xref: /linux/drivers/hv/channel.c (revision 861e10be08c69808065d755d3e3cab5d520a2d32)
1 /*
2  * Copyright (c) 2009, 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  * You should have received a copy of the GNU General Public License along with
14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
15  * Place - Suite 330, Boston, MA 02111-1307 USA.
16  *
17  * Authors:
18  *   Haiyang Zhang <haiyangz@microsoft.com>
19  *   Hank Janssen  <hjanssen@microsoft.com>
20  */
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 
23 #include <linux/kernel.h>
24 #include <linux/sched.h>
25 #include <linux/wait.h>
26 #include <linux/mm.h>
27 #include <linux/slab.h>
28 #include <linux/module.h>
29 #include <linux/hyperv.h>
30 
31 #include "hyperv_vmbus.h"
32 
33 #define NUM_PAGES_SPANNED(addr, len) \
34 ((PAGE_ALIGN(addr + len) >> PAGE_SHIFT) - (addr >> PAGE_SHIFT))
35 
36 /*
37  * vmbus_setevent- Trigger an event notification on the specified
38  * channel.
39  */
40 static void vmbus_setevent(struct vmbus_channel *channel)
41 {
42 	struct hv_monitor_page *monitorpage;
43 
44 	if (channel->offermsg.monitor_allocated) {
45 		/* Each u32 represents 32 channels */
46 		sync_set_bit(channel->offermsg.child_relid & 31,
47 			(unsigned long *) vmbus_connection.send_int_page +
48 			(channel->offermsg.child_relid >> 5));
49 
50 		monitorpage = vmbus_connection.monitor_pages;
51 		monitorpage++; /* Get the child to parent monitor page */
52 
53 		sync_set_bit(channel->monitor_bit,
54 			(unsigned long *)&monitorpage->trigger_group
55 					[channel->monitor_grp].pending);
56 
57 	} else {
58 		vmbus_set_event(channel->offermsg.child_relid);
59 	}
60 }
61 
62 /*
63  * vmbus_get_debug_info -Retrieve various channel debug info
64  */
65 void vmbus_get_debug_info(struct vmbus_channel *channel,
66 			      struct vmbus_channel_debug_info *debuginfo)
67 {
68 	struct hv_monitor_page *monitorpage;
69 	u8 monitor_group = (u8)channel->offermsg.monitorid / 32;
70 	u8 monitor_offset = (u8)channel->offermsg.monitorid % 32;
71 
72 	debuginfo->relid = channel->offermsg.child_relid;
73 	debuginfo->state = channel->state;
74 	memcpy(&debuginfo->interfacetype,
75 	       &channel->offermsg.offer.if_type, sizeof(uuid_le));
76 	memcpy(&debuginfo->interface_instance,
77 	       &channel->offermsg.offer.if_instance,
78 	       sizeof(uuid_le));
79 
80 	monitorpage = (struct hv_monitor_page *)vmbus_connection.monitor_pages;
81 
82 	debuginfo->monitorid = channel->offermsg.monitorid;
83 
84 	debuginfo->servermonitor_pending =
85 			monitorpage->trigger_group[monitor_group].pending;
86 	debuginfo->servermonitor_latency =
87 			monitorpage->latency[monitor_group][monitor_offset];
88 	debuginfo->servermonitor_connectionid =
89 			monitorpage->parameter[monitor_group]
90 					[monitor_offset].connectionid.u.id;
91 
92 	monitorpage++;
93 
94 	debuginfo->clientmonitor_pending =
95 			monitorpage->trigger_group[monitor_group].pending;
96 	debuginfo->clientmonitor_latency =
97 			monitorpage->latency[monitor_group][monitor_offset];
98 	debuginfo->clientmonitor_connectionid =
99 			monitorpage->parameter[monitor_group]
100 					[monitor_offset].connectionid.u.id;
101 
102 	hv_ringbuffer_get_debuginfo(&channel->inbound, &debuginfo->inbound);
103 	hv_ringbuffer_get_debuginfo(&channel->outbound, &debuginfo->outbound);
104 }
105 
106 /*
107  * vmbus_open - Open the specified channel.
