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
  29#include <linux/hyperv.h>
  30#include <asm/hyperv-tlfs.h>
  31
  32#include <asm/mshyperv.h>
  33
  34#define CREATE_TRACE_POINTS
  35#include "hv_trace_balloon.h"
  36
  37/*
  38 * We begin with definitions supporting the Dynamic Memory protocol
  39 * with the host.
  40 *
  41 * Begin protocol definitions.
  42 */
  43
  44
  45
  46/*
  47 * Protocol versions. The low word is the minor version, the high word the major
  48 * version.
  49 *
  50 * History:
  51 * Initial version 1.0
  52 * Changed to 0.1 on 2009/03/25
  53 * Changes to 0.2 on 2009/05/14
  54 * Changes to 0.3 on 2009/12/03
  55 * Changed to 1.0 on 2011/04/05
  56 */
  57
  58#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
  59#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
  60#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)
  61
  62enum {
  63	DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
  64	DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),
  65	DYNMEM_PROTOCOL_VERSION_3 = DYNMEM_MAKE_VERSION(2, 0),
  66
  67	DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
  68	DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,
  69	DYNMEM_PROTOCOL_VERSION_WIN10 = DYNMEM_PROTOCOL_VERSION_3,
  70
  71	DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN10
  72};
  73
  74
  75
  76/*
  77 * Message Types
  78 */
  79
  80enum dm_message_type {
  81	/*
  82	 * Version 0.3
  83	 */
  84	DM_ERROR			= 0,
  85	DM_VERSION_REQUEST		= 1,
  86	DM_VERSION_RESPONSE		= 2,
  87	DM_CAPABILITIES_REPORT		= 3,
  88	DM_CAPABILITIES_RESPONSE	= 4,
  89	DM_STATUS_REPORT		= 5,
  90	DM_BALLOON_REQUEST		= 6,
  91	DM_BALLOON_RESPONSE		= 7,
  92	DM_UNBALLOON_REQUEST		= 8,
  93	DM_UNBALLOON_RESPONSE		= 9,
  94	DM_MEM_HOT_ADD_REQUEST		= 10,
  95	DM_MEM_HOT_ADD_RESPONSE		= 11,
  96	DM_VERSION_03_MAX		= 11,
  97	/*
  98	 * Version 1.0.
  99	 */
 100	DM_INFO_MESSAGE			= 12,
 101	DM_VERSION_1_MAX		= 12
 102};
 103
 104
 105/*
 106 * Structures defining the dynamic memory management
 107 * protocol.
 108 */
 109
 110union dm_version {
 111	struct {
 112		__u16 minor_version;
 113		__u16 major_version;
 114	};
 115	__u32 version;
 116} __packed;
 117
 118
 119union dm_caps {
 120	struct {
 121		__u64 balloon:1;
 122		__u64 hot_add:1;
 123		/*
 124		 * To support guests that may have alignment
 125		 * limitations on hot-add, the guest can specify
 126		 * its alignment requirements; a value of n
 127		 * represents an alignment of 2^n in mega bytes.
 128		 */
 129		__u64 hot_add_alignment:4;
 130		__u64 reservedz:58;
 131	} cap_bits;
 132	__u64 caps;
 133} __packed;
 134
 135union dm_mem_page_range {
 136	struct  {
 137		/*
 138		 * The PFN number of the first page in the range.
 139		 * 40 bits is the architectural limit of a PFN
 140		 * number for AMD64.
 141		 */
 142		__u64 start_page:40;
 143		/*
 144		 * The number of pages in the range.
 145		 */
 146		__u64 page_cnt:24;
 147	} finfo;
 148	__u64  page_range;
 149} __packed;
 150
 151
 152
 153/*
 154 * The header for all dynamic memory messages:
 155 *
 156 * type: Type of the message.
 157 * size: Size of the message in bytes; including the header.
 158 * trans_id: The guest is responsible for manufacturing this ID.
 159 */
 160
 161struct dm_header {
 162	__u16 type;
 163	__u16 size;
 164	__u32 trans_id;
 165} __packed;
 166
 167/*
 168 * A generic message format for dynamic memory.
 169 * Specific message formats are defined later in the file.
 170 */
 171
 172struct dm_message {
 173	struct dm_header hdr;
 174	__u8 data[]; /* enclosed message */
 175} __packed;
 176
 177
 178/*
 179 * Specific message types supporting the dynamic memory protocol.
 180 */
 181
 182/*
 183 * Version negotiation message. Sent from the guest to the host.
 184 * The guest is free to try different versions until the host
 185 * accepts the version.
 186 *
 187 * dm_version: The protocol version requested.
 188 * is_last_attempt: If TRUE, this is the last version guest will request.
 189 * reservedz: Reserved field, set to zero.
 190 */
 191
 192struct dm_version_request {
 193	struct dm_header hdr;
 194	union dm_version version;
 195	__u32 is_last_attempt:1;
 196	__u32 reservedz:31;
 197} __packed;
 198
 199/*
 200 * Version response message; Host to Guest and indicates
 201 * if the host has accepted the version sent by the guest.
 202 *
