xref: /openbmc/linux/drivers/scsi/storvsc_drv.c (revision b96fc2f3)
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  *   K. Y. Srinivasan <kys@microsoft.com>
21  */
22 
23 #include <linux/kernel.h>
24 #include <linux/wait.h>
25 #include <linux/sched.h>
26 #include <linux/completion.h>
27 #include <linux/string.h>
28 #include <linux/mm.h>
29 #include <linux/delay.h>
30 #include <linux/init.h>
31 #include <linux/slab.h>
32 #include <linux/module.h>
33 #include <linux/device.h>
34 #include <linux/hyperv.h>
35 #include <linux/blkdev.h>
36 #include <scsi/scsi.h>
37 #include <scsi/scsi_cmnd.h>
38 #include <scsi/scsi_host.h>
39 #include <scsi/scsi_device.h>
40 #include <scsi/scsi_tcq.h>
41 #include <scsi/scsi_eh.h>
42 #include <scsi/scsi_devinfo.h>
43 #include <scsi/scsi_dbg.h>
44 
45 /*
46  * All wire protocol details (storage protocol between the guest and the host)
47  * are consolidated here.
48  *
49  * Begin protocol definitions.
50  */
51 
52 /*
53  * Version history:
54  * V1 Beta: 0.1
55  * V1 RC < 2008/1/31: 1.0
56  * V1 RC > 2008/1/31:  2.0
57  * Win7: 4.2
58  * Win8: 5.1
59  * Win8.1: 6.0
60  * Win10: 6.2
61  */
62 
63 #define VMSTOR_PROTO_VERSION(MAJOR_, MINOR_)	((((MAJOR_) & 0xff) << 8) | \
64 						(((MINOR_) & 0xff)))
65 
66 #define VMSTOR_PROTO_VERSION_WIN6	VMSTOR_PROTO_VERSION(2, 0)
67 #define VMSTOR_PROTO_VERSION_WIN7	VMSTOR_PROTO_VERSION(4, 2)
68 #define VMSTOR_PROTO_VERSION_WIN8	VMSTOR_PROTO_VERSION(5, 1)
69 #define VMSTOR_PROTO_VERSION_WIN8_1	VMSTOR_PROTO_VERSION(6, 0)
70 #define VMSTOR_PROTO_VERSION_WIN10	VMSTOR_PROTO_VERSION(6, 2)
71 
72 /*  Packet structure describing virtual storage requests. */
73 enum vstor_packet_operation {
74 	VSTOR_OPERATION_COMPLETE_IO		= 1,
75 	VSTOR_OPERATION_REMOVE_DEVICE		= 2,
76 	VSTOR_OPERATION_EXECUTE_SRB		= 3,
77 	VSTOR_OPERATION_RESET_LUN		= 4,
78 	VSTOR_OPERATION_RESET_ADAPTER		= 5,
79 	VSTOR_OPERATION_RESET_BUS		= 6,
80 	VSTOR_OPERATION_BEGIN_INITIALIZATION	= 7,
81 	VSTOR_OPERATION_END_INITIALIZATION	= 8,
82 	VSTOR_OPERATION_QUERY_PROTOCOL_VERSION	= 9,
83 	VSTOR_OPERATION_QUERY_PROPERTIES	= 10,
84 	VSTOR_OPERATION_ENUMERATE_BUS		= 11,
85 	VSTOR_OPERATION_FCHBA_DATA              = 12,
86 	VSTOR_OPERATION_CREATE_SUB_CHANNELS     = 13,
87 	VSTOR_OPERATION_MAXIMUM                 = 13
88 };
89 
90 /*
91  * WWN packet for Fibre Channel HBA
92  */
93 
94 struct hv_fc_wwn_packet {
95 	bool	primary_active;
96 	u8	reserved1;
97 	u8	reserved2;
98 	u8	primary_port_wwn[8];
99 	u8	primary_node_wwn[8];
100 	u8	secondary_port_wwn[8];
101 	u8	secondary_node_wwn[8];
102 };
103 
104 
105 
106 /*
107  * SRB Flag Bits
108  */
109 
110 #define SRB_FLAGS_QUEUE_ACTION_ENABLE		0x00000002
111 #define SRB_FLAGS_DISABLE_DISCONNECT		0x00000004
112 #define SRB_FLAGS_DISABLE_SYNCH_TRANSFER	0x00000008
113 #define SRB_FLAGS_BYPASS_FROZEN_QUEUE		0x00000010
114 #define SRB_FLAGS_DISABLE_AUTOSENSE		0x00000020
115 #define SRB_FLAGS_DATA_IN			0x00000040
116 #define SRB_FLAGS_DATA_OUT			0x00000080
117 #define SRB_FLAGS_NO_DATA_TRANSFER		0x00000000
118 #define SRB_FLAGS_UNSPECIFIED_DIRECTION	(SRB_FLAGS_DATA_IN | SRB_FLAGS_DATA_OUT)
119 #define SRB_FLAGS_NO_QUEUE_FREEZE		0x00000100
120 #define SRB_FLAGS_ADAPTER_CACHE_ENABLE		0x00000200
121 #define SRB_FLAGS_FREE_SENSE_BUFFER		0x00000400
122 
123 /*
124  * This flag indicates the request is part of the workflow for processing a D3.
125  */
126 #define SRB_FLAGS_D3_PROCESSING			0x00000800
127 #define SRB_FLAGS_IS_ACTIVE			0x00010000
128 #define SRB_FLAGS_ALLOCATED_FROM_ZONE		0x00020000
129 #define SRB_FLAGS_SGLIST_FROM_POOL		0x00040000
130 #define SRB_FLAGS_BYPASS_LOCKED_QUEUE		0x00080000
131 #define SRB_FLAGS_NO_KEEP_AWAKE			0x00100000
132 #define SRB_FLAGS_PORT_DRIVER_ALLOCSENSE	0x00200000
133 #define SRB_FLAGS_PORT_DRIVER_SENSEHASPORT	0x00400000
134 #define SRB_FLAGS_DONT_START_NEXT_PACKET	0x00800000
135 #define SRB_FLAGS_PORT_DRIVER_RESERVED		0x0F000000
136 #define SRB_FLAGS_CLASS_DRIVER_RESERVED		0xF0000000
137 
138 
139 /*
140  * Platform neutral description of a scsi request -
141  * this remains the same across the write regardless of 32/64 bit
142  * note: it's patterned off the SCSI_PASS_THROUGH structure
143  */
144 #define STORVSC_MAX_CMD_LEN			0x10
145 
146 #define POST_WIN7_STORVSC_SENSE_BUFFER_SIZE	0x14
147 #define PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE	0x12
148 
149 #define STORVSC_SENSE_BUFFER_SIZE		0x14
150 #define STORVSC_MAX_BUF_LEN_WITH_PADDING	0x14
151 
152 /*
153  * Sense buffer size changed in win8; have a run-time
154  * variable to track the size we should use.  This value will
155  * likely change during protocol negotiation but it is valid
156  * to start by assuming pre-Win8.
157  */
158 static int sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
159 
160 /*
161  * The storage protocol version is determined during the
162  * initial exchange with the host.  It will indicate which
163  * storage functionality is available in the host.
164 */
165 static int vmstor_proto_version;
166 
167 struct vmscsi_win8_extension {
168 	/*
169 	 * The following were added in Windows 8
170 	 */
171 	u16 reserve;
172 	u8  queue_tag;
173 	u8  queue_action;
174 	u32 srb_flags;
175 	u32 time_out_value;
176 	u32 queue_sort_ey;
177 } __packed;
178 
179 struct vmscsi_request {
180 	u16 length;
181 	u8 srb_status;
182 	u8 scsi_status;
183 
184 	u8  port_number;
185 	u8  path_id;
186 	u8  target_id;
187 	u8  lun;
188 
189 	u8  cdb_length;
190 	u8  sense_info_length;
191 	u8  data_in;
192 	u8  reserved;
193 
194 	u32 data_transfer_length;
195 
196 	union {
197 		u8 cdb[STORVSC_MAX_CMD_LEN];
198 		u8 sense_data[STORVSC_SENSE_BUFFER_SIZE];
199 		u8 reserved_array[STORVSC_MAX_BUF_LEN_WITH_PADDING];
200 	};
201 	/*
202 	 * The following was added in win8.
203 	 */
204 	struct vmscsi_win8_extension win8_extension;
205 
206 } __attribute((packed));
207 
208 
209 /*
210  * The size of the vmscsi_request has changed in win8. The
211  * additional size is because of new elements added to the
212  * structure. These elements are valid only when we are talking
213  * to a win8 host.
214  * Track the correction to size we need to apply. This value
215  * will likely change during protocol negotiation but it is
216  * valid to start by assuming pre-Win8.
217  */
218 static int vmscsi_size_delta = sizeof(struct vmscsi_win8_extension);
219 
220 /*
221  * The list of storage protocols in order of preference.