108  */
109 int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
110 		     u32 recv_ringbuffer_size, void *userdata, u32 userdatalen,
111 		     void (*onchannelcallback)(void *context), void *context)
112 {
113 	struct vmbus_channel_open_channel *open_msg;
114 	struct vmbus_channel_msginfo *open_info = NULL;
115 	void *in, *out;
116 	unsigned long flags;
117 	int ret, t, err = 0;
118 
119 	newchannel->onchannel_callback = onchannelcallback;
120 	newchannel->channel_callback_context = context;
121 
122 	/* Allocate the ring buffer */
123 	out = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
124 		get_order(send_ringbuffer_size + recv_ringbuffer_size));
125 
126 	if (!out)
127 		return -ENOMEM;
128 
129 
130 	in = (void *)((unsigned long)out + send_ringbuffer_size);
131 
132 	newchannel->ringbuffer_pages = out;
133 	newchannel->ringbuffer_pagecount = (send_ringbuffer_size +
134 					   recv_ringbuffer_size) >> PAGE_SHIFT;
135 
136 	ret = hv_ringbuffer_init(
137 		&newchannel->outbound, out, send_ringbuffer_size);
138 
139 	if (ret != 0) {
140 		err = ret;
141 		goto error0;
142 	}
143 
144 	ret = hv_ringbuffer_init(
145 		&newchannel->inbound, in, recv_ringbuffer_size);
146 	if (ret != 0) {
147 		err = ret;
148 		goto error0;
149 	}
150 
151 
152 	/* Establish the gpadl for the ring buffer */
153 	newchannel->ringbuffer_gpadlhandle = 0;
154 
155 	ret = vmbus_establish_gpadl(newchannel,
156 					 newchannel->outbound.ring_buffer,
157 					 send_ringbuffer_size +
158 					 recv_ringbuffer_size,
159 					 &newchannel->ringbuffer_gpadlhandle);
160 
161 	if (ret != 0) {
162 		err = ret;
163 		goto error0;
164 	}
165 
166 	/* Create and init the channel open message */
167 	open_info = kmalloc(sizeof(*open_info) +
168 			   sizeof(struct vmbus_channel_open_channel),
169 			   GFP_KERNEL);
170 	if (!open_info) {
171 		err = -ENOMEM;
172 		goto error0;
173 	}
174 
175 	init_completion(&open_info->waitevent);
176 
177 	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
178 	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
179 	open_msg->openid = newchannel->offermsg.child_relid;
180 	open_msg->child_relid = newchannel->offermsg.child_relid;
181 	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
182 	open_msg->downstream_ringbuffer_pageoffset = send_ringbuffer_size >>
183 						  PAGE_SHIFT;
184 	open_msg->server_contextarea_gpadlhandle = 0;
185 
186 	if (userdatalen > MAX_USER_DEFINED_BYTES) {
187 		err = -EINVAL;
188 		goto error0;
189 	}
190 
191 	if (userdatalen)
192 		memcpy(open_msg->userdata, userdata, userdatalen);
193 
194 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
195 	list_add_tail(&open_info->msglistentry,
196 		      &vmbus_connection.chn_msg_list);
197 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
198 
199 	ret = vmbus_post_msg(open_msg,
200 			       sizeof(struct vmbus_channel_open_channel));
201 
202 	if (ret != 0)
203 		goto error1;
204 
205 	t = wait_for_completion_timeout(&open_info->waitevent, 5*HZ);
206 	if (t == 0) {
207 		err = -ETIMEDOUT;
208 		goto error1;
209 	}
210 
211 
212 	if (open_info->response.open_result.status)
213 		err = open_info->response.open_result.status;
214 
215 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
216 	list_del(&open_info->msglistentry);
217 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
218 
219 	kfree(open_info);
220 	return err;
221 
222 error1:
223 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