 203 * is_accepted: If TRUE, host has accepted the version and the guest
 204 * should proceed to the next stage of the protocol. FALSE indicates that
 205 * guest should re-try with a different version.
 206 *
 207 * reservedz: Reserved field, set to zero.
 208 */
 209
 210struct dm_version_response {
 211	struct dm_header hdr;
 212	__u64 is_accepted:1;
 213	__u64 reservedz:63;
 214} __packed;
 215
 216/*
 217 * Message reporting capabilities. This is sent from the guest to the
 218 * host.
 219 */
 220
 221struct dm_capabilities {
 222	struct dm_header hdr;
 223	union dm_caps caps;
 224	__u64 min_page_cnt;
 225	__u64 max_page_number;
 226} __packed;
 227
 228/*
 229 * Response to the capabilities message. This is sent from the host to the
 230 * guest. This message notifies if the host has accepted the guest's
 231 * capabilities. If the host has not accepted, the guest must shutdown
 232 * the service.
 233 *
 234 * is_accepted: Indicates if the host has accepted guest's capabilities.
 235 * reservedz: Must be 0.
 236 */
 237
 238struct dm_capabilities_resp_msg {
 239	struct dm_header hdr;
 240	__u64 is_accepted:1;
 241	__u64 reservedz:63;
 242} __packed;
 243
 244/*
 245 * This message is used to report memory pressure from the guest.
 246 * This message is not part of any transaction and there is no
 247 * response to this message.
 248 *
 249 * num_avail: Available memory in pages.
 250 * num_committed: Committed memory in pages.
 251 * page_file_size: The accumulated size of all page files
 252 *		   in the system in pages.
 253 * zero_free: The number of zero and free pages.
 254 * page_file_writes: The writes to the page file in pages.
 255 * io_diff: An indicator of file cache efficiency or page file activity,
 256 *	    calculated as File Cache Page Fault Count - Page Read Count.
 257 *	    This value is in pages.
 258 *
 259 * Some of these metrics are Windows specific and fortunately
 260 * the algorithm on the host side that computes the guest memory
 261 * pressure only uses num_committed value.
 262 */
 263
 264struct dm_status {
 265	struct dm_header hdr;
 266	__u64 num_avail;
 267	__u64 num_committed;
 268	__u64 page_file_size;
 269	__u64 zero_free;
 270	__u32 page_file_writes;
 271	__u32 io_diff;
 272} __packed;
 273
 274
 275/*
 276 * Message to ask the guest to allocate memory - balloon up message.
 277 * This message is sent from the host to the guest. The guest may not be
 278 * able to allocate as much memory as requested.
 279 *
 280 * num_pages: number of pages to allocate.
 281 */
 282
 283struct dm_balloon {
 284	struct dm_header hdr;
 285	__u32 num_pages;
 286	__u32 reservedz;
 287} __packed;
 288
 289
 290/*
 291 * Balloon response message; this message is sent from the guest
 292 * to the host in response to the balloon message.
 293 *
 294 * reservedz: Reserved; must be set to zero.
 295 * more_pages: If FALSE, this is the last message of the transaction.
 296 * if TRUE there will atleast one more message from the guest.
 297 *
 298 * range_count: The number of ranges in the range array.
 299 *
 300 * range_array: An array of page ranges returned to the host.
 301 *
 302 */
 303
 304struct dm_balloon_response {
 305	struct dm_header hdr;
 306	__u32 reservedz;
 307	__u32 more_pages:1;
 308	__u32 range_count:31;
 309	union dm_mem_page_range range_array[];
 310} __packed;
 311
 312/*
 313 * Un-balloon message; this message is sent from the host
 314 * to the guest to give guest more memory.
 315 *
 316 * more_pages: If FALSE, this is the last message of the transaction.
 317 * if TRUE there will atleast one more message from the guest.
 318 *
 319 * reservedz: Reserved; must be set to zero.
 320 *
 321 * range_count: The number of ranges in the range array.
 322 *
 323 * range_array: An array of page ranges returned to the host.
 324 *
 325 */
 326
 327struct dm_unballoon_request {
 328	struct dm_header hdr;
 329	__u32 more_pages:1;
 330	__u32 reservedz:31;
 331	__u32 range_count;
 332	union dm_mem_page_range range_array[];
 333} __packed;
 334
 335/*
 336 * Un-balloon response message; this message is sent from the guest
 337 * to the host in response to an unballoon request.
 338 *
 339 */
 340
 341struct dm_unballoon_response {
 342	struct dm_header hdr;
 343} __packed;
 344
 345
 346/*
 347 * Hot add request message. Message sent from the host to the guest.
 348 *
 349 * mem_range: Memory range to hot add.
 350 *
 
