xref: /linux/drivers/hv/hv_balloon.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2012, Microsoft Corporation.
4  *
5  * Author:
6  *   K. Y. Srinivasan <kys@microsoft.com>
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 
11 #include <linux/cleanup.h>
12 #include <linux/kernel.h>
13 #include <linux/jiffies.h>
14 #include <linux/mman.h>
15 #include <linux/debugfs.h>
16 #include <linux/delay.h>
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 #include <linux/kthread.h>
21 #include <linux/completion.h>
22 #include <linux/count_zeros.h>
23 #include <linux/memory_hotplug.h>
24 #include <linux/memory.h>
25 #include <linux/notifier.h>
26 #include <linux/percpu_counter.h>
27 #include <linux/page_reporting.h>
28 #include <linux/sizes.h>
29 
30 #include <linux/hyperv.h>
31 #include <asm/hyperv-tlfs.h>
32 
33 #include <asm/mshyperv.h>
34 
35 #define CREATE_TRACE_POINTS
36 #include "hv_trace_balloon.h"
37 
38 /*
39  * We begin with definitions supporting the Dynamic Memory protocol
40  * with the host.
41  *
42  * Begin protocol definitions.
43  */
44 
45 /*
46  * Protocol versions. The low word is the minor version, the high word the major
47  * version.
48  *
49  * History:
50  * Initial version 1.0
51  * Changed to 0.1 on 2009/03/25
52  * Changes to 0.2 on 2009/05/14
53  * Changes to 0.3 on 2009/12/03
54  * Changed to 1.0 on 2011/04/05
55  */
56 
57 #define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
58 #define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
59 #define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
60 
61 enum {
62 	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
63 	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
64 	DYNMEM_PROTOCOL_VERSION_3 = DYNMEM_MAKE_VERSION(2, 0),
65 
66 	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
67 	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
68 	DYNMEM_PROTOCOL_VERSION_WIN10 = DYNMEM_PROTOCOL_VERSION_3,
69 
70 	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN10
71 };
72 
73 /*
74  * Message Types
75  */
76 
77 enum dm_message_type {
78 	/*
79 	 * Version 0.3
80 	 */
81 	DM_ERROR			= 0,
82 	DM_VERSION_REQUEST		= 1,
83 	DM_VERSION_RESPONSE		= 2,
84 	DM_CAPABILITIES_REPORT		= 3,
85 	DM_CAPABILITIES_RESPONSE	= 4,
86 	DM_STATUS_REPORT		= 5,
87 	DM_BALLOON_REQUEST		= 6,
88 	DM_BALLOON_RESPONSE		= 7,
89 	DM_UNBALLOON_REQUEST		= 8,
90 	DM_UNBALLOON_RESPONSE		= 9,
91 	DM_MEM_HOT_ADD_REQUEST		= 10,
92 	DM_MEM_HOT_ADD_RESPONSE		= 11,
93 	DM_VERSION_03_MAX		= 11,
94 	/*
95 	 * Version 1.0.
96 	 */
97 	DM_INFO_MESSAGE			= 12,
98 	DM_VERSION_1_MAX		= 12
99 };
100 
101 /*
102  * Structures defining the dynamic memory management
103  * protocol.
104  */
105 
106 union dm_version {
107 	struct {
108 		__u16 minor_version;
109 		__u16 major_version;
110 	};
111 	__u32 version;
112 } __packed;
113 
114 union dm_caps {
115 	struct {
116 		__u64 balloon:1;
117 		__u64 hot_add:1;
118 		/*
119 		 * To support guests that may have alignment
120 		 * limitations on hot-add, the guest can specify
121 		 * its alignment requirements; a value of n
122 		 * represents an alignment of 2^n in mega bytes.
123 		 */
124 		__u64 hot_add_alignment:4;
125 		__u64 reservedz:58;
126 	} cap_bits;
127 	__u64 caps;
128 } __packed;
129 
130 union dm_mem_page_range {
131 	struct  {
132 		/*
133 		 * The PFN number of the first page in the range.
134 		 * 40 bits is the architectural limit of a PFN
135 		 * number for AMD64.
136 		 */
137 		__u64 start_page:40;
138 		/*
139 		 * The number of pages in the range.
140 		 */
141 		__u64 page_cnt:24;
142 	} finfo;
143 	__u64  page_range;
144 } __packed;
145 
146 /*
147  * The header for all dynamic memory messages:
148  *
149  * type: Type of the message.
150  * size: Size of the message in bytes; including the header.
151  * trans_id: The guest is responsible for manufacturing this ID.
152  */
153 
154 struct dm_header {
155 	__u16 type;
156 	__u16 size;
157 	__u32 trans_id;
158 } __packed;
159 
160 /*
161  * A generic message format for dynamic memory.
162  * Specific message formats are defined later in the file.
163  */
164 
165 struct dm_message {
166 	struct dm_header hdr;
167 	__u8 data[]; /* enclosed message */
168 } __packed;
169 
170 /*
171  * Specific message types supporting the dynamic memory protocol.
172  */
173 
174 /*
175  * Version negotiation message. Sent from the guest to the host.
176  * The guest is free to try different versions until the host
177  * accepts the version.
178  *
179  * dm_version: The protocol version requested.
180  * is_last_attempt: If TRUE, this is the last version guest will request.
181  * reservedz: Reserved field, set to zero.
182  */
183 
184 struct dm_version_request {
185 	struct dm_header hdr;
186 	union dm_version version;
187 	__u32 is_last_attempt:1;
188 	__u32 reservedz:31;
189 } __packed;
190 
191 /*
192  * Version response message; Host to Guest and indicates
193  * if the host has accepted the version sent by the guest.
194  *
195  * is_accepted: If TRUE, host has accepted the version and the guest
196  * should proceed to the next stage of the protocol. FALSE indicates that
197  * guest should re-try with a different version.
198  *
199  * reservedz: Reserved field, set to zero.
200  */
201 
202 struct dm_version_response {
203 	struct dm_header hdr;
204 	__u64 is_accepted:1;
205 	__u64 reservedz:63;
206 } __packed;
207 
208 /*
209  * Message reporting capabilities. This is sent from the guest to the
210  * host.
211  */
212 
213 struct dm_capabilities {
214 	struct dm_header hdr;
215 	union dm_caps caps;
216 	__u64 min_page_cnt;
217 	__u64 max_page_number;
218 } __packed;
219 
220 /*
221  * Response to the capabilities message. This is sent from the host to the
222  * guest. This message notifies if the host has accepted the guest's
223  * capabilities. If the host has not accepted, the guest must shutdown
224  * the service.
225  *
226  * is_accepted: Indicates if the host has accepted guest's capabilities.
227  * reservedz: Must be 0.
228  */
229 
230 struct dm_capabilities_resp_msg {
231 	struct dm_header hdr;
232 	__u64 is_accepted:1;
233 	__u64 reservedz:63;
234 } __packed;
235 
236 /*
237  * This message is used to report memory pressure from the guest.
238  * This message is not part of any transaction and there is no
239  * response to this message.
240  *
241  * num_avail: Available memory in pages.
242  * num_committed: Committed memory in pages.
243  * page_file_size: The accumulated size of all page files
244  *		   in the system in pages.
245  * zero_free: The number of zero and free pages.
246  * page_file_writes: The writes to the page file in pages.
247  * io_diff: An indicator of file cache efficiency or page file activity,
248  *	    calculated as File Cache Page Fault Count - Page Read Count.
249  *	    This value is in pages.
250  *
251  * Some of these metrics are Windows specific and fortunately
252  * the algorithm on the host side that computes the guest memory
253  * pressure only uses num_committed value.
254  */
255 
256 struct dm_status {
257 	struct dm_header hdr;
258 	__u64 num_avail;
259 	__u64 num_committed;
260 	__u64 page_file_size;
261 	__u64 zero_free;
262 	__u32 page_file_writes;
263 	__u32 io_diff;
264 } __packed;
265 
266 /*
267  * Message to ask the guest to allocate memory - balloon up message.
268  * This message is sent from the host to the guest. The guest may not be
269  * able to allocate as much memory as requested.
270  *
271  * num_pages: number of pages to allocate.
272  */
273 
274 struct dm_balloon {
275 	struct dm_header hdr;
276 	__u32 num_pages;
277 	__u32 reservedz;
278 } __packed;
279 
280 /*
281  * Balloon response message; this message is sent from the guest
282  * to the host in response to the balloon message.
283  *
284  * reservedz: Reserved; must be set to zero.
285  * more_pages: If FALSE, this is the last message of the transaction.
286  * if TRUE there will be at least one more message from the guest.
287  *
288  * range_count: The number of ranges in the range array.
289  *
290  * range_array: An array of page ranges returned to the host.
291  *
292  */
293 
294 struct dm_balloon_response {
295 	struct dm_header hdr;
296 	__u32 reservedz;
297 	__u32 more_pages:1;
298 	__u32 range_count:31;
299 	union dm_mem_page_range range_array[];
300 } __packed;
301 
302 /*
303  * Un-balloon message; this message is sent from the host
304  * to the guest to give guest more memory.
305  *
306  * more_pages: If FALSE, this is the last message of the transaction.
307  * if TRUE there will be at least one more message from the guest.
308  *
309  * reservedz: Reserved; must be set to zero.
310  *
311  * range_count: The number of ranges in the range array.
312  *
313  * range_array: An array of page ranges returned to the host.
314  *
315  */
316 
317 struct dm_unballoon_request {
318 	struct dm_header hdr;
319 	__u32 more_pages:1;
320 	__u32 reservedz:31;
321 	__u32 range_count;
322 	union dm_mem_page_range range_array[];
323 } __packed;
324 
325 /*
326  * Un-balloon response message; this message is sent from the guest
327  * to the host in response to an unballoon request.