224 	list_del(&open_info->msglistentry);
225 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
226 
227 error0:
228 	free_pages((unsigned long)out,
229 		get_order(send_ringbuffer_size + recv_ringbuffer_size));
230 	kfree(open_info);
231 	return err;
232 }
233 EXPORT_SYMBOL_GPL(vmbus_open);
234 
235 /*
236  * create_gpadl_header - Creates a gpadl for the specified buffer
237  */
238 static int create_gpadl_header(void *kbuffer, u32 size,
239 					 struct vmbus_channel_msginfo **msginfo,
240 					 u32 *messagecount)
241 {
242 	int i;
243 	int pagecount;
244 	unsigned long long pfn;
245 	struct vmbus_channel_gpadl_header *gpadl_header;
246 	struct vmbus_channel_gpadl_body *gpadl_body;
247 	struct vmbus_channel_msginfo *msgheader;
248 	struct vmbus_channel_msginfo *msgbody = NULL;
249 	u32 msgsize;
250 
251 	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
252 
253 	pagecount = size >> PAGE_SHIFT;
254 	pfn = virt_to_phys(kbuffer) >> PAGE_SHIFT;
255 
256 	/* do we need a gpadl body msg */
257 	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
258 		  sizeof(struct vmbus_channel_gpadl_header) -
259 		  sizeof(struct gpa_range);
260 	pfncount = pfnsize / sizeof(u64);
261 
262 	if (pagecount > pfncount) {
263 		/* we need a gpadl body */
264 		/* fill in the header */
265 		msgsize = sizeof(struct vmbus_channel_msginfo) +
266 			  sizeof(struct vmbus_channel_gpadl_header) +
267 			  sizeof(struct gpa_range) + pfncount * sizeof(u64);
268 		msgheader =  kzalloc(msgsize, GFP_KERNEL);
269 		if (!msgheader)
270 			goto nomem;
271 
272 		INIT_LIST_HEAD(&msgheader->submsglist);
273 		msgheader->msgsize = msgsize;
274 
275 		gpadl_header = (struct vmbus_channel_gpadl_header *)
276 			msgheader->msg;
277 		gpadl_header->rangecount = 1;
278 		gpadl_header->range_buflen = sizeof(struct gpa_range) +
279 					 pagecount * sizeof(u64);
280 		gpadl_header->range[0].byte_offset = 0;
281 		gpadl_header->range[0].byte_count = size;
282 		for (i = 0; i < pfncount; i++)
283 			gpadl_header->range[0].pfn_array[i] = pfn+i;
284 		*msginfo = msgheader;
285 		*messagecount = 1;
286 
287 		pfnsum = pfncount;
288 		pfnleft = pagecount - pfncount;
289 
290 		/* how many pfns can we fit */
291 		pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
292 			  sizeof(struct vmbus_channel_gpadl_body);
293 		pfncount = pfnsize / sizeof(u64);
294 
295 		/* fill in the body */
296 		while (pfnleft) {
297 			if (pfnleft > pfncount)
298 				pfncurr = pfncount;
299 			else
300 				pfncurr = pfnleft;
301 
302 			msgsize = sizeof(struct vmbus_channel_msginfo) +
303 				  sizeof(struct vmbus_channel_gpadl_body) +
304 				  pfncurr * sizeof(u64);
305 			msgbody = kzalloc(msgsize, GFP_KERNEL);
306 
307 			if (!msgbody) {
308 				struct vmbus_channel_msginfo *pos = NULL;
309 				struct vmbus_channel_msginfo *tmp = NULL;
310 				/*
311 				 * Free up all the allocated messages.
312 				 */
313 				list_for_each_entry_safe(pos, tmp,
314 					&msgheader->submsglist,
315 					msglistentry) {
316 
317 					list_del(&pos->msglistentry);
318 					kfree(pos);
319 				}
320 
321 				goto nomem;
322 			}
323 
324 			msgbody->msgsize = msgsize;
325 			(*messagecount)++;
326 			gpadl_body =
327 				(struct vmbus_channel_gpadl_body *)msgbody->msg;
328 
329 			/*
330 			 * Gpadl is u32 and we are using a pointer which could
331 			 * be 64-bit
332 			 * This is governed by the guest/host protocol and
333 			 * so the hypervisor gurantees that this is ok.