 
 351 */
 352
 353struct dm_hot_add {
 354	struct dm_header hdr;
 355	union dm_mem_page_range range;
 356} __packed;
 357
 358/*
 359 * Hot add response message.
 360 * This message is sent by the guest to report the status of a hot add request.
 361 * If page_count is less than the requested page count, then the host should
 362 * assume all further hot add requests will fail, since this indicates that
 363 * the guest has hit an upper physical memory barrier.
 364 *
 365 * Hot adds may also fail due to low resources; in this case, the guest must
 366 * not complete this message until the hot add can succeed, and the host must
 367 * not send a new hot add request until the response is sent.
 368 * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
 369 * times it fails the request.
 370 *
 371 *
 372 * page_count: number of pages that were successfully hot added.
 373 *
 374 * result: result of the operation 1: success, 0: failure.
 375 *
 376 */
 377
 378struct dm_hot_add_response {
 379	struct dm_header hdr;
 380	__u32 page_count;
 381	__u32 result;
 382} __packed;
 383
 384/*
 385 * Types of information sent from host to the guest.
 386 */
 387
 388enum dm_info_type {
 389	INFO_TYPE_MAX_PAGE_CNT = 0,
 390	MAX_INFO_TYPE
 391};
 392
 393
 394/*
 395 * Header for the information message.
 396 */
 397
 398struct dm_info_header {
 399	enum dm_info_type type;
 400	__u32 data_size;
 401} __packed;
 402
 403/*
 404 * This message is sent from the host to the guest to pass
 405 * some relevant information (win8 addition).
 406 *
 407 * reserved: no used.
 408 * info_size: size of the information blob.
 409 * info: information blob.
 410 */
 411
 412struct dm_info_msg {
 413	struct dm_header hdr;
 414	__u32 reserved;
 415	__u32 info_size;
 416	__u8  info[];
 417};
 418
 419/*
 420 * End protocol definitions.
 421 */
 422
 423/*
 424 * State to manage hot adding memory into the guest.
 425 * The range start_pfn : end_pfn specifies the range
 426 * that the host has asked us to hot add. The range
 427 * start_pfn : ha_end_pfn specifies the range that we have
 428 * currently hot added. We hot add in multiples of 128M
 429 * chunks; it is possible that we may not be able to bring
 430 * online all the pages in the region. The range
 431 * covered_start_pfn:covered_end_pfn defines the pages that can
 432 * be brough online.
 433 */
 434
 435struct hv_hotadd_state {
 436	struct list_head list;
 437	unsigned long start_pfn;
 438	unsigned long covered_start_pfn;
 439	unsigned long covered_end_pfn;
 440	unsigned long ha_end_pfn;
 441	unsigned long end_pfn;
 442	/*
 443	 * A list of gaps.
 444	 */
 445	struct list_head gap_list;
 446};
 447
 448struct hv_hotadd_gap {
 449	struct list_head list;
 450	unsigned long start_pfn;
 451	unsigned long end_pfn;
 452};
 453
 454struct balloon_state {
 455	__u32 num_pages;
 456	struct work_struct wrk;
 457};
 458
 459struct hot_add_wrk {
 460	union dm_mem_page_range ha_page_range;
 461	union dm_mem_page_range ha_region_range;
 462	struct work_struct wrk;
 463};
 464
 465static bool allow_hibernation;
 466static bool hot_add = true;
 467static bool do_hot_add;
 468/*
 469 * Delay reporting memory pressure by
 470 * the specified number of seconds.
 471 */
 472static uint pressure_report_delay = 45;
 473extern unsigned int page_reporting_order;
 474#define HV_MAX_FAILURES	2
 475
 476/*
 477 * The last time we posted a pressure report to host.
 478 */
 479static unsigned long last_post_time;
 480
 481static int hv_hypercall_multi_failure;
 482
 483module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
 484MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");
 485
 486module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
 487MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
 488static atomic_t trans_id = ATOMIC_INIT(0);
 489
 490static int dm_ring_size = VMBUS_RING_SIZE(16 * 1024);
 491
 492/*
 493 * Driver specific state.
 494 */
 495
 496enum hv_dm_state {
 497	DM_INITIALIZING = 0,
 498	DM_INITIALIZED,
 499	DM_BALLOON_UP,
 500	DM_BALLOON_DOWN,
 501	DM_HOT_ADD,
 502	DM_INIT_ERROR
 503};
 504
 505
 506static __u8 recv_buffer[HV_HYP_PAGE_SIZE];
 507static __u8 balloon_up_send_buffer[HV_HYP_PAGE_SIZE];
 508#define PAGES_IN_2M (2 * 1024 * 1024 / PAGE_SIZE)
 509#define HA_CHUNK (128 * 1024 * 1024 / PAGE_SIZE)
 510
 511struct hv_dynmem_device {
 512	struct hv_device *dev;
 513	enum hv_dm_state state;
 514	struct completion host_event;
 515	struct completion config_event;
 516
 517	/*
 518	 * Number of pages we have currently ballooned out.
 519	 */
 520	unsigned int num_pages_ballooned;
 521	unsigned int num_pages_onlined;
 522	unsigned int num_pages_added;
 523
 524	/*
 525	 * State to manage the ballooning (up) operation.
 526	 */
 527	struct balloon_state balloon_wrk;
 528
 529	/*
 530	 * State to execute the "hot-add" operation.
 531	 */
 532	struct hot_add_wrk ha_wrk;
 533
 534	/*
 535	 * This state tracks if the host has specified a hot-add
 536	 * region.
 537	 */
 538	bool host_specified_ha_region;
 539
 540	/*
 541	 * State to synchronize hot-add.
 542	 */
 543	struct completion  ol_waitevent;
 