328  *
329  */
330 
331 struct dm_unballoon_response {
332 	struct dm_header hdr;
333 } __packed;
334 
335 /*
336  * Hot add request message. Message sent from the host to the guest.
337  *
338  * mem_range: Memory range to hot add.
339  *
340  */
341 
342 struct dm_hot_add {
343 	struct dm_header hdr;
344 	union dm_mem_page_range range;
345 } __packed;
346 
347 /*
348  * Hot add response message.
349  * This message is sent by the guest to report the status of a hot add request.
350  * If page_count is less than the requested page count, then the host should
351  * assume all further hot add requests will fail, since this indicates that
352  * the guest has hit an upper physical memory barrier.
353  *
354  * Hot adds may also fail due to low resources; in this case, the guest must
355  * not complete this message until the hot add can succeed, and the host must
356  * not send a new hot add request until the response is sent.
357  * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
358  * times it fails the request.
359  *
360  *
361  * page_count: number of pages that were successfully hot added.
362  *
363  * result: result of the operation 1: success, 0: failure.
364  *
365  */
366 
367 struct dm_hot_add_response {
368 	struct dm_header hdr;
369 	__u32 page_count;
370 	__u32 result;
371 } __packed;
372 
373 /*
374  * Types of information sent from host to the guest.
375  */
376 
377 enum dm_info_type {
378 	INFO_TYPE_MAX_PAGE_CNT = 0,
379 	MAX_INFO_TYPE
380 };
381 
382 /*
383  * Header for the information message.
384  */
385 
386 struct dm_info_header {
387 	enum dm_info_type type;
388 	__u32 data_size;
389 } __packed;
390 
391 /*
392  * This message is sent from the host to the guest to pass
393  * some relevant information (win8 addition).
394  *
395  * reserved: no used.
396  * info_size: size of the information blob.
397  * info: information blob.
398  */
399 
400 struct dm_info_msg {
401 	struct dm_header hdr;
402 	__u32 reserved;
403 	__u32 info_size;
404 	__u8  info[];
405 };
406 
407 /*
408  * End protocol definitions.
409  */
410 
411 /*
412  * State to manage hot adding memory into the guest.
413  * The range start_pfn : end_pfn specifies the range
414  * that the host has asked us to hot add. The range
415  * start_pfn : ha_end_pfn specifies the range that we have
416  * currently hot added. We hot add in chunks equal to the
417  * memory block size; it is possible that we may not be able
418  * to bring online all the pages in the region. The range
419  * covered_start_pfn:covered_end_pfn defines the pages that can
420  * be brought online.
421  */
422 
423 struct hv_hotadd_state {
424 	struct list_head list;
425 	unsigned long start_pfn;
426 	unsigned long covered_start_pfn;
427 	unsigned long covered_end_pfn;
428 	unsigned long ha_end_pfn;
429 	unsigned long end_pfn;
430 	/*
431 	 * A list of gaps.
432 	 */
433 	struct list_head gap_list;
434 };
435 
436 struct hv_hotadd_gap {
437 	struct list_head list;
438 	unsigned long start_pfn;
439 	unsigned long end_pfn;
440 };
441 
442 struct balloon_state {
443 	__u32 num_pages;
444 	struct work_struct wrk;
445 };
446 
447 struct hot_add_wrk {
448 	union dm_mem_page_range ha_page_range;
449 	union dm_mem_page_range ha_region_range;
450 	struct work_struct wrk;
451 };
452 
453 static bool allow_hibernation;
454 static bool hot_add = true;
455 static bool do_hot_add;
456 /*
457  * Delay reporting memory pressure by
458  * the specified number of seconds.
459  */
460 static uint pressure_report_delay = 45;
461 extern unsigned int page_reporting_order;
462 #define HV_MAX_FAILURES	2
463 
464 /*
465  * The last time we posted a pressure report to host.
466  */
467 static unsigned long last_post_time;
468 
469 static int hv_hypercall_multi_failure;
470 
471 module_param(hot_add, bool, 0644);
472 MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
473 
474 module_param(pressure_report_delay, uint, 0644);
475 MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
476 static atomic_t trans_id = ATOMIC_INIT(0);
477 
478 static int dm_ring_size = VMBUS_RING_SIZE(16 * 1024);
479 
480 /*
481  * Driver specific state.
482  */
483 
484 enum hv_dm_state {
485 	DM_INITIALIZING = 0,
486 	DM_INITIALIZED,
487 	DM_BALLOON_UP,
488 	DM_BALLOON_DOWN,
489 	DM_HOT_ADD,
490 	DM_INIT_ERROR
491 };
492 
493 static __u8 recv_buffer[HV_HYP_PAGE_SIZE];
494 static __u8 balloon_up_send_buffer[HV_HYP_PAGE_SIZE];
495 
496 static unsigned long ha_pages_in_chunk;
497 #define HA_BYTES_IN_CHUNK (ha_pages_in_chunk << PAGE_SHIFT)
498 
499 #define PAGES_IN_2M (2 * 1024 * 1024 / PAGE_SIZE)
500 
501 struct hv_dynmem_device {
502 	struct hv_device *dev;
503 	enum hv_dm_state state;
504 	struct completion host_event;
505 	struct completion config_event;
506 
507 	/*
508 	 * Number of pages we have currently ballooned out.
509 	 */
510 	unsigned int num_pages_ballooned;
511 	unsigned int num_pages_onlined;
512 	unsigned int num_pages_added;
513 
514 	/*
515 	 * State to manage the ballooning (up) operation.
516 	 */
517 	struct balloon_state balloon_wrk;
518 
519 	/*
520 	 * State to execute the "hot-add" operation.
521 	 */
522 	struct hot_add_wrk ha_wrk;
523 
524 	/*
525 	 * This state tracks if the host has specified a hot-add
526 	 * region.
527 	 */
528 	bool host_specified_ha_region;
529 
530 	/*
531 	 * State to synchronize hot-add.
532 	 */
533 	struct completion  ol_waitevent;
534 	/*
535 	 * This thread handles hot-add
536 	 * requests from the host as well as notifying
537 	 * the host with regards to memory pressure in
538 	 * the guest.
539 	 */
540 	struct task_struct *thread;
541 
542 	/*
543 	 * Protects ha_region_list, num_pages_onlined counter and individual
544 	 * regions from ha_region_list.
545 	 */
546 	spinlock_t ha_lock;
547 
548 	/*
549 	 * A list of hot-add regions.
550 	 */
551 	struct list_head ha_region_list;
552 
553 	/*
554 	 * We start with the highest version we can support
555 	 * and downgrade based on the host; we save here the
556 	 * next version to try.
557 	 */
558 	__u32 next_version;
559 
560 	/*
561 	 * The negotiated version agreed by host.
562 	 */
563 	__u32 version;
564 
565 	struct page_reporting_dev_info pr_dev_info;
566 
567 	/*
568 	 * Maximum number of pages that can be hot_add-ed
569 	 */
570 	__u64 max_dynamic_page_count;
571 };
572 
573 static struct hv_dynmem_device dm_device;
574 
575 static void post_status(struct hv_dynmem_device *dm);
576 
577 static void enable_page_reporting(void);
578 
579 static void disable_page_reporting(void);
580 
581 #ifdef CONFIG_MEMORY_HOTPLUG
has_pfn_is_backed(struct hv_hotadd_state * has,unsigned long pfn)582 static inline bool has_pfn_is_backed(struct hv_hotadd_state *has,
583 				     unsigned long pfn)
584 {
585 	struct hv_hotadd_gap *gap;
586 
587 	/* The page is not backed. */
588 	if (pfn < has->covered_start_pfn || pfn >= has->covered_end_pfn)
589 		return false;
590 
591 	/* Check for gaps. */
592 	list_for_each_entry(gap, &has->gap_list, list) {
593 		if (pfn >= gap->start_pfn && pfn < gap->end_pfn)
594 			return false;
595 	}
596 
597 	return true;
598 }
599 
hv_page_offline_check(unsigned long start_pfn,unsigned long nr_pages)600 static unsigned long hv_page_offline_check(unsigned long start_pfn,
601 					   unsigned long nr_pages)
602 {
603 	unsigned long pfn = start_pfn, count = 0;
604 	struct hv_hotadd_state *has;
605 	bool found;
606 
607 	while (pfn < start_pfn + nr_pages) {
608 		/*
609 		 * Search for HAS which covers the pfn and when we find one
610 		 * count how many consequitive PFNs are covered.
611 		 */
612 		found = false;
613 		list_for_each_entry(has, &dm_device.ha_region_list, list) {
614 			while ((pfn >= has->start_pfn) &&
615 			       (pfn < has->end_pfn) &&
616 			       (pfn < start_pfn + nr_pages)) {
617 				found = true;
618 				if (has_pfn_is_backed(has, pfn))
619 					count++;
620 				pfn++;
621 			}
622 		}
623 
624 		/*
625 		 * This PFN is not in any HAS (e.g. we're offlining a region
626 		 * which was present at boot), no need to account for it. Go
627 		 * to the next one.
628 		 */
629 		if (!found)
630 			pfn++;
631 	}
632 
633 	return count;
634 }
635 
hv_memory_notifier(struct notifier_block * nb,unsigned long val,void * v)636 static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
637 			      void *v)
638 {
639 	struct memory_notify *mem = (struct memory_notify *)v;
640 	unsigned long pfn_count;
641 
642 	switch (val) {
643 	case MEM_ONLINE:
644 	case MEM_CANCEL_ONLINE:
645 		complete(&dm_device.ol_waitevent);
646 		break;
647 
648 	case MEM_OFFLINE:
649 		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
650 			pfn_count = hv_page_offline_check(mem->start_pfn,
651 							  mem->nr_pages);
652 			if (pfn_count <= dm_device.num_pages_onlined) {
653 				dm_device.num_pages_onlined -= pfn_count;
654 			} else {
655 				/*
656 				 * We're offlining more pages than we
657 				 * managed to online. This is
658 				 * unexpected. In any case don't let
659 				 * num_pages_onlined wrap around zero.