334 			 */
335 			for (i = 0; i < pfncurr; i++)
336 				gpadl_body->pfn[i] = pfn + pfnsum + i;
337 
338 			/* add to msg header */
339 			list_add_tail(&msgbody->msglistentry,
340 				      &msgheader->submsglist);
341 			pfnsum += pfncurr;
342 			pfnleft -= pfncurr;
343 		}
344 	} else {
345 		/* everything fits in a header */
346 		msgsize = sizeof(struct vmbus_channel_msginfo) +
347 			  sizeof(struct vmbus_channel_gpadl_header) +
348 			  sizeof(struct gpa_range) + pagecount * sizeof(u64);
349 		msgheader = kzalloc(msgsize, GFP_KERNEL);
350 		if (msgheader == NULL)
351 			goto nomem;
352 		msgheader->msgsize = msgsize;
353 
354 		gpadl_header = (struct vmbus_channel_gpadl_header *)
355 			msgheader->msg;
356 		gpadl_header->rangecount = 1;
357 		gpadl_header->range_buflen = sizeof(struct gpa_range) +
358 					 pagecount * sizeof(u64);
359 		gpadl_header->range[0].byte_offset = 0;
360 		gpadl_header->range[0].byte_count = size;
361 		for (i = 0; i < pagecount; i++)
362 			gpadl_header->range[0].pfn_array[i] = pfn+i;
363 
364 		*msginfo = msgheader;
365 		*messagecount = 1;
366 	}
367 
368 	return 0;
369 nomem:
370 	kfree(msgheader);
371 	kfree(msgbody);
372 	return -ENOMEM;
373 }
374 
375 /*
376  * vmbus_establish_gpadl - Estabish a GPADL for the specified buffer
377  *
378  * @channel: a channel
379  * @kbuffer: from kmalloc
380  * @size: page-size multiple
381  * @gpadl_handle: some funky thing
382  */
383 int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
384 			       u32 size, u32 *gpadl_handle)
385 {
386 	struct vmbus_channel_gpadl_header *gpadlmsg;
387 	struct vmbus_channel_gpadl_body *gpadl_body;
388 	struct vmbus_channel_msginfo *msginfo = NULL;
389 	struct vmbus_channel_msginfo *submsginfo;
390 	u32 msgcount;
391 	struct list_head *curr;
392 	u32 next_gpadl_handle;
393 	unsigned long flags;
394 	int ret = 0;
395 	int t;
396 
397 	next_gpadl_handle = atomic_read(&vmbus_connection.next_gpadl_handle);
398 	atomic_inc(&vmbus_connection.next_gpadl_handle);
399 
400 	ret = create_gpadl_header(kbuffer, size, &msginfo, &msgcount);
401 	if (ret)
402 		return ret;
403 
404 	init_completion(&msginfo->waitevent);
405 
406 	gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
407 	gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
408 	gpadlmsg->child_relid = channel->offermsg.child_relid;
409 	gpadlmsg->gpadl = next_gpadl_handle;
410 
411 
412 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
413 	list_add_tail(&msginfo->msglistentry,
414 		      &vmbus_connection.chn_msg_list);
415 
416 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
417 
418 	ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
419 			       sizeof(*msginfo));
420 	if (ret != 0)
421 		goto cleanup;
422 
423 	if (msgcount > 1) {
424 		list_for_each(curr, &msginfo->submsglist) {
425 
426 			submsginfo = (struct vmbus_channel_msginfo *)curr;
427 			gpadl_body =
428 			     (struct vmbus_channel_gpadl_body *)submsginfo->msg;
429 
430 			gpadl_body->header.msgtype =
431 				CHANNELMSG_GPADL_BODY;
432 			gpadl_body->gpadl = next_gpadl_handle;
433 
434 			ret = vmbus_post_msg(gpadl_body,
435 					       submsginfo->msgsize -
436 					       sizeof(*submsginfo));
437 			if (ret != 0)
438 				goto cleanup;
439 
440 		}
441 	}
442 	t = wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
443 	BUG_ON(t == 0);
444 
445 
446 	/* At this point, we received the gpadl created msg */
447 	*gpadl_handle = gpadlmsg->gpadl;
448 
449 cleanup:
450 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
451 	list_del(&msginfo->msglistentry);
452 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
453 
454 	kfree(msginfo);
455 	return ret;
456 }
457 EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
458 
459 /*
460  * vmbus_teardown_gpadl -Teardown the specified GPADL handle
461  */
462 int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
463 {
464 	struct vmbus_channel_gpadl_teardown *msg;
465 	struct vmbus_channel_msginfo *info;
466 	unsigned long flags;
467 	int ret, t;
468 
469 	info = kmalloc(sizeof(*info) +
470 		       sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
471 	if (!info)
472 		return -ENOMEM;