 544	/*
 545	 * This thread handles hot-add
 546	 * requests from the host as well as notifying
 547	 * the host with regards to memory pressure in
 548	 * the guest.
 549	 */
 550	struct task_struct *thread;
 551
 552	/*
 553	 * Protects ha_region_list, num_pages_onlined counter and individual
 554	 * regions from ha_region_list.
 555	 */
 556	spinlock_t ha_lock;
 557
 558	/*
 559	 * A list of hot-add regions.
 560	 */
 561	struct list_head ha_region_list;
 562
 563	/*
 564	 * We start with the highest version we can support
 565	 * and downgrade based on the host; we save here the
 566	 * next version to try.
 567	 */
 568	__u32 next_version;
 569
 570	/*
 571	 * The negotiated version agreed by host.
 572	 */
 573	__u32 version;
 574
 575	struct page_reporting_dev_info pr_dev_info;
 576
 577	/*
 578	 * Maximum number of pages that can be hot_add-ed
 579	 */
 580	__u64 max_dynamic_page_count;
 581};
 582
 583static struct hv_dynmem_device dm_device;
 584
 585static void post_status(struct hv_dynmem_device *dm);
 586
 587static void enable_page_reporting(void);
 588
 589static void disable_page_reporting(void);
 590
 591#ifdef CONFIG_MEMORY_HOTPLUG
 592static inline bool has_pfn_is_backed(struct hv_hotadd_state *has,
 593				     unsigned long pfn)
 594{
 595	struct hv_hotadd_gap *gap;
 596
 597	/* The page is not backed. */
 598	if ((pfn < has->covered_start_pfn) || (pfn >= has->covered_end_pfn))
 599		return false;
 600
 601	/* Check for gaps. */
 602	list_for_each_entry(gap, &has->gap_list, list) {
 603		if ((pfn >= gap->start_pfn) && (pfn < gap->end_pfn))
 604			return false;
 605	}
 606
 607	return true;
 608}
 609
 610static unsigned long hv_page_offline_check(unsigned long start_pfn,
 611					   unsigned long nr_pages)
 612{
 613	unsigned long pfn = start_pfn, count = 0;
 614	struct hv_hotadd_state *has;
 615	bool found;
 616
 617	while (pfn < start_pfn + nr_pages) {
 618		/*
 619		 * Search for HAS which covers the pfn and when we find one
 620		 * count how many consequitive PFNs are covered.
 621		 */
 622		found = false;
 623		list_for_each_entry(has, &dm_device.ha_region_list, list) {
 624			while ((pfn >= has->start_pfn) &&
 625			       (pfn < has->end_pfn) &&
 626			       (pfn < start_pfn + nr_pages)) {
 627				found = true;
 628				if (has_pfn_is_backed(has, pfn))
 629					count++;
 630				pfn++;
 631			}
 632		}
 633
 634		/*
 635		 * This PFN is not in any HAS (e.g. we're offlining a region
 636		 * which was present at boot), no need to account for it. Go
 637		 * to the next one.
 638		 */
 639		if (!found)
 640			pfn++;
 641	}
 642
 643	return count;
 644}
 645
 646static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
 647			      void *v)
 648{
 649	struct memory_notify *mem = (struct memory_notify *)v;
 650	unsigned long pfn_count;
 651
 652	switch (val) {
 653	case MEM_ONLINE:
 654	case MEM_CANCEL_ONLINE:
 655		complete(&dm_device.ol_waitevent);
 