222  */
223 struct vmstor_protocol {
224 	int protocol_version;
225 	int sense_buffer_size;
226 	int vmscsi_size_delta;
227 };
228 
229 
230 static const struct vmstor_protocol vmstor_protocols[] = {
231 	{
232 		VMSTOR_PROTO_VERSION_WIN10,
233 		POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
234 		0
235 	},
236 	{
237 		VMSTOR_PROTO_VERSION_WIN8_1,
238 		POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
239 		0
240 	},
241 	{
242 		VMSTOR_PROTO_VERSION_WIN8,
243 		POST_WIN7_STORVSC_SENSE_BUFFER_SIZE,
244 		0
245 	},
246 	{
247 		VMSTOR_PROTO_VERSION_WIN7,
248 		PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE,
249 		sizeof(struct vmscsi_win8_extension),
250 	},
251 	{
252 		VMSTOR_PROTO_VERSION_WIN6,
253 		PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE,
254 		sizeof(struct vmscsi_win8_extension),
255 	}
256 };
257 
258 
259 /*
260  * This structure is sent during the intialization phase to get the different
261  * properties of the channel.
262  */
263 
264 #define STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL		0x1
265 
266 struct vmstorage_channel_properties {
267 	u32 reserved;
268 	u16 max_channel_cnt;
269 	u16 reserved1;
270 
271 	u32 flags;
272 	u32   max_transfer_bytes;
273 
274 	u64  reserved2;
275 } __packed;
276 
277 /*  This structure is sent during the storage protocol negotiations. */
278 struct vmstorage_protocol_version {
279 	/* Major (MSW) and minor (LSW) version numbers. */
280 	u16 major_minor;
281 
282 	/*
283 	 * Revision number is auto-incremented whenever this file is changed
284 	 * (See FILL_VMSTOR_REVISION macro above).  Mismatch does not
285 	 * definitely indicate incompatibility--but it does indicate mismatched
286 	 * builds.
287 	 * This is only used on the windows side. Just set it to 0.
288 	 */
289 	u16 revision;
290 } __packed;
291 
292 /* Channel Property Flags */
293 #define STORAGE_CHANNEL_REMOVABLE_FLAG		0x1
294 #define STORAGE_CHANNEL_EMULATED_IDE_FLAG	0x2
295 
296 struct vstor_packet {
297 	/* Requested operation type */
298 	enum vstor_packet_operation operation;
299 
300 	/*  Flags - see below for values */
301 	u32 flags;
302 
303 	/* Status of the request returned from the server side. */
304 	u32 status;
305 
306 	/* Data payload area */
307 	union {
308 		/*
309 		 * Structure used to forward SCSI commands from the
310 		 * client to the server.
311 		 */
312 		struct vmscsi_request vm_srb;
313 
314 		/* Structure used to query channel properties. */
315 		struct vmstorage_channel_properties storage_channel_properties;
316 
317 		/* Used during version negotiations. */
318 		struct vmstorage_protocol_version version;
319 
320 		/* Fibre channel address packet */
321 		struct hv_fc_wwn_packet wwn_packet;
322 
323 		/* Number of sub-channels to create */
324 		u16 sub_channel_count;
325 
326 		/* This will be the maximum of the union members */
327 		u8  buffer[0x34];
328 	};
329 } __packed;
330 
331 /*
332  * Packet Flags:
333  *
334  * This flag indicates that the server should send back a completion for this
335  * packet.
336  */
337 
338 #define REQUEST_COMPLETION_FLAG	0x1
339 
340 /* Matches Windows-end */
341 enum storvsc_request_type {
342 	WRITE_TYPE = 0,
343 	READ_TYPE,
344 	UNKNOWN_TYPE,
345 };
346 
347 /*
348  * SRB status codes and masks; a subset of the codes used here.
349  */
350 
351 #define SRB_STATUS_AUTOSENSE_VALID	0x80
352 #define SRB_STATUS_INVALID_LUN	0x20
353 #define SRB_STATUS_SUCCESS	0x01
354 #define SRB_STATUS_ABORTED	0x02
355 #define SRB_STATUS_ERROR	0x04
356 
357 /*
358  * This is the end of Protocol specific defines.
359  */
360 
361 static int storvsc_ringbuffer_size = (256 * PAGE_SIZE);
362 static u32 max_outstanding_req_per_channel;
363 
364 static int storvsc_vcpus_per_sub_channel = 4;
365 
366 module_param(storvsc_ringbuffer_size, int, S_IRUGO);
367 MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");
368 
369 module_param(storvsc_vcpus_per_sub_channel, int, S_IRUGO);
370 MODULE_PARM_DESC(vcpus_per_sub_channel, "Ratio of VCPUs to subchannels");
371 /*
372  * Timeout in seconds for all devices managed by this driver.
373  */
374 static int storvsc_timeout = 180;
375 
376 static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
377 
378 
379 static void storvsc_on_channel_callback(void *context);
380 
381 #define STORVSC_MAX_LUNS_PER_TARGET			255
382 #define STORVSC_MAX_TARGETS				2
383 #define STORVSC_MAX_CHANNELS				8
384 
385 #define STORVSC_FC_MAX_LUNS_PER_TARGET			255
386 #define STORVSC_FC_MAX_TARGETS				128
387 #define STORVSC_FC_MAX_CHANNELS				8
388 
389 #define STORVSC_IDE_MAX_LUNS_PER_TARGET			64
390 #define STORVSC_IDE_MAX_TARGETS				1
391 #define STORVSC_IDE_MAX_CHANNELS			1
392 
393 struct storvsc_cmd_request {
394 	struct scsi_cmnd *cmd;
395 
396 	unsigned int bounce_sgl_count;
397 	struct scatterlist *bounce_sgl;
398 
399 	struct hv_device *device;
400 
401 	/* Synchronize the request/response if needed */
402 	struct completion wait_event;
403 
404 	struct vmbus_channel_packet_multipage_buffer mpb;
405 	struct vmbus_packet_mpb_array *payload;
406 	u32 payload_sz;
407 
408 	struct vstor_packet vstor_packet;
409 };
410 
411 
412 /* A storvsc device is a device object that contains a vmbus channel */
413 struct storvsc_device {
414 	struct hv_device *device;
415 
416 	bool	 destroy;
417 	bool	 drain_notify;
418 	bool	 open_sub_channel;
419 	atomic_t num_outstanding_req;
420 	struct Scsi_Host *host;
421 
422 	wait_queue_head_t waiting_to_drain;
423 
424 	/*
425 	 * Each unique Port/Path/Target represents 1 channel ie scsi
426 	 * controller. In reality, the pathid, targetid is always 0
427 	 * and the port is set by us
428 	 */
429 	unsigned int port_number;
430 	unsigned char path_id;
431 	unsigned char target_id;
432 
433 	/*
434 	 * Max I/O, the device can support.
435 	 */
436 	u32   max_transfer_bytes;
437 	/* Used for vsc/vsp channel reset process */
438 	struct storvsc_cmd_request init_request;
439 	struct storvsc_cmd_request reset_request;
440 };
441 
442 struct hv_host_device {
443 	struct hv_device *dev;
444 	unsigned int port;
445 	unsigned char path;
446 	unsigned char target;
447 };
448 
449 struct storvsc_scan_work {
450 	struct work_struct work;
451 	struct Scsi_Host *host;
452 	uint lun;
453 };
454 
455 static void storvsc_device_scan(struct work_struct *work)
456 {
457 	struct storvsc_scan_work *wrk;
458 	uint lun;
459 	struct scsi_device *sdev;
460 
461 	wrk = container_of(work, struct storvsc_scan_work, work);
462 	lun = wrk->lun;
463 
464 	sdev = scsi_device_lookup(wrk->host, 0, 0, lun);
465 	if (!sdev)
466 		goto done;
467 	scsi_rescan_device(&sdev->sdev_gendev);
468 	scsi_device_put(sdev);
469 
470 done:
471 	kfree(wrk);
472 }
473 
474 static void storvsc_host_scan(struct work_struct *work)
475 {
476 	struct storvsc_scan_work *wrk;
477 	struct Scsi_Host *host;
478 	struct scsi_device *sdev;
479 
480 	wrk = container_of(work, struct storvsc_scan_work, work);
481 	host = wrk->host;
482 
483 	/*
484 	 * Before scanning the host, first check to see if any of the
485 	 * currrently known devices have been hot removed. We issue a
486 	 * "unit ready" command against all currently known devices.
487 	 * This I/O will result in an error for devices that have been
488 	 * removed. As part of handling the I/O error, we remove the device.
489 	 *
490 	 * When a LUN is added or removed, the host sends us a signal to
491 	 * scan the host. Thus we are forced to discover the LUNs that
492 	 * may have been removed this way.