473 
474 	init_completion(&info->waitevent);
475 
476 	msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
477 
478 	msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
479 	msg->child_relid = channel->offermsg.child_relid;
480 	msg->gpadl = gpadl_handle;
481 
482 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
483 	list_add_tail(&info->msglistentry,
484 		      &vmbus_connection.chn_msg_list);
485 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
486 	ret = vmbus_post_msg(msg,
487 			       sizeof(struct vmbus_channel_gpadl_teardown));
488 
489 	BUG_ON(ret != 0);
490 	t = wait_for_completion_timeout(&info->waitevent, 5*HZ);
491 	BUG_ON(t == 0);
492 
493 	/* Received a torndown response */
494 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
495 	list_del(&info->msglistentry);
496 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
497 
498 	kfree(info);
499 	return ret;
500 }
501 EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
502 
503 /*
504  * vmbus_close - Close the specified channel
505  */
506 void vmbus_close(struct vmbus_channel *channel)
507 {
508 	struct vmbus_channel_close_channel *msg;
509 	int ret;
510 	unsigned long flags;
511 
512 	/* Stop callback and cancel the timer asap */
513 	spin_lock_irqsave(&channel->inbound_lock, flags);
514 	channel->onchannel_callback = NULL;
515 	spin_unlock_irqrestore(&channel->inbound_lock, flags);
516 
517 	/* Send a closing message */
518 
519 	msg = &channel->close_msg.msg;
520 
521 	msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
522 	msg->child_relid = channel->offermsg.child_relid;
523 
524 	ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel));
525 
526 	BUG_ON(ret != 0);
527 	/* Tear down the gpadl for the channel's ring buffer */
528 	if (channel->ringbuffer_gpadlhandle)
529 		vmbus_teardown_gpadl(channel,
530 					  channel->ringbuffer_gpadlhandle);
531 
532 	/* Cleanup the ring buffers for this channel */
533 	hv_ringbuffer_cleanup(&channel->outbound);
534 	hv_ringbuffer_cleanup(&channel->inbound);
535 
536 	free_pages((unsigned long)channel->ringbuffer_pages,
537 		get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
538 
539 
540 }
541 EXPORT_SYMBOL_GPL(vmbus_close);
542 
543 /**
544  * vmbus_sendpacket() - Send the specified buffer on the given channel
545  * @channel: Pointer to vmbus_channel structure.
546  * @buffer: Pointer to the buffer you want to receive the data into.
547  * @bufferlen: Maximum size of what the the buffer will hold
548  * @requestid: Identifier of the request
549  * @type: Type of packet that is being send e.g. negotiate, time
550  * packet etc.
551  *
552  * Sends data in @buffer directly to hyper-v via the vmbus
553  * This will send the data unparsed to hyper-v.
554  *
555  * Mainly used by Hyper-V drivers.
556  */
557 int vmbus_sendpacket(struct vmbus_channel *channel, const void *buffer,
558 			   u32 bufferlen, u64 requestid,
559 			   enum vmbus_packet_type type, u32 flags)
560 {
561 	struct vmpacket_descriptor desc;
562 	u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
563 	u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
564 	struct scatterlist bufferlist[3];
565 	u64 aligned_data = 0;
566 	int ret;
567 
568 
569 	/* Setup the descriptor */
570 	desc.type = type; /* VmbusPacketTypeDataInBand; */
571 	desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
572 	/* in 8-bytes granularity */
573 	desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
574 	desc.len8 = (u16)(packetlen_aligned >> 3);
575 	desc.trans_id = requestid;
576 
577 	sg_init_table(bufferlist, 3);
578 	sg_set_buf(&bufferlist[0], &desc, sizeof(struct vmpacket_descriptor));
579 	sg_set_buf(&bufferlist[1], buffer, bufferlen);
580 	sg_set_buf(&bufferlist[2], &aligned_data,
581 		   packetlen_aligned - packetlen);
582 
583 	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3);
584 
585 	if (ret == 0 && !hv_get_ringbuffer_interrupt_mask(&channel->outbound))
586 		vmbus_setevent(channel);
587 
588 	return ret;
589 }
590 EXPORT_SYMBOL(vmbus_sendpacket);
591 
592 /*
593  * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
594  * packets using a GPADL Direct packet type.
