		 * the current transaction is complete.
		 */
		fcopy_transaction.fcopy_context = context;
		return;
	}

	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
			 &requestid);
	if (recvlen <= 0)
		return;

	icmsghdr = (struct icmsg_hdr *)&recv_buffer[
			sizeof(struct vmbuspipe_hdr)];
	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
		util_fw_version = UTIL_FW_VERSION;
		fcopy_srv_version = WIN8_SRV_VERSION;
		vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
				util_fw_version, fcopy_srv_version);
	} else {
		fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
				sizeof(struct vmbuspipe_hdr) +
				sizeof(struct icmsg_hdr)];

		/*
		 * Stash away this global state for completing the
		 * transaction; note transactions are serialized.
		 */

		fcopy_transaction.active = true;
		fcopy_transaction.recv_len = recvlen;
		fcopy_transaction.recv_channel = channel;
		fcopy_transaction.recv_req_id = requestid;
		fcopy_transaction.fcopy_msg = fcopy_msg;

		/*
		 * Send the information to the user-level daemon.
		 */
		schedule_delayed_work(&fcopy_work, 5*HZ);
		fcopy_send_data();
		return;
	}
	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
			VM_PKT_DATA_INBAND, 0);
}

/*
 * Create a char device that can support read/write for passing
 * the payload.
 */

static ssize_t fcopy_read(struct file *file, char __user *buf,
		size_t count, loff_t *ppos)
{
	void *src;
	size_t copy_size;
	int operation;

	/*
	 * Wait until there is something to be read.
	 */
	if (down_interruptible(&fcopy_transaction.read_sema))
		return -EINTR;

	/*
	 * The channel may be rescinded and in this case, we will wakeup the
	 * the thread blocked on the semaphore and we will use the opened
	 * state to correctly handle this case.
	 */
	if (!opened)
		return -ENODEV;

	operation = fcopy_transaction.fcopy_msg->operation;

	if (operation == START_FILE_COPY) {
		src = &fcopy_transaction.message;
		copy_size = sizeof(struct hv_start_fcopy);
		if (count < copy_size)
			return 0;
	} else {
		src = fcopy_transaction.fcopy_msg;
		copy_size = sizeof(struct hv_do_fcopy);
		if (count < copy_size)
			return 0;
	}
	if (copy_to_user(buf, src, copy_size))
		return -EFAULT;

	return copy_size;
}

static ssize_t fcopy_write(struct file *file, const char __user *buf,
			size_t count, loff_t *ppos)
{
	int response = 0;

	if (count != sizeof(int))
		return -EINVAL;

	if (copy_from_user(&response, buf, sizeof(int)))
		return -EFAULT;

	if (in_hand_shake) {
		if (fcopy_handle_handshake(response))
			return -EINVAL;
		return sizeof(int);
	}

	/*
	 * Complete the transaction by forwarding the result
	 * to the host. But first, cancel the timeout.
	 */
	if (cancel_delayed_work_sync(&fcopy_work))
		fcopy_respond_to_host(response);

	return sizeof(int);
}

static int fcopy_open(struct inode *inode, struct file *f)
{
	/*
	 * The user level daemon that will open this device is
	 * really an extension of this driver. We can have only
	 * active open at a time.
	 */
	if (opened)
		return -EBUSY;

	/*
	 * The daemon is alive; setup the state.
	 */
	opened = true;
	return 0;
}

static int fcopy_release(struct inode *inode, struct file *f)
{
	/*
	 * The daemon has exited; reset the state.
	 */
	in_hand_shake = true;
	opened = false;
	return 0;
}


static const struct file_operations fcopy_fops = {
	.read           = fcopy_read,
	.write          = fcopy_write,
	.release	= fcopy_release,
	.open		= fcopy_open,
};

static struct miscdevice fcopy_misc = {
	.minor          = MISC_DYNAMIC_MINOR,
	.name           = "vmbus/hv_fcopy",
	.fops           = &fcopy_fops,
};

static int fcopy_dev_init(void)
{
	return misc_register(&fcopy_misc);
}

static void fcopy_dev_deinit(void)
{

	/*
	 * The device is going away - perhaps because the
	 * host has rescinded the channel. Setup state so that
	 * user level daemon can gracefully exit if it is blocked
	 * on the read semaphore.
	 */
	opened = false;
	/*
	 * Signal the semaphore as the device is
	 * going away.
	 */
	up(&fcopy_transaction.read_sema);
	misc_deregister(&fcopy_misc);
}

int hv_fcopy_init(struct hv_util_service *srv)
{
	recv_buffer = srv->recv_buffer;

	/*
	 * When this driver loads, the user level daemon that
	 * processes the host requests may not yet be running.
	 * Defer processing channel callbacks until the daemon
	 * has registered.
	 */
	fcopy_transaction.active = true;
	sema_init(&fcopy_transaction.read_sema, 0);

	return fcopy_dev_init();
}

void hv_fcopy_deinit(void)
{
	cancel_delayed_work_sync(&fcopy_work);
	fcopy_dev_deinit();
}