493 	 */
494 	mutex_lock(&host->scan_mutex);
495 	shost_for_each_device(sdev, host)
496 		scsi_test_unit_ready(sdev, 1, 1, NULL);
497 	mutex_unlock(&host->scan_mutex);
498 	/*
499 	 * Now scan the host to discover LUNs that may have been added.
500 	 */
501 	scsi_scan_host(host);
502 
503 	kfree(wrk);
504 }
505 
506 static void storvsc_remove_lun(struct work_struct *work)
507 {
508 	struct storvsc_scan_work *wrk;
509 	struct scsi_device *sdev;
510 
511 	wrk = container_of(work, struct storvsc_scan_work, work);
512 	if (!scsi_host_get(wrk->host))
513 		goto done;
514 
515 	sdev = scsi_device_lookup(wrk->host, 0, 0, wrk->lun);
516 
517 	if (sdev) {
518 		scsi_remove_device(sdev);
519 		scsi_device_put(sdev);
520 	}
521 	scsi_host_put(wrk->host);
522 
523 done:
524 	kfree(wrk);
525 }
526 
527 
528 /*
529  * We can get incoming messages from the host that are not in response to
530  * messages that we have sent out. An example of this would be messages
531  * received by the guest to notify dynamic addition/removal of LUNs. To
532  * deal with potential race conditions where the driver may be in the
533  * midst of being unloaded when we might receive an unsolicited message
534  * from the host, we have implemented a mechanism to gurantee sequential
535  * consistency:
536  *
537  * 1) Once the device is marked as being destroyed, we will fail all
538  *    outgoing messages.
539  * 2) We permit incoming messages when the device is being destroyed,
540  *    only to properly account for messages already sent out.
541  */
542 
543 static inline struct storvsc_device *get_out_stor_device(
544 					struct hv_device *device)
545 {
546 	struct storvsc_device *stor_device;
547 
548 	stor_device = hv_get_drvdata(device);
549 
550 	if (stor_device && stor_device->destroy)
551 		stor_device = NULL;
552 
553 	return stor_device;
554 }
555 
556 
557 static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
558 {
559 	dev->drain_notify = true;
560 	wait_event(dev->waiting_to_drain,
561 		   atomic_read(&dev->num_outstanding_req) == 0);
562 	dev->drain_notify = false;
563 }
564 
565 static inline struct storvsc_device *get_in_stor_device(
566 					struct hv_device *device)
567 {
568 	struct storvsc_device *stor_device;
569 
570 	stor_device = hv_get_drvdata(device);
571 
572 	if (!stor_device)
573 		goto get_in_err;
574 
575 	/*
576 	 * If the device is being destroyed; allow incoming
577 	 * traffic only to cleanup outstanding requests.
578 	 */
579 
580 	if (stor_device->destroy  &&
581 		(atomic_read(&stor_device->num_outstanding_req) == 0))
582 		stor_device = NULL;
583 
584 get_in_err:
585 	return stor_device;
586 
587 }
588 
589 static void destroy_bounce_buffer(struct scatterlist *sgl,
590 				  unsigned int sg_count)
591 {
592 	int i;
593 	struct page *page_buf;
594 
595 	for (i = 0; i < sg_count; i++) {
596 		page_buf = sg_page((&sgl[i]));
597 		if (page_buf != NULL)
598 			__free_page(page_buf);
599 	}
600 
601 	kfree(sgl);
602 }
603 
604 static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
605 {
606 	int i;
607 
608 	/* No need to check */
609 	if (sg_count < 2)
610 		return -1;
611 
612 	/* We have at least 2 sg entries */
613 	for (i = 0; i < sg_count; i++) {
614 		if (i == 0) {
615 			/* make sure 1st one does not have hole */
616 			if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
617 				return i;
618 		} else if (i == sg_count - 1) {
619 			/* make sure last one does not have hole */
620 			if (sgl[i].offset != 0)
621 				return i;
622 		} else {
623 			/* make sure no hole in the middle */
624 			if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
625 				return i;
626 		}
627 	}
628 	return -1;
629 }
630 
631 static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl,
632 						unsigned int sg_count,
633 						unsigned int len,
634 						int write)
635 {
636 	int i;
637 	int num_pages;
638 	struct scatterlist *bounce_sgl;
639 	struct page *page_buf;
640 	unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE);
641 
642 	num_pages = ALIGN(len, PAGE_SIZE) >> PAGE_SHIFT;
643 
644 	bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC);
645 	if (!bounce_sgl)
646 		return NULL;
647 
648 	sg_init_table(bounce_sgl, num_pages);
649 	for (i = 0; i < num_pages; i++) {
650 		page_buf = alloc_page(GFP_ATOMIC);
651 		if (!page_buf)
652 			goto cleanup;
653 		sg_set_page(&bounce_sgl[i], page_buf, buf_len, 0);
654 	}
655 
656 	return bounce_sgl;
657 
658 cleanup:
659 	destroy_bounce_buffer(bounce_sgl, num_pages);
660 	return NULL;
661 }
662 
663 /* Assume the original sgl has enough room */
664 static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
665 					    struct scatterlist *bounce_sgl,
666 					    unsigned int orig_sgl_count,
667 					    unsigned int bounce_sgl_count)
668 {
669 	int i;
670 	int j = 0;
671 	unsigned long src, dest;
672 	unsigned int srclen, destlen, copylen;
673 	unsigned int total_copied = 0;
674 	unsigned long bounce_addr = 0;
675 	unsigned long dest_addr = 0;
676 	unsigned long flags;
677 	struct scatterlist *cur_dest_sgl;
678 	struct scatterlist *cur_src_sgl;
679 
680 	local_irq_save(flags);
681 	cur_dest_sgl = orig_sgl;
682 	cur_src_sgl = bounce_sgl;
683 	for (i = 0; i < orig_sgl_count; i++) {
684 		dest_addr = (unsigned long)
685 				kmap_atomic(sg_page(cur_dest_sgl)) +
686 				cur_dest_sgl->offset;
687 		dest = dest_addr;
688 		destlen = cur_dest_sgl->length;
689 
690 		if (bounce_addr == 0)
691 			bounce_addr = (unsigned long)kmap_atomic(
692 							sg_page(cur_src_sgl));
693 
694 		while (destlen) {
695 			src = bounce_addr + cur_src_sgl->offset;
696 			srclen = cur_src_sgl->length - cur_src_sgl->offset;
697 
698 			copylen = min(srclen, destlen);
699 			memcpy((void *)dest, (void *)src, copylen);
700 
701 			total_copied += copylen;
702 			cur_src_sgl->offset += copylen;
703 			destlen -= copylen;
704 			dest += copylen;
705 
706 			if (cur_src_sgl->offset == cur_src_sgl->length) {
707 				/* full */
708 				kunmap_atomic((void *)bounce_addr);
709 				j++;
710 
711 				/*
712 				 * It is possible that the number of elements
713 				 * in the bounce buffer may not be equal to
714 				 * the number of elements in the original
715 				 * scatter list. Handle this correctly.
716 				 */
717 
718 				if (j == bounce_sgl_count) {
719 					/*
720 					 * We are done; cleanup and return.