595  */
596 int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
597 				     struct hv_page_buffer pagebuffers[],
598 				     u32 pagecount, void *buffer, u32 bufferlen,
599 				     u64 requestid)
600 {
601 	int ret;
602 	int i;
603 	struct vmbus_channel_packet_page_buffer desc;
604 	u32 descsize;
605 	u32 packetlen;
606 	u32 packetlen_aligned;
607 	struct scatterlist bufferlist[3];
608 	u64 aligned_data = 0;
609 
610 	if (pagecount > MAX_PAGE_BUFFER_COUNT)
611 		return -EINVAL;
612 
613 
614 	/*
615 	 * Adjust the size down since vmbus_channel_packet_page_buffer is the
616 	 * largest size we support
617 	 */
618 	descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
619 			  ((MAX_PAGE_BUFFER_COUNT - pagecount) *
620 			  sizeof(struct hv_page_buffer));
621 	packetlen = descsize + bufferlen;
622 	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
623 
624 	/* Setup the descriptor */
625 	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
626 	desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
627 	desc.dataoffset8 = descsize >> 3; /* in 8-bytes grandularity */
628 	desc.length8 = (u16)(packetlen_aligned >> 3);
629 	desc.transactionid = requestid;
630 	desc.rangecount = pagecount;
631 
632 	for (i = 0; i < pagecount; i++) {
633 		desc.range[i].len = pagebuffers[i].len;
634 		desc.range[i].offset = pagebuffers[i].offset;
635 		desc.range[i].pfn	 = pagebuffers[i].pfn;
636 	}
637 
638 	sg_init_table(bufferlist, 3);
639 	sg_set_buf(&bufferlist[0], &desc, descsize);
640 	sg_set_buf(&bufferlist[1], buffer, bufferlen);
641 	sg_set_buf(&bufferlist[2], &aligned_data,
642 		packetlen_aligned - packetlen);
643 
644 	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3);
645 
646 	if (ret == 0 && !hv_get_ringbuffer_interrupt_mask(&channel->outbound))
647 		vmbus_setevent(channel);
648 
649 	return ret;
650 }
651 EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
652 
653 /*
654  * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
655  * using a GPADL Direct packet type.
656  */
657 int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
658 				struct hv_multipage_buffer *multi_pagebuffer,
659 				void *buffer, u32 bufferlen, u64 requestid)
660 {
661 	int ret;
662 	struct vmbus_channel_packet_multipage_buffer desc;
663 	u32 descsize;
664 	u32 packetlen;
665 	u32 packetlen_aligned;
666 	struct scatterlist bufferlist[3];
667 	u64 aligned_data = 0;
668 	u32 pfncount = NUM_PAGES_SPANNED(multi_pagebuffer->offset,
669 					 multi_pagebuffer->len);
670 
671 
672 	if ((pfncount < 0) || (pfncount > MAX_MULTIPAGE_BUFFER_COUNT))
673 		return -EINVAL;
674 
675 	/*
676 	 * Adjust the size down since vmbus_channel_packet_multipage_buffer is
677 	 * the largest size we support
678 	 */
679 	descsize = sizeof(struct vmbus_channel_packet_multipage_buffer) -
680 			  ((MAX_MULTIPAGE_BUFFER_COUNT - pfncount) *
681 			  sizeof(u64));
682 	packetlen = descsize + bufferlen;
683 	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
684 
685 
686 	/* Setup the descriptor */
687 	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
688 	desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
689 	desc.dataoffset8 = descsize >> 3; /* in 8-bytes grandularity */
690 	desc.length8 = (u16)(packetlen_aligned >> 3);
691 	desc.transactionid = requestid;
692 	desc.rangecount = 1;
693 
694 	desc.range.len = multi_pagebuffer->len;
695 	desc.range.offset = multi_pagebuffer->offset;
696 
697 	memcpy(desc.range.pfn_array, multi_pagebuffer->pfn_array,
698 	       pfncount * sizeof(u64));
699 
700 	sg_init_table(bufferlist, 3);
701 	sg_set_buf(&bufferlist[0], &desc, descsize);
702 	sg_set_buf(&bufferlist[1], buffer, bufferlen);
703 	sg_set_buf(&bufferlist[2], &aligned_data,
704 		packetlen_aligned - packetlen);
705 
706 	ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3);
707 
708 	if (ret == 0 && !hv_get_ringbuffer_interrupt_mask(&channel->outbound))
709 		vmbus_setevent(channel);
710 
711 	return ret;
712 }
713 EXPORT_SYMBOL_GPL(vmbus_sendpacket_multipagebuffer);
714 
715 /**
716  * vmbus_recvpacket() - Retrieve the user packet on the specified channel
717  * @channel: Pointer to vmbus_channel structure.