 
 
 656		break;
 657
 658	case MEM_OFFLINE:
 659		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
 660			pfn_count = hv_page_offline_check(mem->start_pfn,
 661							  mem->nr_pages);
 662			if (pfn_count <= dm_device.num_pages_onlined) {
 663				dm_device.num_pages_onlined -= pfn_count;
 664			} else {
 665				/*
 666				 * We're offlining more pages than we
 667				 * managed to online. This is
 668				 * unexpected. In any case don't let
 669				 * num_pages_onlined wrap around zero.
 670				 */
 671				WARN_ON_ONCE(1);
 672				dm_device.num_pages_onlined = 0;
 673			}
 674		}
 
 675		break;
 676	case MEM_GOING_ONLINE:
 677	case MEM_GOING_OFFLINE:
 678	case MEM_CANCEL_OFFLINE:
 679		break;
 680	}
 681	return NOTIFY_OK;
 682}
 683
 684static struct notifier_block hv_memory_nb = {
 685	.notifier_call = hv_memory_notifier,
 686	.priority = 0
 687};
 688
 689/* Check if the particular page is backed and can be onlined and online it. */
 690static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
 691{
 692	if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
 693		if (!PageOffline(pg))
 694			__SetPageOffline(pg);
 695		return;
 696	}
 697	if (PageOffline(pg))
 698		__ClearPageOffline(pg);
 699
 700	/* This frame is currently backed; online the page. */
 701	generic_online_page(pg, 0);
 
 
 702
 703	lockdep_assert_held(&dm_device.ha_lock);
 704	dm_device.num_pages_onlined++;
 705}
 706
 707static void hv_bring_pgs_online(struct hv_hotadd_state *has,
 708				unsigned long start_pfn, unsigned long size)
 709{
 710	int i;
 711
 712	pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
 713	for (i = 0; i < size; i++)
 714		hv_page_online_one(has, pfn_to_page(start_pfn + i));
 715}
 716
 717static void hv_mem_hot_add(unsigned long start, unsigned long size,
 718				unsigned long pfn_count,
 719				struct hv_hotadd_state *has)
 720{
 721	int ret = 0;
 722	int i, nid;
 723	unsigned long start_pfn;
 724	unsigned long processed_pfn;
 725	unsigned long total_pfn = pfn_count;
 
 726
 727	for (i = 0; i < (size/HA_CHUNK); i++) {
 728		start_pfn = start + (i * HA_CHUNK);
 729
 730		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
 731			has->ha_end_pfn +=  HA_CHUNK;
 732
 733			if (total_pfn > HA_CHUNK) {
 734				processed_pfn = HA_CHUNK;
 735				total_pfn -= HA_CHUNK;
 736			} else {
 737				processed_pfn = total_pfn;
 738				total_pfn = 0;
 739			}
 740
 741			has->covered_end_pfn +=  processed_pfn;
 742		}
 743
 744		reinit_completion(&dm_device.ol_waitevent);
 
 
 