721 					 */
722 					kunmap_atomic((void *)(dest_addr -
723 						cur_dest_sgl->offset));
724 					local_irq_restore(flags);
725 					return total_copied;
726 				}
727 
728 				/* if we need to use another bounce buffer */
729 				if (destlen || i != orig_sgl_count - 1) {
730 					cur_src_sgl = sg_next(cur_src_sgl);
731 					bounce_addr = (unsigned long)
732 							kmap_atomic(
733 							sg_page(cur_src_sgl));
734 				}
735 			} else if (destlen == 0 && i == orig_sgl_count - 1) {
736 				/* unmap the last bounce that is < PAGE_SIZE */
737 				kunmap_atomic((void *)bounce_addr);
738 			}
739 		}
740 
741 		kunmap_atomic((void *)(dest_addr - cur_dest_sgl->offset));
742 		cur_dest_sgl = sg_next(cur_dest_sgl);
743 	}
744 
745 	local_irq_restore(flags);
746 
747 	return total_copied;
748 }
749 
750 /* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */
751 static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
752 					  struct scatterlist *bounce_sgl,
753 					  unsigned int orig_sgl_count)
754 {
755 	int i;
756 	int j = 0;
757 	unsigned long src, dest;
758 	unsigned int srclen, destlen, copylen;
759 	unsigned int total_copied = 0;
760 	unsigned long bounce_addr = 0;
761 	unsigned long src_addr = 0;
762 	unsigned long flags;
763 	struct scatterlist *cur_src_sgl;
764 	struct scatterlist *cur_dest_sgl;
765 
766 	local_irq_save(flags);
767 
768 	cur_src_sgl = orig_sgl;
769 	cur_dest_sgl = bounce_sgl;
770 
771 	for (i = 0; i < orig_sgl_count; i++) {
772 		src_addr = (unsigned long)
773 				kmap_atomic(sg_page(cur_src_sgl)) +
774 				cur_src_sgl->offset;
775 		src = src_addr;
776 		srclen = cur_src_sgl->length;
777 
778 		if (bounce_addr == 0)
779 			bounce_addr = (unsigned long)
780 					kmap_atomic(sg_page(cur_dest_sgl));
781 
782 		while (srclen) {
783 			/* assume bounce offset always == 0 */
784 			dest = bounce_addr + cur_dest_sgl->length;
785 			destlen = PAGE_SIZE - cur_dest_sgl->length;
786 
787 			copylen = min(srclen, destlen);
788 			memcpy((void *)dest, (void *)src, copylen);
789 
790 			total_copied += copylen;
791 			cur_dest_sgl->length += copylen;
792 			srclen -= copylen;
793 			src += copylen;
794 
795 			if (cur_dest_sgl->length == PAGE_SIZE) {
796 				/* full..move to next entry */
797 				kunmap_atomic((void *)bounce_addr);
798 				bounce_addr = 0;
799 				j++;
800 			}
801 
802 			/* if we need to use another bounce buffer */
803 			if (srclen && bounce_addr == 0) {
804 				cur_dest_sgl = sg_next(cur_dest_sgl);
805 				bounce_addr = (unsigned long)
806 						kmap_atomic(
807 						sg_page(cur_dest_sgl));
808 			}
809 
810 		}
811 
812 		kunmap_atomic((void *)(src_addr - cur_src_sgl->offset));
813 		cur_src_sgl = sg_next(cur_src_sgl);
814 	}
815 
816 	if (bounce_addr)
817 		kunmap_atomic((void *)bounce_addr);
818 
819 	local_irq_restore(flags);
820 
821 	return total_copied;
822 }
823 
824 static void handle_sc_creation(struct vmbus_channel *new_sc)
825 {
826 	struct hv_device *device = new_sc->primary_channel->device_obj;
827 	struct storvsc_device *stor_device;
828 	struct vmstorage_channel_properties props;
829 
830 	stor_device = get_out_stor_device(device);
831 	if (!stor_device)
832 		return;
833 
834 	if (stor_device->open_sub_channel == false)
835 		return;
836 
837 	memset(&props, 0, sizeof(struct vmstorage_channel_properties));
838 
839 	vmbus_open(new_sc,
840 		   storvsc_ringbuffer_size,
841 		   storvsc_ringbuffer_size,
842 		   (void *)&props,
843 		   sizeof(struct vmstorage_channel_properties),
844 		   storvsc_on_channel_callback, new_sc);
845 }
846 
847 static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
848 {
849 	struct storvsc_device *stor_device;
850 	int num_cpus = num_online_cpus();
851 	int num_sc;
852 	struct storvsc_cmd_request *request;
853 	struct vstor_packet *vstor_packet;
854 	int ret, t;
855 
856 	num_sc = ((max_chns > num_cpus) ? num_cpus : max_chns);
857 	stor_device = get_out_stor_device(device);
858 	if (!stor_device)
859 		return;
860 
861 	request = &stor_device->init_request;
862 	vstor_packet = &request->vstor_packet;
863 
864 	stor_device->open_sub_channel = true;
865 	/*
866 	 * Establish a handler for dealing with subchannels.
867 	 */
868 	vmbus_set_sc_create_callback(device->channel, handle_sc_creation);
869 
870 	/*
871 	 * Check to see if sub-channels have already been created. This
872 	 * can happen when this driver is re-loaded after unloading.
873 	 */
874 
875 	if (vmbus_are_subchannels_present(device->channel))
876 		return;
877 
878 	stor_device->open_sub_channel = false;
879 	/*
880 	 * Request the host to create sub-channels.
881 	 */
882 	memset(request, 0, sizeof(struct storvsc_cmd_request));
883 	init_completion(&request->wait_event);
884 	vstor_packet->operation = VSTOR_OPERATION_CREATE_SUB_CHANNELS;
885 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
886 	vstor_packet->sub_channel_count = num_sc;
887 
888 	ret = vmbus_sendpacket(device->channel, vstor_packet,
889 			       (sizeof(struct vstor_packet) -
890 			       vmscsi_size_delta),
891 			       (unsigned long)request,
892 			       VM_PKT_DATA_INBAND,
893 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
894 
895 	if (ret != 0)
896 		return;
897 
898 	t = wait_for_completion_timeout(&request->wait_event, 10*HZ);
899 	if (t == 0)
900 		return;
901 
902 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
903 	    vstor_packet->status != 0)
904 		return;
905 
906 	/*
907 	 * Now that we created the sub-channels, invoke the check; this
908 	 * may trigger the callback.
909 	 */
910 	stor_device->open_sub_channel = true;
911 	vmbus_are_subchannels_present(device->channel);
912 }
913 
914 static int storvsc_channel_init(struct hv_device *device)
915 {
916 	struct storvsc_device *stor_device;
917 	struct storvsc_cmd_request *request;
918 	struct vstor_packet *vstor_packet;
919 	int ret, t, i;
920 	int max_chns;
921 	bool process_sub_channels = false;
922 
923 	stor_device = get_out_stor_device(device);
924 	if (!stor_device)
925 		return -ENODEV;
926 
927 	request = &stor_device->init_request;
928 	vstor_packet = &request->vstor_packet;
929 
930 	/*
931 	 * Now, initiate the vsc/vsp initialization protocol on the open
932 	 * channel
933 	 */
934 	memset(request, 0, sizeof(struct storvsc_cmd_request));
935 	init_completion(&request->wait_event);
936 	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
937 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
938 
939 	ret = vmbus_sendpacket(device->channel, vstor_packet,
940 			       (sizeof(struct vstor_packet) -
941 			       vmscsi_size_delta),
942 			       (unsigned long)request,
943 			       VM_PKT_DATA_INBAND,
944 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
945 	if (ret != 0)
946 		goto cleanup;
947 
948 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
949 	if (t == 0) {
950 		ret = -ETIMEDOUT;
951 		goto cleanup;
952 	}
953 
954 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
955 	    vstor_packet->status != 0) {
956 		ret = -EINVAL;
957 		goto cleanup;
958 	}
959 
960 
961 	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
962 		/* reuse the packet for version range supported */
963 		memset(vstor_packet, 0, sizeof(struct vstor_packet));
964 		vstor_packet->operation =
965 			VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
966 		vstor_packet->flags = REQUEST_COMPLETION_FLAG;
967 
968 		vstor_packet->version.major_minor =
969 			vmstor_protocols[i].protocol_version;
970 
971 		/*
972 		 * The revision number is only used in Windows; set it to 0.
973 		 */
974 		vstor_packet->version.revision = 0;
975 
976 		ret = vmbus_sendpacket(device->channel, vstor_packet,
977 			       (sizeof(struct vstor_packet) -
978 				vmscsi_size_delta),
979 			       (unsigned long)request,
980 			       VM_PKT_DATA_INBAND,
981 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
982 		if (ret != 0)
983 			goto cleanup;
984 
985 		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
986 		if (t == 0) {
987 			ret = -ETIMEDOUT;
988 			goto cleanup;
989 		}
990 
991 		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO) {
992 			ret = -EINVAL;
993 			goto cleanup;
994 		}
995 
996 		if (vstor_packet->status == 0) {
997 			vmstor_proto_version =
998 				vmstor_protocols[i].protocol_version;
999 
1000 			sense_buffer_size =
1001 				vmstor_protocols[i].sense_buffer_size;
1002 
1003 			vmscsi_size_delta =
1004 				vmstor_protocols[i].vmscsi_size_delta;
1005 
1006 			break;
1007 		}
1008 	}
1009 
1010 	if (vstor_packet->status != 0) {
1011 		ret = -EINVAL;
1012 		goto cleanup;
1013 	}
1014 
1015 
1016 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
1017 	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
1018 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
1019 
1020 	ret = vmbus_sendpacket(device->channel, vstor_packet,
1021 			       (sizeof(struct vstor_packet) -
1022 				vmscsi_size_delta),
1023 			       (unsigned long)request,
1024 			       VM_PKT_DATA_INBAND,
1025 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
1026 
1027 	if (ret != 0)
1028 		goto cleanup;
1029 
1030 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
1031 	if (t == 0) {
1032 		ret = -ETIMEDOUT;
1033 		goto cleanup;
1034 	}
1035 
1036 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
1037 	    vstor_packet->status != 0) {
1038 		ret = -EINVAL;
1039 		goto cleanup;
1040 	}
1041 
1042 	/*
1043 	 * Check to see if multi-channel support is there.
1044 	 * Hosts that implement protocol version of 5.1 and above
1045 	 * support multi-channel.