660 				 */
661 				WARN_ON_ONCE(1);
662 				dm_device.num_pages_onlined = 0;
663 			}
664 		}
665 		break;
666 	case MEM_GOING_ONLINE:
667 	case MEM_GOING_OFFLINE:
668 	case MEM_CANCEL_OFFLINE:
669 		break;
670 	}
671 	return NOTIFY_OK;
672 }
673 
674 static struct notifier_block hv_memory_nb = {
675 	.notifier_call = hv_memory_notifier,
676 	.priority = 0
677 };
678 
679 /* Check if the particular page is backed and can be onlined and online it. */
hv_page_online_one(struct hv_hotadd_state * has,struct page * pg)680 static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
681 {
682 	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
683 		if (!PageOffline(pg))
684 			__SetPageOffline(pg);
685 		return;
686 	} else if (!PageOffline(pg))
687 		return;
688 
689 	/* This frame is currently backed; online the page. */
690 	generic_online_page(pg, 0);
691 
692 	lockdep_assert_held(&dm_device.ha_lock);
693 	dm_device.num_pages_onlined++;
694 }
695 
hv_bring_pgs_online(struct hv_hotadd_state * has,unsigned long start_pfn,unsigned long size)696 static void hv_bring_pgs_online(struct hv_hotadd_state *has,
697 				unsigned long start_pfn, unsigned long size)
698 {
699 	int i;
700 
701 	pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
702 	for (i = 0; i < size; i++)
703 		hv_page_online_one(has, pfn_to_page(start_pfn + i));
704 }
705 
hv_mem_hot_add(unsigned long start,unsigned long size,unsigned long pfn_count,struct hv_hotadd_state * has)706 static void hv_mem_hot_add(unsigned long start, unsigned long size,
707 				unsigned long pfn_count,
708 				struct hv_hotadd_state *has)
709 {
710 	int ret = 0;
711 	int i, nid;
712 	unsigned long start_pfn;
713 	unsigned long processed_pfn;
714 	unsigned long total_pfn = pfn_count;
715 
716 	for (i = 0; i < (size/ha_pages_in_chunk); i++) {
717 		start_pfn = start + (i * ha_pages_in_chunk);
718 
719 		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
720 			has->ha_end_pfn += ha_pages_in_chunk;
721 			processed_pfn = umin(total_pfn, ha_pages_in_chunk);
722 			total_pfn -= processed_pfn;
723 			has->covered_end_pfn += processed_pfn;
724 		}
725 
726 		reinit_completion(&dm_device.ol_waitevent);
727 
728 		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
729 		ret = add_memory(nid, PFN_PHYS((start_pfn)),
730 				 HA_BYTES_IN_CHUNK, MHP_MERGE_RESOURCE);
731 
732 		if (ret) {
733 			pr_err("hot_add memory failed error is %d\n", ret);
734 			if (ret == -EEXIST) {
735 				/*
736 				 * This error indicates that the error
737 				 * is not a transient failure. This is the
738 				 * case where the guest's physical address map
739 				 * precludes hot adding memory. Stop all further
740 				 * memory hot-add.
741 				 */
742 				do_hot_add = false;
743 			}
744 			scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
745 				has->ha_end_pfn -= ha_pages_in_chunk;
746 				has->covered_end_pfn -=  processed_pfn;
747 			}
748 			break;
749 		}
750 
751 		/*
752 		 * Wait for memory to get onlined. If the kernel onlined the
753 		 * memory when adding it, this will return directly. Otherwise,
754 		 * it will wait for user space to online the memory. This helps
755 		 * to avoid adding memory faster than it is getting onlined. As
756 		 * adding succeeded, it is ok to proceed even if the memory was
757 		 * not onlined in time.
758 		 */
759 		wait_for_completion_timeout(&dm_device.ol_waitevent, 5 * HZ);
760 		post_status(&dm_device);
761 	}
762 }
763 
hv_online_page(struct page * pg,unsigned int order)764 static void hv_online_page(struct page *pg, unsigned int order)
765 {
766 	struct hv_hotadd_state *has;
767 	unsigned long pfn = page_to_pfn(pg);
768 
769 	guard(spinlock_irqsave)(&dm_device.ha_lock);
770 	list_for_each_entry(has, &dm_device.ha_region_list, list) {
771 		/* The page belongs to a different HAS. */
772 		if (pfn < has->start_pfn ||
773 		    (pfn + (1UL << order) > has->end_pfn))
774 			continue;
775 
776 		hv_bring_pgs_online(has, pfn, 1UL << order);
777 		break;
778 	}
779 }
780 
pfn_covered(unsigned long start_pfn,unsigned long pfn_cnt)781 static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
782 {
783 	struct hv_hotadd_state *has;
784 	struct hv_hotadd_gap *gap;
785 	unsigned long residual;
786 	int ret = 0;
787 
788 	guard(spinlock_irqsave)(&dm_device.ha_lock);
789 	list_for_each_entry(has, &dm_device.ha_region_list, list) {
790 		/*
791 		 * If the pfn range we are dealing with is not in the current
792 		 * "hot add block", move on.
793 		 */
794 		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
795 			continue;
796 
797 		/*
798 		 * If the current start pfn is not where the covered_end
799 		 * is, create a gap and update covered_end_pfn.
800 		 */
801 		if (has->covered_end_pfn != start_pfn) {
802 			gap = kzalloc(sizeof(struct hv_hotadd_gap), GFP_ATOMIC);
803 			if (!gap) {
804 				ret = -ENOMEM;
805 				break;
806 			}
807 
808 			INIT_LIST_HEAD(&gap->list);
809 			gap->start_pfn = has->covered_end_pfn;
810 			gap->end_pfn = start_pfn;
811 			list_add_tail(&gap->list, &has->gap_list);
812 
813 			has->covered_end_pfn = start_pfn;
814 		}
815 
816 		/*
817 		 * If the current hot add-request extends beyond
818 		 * our current limit; extend it.
819 		 */
820 		if ((start_pfn + pfn_cnt) > has->end_pfn) {
821 			/* Extend the region by multiples of ha_pages_in_chunk */
822 			residual = (start_pfn + pfn_cnt - has->end_pfn);
823 			has->end_pfn += ALIGN(residual, ha_pages_in_chunk);
824 		}
825 
826 		ret = 1;
827 		break;
828 	}
829 
830 	return ret;
831 }
832 
handle_pg_range(unsigned long pg_start,unsigned long pg_count)833 static unsigned long handle_pg_range(unsigned long pg_start,
834 				     unsigned long pg_count)
835 {
836 	unsigned long start_pfn = pg_start;
837 	unsigned long pfn_cnt = pg_count;
838 	unsigned long size;
839 	struct hv_hotadd_state *has;
840 	unsigned long pgs_ol = 0;
841 	unsigned long old_covered_state;
842 	unsigned long res = 0, flags;
843 
844 	pr_debug("Hot adding %lu pages starting at pfn 0x%lx.\n", pg_count,
845 		 pg_start);
846 
847 	spin_lock_irqsave(&dm_device.ha_lock, flags);
848 	list_for_each_entry(has, &dm_device.ha_region_list, list) {
849 		/*
850 		 * If the pfn range we are dealing with is not in the current
851 		 * "hot add block", move on.
852 		 */
853 		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
854 			continue;
855 
856 		old_covered_state = has->covered_end_pfn;
857 
858 		if (start_pfn < has->ha_end_pfn) {
859 			/*
860 			 * This is the case where we are backing pages
861 			 * in an already hot added region. Bring
862 			 * these pages online first.
863 			 */
864 			pgs_ol = has->ha_end_pfn - start_pfn;
865 			if (pgs_ol > pfn_cnt)
866 				pgs_ol = pfn_cnt;
867 
868 			has->covered_end_pfn +=  pgs_ol;
869 			pfn_cnt -= pgs_ol;
870 			/*
871 			 * Check if the corresponding memory block is already
872 			 * online. It is possible to observe struct pages still
873 			 * being uninitialized here so check section instead.
874 			 * In case the section is online we need to bring the
875 			 * rest of pfns (which were not backed previously)
876 			 * online too.
877 			 */
878 			if (start_pfn > has->start_pfn &&
879 			    online_section_nr(pfn_to_section_nr(start_pfn)))
880 				hv_bring_pgs_online(has, start_pfn, pgs_ol);
881 		}
882 
883 		if (has->ha_end_pfn < has->end_pfn && pfn_cnt > 0) {
884 			/*
885 			 * We have some residual hot add range
886 			 * that needs to be hot added; hot add
887 			 * it now. Hot add a multiple of
888 			 * ha_pages_in_chunk that fully covers the pages
889 			 * we have.
890 			 */
891 			size = (has->end_pfn - has->ha_end_pfn);
892 			if (pfn_cnt <= size) {
893 				size = ALIGN(pfn_cnt, ha_pages_in_chunk);
894 			} else {
895 				pfn_cnt = size;
896 			}
897 			spin_unlock_irqrestore(&dm_device.ha_lock, flags);
898 			hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
899 			spin_lock_irqsave(&dm_device.ha_lock, flags);
900 		}
901 		/*
902 		 * If we managed to online any pages that were given to us,
903 		 * we declare success.