 
 745
 746		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 747		ret = add_memory(nid, PFN_PHYS((start_pfn)),
 748				(HA_CHUNK << PAGE_SHIFT), MHP_MERGE_RESOURCE);
 749
 750		if (ret) {
 751			pr_err("hot_add memory failed error is %d\n", ret);
 752			if (ret == -EEXIST) {
 753				/*
 754				 * This error indicates that the error
 755				 * is not a transient failure. This is the
 756				 * case where the guest's physical address map
 757				 * precludes hot adding memory. Stop all further
 758				 * memory hot-add.
 759				 */
 760				do_hot_add = false;
 761			}
 762			scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
 763				has->ha_end_pfn -= HA_CHUNK;
 764				has->covered_end_pfn -=  processed_pfn;
 765			}
 766			break;
 767		}
 768
 769		/*
 770		 * Wait for memory to get onlined. If the kernel onlined the
 771		 * memory when adding it, this will return directly. Otherwise,
 772		 * it will wait for user space to online the memory. This helps
 773		 * to avoid adding memory faster than it is getting onlined. As
 774		 * adding succeeded, it is ok to proceed even if the memory was
 775		 * not onlined in time.
 776		 */
 777		wait_for_completion_timeout(&dm_device.ol_waitevent, 5 * HZ);
 
 
 778		post_status(&dm_device);
 779	}
 780}
 781
 782static void hv_online_page(struct page *pg, unsigned int order)
 783{
 784	struct hv_hotadd_state *has;
 
 785	unsigned long pfn = page_to_pfn(pg);
 786
 787	guard(spinlock_irqsave)(&dm_device.ha_lock);
 788	list_for_each_entry(has, &dm_device.ha_region_list, list) {
 789		/* The page belongs to a different HAS. */
 790		if ((pfn < has->start_pfn) ||
 791				(pfn + (1UL << order) > has->end_pfn))
 792			continue;
 793
 794		hv_bring_pgs_online(has, pfn, 1UL << order);
 795		break;
 796	}
 
 797}
 798
 799static int pfn_covered(unsigned long start_pfn, unsigned long pfn_cnt)
 800{
 801	struct hv_hotadd_state *has;
 802	struct hv_hotadd_gap *gap;
 803	unsigned long residual, new_inc;
 804	int ret = 0;
 
 805
 806	guard(spinlock_irqsave)(&dm_device.ha_lock);
 807	list_for_each_entry(has, &dm_device.ha_region_list, list) {
 808		/*
 809		 * If the pfn range we are dealing with is not in the current
 810		 * "hot add block", move on.
 811		 */
 812		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 813			continue;
 814
 815		/*
 816		 * If the current start pfn is not where the covered_end
 817		 * is, create a gap and update covered_end_pfn.
 818		 */
 819		if (has->covered_end_pfn != start_pfn) {
 820			gap = kzalloc(sizeof(struct hv_hotadd_gap), GFP_ATOMIC);
 821			if (!gap) {
 822				ret = -ENOMEM;
 823				break;
 824			}
 825
 826			INIT_LIST_HEAD(&gap->list);
 827			gap->start_pfn = has->covered_end_pfn;
 828			gap->end_pfn = start_pfn;
 829			list_add_tail(&gap->list, &has->gap_list);
 830
 831			has->covered_end_pfn = start_pfn;
 832		}
 833
 834		/*
 835		 * If the current hot add-request extends beyond
 836		 * our current limit; extend it.
 837		 */
 838		if ((start_pfn + pfn_cnt) > has->end_pfn) {
 839			residual = (start_pfn + pfn_cnt - has->end_pfn);
 840			/*
 841			 * Extend the region by multiples of HA_CHUNK.
 842			 */
 843			new_inc = (residual / HA_CHUNK) * HA_CHUNK;
 844			if (residual % HA_CHUNK)
 845				new_inc += HA_CHUNK;
 846
 847			has->end_pfn += new_inc;
 848		}
 849
 850		ret = 1;
 851		break;
 852	}
 