1046 	 */
1047 	max_chns = vstor_packet->storage_channel_properties.max_channel_cnt;
1048 	if (vmstor_proto_version >= VMSTOR_PROTO_VERSION_WIN8) {
1049 		if (vstor_packet->storage_channel_properties.flags &
1050 		    STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL)
1051 			process_sub_channels = true;
1052 	}
1053 	stor_device->max_transfer_bytes =
1054 		vstor_packet->storage_channel_properties.max_transfer_bytes;
1055 
1056 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
1057 	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
1058 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
1059 
1060 	ret = vmbus_sendpacket(device->channel, vstor_packet,
1061 			       (sizeof(struct vstor_packet) -
1062 				vmscsi_size_delta),
1063 			       (unsigned long)request,
1064 			       VM_PKT_DATA_INBAND,
1065 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
1066 
1067 	if (ret != 0)
1068 		goto cleanup;
1069 
1070 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
1071 	if (t == 0) {
1072 		ret = -ETIMEDOUT;
1073 		goto cleanup;
1074 	}
1075 
1076 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
1077 	    vstor_packet->status != 0) {
1078 		ret = -EINVAL;
1079 		goto cleanup;
1080 	}
1081 
1082 	if (process_sub_channels)
1083 		handle_multichannel_storage(device, max_chns);
1084 
1085 
1086 cleanup:
1087 	return ret;
1088 }
1089 
1090 static void storvsc_handle_error(struct vmscsi_request *vm_srb,
1091 				struct scsi_cmnd *scmnd,
1092 				struct Scsi_Host *host,
1093 				u8 asc, u8 ascq)
1094 {
1095 	struct storvsc_scan_work *wrk;
1096 	void (*process_err_fn)(struct work_struct *work);
1097 	bool do_work = false;
1098 
1099 	switch (vm_srb->srb_status) {
1100 	case SRB_STATUS_ERROR:
1101 		/*
1102 		 * If there is an error; offline the device since all
1103 		 * error recovery strategies would have already been
1104 		 * deployed on the host side. However, if the command
1105 		 * were a pass-through command deal with it appropriately.
1106 		 */
1107 		switch (scmnd->cmnd[0]) {
1108 		case ATA_16:
1109 		case ATA_12:
1110 			set_host_byte(scmnd, DID_PASSTHROUGH);
1111 			break;
1112 		/*
1113 		 * On Some Windows hosts TEST_UNIT_READY command can return
1114 		 * SRB_STATUS_ERROR, let the upper level code deal with it
1115 		 * based on the sense information.
1116 		 */
1117 		case TEST_UNIT_READY:
1118 			break;
1119 		default:
1120 			set_host_byte(scmnd, DID_TARGET_FAILURE);
1121 		}
1122 		break;
1123 	case SRB_STATUS_INVALID_LUN:
1124 		do_work = true;
1125 		process_err_fn = storvsc_remove_lun;
1126 		break;
1127 	case (SRB_STATUS_ABORTED | SRB_STATUS_AUTOSENSE_VALID):
1128 		if ((asc == 0x2a) && (ascq == 0x9)) {
1129 			do_work = true;
1130 			process_err_fn = storvsc_device_scan;
1131 			/*
1132 			 * Retry the I/O that trigerred this.
1133 			 */
1134 			set_host_byte(scmnd, DID_REQUEUE);
1135 		}
1136 		break;
1137 	}
1138 
1139 	if (!do_work)
1140 		return;
1141 
1142 	/*
1143 	 * We need to schedule work to process this error; schedule it.
1144 	 */
1145 	wrk = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
1146 	if (!wrk) {
1147 		set_host_byte(scmnd, DID_TARGET_FAILURE);
1148 		return;
1149 	}
1150 
1151 	wrk->host = host;
1152 	wrk->lun = vm_srb->lun;
1153 	INIT_WORK(&wrk->work, process_err_fn);
1154 	schedule_work(&wrk->work);
1155 }
1156 
1157 
1158 static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
1159 {
1160 	struct scsi_cmnd *scmnd = cmd_request->cmd;
1161 	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
1162 	struct scsi_sense_hdr sense_hdr;
1163 	struct vmscsi_request *vm_srb;
1164 	struct Scsi_Host *host;
1165 	struct storvsc_device *stor_dev;
1166 	struct hv_device *dev = host_dev->dev;
1167 	u32 payload_sz = cmd_request->payload_sz;
1168 	void *payload = cmd_request->payload;
1169 
1170 	stor_dev = get_in_stor_device(dev);
1171 	host = stor_dev->host;
1172 
1173 	vm_srb = &cmd_request->vstor_packet.vm_srb;
1174 	if (cmd_request->bounce_sgl_count) {
1175 		if (vm_srb->data_in == READ_TYPE)
1176 			copy_from_bounce_buffer(scsi_sglist(scmnd),
1177 					cmd_request->bounce_sgl,
1178 					scsi_sg_count(scmnd),
1179 					cmd_request->bounce_sgl_count);
1180 		destroy_bounce_buffer(cmd_request->bounce_sgl,
1181 					cmd_request->bounce_sgl_count);
1182 	}
1183 
1184 	scmnd->result = vm_srb->scsi_status;
1185 
1186 	if (scmnd->result) {
1187 		if (scsi_normalize_sense(scmnd->sense_buffer,
1188 				SCSI_SENSE_BUFFERSIZE, &sense_hdr))
1189 			scsi_print_sense_hdr(scmnd->device, "storvsc",
1190 					     &sense_hdr);
1191 	}
1192 
1193 	if (vm_srb->srb_status != SRB_STATUS_SUCCESS)
1194 		storvsc_handle_error(vm_srb, scmnd, host, sense_hdr.asc,
1195 					 sense_hdr.ascq);
1196 
1197 	scsi_set_resid(scmnd,
1198 		cmd_request->payload->range.len -
1199 		vm_srb->data_transfer_length);
1200 
1201 	scmnd->scsi_done(scmnd);
1202 
1203 	if (payload_sz >
1204 		sizeof(struct vmbus_channel_packet_multipage_buffer))
1205 		kfree(payload);
1206 }
1207 
1208 static void storvsc_on_io_completion(struct hv_device *device,
1209 				  struct vstor_packet *vstor_packet,
1210 				  struct storvsc_cmd_request *request)
1211 {
1212 	struct storvsc_device *stor_device;
1213 	struct vstor_packet *stor_pkt;
1214 
1215 	stor_device = hv_get_drvdata(device);
1216 	stor_pkt = &request->vstor_packet;
1217 
1218 	/*
1219 	 * The current SCSI handling on the host side does
1220 	 * not correctly handle:
1221 	 * INQUIRY command with page code parameter set to 0x80
1222 	 * MODE_SENSE command with cmd[2] == 0x1c
1223 	 *
1224 	 * Setup srb and scsi status so this won't be fatal.
1225 	 * We do this so we can distinguish truly fatal failues
1226 	 * (srb status == 0x4) and off-line the device in that case.