904 		 */
905 		res = has->covered_end_pfn - old_covered_state;
906 		break;
907 	}
908 	spin_unlock_irqrestore(&dm_device.ha_lock, flags);
909 
910 	return res;
911 }
912 
process_hot_add(unsigned long pg_start,unsigned long pfn_cnt,unsigned long rg_start,unsigned long rg_size)913 static unsigned long process_hot_add(unsigned long pg_start,
914 					unsigned long pfn_cnt,
915 					unsigned long rg_start,
916 					unsigned long rg_size)
917 {
918 	struct hv_hotadd_state *ha_region = NULL;
919 	int covered;
920 
921 	if (pfn_cnt == 0)
922 		return 0;
923 
924 	if (!dm_device.host_specified_ha_region) {
925 		covered = pfn_covered(pg_start, pfn_cnt);
926 		if (covered < 0)
927 			return 0;
928 
929 		if (covered)
930 			goto do_pg_range;
931 	}
932 
933 	/*
934 	 * If the host has specified a hot-add range; deal with it first.
935 	 */
936 
937 	if (rg_size != 0) {
938 		ha_region = kzalloc(sizeof(struct hv_hotadd_state), GFP_KERNEL);
939 		if (!ha_region)
940 			return 0;
941 
942 		INIT_LIST_HEAD(&ha_region->list);
943 		INIT_LIST_HEAD(&ha_region->gap_list);
944 
945 		ha_region->start_pfn = rg_start;
946 		ha_region->ha_end_pfn = rg_start;
947 		ha_region->covered_start_pfn = pg_start;
948 		ha_region->covered_end_pfn = pg_start;
949 		ha_region->end_pfn = rg_start + rg_size;
950 
951 		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
952 			list_add_tail(&ha_region->list, &dm_device.ha_region_list);
953 		}
954 	}
955 
956 do_pg_range:
957 	/*
958 	 * Process the page range specified; bringing them
959 	 * online if possible.
960 	 */
961 	return handle_pg_range(pg_start, pfn_cnt);
962 }
963 
964 #endif
965 
hot_add_req(struct work_struct * dummy)966 static void hot_add_req(struct work_struct *dummy)
967 {
968 	struct dm_hot_add_response resp;
969 #ifdef CONFIG_MEMORY_HOTPLUG
970 	unsigned long pg_start, pfn_cnt;
971 	unsigned long rg_start, rg_sz;
972 #endif
973 	struct hv_dynmem_device *dm = &dm_device;
974 
975 	memset(&resp, 0, sizeof(struct dm_hot_add_response));
976 	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
977 	resp.hdr.size = sizeof(struct dm_hot_add_response);
978 
979 #ifdef CONFIG_MEMORY_HOTPLUG
980 	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
981 	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
982 
983 	rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
984 	rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
985 
986 	if (rg_start == 0 && !dm->host_specified_ha_region) {
987 		/*
988 		 * The host has not specified the hot-add region.
989 		 * Based on the hot-add page range being specified,
990 		 * compute a hot-add region that can cover the pages
991 		 * that need to be hot-added while ensuring the alignment
992 		 * and size requirements of Linux as it relates to hot-add.
993 		 */
994 		rg_start = ALIGN_DOWN(pg_start, ha_pages_in_chunk);
995 		rg_sz = ALIGN(pfn_cnt, ha_pages_in_chunk);
996 	}
997 
998 	if (do_hot_add)
999 		resp.page_count = process_hot_add(pg_start, pfn_cnt,
1000 						  rg_start, rg_sz);
1001 
1002 	dm->num_pages_added += resp.page_count;
1003 #endif
1004 	/*
1005 	 * The result field of the response structure has the
1006 	 * following semantics:
1007 	 *
1008 	 * 1. If all or some pages hot-added: Guest should return success.
1009 	 *
1010 	 * 2. If no pages could be hot-added:
1011 	 *
1012 	 * If the guest returns success, then the host
1013 	 * will not attempt any further hot-add operations. This
1014 	 * signifies a permanent failure.
1015 	 *
1016 	 * If the guest returns failure, then this failure will be
1017 	 * treated as a transient failure and the host may retry the
1018 	 * hot-add operation after some delay.
1019 	 */
1020 	if (resp.page_count > 0)
1021 		resp.result = 1;
1022 	else if (!do_hot_add)
1023 		resp.result = 1;
1024 	else
1025 		resp.result = 0;
1026 
1027 	if (!do_hot_add || resp.page_count == 0) {
1028 		if (!allow_hibernation)
1029 			pr_err("Memory hot add failed\n");
1030 		else
1031 			pr_info("Ignore hot-add request!\n");
1032 	}
1033 
1034 	dm->state = DM_INITIALIZED;
1035 	resp.hdr.trans_id = atomic_inc_return(&trans_id);
1036 	vmbus_sendpacket(dm->dev->channel, &resp,
1037 			sizeof(struct dm_hot_add_response),
1038 			(unsigned long)NULL,
1039 			VM_PKT_DATA_INBAND, 0);
1040 }
1041 
process_info(struct hv_dynmem_device * dm,struct dm_info_msg * msg)1042 static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
1043 {
1044 	struct dm_info_header *info_hdr;
1045 
1046 	info_hdr = (struct dm_info_header *)msg->info;
1047 
1048 	switch (info_hdr->type) {
1049 	case INFO_TYPE_MAX_PAGE_CNT:
1050 		if (info_hdr->data_size == sizeof(__u64)) {
1051 			__u64 *max_page_count = (__u64 *)&info_hdr[1];
1052 
1053 			pr_info("Max. dynamic memory size: %llu MB\n",
1054 				(*max_page_count) >> (20 - HV_HYP_PAGE_SHIFT));
1055 			dm->max_dynamic_page_count = *max_page_count;
1056 		}
1057 
1058 		break;
1059 	default:
1060 		pr_warn("Received Unknown type: %d\n", info_hdr->type);
1061 	}
1062 }
1063 
compute_balloon_floor(void)1064 static unsigned long compute_balloon_floor(void)
1065 {
1066 	unsigned long min_pages;
1067 	unsigned long nr_pages = totalram_pages();
1068 #define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
1069 	/* Simple continuous piecewiese linear function:
1070 	 *  max MiB -> min MiB  gradient
1071 	 *       0         0
1072 	 *      16        16
1073 	 *      32        24
1074 	 *     128        72    (1/2)
1075 	 *     512       168    (1/4)
1076 	 *    2048       360    (1/8)
1077 	 *    8192       744    (1/16)
1078 	 *   32768      1512	(1/32)
1079 	 */
1080 	if (nr_pages < MB2PAGES(128))
1081 		min_pages = MB2PAGES(8) + (nr_pages >> 1);
1082 	else if (nr_pages < MB2PAGES(512))
1083 		min_pages = MB2PAGES(40) + (nr_pages >> 2);
1084 	else if (nr_pages < MB2PAGES(2048))
1085 		min_pages = MB2PAGES(104) + (nr_pages >> 3);
1086 	else if (nr_pages < MB2PAGES(8192))
1087 		min_pages = MB2PAGES(232) + (nr_pages >> 4);
1088 	else
1089 		min_pages = MB2PAGES(488) + (nr_pages >> 5);
1090 #undef MB2PAGES
1091 	return min_pages;
1092 }
1093 
1094 /*
1095  * Compute total committed memory pages
1096  */
1097 
get_pages_committed(struct hv_dynmem_device * dm)1098 static unsigned long get_pages_committed(struct hv_dynmem_device *dm)
1099 {
1100 	return vm_memory_committed() +
1101 		dm->num_pages_ballooned +
1102 		(dm->num_pages_added > dm->num_pages_onlined ?
1103 		 dm->num_pages_added - dm->num_pages_onlined : 0) +
1104 		compute_balloon_floor();
1105 }
1106 
1107 /*
1108  * Post our status as it relates memory pressure to the
1109  * host. Host expects the guests to post this status
1110  * periodically at 1 second intervals.
1111  *
1112  * The metrics specified in this protocol are very Windows
1113  * specific and so we cook up numbers here to convey our memory
1114  * pressure.
1115  */
1116 
post_status(struct hv_dynmem_device * dm)1117 static void post_status(struct hv_dynmem_device *dm)
1118 {
1119 	struct dm_status status;
1120 	unsigned long now = jiffies;
1121 	unsigned long last_post = last_post_time;
1122 	unsigned long num_pages_avail, num_pages_committed;
1123 
1124 	if (pressure_report_delay > 0) {
1125 		--pressure_report_delay;
1126 		return;
1127 	}
1128 
1129 	if (!time_after(now, (last_post_time + HZ)))
1130 		return;
1131 
1132 	memset(&status, 0, sizeof(struct dm_status));
1133 	status.hdr.type = DM_STATUS_REPORT;
1134 	status.hdr.size = sizeof(struct dm_status);
1135 	status.hdr.trans_id = atomic_inc_return(&trans_id);
1136 
1137 	/*
1138 	 * The host expects the guest to report free and committed memory.
1139 	 * Furthermore, the host expects the pressure information to include
1140 	 * the ballooned out pages. For a given amount of memory that we are
1141 	 * managing we need to compute a floor below which we should not
1142 	 * balloon. Compute this and add it to the pressure report.
1143 	 * We also need to report all offline pages (num_pages_added -
1144 	 * num_pages_onlined) as committed to the host, otherwise it can try
1145 	 * asking us to balloon them out.
1146 	 */
1147 	num_pages_avail = si_mem_available();
1148 	num_pages_committed = get_pages_committed(dm);
1149 
1150 	trace_balloon_status(num_pages_avail, num_pages_committed,
1151 			     vm_memory_committed(), dm->num_pages_ballooned,
1152 			     dm->num_pages_added, dm->num_pages_onlined);
1153 
1154 	/* Convert numbers of pages into numbers of HV_HYP_PAGEs. */
1155 	status.num_avail = num_pages_avail * NR_HV_HYP_PAGES_IN_PAGE;
1156 	status.num_committed = num_pages_committed * NR_HV_HYP_PAGES_IN_PAGE;
1157 
1158 	/*
1159 	 * If our transaction ID is no longer current, just don't
1160 	 * send the status. This can happen if we were interrupted
1161 	 * after we picked our transaction ID.