718  * @buffer: Pointer to the buffer you want to receive the data into.
719  * @bufferlen: Maximum size of what the the buffer will hold
720  * @buffer_actual_len: The actual size of the data after it was received
721  * @requestid: Identifier of the request
722  *
723  * Receives directly from the hyper-v vmbus and puts the data it received
724  * into Buffer. This will receive the data unparsed from hyper-v.
725  *
726  * Mainly used by Hyper-V drivers.
727  */
728 int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
729 			u32 bufferlen, u32 *buffer_actual_len, u64 *requestid)
730 {
731 	struct vmpacket_descriptor desc;
732 	u32 packetlen;
733 	u32 userlen;
734 	int ret;
735 
736 	*buffer_actual_len = 0;
737 	*requestid = 0;
738 
739 
740 	ret = hv_ringbuffer_peek(&channel->inbound, &desc,
741 			     sizeof(struct vmpacket_descriptor));
742 	if (ret != 0)
743 		return 0;
744 
745 	packetlen = desc.len8 << 3;
746 	userlen = packetlen - (desc.offset8 << 3);
747 
748 	*buffer_actual_len = userlen;
749 
750 	if (userlen > bufferlen) {
751 
752 		pr_err("Buffer too small - got %d needs %d\n",
753 			   bufferlen, userlen);
754 		return -ETOOSMALL;
755 	}
756 
757 	*requestid = desc.trans_id;
758 
759 	/* Copy over the packet to the user buffer */
760 	ret = hv_ringbuffer_read(&channel->inbound, buffer, userlen,
761 			     (desc.offset8 << 3));
762 
763 
764 	return 0;
765 }
766 EXPORT_SYMBOL(vmbus_recvpacket);
767 
768 /*
769  * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
770  */
771 int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
772 			      u32 bufferlen, u32 *buffer_actual_len,
773 			      u64 *requestid)
774 {
775 	struct vmpacket_descriptor desc;
776 	u32 packetlen;
777 	u32 userlen;
778 	int ret;
779 
780 	*buffer_actual_len = 0;
781 	*requestid = 0;
782 
783 
784 	ret = hv_ringbuffer_peek(&channel->inbound, &desc,
785 			     sizeof(struct vmpacket_descriptor));
786 	if (ret != 0)
787 		return 0;
788 
789 
790 	packetlen = desc.len8 << 3;
791 	userlen = packetlen - (desc.offset8 << 3);
792 
793 	*buffer_actual_len = packetlen;
794 
795 	if (packetlen > bufferlen) {
796 		pr_err("Buffer too small - needed %d bytes but "
797 			"got space for only %d bytes\n",
798 			packetlen, bufferlen);
799 		return -ENOBUFS;
800 	}
801 
802 	*requestid = desc.trans_id;
803 
804 	/* Copy over the entire packet to the user buffer */
805 	ret = hv_ringbuffer_read(&channel->inbound, buffer, packetlen, 0);
806 
807 	return 0;
808 }
809 EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
810