1227 	 */
1228 
1229 	if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
1230 	   (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) {
1231 		vstor_packet->vm_srb.scsi_status = 0;
1232 		vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
1233 	}
1234 
1235 
1236 	/* Copy over the status...etc */
1237 	stor_pkt->vm_srb.scsi_status = vstor_packet->vm_srb.scsi_status;
1238 	stor_pkt->vm_srb.srb_status = vstor_packet->vm_srb.srb_status;
1239 	stor_pkt->vm_srb.sense_info_length =
1240 	vstor_packet->vm_srb.sense_info_length;
1241 
1242 
1243 	if ((vstor_packet->vm_srb.scsi_status & 0xFF) == 0x02) {
1244 		/* CHECK_CONDITION */
1245 		if (vstor_packet->vm_srb.srb_status &
1246 			SRB_STATUS_AUTOSENSE_VALID) {
1247 			/* autosense data available */
1248 
1249 			memcpy(request->cmd->sense_buffer,
1250 			       vstor_packet->vm_srb.sense_data,
1251 			       vstor_packet->vm_srb.sense_info_length);
1252 
1253 		}
1254 	}
1255 
1256 	stor_pkt->vm_srb.data_transfer_length =
1257 	vstor_packet->vm_srb.data_transfer_length;
1258 
1259 	storvsc_command_completion(request);
1260 
1261 	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
1262 		stor_device->drain_notify)
1263 		wake_up(&stor_device->waiting_to_drain);
1264 
1265 
1266 }
1267 
1268 static void storvsc_on_receive(struct hv_device *device,
1269 			     struct vstor_packet *vstor_packet,
1270 			     struct storvsc_cmd_request *request)
1271 {
1272 	struct storvsc_scan_work *work;
1273 	struct storvsc_device *stor_device;
1274 
1275 	switch (vstor_packet->operation) {
1276 	case VSTOR_OPERATION_COMPLETE_IO:
1277 		storvsc_on_io_completion(device, vstor_packet, request);
1278 		break;
1279 
1280 	case VSTOR_OPERATION_REMOVE_DEVICE:
1281 	case VSTOR_OPERATION_ENUMERATE_BUS:
1282 		stor_device = get_in_stor_device(device);
1283 		work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
1284 		if (!work)
1285 			return;
1286 
1287 		INIT_WORK(&work->work, storvsc_host_scan);
1288 		work->host = stor_device->host;
1289 		schedule_work(&work->work);
1290 		break;
1291 
1292 	default:
1293 		break;
1294 	}
1295 }
1296 
1297 static void storvsc_on_channel_callback(void *context)
1298 {
1299 	struct vmbus_channel *channel = (struct vmbus_channel *)context;
1300 	struct hv_device *device;
1301 	struct storvsc_device *stor_device;
1302 	u32 bytes_recvd;
1303 	u64 request_id;
1304 	unsigned char packet[ALIGN(sizeof(struct vstor_packet), 8)];
1305 	struct storvsc_cmd_request *request;
1306 	int ret;
1307 
1308 	if (channel->primary_channel != NULL)
1309 		device = channel->primary_channel->device_obj;
1310 	else
1311 		device = channel->device_obj;
1312 
1313 	stor_device = get_in_stor_device(device);
1314 	if (!stor_device)
1315 		return;
1316 
1317 	do {
1318 		ret = vmbus_recvpacket(channel, packet,
1319 				       ALIGN((sizeof(struct vstor_packet) -
1320 					     vmscsi_size_delta), 8),
1321 				       &bytes_recvd, &request_id);
1322 		if (ret == 0 && bytes_recvd > 0) {
1323 
1324 			request = (struct storvsc_cmd_request *)
1325 					(unsigned long)request_id;
1326 
1327 			if ((request == &stor_device->init_request) ||
1328 			    (request == &stor_device->reset_request)) {
1329 
1330 				memcpy(&request->vstor_packet, packet,
1331 				       (sizeof(struct vstor_packet) -
1332 					vmscsi_size_delta));
1333 				complete(&request->wait_event);
1334 			} else {
1335 				storvsc_on_receive(device,
1336 						(struct vstor_packet *)packet,
1337 						request);
1338 			}
1339 		} else {
1340 			break;
1341 		}
1342 	} while (1);
1343 
1344 	return;
1345 }
1346 
1347 static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
1348 {
1349 	struct vmstorage_channel_properties props;
1350 	int ret;
1351 
1352 	memset(&props, 0, sizeof(struct vmstorage_channel_properties));
1353 
1354 	ret = vmbus_open(device->channel,
1355 			 ring_size,
1356 			 ring_size,
1357 			 (void *)&props,
1358 			 sizeof(struct vmstorage_channel_properties),
1359 			 storvsc_on_channel_callback, device->channel);
1360 
1361 	if (ret != 0)
1362 		return ret;
1363 
1364 	ret = storvsc_channel_init(device);
1365 
1366 	return ret;
1367 }
1368 
1369 static int storvsc_dev_remove(struct hv_device *device)
1370 {
1371 	struct storvsc_device *stor_device;
1372 	unsigned long flags;
1373 
1374 	stor_device = hv_get_drvdata(device);
1375 
1376 	spin_lock_irqsave(&device->channel->inbound_lock, flags);
1377 	stor_device->destroy = true;
1378 	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
1379 
1380 	/*
1381 	 * At this point, all outbound traffic should be disable. We
1382 	 * only allow inbound traffic (responses) to proceed so that
1383 	 * outstanding requests can be completed.
1384 	 */
1385 
1386 	storvsc_wait_to_drain(stor_device);
1387 
1388 	/*
1389 	 * Since we have already drained, we don't need to busy wait
1390 	 * as was done in final_release_stor_device()
1391 	 * Note that we cannot set the ext pointer to NULL until
1392 	 * we have drained - to drain the outgoing packets, we need to
1393 	 * allow incoming packets.
1394 	 */
1395 	spin_lock_irqsave(&device->channel->inbound_lock, flags);
1396 	hv_set_drvdata(device, NULL);
1397 	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);
1398 
1399 	/* Close the channel */
1400 	vmbus_close(device->channel);
1401 
1402 	kfree(stor_device);
1403 	return 0;
1404 }
1405 
1406 static int storvsc_do_io(struct hv_device *device,
1407 			 struct storvsc_cmd_request *request)
1408 {
1409 	struct storvsc_device *stor_device;
1410 	struct vstor_packet *vstor_packet;
1411 	struct vmbus_channel *outgoing_channel;
1412 	int ret = 0;
1413 
1414 	vstor_packet = &request->vstor_packet;
1415 	stor_device = get_out_stor_device(device);
1416 
1417 	if (!stor_device)
1418 		return -ENODEV;
1419 
1420 
1421 	request->device  = device;
1422 	/*
1423 	 * Select an an appropriate channel to send the request out.
1424 	 */
1425 
1426 	outgoing_channel = vmbus_get_outgoing_channel(device->channel);
1427 
1428 
1429 	vstor_packet->flags |= REQUEST_COMPLETION_FLAG;
1430 
1431 	vstor_packet->vm_srb.length = (sizeof(struct vmscsi_request) -
1432 					vmscsi_size_delta);
1433 
1434 
1435 	vstor_packet->vm_srb.sense_info_length = sense_buffer_size;
1436 
1437 
1438 	vstor_packet->vm_srb.data_transfer_length =
1439 	request->payload->range.len;
1440 
1441 	vstor_packet->operation = VSTOR_OPERATION_EXECUTE_SRB;
1442 
1443 	if (request->payload->range.len) {
1444 
1445 		ret = vmbus_sendpacket_mpb_desc(outgoing_channel,
1446 				request->payload, request->payload_sz,
1447 				vstor_packet,
1448 				(sizeof(struct vstor_packet) -
1449 				vmscsi_size_delta),
1450 				(unsigned long)request);
1451 	} else {
1452 		ret = vmbus_sendpacket(outgoing_channel, vstor_packet,
1453 			       (sizeof(struct vstor_packet) -
1454 				vmscsi_size_delta),
1455 			       (unsigned long)request,
1456 			       VM_PKT_DATA_INBAND,
1457 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
1458 	}
1459 
1460 	if (ret != 0)
1461 		return ret;
1462 
1463 	atomic_inc(&stor_device->num_outstanding_req);
1464 
1465 	return ret;
1466 }
1467 
1468 static int storvsc_device_configure(struct scsi_device *sdevice)
1469 {
1470 
1471 	blk_queue_max_segment_size(sdevice->request_queue, PAGE_SIZE);
1472 
1473 	blk_queue_bounce_limit(sdevice->request_queue, BLK_BOUNCE_ANY);
1474 
1475 	blk_queue_rq_timeout(sdevice->request_queue, (storvsc_timeout * HZ));
1476 
1477 	sdevice->no_write_same = 1;
1478 
1479 	/*
1480 	 * Add blist flags to permit the reading of the VPD pages even when
1481 	 * the target may claim SPC-2 compliance. MSFT targets currently
1482 	 * claim SPC-2 compliance while they implement post SPC-2 features.
1483 	 * With this patch we can correctly handle WRITE_SAME_16 issues.
1484 	 */
1485 	sdevice->sdev_bflags |= msft_blist_flags;
1486 
1487 	/*
1488 	 * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3
1489 	 * if the device is a MSFT virtual device.  If the host is
1490 	 * WIN10 or newer, allow write_same.
1491 	 */
1492 	if (!strncmp(sdevice->vendor, "Msft", 4)) {
1493 		switch (vmstor_proto_version) {
1494 		case VMSTOR_PROTO_VERSION_WIN8:
1495 		case VMSTOR_PROTO_VERSION_WIN8_1:
1496 			sdevice->scsi_level = SCSI_SPC_3;
1497 			break;
1498 		}
1499 
1500 		if (vmstor_proto_version >= VMSTOR_PROTO_VERSION_WIN10)
1501 			sdevice->no_write_same = 0;
1502 	}
1503 
1504 	return 0;
1505 }
1506 
1507 static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
1508 			   sector_t capacity, int *info)
1509 {
1510 	sector_t nsect = capacity;
1511 	sector_t cylinders = nsect;
1512 	int heads, sectors_pt;
1513 
1514 	/*
1515 	 * We are making up these values; let us keep it simple.