1162 	 */
1163 	if (status.hdr.trans_id != atomic_read(&trans_id))
1164 		return;
1165 
1166 	/*
1167 	 * If the last post time that we sampled has changed,
1168 	 * we have raced, don't post the status.
1169 	 */
1170 	if (last_post != last_post_time)
1171 		return;
1172 
1173 	last_post_time = jiffies;
1174 	vmbus_sendpacket(dm->dev->channel, &status,
1175 				sizeof(struct dm_status),
1176 				(unsigned long)NULL,
1177 				VM_PKT_DATA_INBAND, 0);
1178 }
1179 
free_balloon_pages(struct hv_dynmem_device * dm,union dm_mem_page_range * range_array)1180 static void free_balloon_pages(struct hv_dynmem_device *dm,
1181 			       union dm_mem_page_range *range_array)
1182 {
1183 	int num_pages = range_array->finfo.page_cnt;
1184 	__u64 start_frame = range_array->finfo.start_page;
1185 	struct page *pg;
1186 	int i;
1187 
1188 	for (i = 0; i < num_pages; i++) {
1189 		pg = pfn_to_page(i + start_frame);
1190 		__ClearPageOffline(pg);
1191 		__free_page(pg);
1192 		dm->num_pages_ballooned--;
1193 		adjust_managed_page_count(pg, 1);
1194 	}
1195 }
1196 
alloc_balloon_pages(struct hv_dynmem_device * dm,unsigned int num_pages,struct dm_balloon_response * bl_resp,int alloc_unit)1197 static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
1198 					unsigned int num_pages,
1199 					struct dm_balloon_response *bl_resp,
1200 					int alloc_unit)
1201 {
1202 	unsigned int i, j;
1203 	struct page *pg;
1204 
1205 	for (i = 0; i < num_pages / alloc_unit; i++) {
1206 		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
1207 			HV_HYP_PAGE_SIZE)
1208 			return i * alloc_unit;
1209 
1210 		/*
1211 		 * We execute this code in a thread context. Furthermore,
1212 		 * we don't want the kernel to try too hard.
1213 		 */
1214 		pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
1215 				__GFP_NOMEMALLOC | __GFP_NOWARN,
1216 				get_order(alloc_unit << PAGE_SHIFT));
1217 
1218 		if (!pg)
1219 			return i * alloc_unit;
1220 
1221 		dm->num_pages_ballooned += alloc_unit;
1222 
1223 		/*
1224 		 * If we allocatted 2M pages; split them so we
1225 		 * can free them in any order we get.
1226 		 */
1227 
1228 		if (alloc_unit != 1)
1229 			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
1230 
1231 		/* mark all pages offline */
1232 		for (j = 0; j < alloc_unit; j++) {
1233 			__SetPageOffline(pg + j);
1234 			adjust_managed_page_count(pg + j, -1);
1235 		}
1236 
1237 		bl_resp->range_count++;
1238 		bl_resp->range_array[i].finfo.start_page =
1239 			page_to_pfn(pg);
1240 		bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
1241 		bl_resp->hdr.size += sizeof(union dm_mem_page_range);
1242 	}
1243 
1244 	return i * alloc_unit;
1245 }
1246 
balloon_up(struct work_struct * dummy)1247 static void balloon_up(struct work_struct *dummy)
1248 {
1249 	unsigned int num_pages = dm_device.balloon_wrk.num_pages;
1250 	unsigned int num_ballooned = 0;
1251 	struct dm_balloon_response *bl_resp;
1252 	int alloc_unit;
1253 	int ret;
1254 	bool done = false;
1255 	int i;
1256 	long avail_pages;
1257 	unsigned long floor;
1258 
1259 	/*
1260 	 * We will attempt 2M allocations. However, if we fail to
1261 	 * allocate 2M chunks, we will go back to PAGE_SIZE allocations.
1262 	 */
1263 	alloc_unit = PAGES_IN_2M;
1264 
1265 	avail_pages = si_mem_available();
1266 	floor = compute_balloon_floor();
1267 
1268 	/* Refuse to balloon below the floor. */
1269 	if (avail_pages < num_pages || avail_pages - num_pages < floor) {
1270 		pr_info("Balloon request will be partially fulfilled. %s\n",
1271 			avail_pages < num_pages ? "Not enough memory." :
1272 			"Balloon floor reached.");
1273 
1274 		num_pages = avail_pages > floor ? (avail_pages - floor) : 0;
1275 	}
1276 
1277 	while (!done) {
1278 		memset(balloon_up_send_buffer, 0, HV_HYP_PAGE_SIZE);
1279 		bl_resp = (struct dm_balloon_response *)balloon_up_send_buffer;
1280 		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
1281 		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
1282 		bl_resp->more_pages = 1;
1283 
1284 		num_pages -= num_ballooned;
1285 		num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
1286 						    bl_resp, alloc_unit);
1287 
1288 		if (alloc_unit != 1 && num_ballooned == 0) {
1289 			alloc_unit = 1;
1290 			continue;
1291 		}
1292 
1293 		if (num_ballooned == 0 || num_ballooned == num_pages) {
1294 			pr_debug("Ballooned %u out of %u requested pages.\n",
1295 				 num_pages, dm_device.balloon_wrk.num_pages);
1296 
1297 			bl_resp->more_pages = 0;
1298 			done = true;
1299 			dm_device.state = DM_INITIALIZED;
1300 		}
1301 
1302 		/*
1303 		 * We are pushing a lot of data through the channel;
1304 		 * deal with transient failures caused because of the
1305 		 * lack of space in the ring buffer.
1306 		 */
1307 
1308 		do {
1309 			bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
1310 			ret = vmbus_sendpacket(dm_device.dev->channel,
1311 						bl_resp,
1312 						bl_resp->hdr.size,
1313 						(unsigned long)NULL,
1314 						VM_PKT_DATA_INBAND, 0);
1315 
1316 			if (ret == -EAGAIN)
1317 				msleep(20);
1318 			post_status(&dm_device);
1319 		} while (ret == -EAGAIN);
1320 
1321 		if (ret) {
1322 			/*
1323 			 * Free up the memory we allocatted.
1324 			 */
1325 			pr_err("Balloon response failed\n");
1326 
1327 			for (i = 0; i < bl_resp->range_count; i++)
1328 				free_balloon_pages(&dm_device,
1329 						   &bl_resp->range_array[i]);
1330 
1331 			done = true;
1332 		}
1333 	}
1334 }
1335 
balloon_down(struct hv_dynmem_device * dm,struct dm_unballoon_request * req)1336 static void balloon_down(struct hv_dynmem_device *dm,
1337 			 struct dm_unballoon_request *req)
1338 {
1339 	union dm_mem_page_range *range_array = req->range_array;
1340 	int range_count = req->range_count;
1341 	struct dm_unballoon_response resp;
1342 	int i;
1343 	unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
1344 
1345 	for (i = 0; i < range_count; i++) {
1346 		free_balloon_pages(dm, &range_array[i]);
1347 		complete(&dm_device.config_event);
1348 	}
1349 
1350 	pr_debug("Freed %u ballooned pages.\n",
1351 		 prev_pages_ballooned - dm->num_pages_ballooned);
1352 
1353 	if (req->more_pages == 1)
1354 		return;
1355 
1356 	memset(&resp, 0, sizeof(struct dm_unballoon_response));
1357 	resp.hdr.type = DM_UNBALLOON_RESPONSE;
1358 	resp.hdr.trans_id = atomic_inc_return(&trans_id);
1359 	resp.hdr.size = sizeof(struct dm_unballoon_response);
1360 
1361 	vmbus_sendpacket(dm_device.dev->channel, &resp,
1362 				sizeof(struct dm_unballoon_response),
1363 				(unsigned long)NULL,
1364 				VM_PKT_DATA_INBAND, 0);
1365 
1366 	dm->state = DM_INITIALIZED;
1367 }
1368 
1369 static void balloon_onchannelcallback(void *context);
1370 
dm_thread_func(void * dm_dev)1371 static int dm_thread_func(void *dm_dev)
1372 {
1373 	struct hv_dynmem_device *dm = dm_dev;
1374 
1375 	while (!kthread_should_stop()) {
1376 		wait_for_completion_interruptible_timeout(&dm_device.config_event, 1 * HZ);
1377 		/*
1378 		 * The host expects us to post information on the memory
1379 		 * pressure every second.
1380 		 */
1381 		reinit_completion(&dm_device.config_event);
1382 		post_status(dm);
1383 		/*
1384 		 * disable free page reporting if multiple hypercall
1385 		 * failure flag set. It is not done in the page_reporting
1386 		 * callback context as that causes a deadlock between
1387 		 * page_reporting_process() and page_reporting_unregister()
1388 		 */
1389 		if (hv_hypercall_multi_failure >= HV_MAX_FAILURES) {
1390 			pr_err("Multiple failures in cold memory discard hypercall, disabling page reporting\n");
1391 			disable_page_reporting();
1392 			/* Reset the flag after disabling reporting */
1393 			hv_hypercall_multi_failure = 0;
1394 		}
1395 	}
1396 
1397 	return 0;
1398 }
1399 
version_resp(struct hv_dynmem_device * dm,struct dm_version_response * vresp)1400 static void version_resp(struct hv_dynmem_device *dm,
1401 			 struct dm_version_response *vresp)
1402 {
1403 	struct dm_version_request version_req;
1404 	int ret;
1405 
1406 	if (vresp->is_accepted) {
1407 		/*
1408 		 * We are done; wakeup the
1409 		 * context waiting for version
1410 		 * negotiation.