 853
 854	return ret;
 855}
 856
 857static unsigned long handle_pg_range(unsigned long pg_start,
 858					unsigned long pg_count)
 859{
 860	unsigned long start_pfn = pg_start;
 861	unsigned long pfn_cnt = pg_count;
 862	unsigned long size;
 863	struct hv_hotadd_state *has;
 864	unsigned long pgs_ol = 0;
 865	unsigned long old_covered_state;
 866	unsigned long res = 0, flags;
 867
 868	pr_debug("Hot adding %lu pages starting at pfn 0x%lx.\n", pg_count,
 869		pg_start);
 870
 871	spin_lock_irqsave(&dm_device.ha_lock, flags);
 872	list_for_each_entry(has, &dm_device.ha_region_list, list) {
 873		/*
 874		 * If the pfn range we are dealing with is not in the current
 875		 * "hot add block", move on.
 876		 */
 877		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 878			continue;
 879
 880		old_covered_state = has->covered_end_pfn;
 881
 882		if (start_pfn < has->ha_end_pfn) {
 883			/*
 884			 * This is the case where we are backing pages
 885			 * in an already hot added region. Bring
 886			 * these pages online first.
 887			 */
 888			pgs_ol = has->ha_end_pfn - start_pfn;
 889			if (pgs_ol > pfn_cnt)
 890				pgs_ol = pfn_cnt;
 891
 892			has->covered_end_pfn +=  pgs_ol;
 893			pfn_cnt -= pgs_ol;
 894			/*
 895			 * Check if the corresponding memory block is already
 896			 * online. It is possible to observe struct pages still
 897			 * being uninitialized here so check section instead.
 898			 * In case the section is online we need to bring the
 899			 * rest of pfns (which were not backed previously)
 900			 * online too.
 901			 */
 902			if (start_pfn > has->start_pfn &&
 903			    online_section_nr(pfn_to_section_nr(start_pfn)))
 904				hv_bring_pgs_online(has, start_pfn, pgs_ol);
 905
 906		}
 907
 908		if ((has->ha_end_pfn < has->end_pfn) && (pfn_cnt > 0)) {
 909			/*
 910			 * We have some residual hot add range
 911			 * that needs to be hot added; hot add
 912			 * it now. Hot add a multiple of
 913			 * HA_CHUNK that fully covers the pages
 914			 * we have.
 915			 */
 916			size = (has->end_pfn - has->ha_end_pfn);
 917			if (pfn_cnt <= size) {
 918				size = ((pfn_cnt / HA_CHUNK) * HA_CHUNK);
 919				if (pfn_cnt % HA_CHUNK)
 920					size += HA_CHUNK;
 921			} else {
 922				pfn_cnt = size;
 923			}
 924			spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 925			hv_mem_hot_add(has->ha_end_pfn, size, pfn_cnt, has);
 926			spin_lock_irqsave(&dm_device.ha_lock, flags);
 927		}
 928		/*
 929		 * If we managed to online any pages that were given to us,
 930		 * we declare success.
 931		 */
 932		res = has->covered_end_pfn - old_covered_state;
 933		break;
 934	}
 935	spin_unlock_irqrestore(&dm_device.ha_lock, flags);
 936
 937	return res;
 938}
 939
 940static unsigned long process_hot_add(unsigned long pg_start,
 941					unsigned long pfn_cnt,
 942					unsigned long rg_start,
 943					unsigned long rg_size)
 944{
 945	struct hv_hotadd_state *ha_region = NULL;
 946	int covered;
 
 947
 948	if (pfn_cnt == 0)
 949		return 0;
 950
 951	if (!dm_device.host_specified_ha_region) {
 952		covered = pfn_covered(pg_start, pfn_cnt);
 953		if (covered < 0)
 954			return 0;
 955
 956		if (covered)
 957			goto do_pg_range;
 958	}
 959
 960	/*
 961	 * If the host has specified a hot-add range; deal with it first.
 962	 */
 963
 964	if (rg_size != 0) {
 965		ha_region = kzalloc(sizeof(struct hv_hotadd_state), GFP_KERNEL);
 966		if (!ha_region)
 967			return 0;
 968
 969		INIT_LIST_HEAD(&ha_region->list);
 970		INIT_LIST_HEAD(&ha_region->gap_list);
 971
 972		ha_region->start_pfn = rg_start;
 973		ha_region->ha_end_pfn = rg_start;
 974		ha_region->covered_start_pfn = pg_start;
 975		ha_region->covered_end_pfn = pg_start;
 976		ha_region->end_pfn = rg_start + rg_size;
 977
 978		scoped_guard(spinlock_irqsave, &dm_device.ha_lock) {
 979			list_add_tail(&ha_region->list, &dm_device.ha_region_list);
 980		}
 981	}
 982
 983do_pg_range:
 984	/*
 985	 * Process the page range specified; bringing them
 986	 * online if possible.
 987	 */
 988	return handle_pg_range(pg_start, pfn_cnt);
 989}
 990
 991#endif
 992
 993static void hot_add_req(struct work_struct *dummy)
 994{
 995	struct dm_hot_add_response resp;
 996#ifdef CONFIG_MEMORY_HOTPLUG
 997	unsigned long pg_start, pfn_cnt;
 998	unsigned long rg_start, rg_sz;
 999#endif
1000	struct hv_dynmem_device *dm = &dm_device;
1001
1002	memset(&resp, 0, sizeof(struct dm_hot_add_response));
1003	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
1004	resp.hdr.size = sizeof(struct dm_hot_add_response);
1005
1006#ifdef CONFIG_MEMORY_HOTPLUG
1007	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
1008	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;
1009
1010	rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
1011	rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;
1012
1013	if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
1014		unsigned long region_size;
1015		unsigned long region_start;
1016
1017		/*
1018		 * The host has not specified the hot-add region.
1019		 * Based on the hot-add page range being specified,
1020		 * compute a hot-add region that can cover the pages
1021		 * that need to be hot-added while ensuring the alignment
1022		 * and size requirements of Linux as it relates to hot-add.
1023		 */
 