1516 	 */
1517 	heads = 0xff;
1518 	sectors_pt = 0x3f;      /* Sectors per track */
1519 	sector_div(cylinders, heads * sectors_pt);
1520 	if ((sector_t)(cylinders + 1) * heads * sectors_pt < nsect)
1521 		cylinders = 0xffff;
1522 
1523 	info[0] = heads;
1524 	info[1] = sectors_pt;
1525 	info[2] = (int)cylinders;
1526 
1527 	return 0;
1528 }
1529 
1530 static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
1531 {
1532 	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
1533 	struct hv_device *device = host_dev->dev;
1534 
1535 	struct storvsc_device *stor_device;
1536 	struct storvsc_cmd_request *request;
1537 	struct vstor_packet *vstor_packet;
1538 	int ret, t;
1539 
1540 
1541 	stor_device = get_out_stor_device(device);
1542 	if (!stor_device)
1543 		return FAILED;
1544 
1545 	request = &stor_device->reset_request;
1546 	vstor_packet = &request->vstor_packet;
1547 
1548 	init_completion(&request->wait_event);
1549 
1550 	vstor_packet->operation = VSTOR_OPERATION_RESET_BUS;
1551 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
1552 	vstor_packet->vm_srb.path_id = stor_device->path_id;
1553 
1554 	ret = vmbus_sendpacket(device->channel, vstor_packet,
1555 			       (sizeof(struct vstor_packet) -
1556 				vmscsi_size_delta),
1557 			       (unsigned long)&stor_device->reset_request,
1558 			       VM_PKT_DATA_INBAND,
1559 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
1560 	if (ret != 0)
1561 		return FAILED;
1562 
1563 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
1564 	if (t == 0)
1565 		return TIMEOUT_ERROR;
1566 
1567 
1568 	/*
1569 	 * At this point, all outstanding requests in the adapter
1570 	 * should have been flushed out and return to us
1571 	 * There is a potential race here where the host may be in
1572 	 * the process of responding when we return from here.
1573 	 * Just wait for all in-transit packets to be accounted for
1574 	 * before we return from here.
1575 	 */
1576 	storvsc_wait_to_drain(stor_device);
1577 
1578 	return SUCCESS;
1579 }
1580 
1581 /*
1582  * The host guarantees to respond to each command, although I/O latencies might
1583  * be unbounded on Azure.  Reset the timer unconditionally to give the host a
1584  * chance to perform EH.
1585  */
1586 static enum blk_eh_timer_return storvsc_eh_timed_out(struct scsi_cmnd *scmnd)
1587 {
1588 	return BLK_EH_RESET_TIMER;
1589 }
1590 
1591 static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
1592 {
1593 	bool allowed = true;
1594 	u8 scsi_op = scmnd->cmnd[0];
1595 
1596 	switch (scsi_op) {
1597 	/* the host does not handle WRITE_SAME, log accident usage */
1598 	case WRITE_SAME:
1599 	/*
1600 	 * smartd sends this command and the host does not handle
1601 	 * this. So, don't send it.
1602 	 */
1603 	case SET_WINDOW:
1604 		scmnd->result = ILLEGAL_REQUEST << 16;
1605 		allowed = false;
1606 		break;
1607 	default:
1608 		break;
1609 	}
1610 	return allowed;
1611 }
1612 
1613 static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
1614 {
1615 	int ret;
1616 	struct hv_host_device *host_dev = shost_priv(host);
1617 	struct hv_device *dev = host_dev->dev;
1618 	struct storvsc_cmd_request *cmd_request = scsi_cmd_priv(scmnd);
1619 	int i;
1620 	struct scatterlist *sgl;
1621 	unsigned int sg_count = 0;
1622 	struct vmscsi_request *vm_srb;
1623 	struct scatterlist *cur_sgl;
1624 	struct vmbus_packet_mpb_array  *payload;
1625 	u32 payload_sz;
1626 	u32 length;
1627 
1628 	if (vmstor_proto_version <= VMSTOR_PROTO_VERSION_WIN8) {
1629 		/*
1630 		 * On legacy hosts filter unimplemented commands.
1631 		 * Future hosts are expected to correctly handle
1632 		 * unsupported commands. Furthermore, it is
1633 		 * possible that some of the currently
1634 		 * unsupported commands maybe supported in
1635 		 * future versions of the host.
1636 		 */
1637 		if (!storvsc_scsi_cmd_ok(scmnd)) {
1638 			scmnd->scsi_done(scmnd);
1639 			return 0;
1640 		}
1641 	}
1642 
1643 	/* Setup the cmd request */
1644 	cmd_request->cmd = scmnd;
1645 
1646 	vm_srb = &cmd_request->vstor_packet.vm_srb;
1647 	vm_srb->win8_extension.time_out_value = 60;
1648 
1649 	vm_srb->win8_extension.srb_flags |=
1650 		(SRB_FLAGS_QUEUE_ACTION_ENABLE |
1651 		SRB_FLAGS_DISABLE_SYNCH_TRANSFER);
1652 
1653 	/* Build the SRB */
1654 	switch (scmnd->sc_data_direction) {
1655 	case DMA_TO_DEVICE:
1656 		vm_srb->data_in = WRITE_TYPE;
1657 		vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_OUT;
1658 		break;
1659 	case DMA_FROM_DEVICE:
1660 		vm_srb->data_in = READ_TYPE;
1661 		vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_IN;
1662 		break;
1663 	case DMA_NONE:
1664 		vm_srb->data_in = UNKNOWN_TYPE;
1665 		vm_srb->win8_extension.srb_flags |= SRB_FLAGS_NO_DATA_TRANSFER;
1666 		break;
1667 	default:
1668 		/*
1669 		 * This is DMA_BIDIRECTIONAL or something else we are never
1670 		 * supposed to see here.
1671 		 */
1672 		WARN(1, "Unexpected data direction: %d\n",
1673 		     scmnd->sc_data_direction);
1674 		return -EINVAL;
1675 	}
1676 
1677 
1678 	vm_srb->port_number = host_dev->port;
1679 	vm_srb->path_id = scmnd->device->channel;
1680 	vm_srb->target_id = scmnd->device->id;
1681 	vm_srb->lun = scmnd->device->lun;
1682 
1683 	vm_srb->cdb_length = scmnd->cmd_len;
1684 
1685 	memcpy(vm_srb->cdb, scmnd->cmnd, vm_srb->cdb_length);
1686 
1687 	sgl = (struct scatterlist *)scsi_sglist(scmnd);
1688 	sg_count = scsi_sg_count(scmnd);
1689 
1690 	length = scsi_bufflen(scmnd);
1691 	payload = (struct vmbus_packet_mpb_array *)&cmd_request->mpb;
1692 	payload_sz = sizeof(cmd_request->mpb);
1693 
1694 	if (sg_count) {
1695 		/* check if we need to bounce the sgl */
1696 		if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) {
1697 			cmd_request->bounce_sgl =
1698 				create_bounce_buffer(sgl, sg_count,
1699 						     length,
1700 						     vm_srb->data_in);
1701 			if (!cmd_request->bounce_sgl)
1702 				return SCSI_MLQUEUE_HOST_BUSY;
1703 
1704 			cmd_request->bounce_sgl_count =
1705 				ALIGN(length, PAGE_SIZE) >> PAGE_SHIFT;
1706 
1707 			if (vm_srb->data_in == WRITE_TYPE)
1708 				copy_to_bounce_buffer(sgl,
1709 					cmd_request->bounce_sgl, sg_count);
1710 
1711 			sgl = cmd_request->bounce_sgl;
1712 			sg_count = cmd_request->bounce_sgl_count;
1713 		}
1714 
1715 
1716 		if (sg_count > MAX_PAGE_BUFFER_COUNT) {
1717 
1718 			payload_sz = (sg_count * sizeof(void *) +
1719 				      sizeof(struct vmbus_packet_mpb_array));
1720 			payload = kmalloc(payload_sz, GFP_ATOMIC);
1721 			if (!payload) {
1722 				if (cmd_request->bounce_sgl_count)
1723 					destroy_bounce_buffer(
1724 					cmd_request->bounce_sgl,
1725 					cmd_request->bounce_sgl_count);
1726 
1727 					return SCSI_MLQUEUE_DEVICE_BUSY;
1728 			}
1729 		}
1730 
1731 		payload->range.len = length;
1732 		payload->range.offset = sgl[0].offset;
1733 
1734 		cur_sgl = sgl;
1735 		for (i = 0; i < sg_count; i++) {
1736 			payload->range.pfn_array[i] =
1737 				page_to_pfn(sg_page((cur_sgl)));
1738 			cur_sgl = sg_next(cur_sgl);
1739 		}
1740 
1741 	} else if (scsi_sglist(scmnd)) {
1742 		payload->range.len = length;
1743 		payload->range.offset =
1744 			virt_to_phys(scsi_sglist(scmnd)) & (PAGE_SIZE-1);
1745 		payload->range.pfn_array[0] =
1746 			virt_to_phys(scsi_sglist(scmnd)) >> PAGE_SHIFT;
1747 	}
1748 
1749 	cmd_request->payload = payload;
1750 	cmd_request->payload_sz = payload_sz;
1751 
1752 	/* Invokes the vsc to start an IO */
1753 	ret = storvsc_do_io(dev, cmd_request);
1754 
1755 	if (ret == -EAGAIN) {
1756 		/* no more space */
1757 
1758 		if (cmd_request->bounce_sgl_count)
1759 			destroy_bounce_buffer(cmd_request->bounce_sgl,
1760 					cmd_request->bounce_sgl_count);
1761 
1762 		return SCSI_MLQUEUE_DEVICE_BUSY;
1763 	}
1764 
1765 	return 0;
1766 }
1767 
1768 static struct scsi_host_template scsi_driver = {
1769 	.module	=		THIS_MODULE,
1770 	.name =			"storvsc_host_t",
1771 	.cmd_size =             sizeof(struct storvsc_cmd_request),
1772 	.bios_param =		storvsc_get_chs,
1773 	.queuecommand =		storvsc_queuecommand,
1774 	.eh_host_reset_handler =	storvsc_host_reset_handler,
1775 	.proc_name =		"storvsc_host",
1776 	.eh_timed_out =		storvsc_eh_timed_out,
1777 	.slave_configure =	storvsc_device_configure,
1778 	.cmd_per_lun =		255,
1779 	.this_id =		-1,
1780 	.use_clustering =	ENABLE_CLUSTERING,
1781 	/* Make sure we dont get a sg segment crosses a page boundary */
1782 	.dma_boundary =		PAGE_SIZE-1,
1783 	.no_write_same =	1,
1784 };
1785 
1786 enum {
1787 	SCSI_GUID,
1788 	IDE_GUID,
1789 	SFC_GUID,
1790 };
1791 
1792 static const struct hv_vmbus_device_id id_table[] = {
1793 	/* SCSI guid */
1794 	{ HV_SCSI_GUID,
1795 	  .driver_data = SCSI_GUID
1796 	},
1797 	/* IDE guid */
1798 	{ HV_IDE_GUID,
1799 	  .driver_data = IDE_GUID
1800 	},
1801 	/* Fibre Channel GUID */
1802 	{
1803 	  HV_SYNTHFC_GUID,
1804 	  .driver_data = SFC_GUID
1805 	},
1806 	{ },
1807 };
1808 
1809 MODULE_DEVICE_TABLE(vmbus, id_table);
1810 
1811 static int storvsc_probe(struct hv_device *device,
1812 			const struct hv_vmbus_device_id *dev_id)
1813 {
1814 	int ret;
1815 	int num_cpus = num_online_cpus();
1816 	struct Scsi_Host *host;
1817 	struct hv_host_device *host_dev;
1818 	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
1819 	int target = 0;
1820 	struct storvsc_device *stor_device;
1821 	int max_luns_per_target;
1822 	int max_targets;
1823 	int max_channels;
1824 	int max_sub_channels = 0;
1825 
1826 	/*
1827 	 * Based on the windows host we are running on,
1828 	 * set state to properly communicate with the host.