1411 		 */
1412 		complete(&dm->host_event);
1413 		return;
1414 	}
1415 	/*
1416 	 * If there are more versions to try, continue
1417 	 * with negotiations; if not
1418 	 * shutdown the service since we are not able
1419 	 * to negotiate a suitable version number
1420 	 * with the host.
1421 	 */
1422 	if (dm->next_version == 0)
1423 		goto version_error;
1424 
1425 	memset(&version_req, 0, sizeof(struct dm_version_request));
1426 	version_req.hdr.type = DM_VERSION_REQUEST;
1427 	version_req.hdr.size = sizeof(struct dm_version_request);
1428 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1429 	version_req.version.version = dm->next_version;
1430 	dm->version = version_req.version.version;
1431 
1432 	/*
1433 	 * Set the next version to try in case current version fails.
1434 	 * Win7 protocol ought to be the last one to try.
1435 	 */
1436 	switch (version_req.version.version) {
1437 	case DYNMEM_PROTOCOL_VERSION_WIN8:
1438 		dm->next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
1439 		version_req.is_last_attempt = 0;
1440 		break;
1441 	default:
1442 		dm->next_version = 0;
1443 		version_req.is_last_attempt = 1;
1444 	}
1445 
1446 	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
1447 				sizeof(struct dm_version_request),
1448 				(unsigned long)NULL,
1449 				VM_PKT_DATA_INBAND, 0);
1450 
1451 	if (ret)
1452 		goto version_error;
1453 
1454 	return;
1455 
1456 version_error:
1457 	dm->state = DM_INIT_ERROR;
1458 	complete(&dm->host_event);
1459 }
1460 
cap_resp(struct hv_dynmem_device * dm,struct dm_capabilities_resp_msg * cap_resp)1461 static void cap_resp(struct hv_dynmem_device *dm,
1462 		     struct dm_capabilities_resp_msg *cap_resp)
1463 {
1464 	if (!cap_resp->is_accepted) {
1465 		pr_err("Capabilities not accepted by host\n");
1466 		dm->state = DM_INIT_ERROR;
1467 	}
1468 	complete(&dm->host_event);
1469 }
1470 
balloon_onchannelcallback(void * context)1471 static void balloon_onchannelcallback(void *context)
1472 {
1473 	struct hv_device *dev = context;
1474 	u32 recvlen;
1475 	u64 requestid;
1476 	struct dm_message *dm_msg;
1477 	struct dm_header *dm_hdr;
1478 	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1479 	struct dm_balloon *bal_msg;
1480 	struct dm_hot_add *ha_msg;
1481 	union dm_mem_page_range *ha_pg_range;
1482 	union dm_mem_page_range *ha_region;
1483 
1484 	memset(recv_buffer, 0, sizeof(recv_buffer));
1485 	vmbus_recvpacket(dev->channel, recv_buffer,
1486 			 HV_HYP_PAGE_SIZE, &recvlen, &requestid);
1487 
1488 	if (recvlen > 0) {
1489 		dm_msg = (struct dm_message *)recv_buffer;
1490 		dm_hdr = &dm_msg->hdr;
1491 
1492 		switch (dm_hdr->type) {
1493 		case DM_VERSION_RESPONSE:
1494 			version_resp(dm,
1495 				     (struct dm_version_response *)dm_msg);
1496 			break;
1497 
1498 		case DM_CAPABILITIES_RESPONSE:
1499 			cap_resp(dm,
1500 				 (struct dm_capabilities_resp_msg *)dm_msg);
1501 			break;
1502 
1503 		case DM_BALLOON_REQUEST:
1504 			if (allow_hibernation) {
1505 				pr_info("Ignore balloon-up request!\n");
1506 				break;
1507 			}
1508 
1509 			if (dm->state == DM_BALLOON_UP)
1510 				pr_warn("Currently ballooning\n");
1511 			bal_msg = (struct dm_balloon *)recv_buffer;
1512 			dm->state = DM_BALLOON_UP;
1513 			dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
1514 			schedule_work(&dm_device.balloon_wrk.wrk);
1515 			break;
1516 
1517 		case DM_UNBALLOON_REQUEST:
1518 			if (allow_hibernation) {
1519 				pr_info("Ignore balloon-down request!\n");
1520 				break;
1521 			}
1522 
1523 			dm->state = DM_BALLOON_DOWN;
1524 			balloon_down(dm,
1525 				     (struct dm_unballoon_request *)recv_buffer);
1526 			break;
1527 
1528 		case DM_MEM_HOT_ADD_REQUEST:
1529 			if (dm->state == DM_HOT_ADD)
1530 				pr_warn("Currently hot-adding\n");
1531 			dm->state = DM_HOT_ADD;
1532 			ha_msg = (struct dm_hot_add *)recv_buffer;
1533 			if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
1534 				/*
1535 				 * This is a normal hot-add request specifying
1536 				 * hot-add memory.
1537 				 */
1538 				dm->host_specified_ha_region = false;
1539 				ha_pg_range = &ha_msg->range;
1540 				dm->ha_wrk.ha_page_range = *ha_pg_range;
1541 				dm->ha_wrk.ha_region_range.page_range = 0;
1542 			} else {
1543 				/*
1544 				 * Host is specifying that we first hot-add
1545 				 * a region and then partially populate this
1546 				 * region.
1547 				 */
1548 				dm->host_specified_ha_region = true;
1549 				ha_pg_range = &ha_msg->range;
1550 				ha_region = &ha_pg_range[1];
1551 				dm->ha_wrk.ha_page_range = *ha_pg_range;
1552 				dm->ha_wrk.ha_region_range = *ha_region;
1553 			}
1554 			schedule_work(&dm_device.ha_wrk.wrk);
1555 			break;
1556 
1557 		case DM_INFO_MESSAGE:
1558 			process_info(dm, (struct dm_info_msg *)dm_msg);
1559 			break;
1560 
1561 		default:
1562 			pr_warn_ratelimited("Unhandled message: type: %d\n", dm_hdr->type);
1563 		}
1564 	}
1565 }
1566 
1567 #define HV_LARGE_REPORTING_ORDER	9
1568 #define HV_LARGE_REPORTING_LEN (HV_HYP_PAGE_SIZE << \
1569 		HV_LARGE_REPORTING_ORDER)
hv_free_page_report(struct page_reporting_dev_info * pr_dev_info,struct scatterlist * sgl,unsigned int nents)1570 static int hv_free_page_report(struct page_reporting_dev_info *pr_dev_info,
1571 			       struct scatterlist *sgl, unsigned int nents)
1572 {
1573 	unsigned long flags;
1574 	struct hv_memory_hint *hint;
1575 	int i, order;
1576 	u64 status;
1577 	struct scatterlist *sg;
1578 
1579 	WARN_ON_ONCE(nents > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
1580 	WARN_ON_ONCE(sgl->length < (HV_HYP_PAGE_SIZE << page_reporting_order));
1581 	local_irq_save(flags);
1582 	hint = *this_cpu_ptr(hyperv_pcpu_input_arg);
1583 	if (!hint) {
1584 		local_irq_restore(flags);
1585 		return -ENOSPC;
1586 	}
1587 
1588 	hint->type = HV_EXT_MEMORY_HEAT_HINT_TYPE_COLD_DISCARD;
1589 	hint->reserved = 0;
1590 	for_each_sg(sgl, sg, nents, i) {
1591 		union hv_gpa_page_range *range;
1592 
1593 		range = &hint->ranges[i];
1594 		range->address_space = 0;
1595 		order = get_order(sg->length);
1596 		/*
1597 		 * Hyper-V expects the additional_pages field in the units
1598 		 * of one of these 3 sizes, 4Kbytes, 2Mbytes or 1Gbytes.
1599 		 * This is dictated by the values of the fields page.largesize
1600 		 * and page_size.
1601 		 * This code however, only uses 4Kbytes and 2Mbytes units
1602 		 * and not 1Gbytes unit.
1603 		 */
1604 
1605 		/* page reporting for pages 2MB or higher */
1606 		if (order >= HV_LARGE_REPORTING_ORDER) {
1607 			range->page.largepage = 1;
1608 			range->page_size = HV_GPA_PAGE_RANGE_PAGE_SIZE_2MB;
1609 			range->base_large_pfn = page_to_hvpfn(
1610 					sg_page(sg)) >> HV_LARGE_REPORTING_ORDER;
1611 			range->page.additional_pages =
1612 				(sg->length / HV_LARGE_REPORTING_LEN) - 1;
1613 		} else {
1614 			/* Page reporting for pages below 2MB */
1615 			range->page.basepfn = page_to_hvpfn(sg_page(sg));
1616 			range->page.largepage = false;
1617 			range->page.additional_pages =
1618 				(sg->length / HV_HYP_PAGE_SIZE) - 1;
1619 		}
1620 	}
1621 
1622 	status = hv_do_rep_hypercall(HV_EXT_CALL_MEMORY_HEAT_HINT, nents, 0,
1623 				     hint, NULL);
1624 	local_irq_restore(flags);
1625 	if (!hv_result_success(status)) {
1626 		pr_err("Cold memory discard hypercall failed with status %llx\n",
1627 		       status);
1628 		if (hv_hypercall_multi_failure > 0)
1629 			hv_hypercall_multi_failure++;
1630 
1631 		if (hv_result(status) == HV_STATUS_INVALID_PARAMETER) {
1632 			pr_err("Underlying Hyper-V does not support order less than 9. Hypercall failed\n");
1633 			pr_err("Defaulting to page_reporting_order %d\n",
1634 			       pageblock_order);
1635 			page_reporting_order = pageblock_order;
1636 			hv_hypercall_multi_failure++;
1637 			return -EINVAL;
1638 		}
1639 
1640 		return -EINVAL;
1641 	}
1642 
1643 	return 0;
1644 }
1645 
enable_page_reporting(void)1646 static void enable_page_reporting(void)
1647 {
1648 	int ret;
1649 
1650 	if (!hv_query_ext_cap(HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT)) {
1651 		pr_debug("Cold memory discard hint not supported by Hyper-V\n");
1652 		return;
1653 	}
1654 
1655 	BUILD_BUG_ON(PAGE_REPORTING_CAPACITY > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
1656 	dm_device.pr_dev_info.report = hv_free_page_report;
1657 	/*
1658 	 * We let the page_reporting_order parameter decide the order
1659 	 * in the page_reporting code
1660 	 */
1661 	dm_device.pr_dev_info.order = 0;
1662 	ret = page_reporting_register(&dm_device.pr_dev_info);
1663 	if (ret < 0) {
1664 		dm_device.pr_dev_info.report = NULL;
1665 		pr_err("Failed to enable cold memory discard: %d\n", ret);
1666 	} else {
1667 		pr_info("Cold memory discard hint enabled with order %d\n",
1668 			page_reporting_order);
1669 	}
1670 }
1671 
disable_page_reporting(void)1672 static void disable_page_reporting(void)
1673 {
1674 	if (dm_device.pr_dev_info.report) {
1675 		page_reporting_unregister(&dm_device.pr_dev_info);
1676 		dm_device.pr_dev_info.report = NULL;
1677 	}
1678 }
1679 
ballooning_enabled(void)1680 static int ballooning_enabled(void)
1681 {
1682 	/*
1683 	 * Disable ballooning if the page size is not 4k (HV_HYP_PAGE_SIZE),
1684 	 * since currently it's unclear to us whether an unballoon request can
1685 	 * make sure all page ranges are guest page size aligned.
1686 	 */
1687 	if (PAGE_SIZE != HV_HYP_PAGE_SIZE) {
1688 		pr_info("Ballooning disabled because page size is not 4096 bytes\n");
1689 		return 0;
1690 	}
1691 
1692 	return 1;
1693 }
1694 
hot_add_enabled(void)1695 static int hot_add_enabled(void)
1696 {
1697 	/*
1698 	 * Disable hot add on ARM64, because we currently rely on
1699 	 * memory_add_physaddr_to_nid() to get a node id of a hot add range,
1700 	 * however ARM64's memory_add_physaddr_to_nid() always return 0 and
1701 	 * DM_MEM_HOT_ADD_REQUEST doesn't have the NUMA node information for
1702 	 * add_memory().
1703 	 */
1704 	if (IS_ENABLED(CONFIG_ARM64)) {
1705 		pr_info("Memory hot add disabled on ARM64\n");
1706 		return 0;
1707 	}
1708 
1709 	return 1;
1710 }
1711 
balloon_connect_vsp(struct hv_device * dev)1712 static int balloon_connect_vsp(struct hv_device *dev)
1713 {
1714 	struct dm_version_request version_req;
1715 	struct dm_capabilities cap_msg;
1716 	unsigned long t;
1717 	int ret;
1718 
1719 	/*
1720 	 * max_pkt_size should be large enough for one vmbus packet header plus
1721 	 * our receive buffer size. Hyper-V sends messages up to
1722 	 * HV_HYP_PAGE_SIZE bytes long on balloon channel.
1723 	 */
1724 	dev->channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
1725 
1726 	ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
1727 			 balloon_onchannelcallback, dev);
1728 	if (ret)
1729 		return ret;
1730 
1731 	/*
1732 	 * Initiate the hand shake with the host and negotiate
1733 	 * a version that the host can support. We start with the
1734 	 * highest version number and go down if the host cannot
1735 	 * support it.
1736 	 */
1737 	memset(&version_req, 0, sizeof(struct dm_version_request));
1738 	version_req.hdr.type = DM_VERSION_REQUEST;
1739 	version_req.hdr.size = sizeof(struct dm_version_request);
1740 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1741 	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
1742 	version_req.is_last_attempt = 0;
1743 	dm_device.version = version_req.version.version;
1744 
1745 	ret = vmbus_sendpacket(dev->channel, &version_req,
1746 			       sizeof(struct dm_version_request),
1747 			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
1748 	if (ret)
1749 		goto out;
1750 
1751 	t = wait_for_completion_timeout(&dm_device.host_event, 5 * HZ);
1752 	if (t == 0) {
1753 		ret = -ETIMEDOUT;
1754 		goto out;
1755 	}
1756 
1757 	/*
1758 	 * If we could not negotiate a compatible version with the host
1759 	 * fail the probe function.
1760 	 */
1761 	if (dm_device.state == DM_INIT_ERROR) {
1762 		ret = -EPROTO;
1763 		goto out;
1764 	}
1765 
1766 	pr_info("Using Dynamic Memory protocol version %u.%u\n",
1767 		DYNMEM_MAJOR_VERSION(dm_device.version),
1768 		DYNMEM_MINOR_VERSION(dm_device.version));
1769 
1770 	/*
1771 	 * Now submit our capabilities to the host.
1772 	 */
1773 	memset(&cap_msg, 0, sizeof(struct dm_capabilities));
1774 	cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
1775 	cap_msg.hdr.size = sizeof(struct dm_capabilities);
1776 	cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
1777 
1778 	/*
1779 	 * When hibernation (i.e. virtual ACPI S4 state) is enabled, the host
1780 	 * currently still requires the bits to be set, so we have to add code
1781 	 * to fail the host's hot-add and balloon up/down requests, if any.
1782 	 */
1783 	cap_msg.caps.cap_bits.balloon = ballooning_enabled();
1784 	cap_msg.caps.cap_bits.hot_add = hot_add_enabled();
1785 
1786 	/*
1787 	 * Specify our alignment requirements for memory hot-add. The value is
1788 	 * the log base 2 of the number of megabytes in a chunk. For example,
1789 	 * with 256 MiB chunks, the value is 8. The number of MiB in a chunk
1790 	 * must be a power of 2.
1791 	 */
1792 	cap_msg.caps.cap_bits.hot_add_alignment =
1793 					ilog2(HA_BYTES_IN_CHUNK / SZ_1M);
1794 
1795 	/*
1796 	 * Currently the host does not use these
1797 	 * values and we set them to what is done in the
1798 	 * Windows driver.
1799 	 */
1800 	cap_msg.min_page_cnt = 0;
1801 	cap_msg.max_page_number = -1;
1802 
1803 	ret = vmbus_sendpacket(dev->channel, &cap_msg,
1804 			       sizeof(struct dm_capabilities),
1805 			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
1806 	if (ret)
1807 		goto out;
1808 
1809 	t = wait_for_completion_timeout(&dm_device.host_event, 5 * HZ);
1810 	if (t == 0) {
1811 		ret = -ETIMEDOUT;
1812 		goto out;
1813 	}
1814 
1815 	/*
1816 	 * If the host does not like our capabilities,
1817 	 * fail the probe function.
1818 	 */
1819 	if (dm_device.state == DM_INIT_ERROR) {
1820 		ret = -EPROTO;
1821 		goto out;
1822 	}
1823 
1824 	return 0;
1825 out:
1826 	vmbus_close(dev->channel);
1827 	return ret;
1828 }
1829 
1830 /*
1831  * DEBUGFS Interface
1832  */
1833 #ifdef CONFIG_DEBUG_FS
1834 
1835 /**
1836  * hv_balloon_debug_show - shows statistics of balloon operations.
1837  * @f: pointer to the &struct seq_file.
1838  * @offset: ignored.
1839  *
1840  * Provides the statistics that can be accessed in hv-balloon in the debugfs.
1841  *
1842  * Return: zero on success or an error code.