1829 	 */
1830 
1831 	if (vmbus_proto_version < VERSION_WIN8) {
1832 		max_luns_per_target = STORVSC_IDE_MAX_LUNS_PER_TARGET;
1833 		max_targets = STORVSC_IDE_MAX_TARGETS;
1834 		max_channels = STORVSC_IDE_MAX_CHANNELS;
1835 	} else {
1836 		max_luns_per_target = STORVSC_MAX_LUNS_PER_TARGET;
1837 		max_targets = STORVSC_MAX_TARGETS;
1838 		max_channels = STORVSC_MAX_CHANNELS;
1839 		/*
1840 		 * On Windows8 and above, we support sub-channels for storage.
1841 		 * The number of sub-channels offerred is based on the number of
1842 		 * VCPUs in the guest.
1843 		 */
1844 		max_sub_channels = (num_cpus / storvsc_vcpus_per_sub_channel);
1845 	}
1846 
1847 	scsi_driver.can_queue = (max_outstanding_req_per_channel *
1848 				 (max_sub_channels + 1));
1849 
1850 	host = scsi_host_alloc(&scsi_driver,
1851 			       sizeof(struct hv_host_device));
1852 	if (!host)
1853 		return -ENOMEM;
1854 
1855 	host_dev = shost_priv(host);
1856 	memset(host_dev, 0, sizeof(struct hv_host_device));
1857 
1858 	host_dev->port = host->host_no;
1859 	host_dev->dev = device;
1860 
1861 
1862 	stor_device = kzalloc(sizeof(struct storvsc_device), GFP_KERNEL);
1863 	if (!stor_device) {
1864 		ret = -ENOMEM;
1865 		goto err_out0;
1866 	}
1867 
1868 	stor_device->destroy = false;
1869 	stor_device->open_sub_channel = false;
1870 	init_waitqueue_head(&stor_device->waiting_to_drain);
1871 	stor_device->device = device;
1872 	stor_device->host = host;
1873 	hv_set_drvdata(device, stor_device);
1874 
1875 	stor_device->port_number = host->host_no;
1876 	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
1877 	if (ret)
1878 		goto err_out1;
1879 
1880 	host_dev->path = stor_device->path_id;
1881 	host_dev->target = stor_device->target_id;
1882 
1883 	switch (dev_id->driver_data) {
1884 	case SFC_GUID:
1885 		host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
1886 		host->max_id = STORVSC_FC_MAX_TARGETS;
1887 		host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
1888 		break;
1889 
1890 	case SCSI_GUID:
1891 		host->max_lun = max_luns_per_target;
1892 		host->max_id = max_targets;
1893 		host->max_channel = max_channels - 1;
1894 		break;
1895 
1896 	default:
1897 		host->max_lun = STORVSC_IDE_MAX_LUNS_PER_TARGET;
1898 		host->max_id = STORVSC_IDE_MAX_TARGETS;
1899 		host->max_channel = STORVSC_IDE_MAX_CHANNELS - 1;
1900 		break;
1901 	}
1902 	/* max cmd length */
1903 	host->max_cmd_len = STORVSC_MAX_CMD_LEN;
1904 
1905 	/*
1906 	 * set the table size based on the info we got
1907 	 * from the host.
1908 	 */
1909 	host->sg_tablesize = (stor_device->max_transfer_bytes >> PAGE_SHIFT);
1910 
1911 	/* Register the HBA and start the scsi bus scan */
1912 	ret = scsi_add_host(host, &device->device);
1913 	if (ret != 0)
1914 		goto err_out2;
1915 
1916 	if (!dev_is_ide) {
1917 		scsi_scan_host(host);
1918 	} else {
1919 		target = (device->dev_instance.b[5] << 8 |
1920 			 device->dev_instance.b[4]);
1921 		ret = scsi_add_device(host, 0, target, 0);
1922 		if (ret) {
1923 			scsi_remove_host(host);
1924 			goto err_out2;
1925 		}
1926 	}
1927 	return 0;
1928 
1929 err_out2:
1930 	/*
1931 	 * Once we have connected with the host, we would need to
1932 	 * to invoke storvsc_dev_remove() to rollback this state and
1933 	 * this call also frees up the stor_device; hence the jump around
1934 	 * err_out1 label.
1935 	 */
1936 	storvsc_dev_remove(device);
1937 	goto err_out0;
1938 
1939 err_out1:
1940 	kfree(stor_device);
1941 
1942 err_out0:
1943 	scsi_host_put(host);
1944 	return ret;
1945 }
1946 
1947 static int storvsc_remove(struct hv_device *dev)
1948 {
1949 	struct storvsc_device *stor_device = hv_get_drvdata(dev);
1950 	struct Scsi_Host *host = stor_device->host;
1951 
1952 	scsi_remove_host(host);
1953 	storvsc_dev_remove(dev);
1954 	scsi_host_put(host);
1955 
1956 	return 0;
1957 }
1958 
1959 static struct hv_driver storvsc_drv = {
1960 	.name = KBUILD_MODNAME,
1961 	.id_table = id_table,
1962 	.probe = storvsc_probe,
1963 	.remove = storvsc_remove,
1964 };
1965 
1966 static int __init storvsc_drv_init(void)
1967 {
1968 
1969 	/*
1970 	 * Divide the ring buffer data size (which is 1 page less
1971 	 * than the ring buffer size since that page is reserved for
1972 	 * the ring buffer indices) by the max request size (which is
1973 	 * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
1974 	 */
1975 	max_outstanding_req_per_channel =
1976 		((storvsc_ringbuffer_size - PAGE_SIZE) /
1977 		ALIGN(MAX_MULTIPAGE_BUFFER_PACKET +
1978 		sizeof(struct vstor_packet) + sizeof(u64) -
1979 		vmscsi_size_delta,
1980 		sizeof(u64)));
1981 
1982 	return vmbus_driver_register(&storvsc_drv);
1983 }
1984 
1985 static void __exit storvsc_drv_exit(void)
1986 {
1987 	vmbus_driver_unregister(&storvsc_drv);
1988 }
1989 
1990 MODULE_LICENSE("GPL");
1991 MODULE_DESCRIPTION("Microsoft Hyper-V virtual storage driver");
1992 module_init(storvsc_drv_init);
1993 module_exit(storvsc_drv_exit);
1994