1843  */
hv_balloon_debug_show(struct seq_file * f,void * offset)1844 static int hv_balloon_debug_show(struct seq_file *f, void *offset)
1845 {
1846 	struct hv_dynmem_device *dm = f->private;
1847 	char *sname;
1848 
1849 	seq_printf(f, "%-22s: %u.%u\n", "host_version",
1850 			DYNMEM_MAJOR_VERSION(dm->version),
1851 			DYNMEM_MINOR_VERSION(dm->version));
1852 
1853 	seq_printf(f, "%-22s:", "capabilities");
1854 	if (ballooning_enabled())
1855 		seq_puts(f, " enabled");
1856 
1857 	if (hot_add_enabled())
1858 		seq_puts(f, " hot_add");
1859 
1860 	seq_puts(f, "\n");
1861 
1862 	seq_printf(f, "%-22s: %u", "state", dm->state);
1863 	switch (dm->state) {
1864 	case DM_INITIALIZING:
1865 			sname = "Initializing";
1866 			break;
1867 	case DM_INITIALIZED:
1868 			sname = "Initialized";
1869 			break;
1870 	case DM_BALLOON_UP:
1871 			sname = "Balloon Up";
1872 			break;
1873 	case DM_BALLOON_DOWN:
1874 			sname = "Balloon Down";
1875 			break;
1876 	case DM_HOT_ADD:
1877 			sname = "Hot Add";
1878 			break;
1879 	case DM_INIT_ERROR:
1880 			sname = "Error";
1881 			break;
1882 	default:
1883 			sname = "Unknown";
1884 	}
1885 	seq_printf(f, " (%s)\n", sname);
1886 
1887 	/* HV Page Size */
1888 	seq_printf(f, "%-22s: %ld\n", "page_size", HV_HYP_PAGE_SIZE);
1889 
1890 	/* Pages added with hot_add */
1891 	seq_printf(f, "%-22s: %u\n", "pages_added", dm->num_pages_added);
1892 
1893 	/* pages that are "onlined"/used from pages_added */
1894 	seq_printf(f, "%-22s: %u\n", "pages_onlined", dm->num_pages_onlined);
1895 
1896 	/* pages we have given back to host */
1897 	seq_printf(f, "%-22s: %u\n", "pages_ballooned", dm->num_pages_ballooned);
1898 
1899 	seq_printf(f, "%-22s: %lu\n", "total_pages_committed",
1900 		   get_pages_committed(dm));
1901 
1902 	seq_printf(f, "%-22s: %llu\n", "max_dynamic_page_count",
1903 		   dm->max_dynamic_page_count);
1904 
1905 	return 0;
1906 }
1907 
1908 DEFINE_SHOW_ATTRIBUTE(hv_balloon_debug);
1909 
hv_balloon_debugfs_init(struct hv_dynmem_device * b)1910 static void  hv_balloon_debugfs_init(struct hv_dynmem_device *b)
1911 {
1912 	debugfs_create_file("hv-balloon", 0444, NULL, b,
1913 			    &hv_balloon_debug_fops);
1914 }
1915 
hv_balloon_debugfs_exit(struct hv_dynmem_device * b)1916 static void  hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
1917 {
1918 	debugfs_lookup_and_remove("hv-balloon", NULL);
1919 }
1920 
1921 #else
1922 
hv_balloon_debugfs_init(struct hv_dynmem_device * b)1923 static inline void hv_balloon_debugfs_init(struct hv_dynmem_device  *b)
1924 {
1925 }
1926 
hv_balloon_debugfs_exit(struct hv_dynmem_device * b)1927 static inline void hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
1928 {
1929 }
1930 
1931 #endif	/* CONFIG_DEBUG_FS */
1932 
balloon_probe(struct hv_device * dev,const struct hv_vmbus_device_id * dev_id)1933 static int balloon_probe(struct hv_device *dev,
1934 			 const struct hv_vmbus_device_id *dev_id)
1935 {
1936 	int ret;
1937 
1938 	allow_hibernation = hv_is_hibernation_supported();
1939 	if (allow_hibernation)
1940 		hot_add = false;
1941 
1942 #ifdef CONFIG_MEMORY_HOTPLUG
1943 	/*
1944 	 * Hot-add must operate in chunks that are of size equal to the
1945 	 * memory block size because that's what the core add_memory()
1946 	 * interface requires. The Hyper-V interface requires that the memory
1947 	 * block size be a power of 2, which is guaranteed by the check in
1948 	 * memory_dev_init().
1949 	 */
1950 	ha_pages_in_chunk = memory_block_size_bytes() / PAGE_SIZE;
1951 	do_hot_add = hot_add;
1952 #else
1953 	/*
1954 	 * Without MEMORY_HOTPLUG, the guest returns a failure status for all
1955 	 * hot add requests from Hyper-V, and the chunk size is used only to
1956 	 * specify alignment to Hyper-V as required by the host/guest protocol.
1957 	 * Somewhat arbitrarily, use 128 MiB.
1958 	 */
1959 	ha_pages_in_chunk = SZ_128M / PAGE_SIZE;
1960 	do_hot_add = false;
1961 #endif
1962 	dm_device.dev = dev;
1963 	dm_device.state = DM_INITIALIZING;
1964 	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN8;
1965 	init_completion(&dm_device.host_event);
1966 	init_completion(&dm_device.config_event);
1967 	INIT_LIST_HEAD(&dm_device.ha_region_list);
1968 	spin_lock_init(&dm_device.ha_lock);
1969 	INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
1970 	INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
1971 	dm_device.host_specified_ha_region = false;
1972 
1973 #ifdef CONFIG_MEMORY_HOTPLUG
1974 	set_online_page_callback(&hv_online_page);
1975 	init_completion(&dm_device.ol_waitevent);
1976 	register_memory_notifier(&hv_memory_nb);
1977 #endif
1978 
1979 	hv_set_drvdata(dev, &dm_device);
1980 
1981 	ret = balloon_connect_vsp(dev);
1982 	if (ret != 0)
1983 		goto connect_error;
1984 
1985 	enable_page_reporting();
1986 	dm_device.state = DM_INITIALIZED;
1987 
1988 	dm_device.thread =
1989 		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
1990 	if (IS_ERR(dm_device.thread)) {
1991 		ret = PTR_ERR(dm_device.thread);
1992 		goto probe_error;
1993 	}
1994 
1995 	hv_balloon_debugfs_init(&dm_device);
1996 
1997 	return 0;
1998 
1999 probe_error:
2000 	dm_device.state = DM_INIT_ERROR;
2001 	dm_device.thread  = NULL;
2002 	disable_page_reporting();
2003 	vmbus_close(dev->channel);
2004 connect_error:
2005 #ifdef CONFIG_MEMORY_HOTPLUG
2006 	unregister_memory_notifier(&hv_memory_nb);
2007 	restore_online_page_callback(&hv_online_page);
2008 #endif
2009 	return ret;
2010 }
2011 
balloon_remove(struct hv_device * dev)2012 static void balloon_remove(struct hv_device *dev)
2013 {
2014 	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
2015 	struct hv_hotadd_state *has, *tmp;
2016 	struct hv_hotadd_gap *gap, *tmp_gap;
2017 
2018 	if (dm->num_pages_ballooned != 0)
2019 		pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
2020 
2021 	hv_balloon_debugfs_exit(dm);
2022 
2023 	cancel_work_sync(&dm->balloon_wrk.wrk);
2024 	cancel_work_sync(&dm->ha_wrk.wrk);
2025 
2026 	kthread_stop(dm->thread);
2027 
2028 	/*
2029 	 * This is to handle the case when balloon_resume()
2030 	 * call has failed and some cleanup has been done as
2031 	 * a part of the error handling.
2032 	 */
2033 	if (dm_device.state != DM_INIT_ERROR) {
2034 		disable_page_reporting();
2035 		vmbus_close(dev->channel);
2036 #ifdef CONFIG_MEMORY_HOTPLUG
2037 		unregister_memory_notifier(&hv_memory_nb);
2038 		restore_online_page_callback(&hv_online_page);
2039 #endif
2040 	}
2041 
2042 	guard(spinlock_irqsave)(&dm_device.ha_lock);
2043 	list_for_each_entry_safe(has, tmp, &dm->ha_region_list, list) {
2044 		list_for_each_entry_safe(gap, tmp_gap, &has->gap_list, list) {
2045 			list_del(&gap->list);
2046 			kfree(gap);
2047 		}
2048 		list_del(&has->list);
2049 		kfree(has);
2050 	}
2051 }
2052 
balloon_suspend(struct hv_device * hv_dev)2053 static int balloon_suspend(struct hv_device *hv_dev)
2054 {
2055 	struct hv_dynmem_device *dm = hv_get_drvdata(hv_dev);
2056 
2057 	tasklet_disable(&hv_dev->channel->callback_event);
2058 
2059 	cancel_work_sync(&dm->balloon_wrk.wrk);
2060 	cancel_work_sync(&dm->ha_wrk.wrk);
2061 
2062 	if (dm->thread) {
2063 		kthread_stop(dm->thread);
2064 		dm->thread = NULL;
2065 		vmbus_close(hv_dev->channel);
2066 	}
2067 
2068 	tasklet_enable(&hv_dev->channel->callback_event);
2069 
2070 	return 0;
2071 }
2072 
balloon_resume(struct hv_device * dev)2073 static int balloon_resume(struct hv_device *dev)
2074 {
2075 	int ret;
2076 
2077 	dm_device.state = DM_INITIALIZING;
2078 
2079 	ret = balloon_connect_vsp(dev);
2080 
2081 	if (ret != 0)
2082 		goto out;
2083 
2084 	dm_device.thread =
2085 		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
2086 	if (IS_ERR(dm_device.thread)) {
2087 		ret = PTR_ERR(dm_device.thread);
2088 		dm_device.thread = NULL;
2089 		goto close_channel;
2090 	}
2091 
2092 	dm_device.state = DM_INITIALIZED;
2093 	return 0;
2094 close_channel:
2095 	vmbus_close(dev->channel);
2096 out:
2097 	dm_device.state = DM_INIT_ERROR;
2098 	disable_page_reporting();
2099 #ifdef CONFIG_MEMORY_HOTPLUG
2100 	unregister_memory_notifier(&hv_memory_nb);
2101 	restore_online_page_callback(&hv_online_page);
2102 #endif
2103 	return ret;
2104 }
2105 
2106 static const struct hv_vmbus_device_id id_table[] = {
2107 	/* Dynamic Memory Class ID */
2108 	/* 525074DC-8985-46e2-8057-A307DC18A502 */
2109 	{ HV_DM_GUID, },
2110 	{ },
2111 };
2112 
2113 MODULE_DEVICE_TABLE(vmbus, id_table);
2114 
2115 static  struct hv_driver balloon_drv = {
2116 	.name = "hv_balloon",
2117 	.id_table = id_table,
2118 	.probe =  balloon_probe,
2119 	.remove =  balloon_remove,
2120 	.suspend = balloon_suspend,
2121 	.resume = balloon_resume,
2122 	.driver = {
2123 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
2124 	},
2125 };
2126 
init_balloon_drv(void)2127 static int __init init_balloon_drv(void)
2128 {
2129 	return vmbus_driver_register(&balloon_drv);
2130 }
2131 
2132 module_init(init_balloon_drv);
2133 
2134 MODULE_DESCRIPTION("Hyper-V Balloon");
2135 MODULE_LICENSE("GPL");
2136