1024		region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
1025		if (pfn_cnt % HA_CHUNK)
1026			region_size += HA_CHUNK;
1027
1028		region_start = (pg_start / HA_CHUNK) * HA_CHUNK;
1029
1030		rg_start = region_start;
1031		rg_sz = region_size;
1032	}
1033
1034	if (do_hot_add)
1035		resp.page_count = process_hot_add(pg_start, pfn_cnt,
1036						rg_start, rg_sz);
1037
1038	dm->num_pages_added += resp.page_count;
1039#endif
1040	/*
1041	 * The result field of the response structure has the
1042	 * following semantics:
1043	 *
1044	 * 1. If all or some pages hot-added: Guest should return success.
1045	 *
1046	 * 2. If no pages could be hot-added:
1047	 *
1048	 * If the guest returns success, then the host
1049	 * will not attempt any further hot-add operations. This
1050	 * signifies a permanent failure.
1051	 *
1052	 * If the guest returns failure, then this failure will be
1053	 * treated as a transient failure and the host may retry the
1054	 * hot-add operation after some delay.
1055	 */
1056	if (resp.page_count > 0)
1057		resp.result = 1;
1058	else if (!do_hot_add)
1059		resp.result = 1;
1060	else
1061		resp.result = 0;
1062
1063	if (!do_hot_add || resp.page_count == 0) {
1064		if (!allow_hibernation)
1065			pr_err("Memory hot add failed\n");
1066		else
1067			pr_info("Ignore hot-add request!\n");
1068	}
1069
1070	dm->state = DM_INITIALIZED;
1071	resp.hdr.trans_id = atomic_inc_return(&trans_id);
1072	vmbus_sendpacket(dm->dev->channel, &resp,
1073			sizeof(struct dm_hot_add_response),
1074			(unsigned long)NULL,
1075			VM_PKT_DATA_INBAND, 0);
1076}
1077
1078static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
1079{
1080	struct dm_info_header *info_hdr;
1081
1082	info_hdr = (struct dm_info_header *)msg->info;
1083
1084	switch (info_hdr->type) {
1085	case INFO_TYPE_MAX_PAGE_CNT:
1086		if (info_hdr->data_size == sizeof(__u64)) {
1087			__u64 *max_page_count = (__u64 *)&info_hdr[1];
1088
1089			pr_info("Max. dynamic memory size: %llu MB\n",
1090				(*max_page_count) >> (20 - HV_HYP_PAGE_SHIFT));
1091			dm->max_dynamic_page_count = *max_page_count;
1092		}
1093
1094		break;
1095	default:
1096		pr_warn("Received Unknown type: %d\n", info_hdr->type);
1097	}
1098}
1099
1100static unsigned long compute_balloon_floor(void)
1101{
1102	unsigned long min_pages;
1103	unsigned long nr_pages = totalram_pages();
1104#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
1105	/* Simple continuous piecewiese linear function:
1106	 *  max MiB -> min MiB  gradient
1107	 *       0         0
1108	 *      16        16
1109	 *      32        24
1110	 *     128        72    (1/2)
1111	 *     512       168    (1/4)
1112	 *    2048       360    (1/8)
1113	 *    8192       744    (1/16)
1114	 *   32768      1512	(1/32)
1115	 */
1116	if (nr_pages < MB2PAGES(128))
1117		min_pages = MB2PAGES(8) + (nr_pages >> 1);
1118	else if (nr_pages < MB2PAGES(512))
1119		min_pages = MB2PAGES(40) + (nr_pages >> 2);
1120	else if (nr_pages < MB2PAGES(2048))
1121		min_pages = MB2PAGES(104) + (nr_pages >> 3);
1122	else if (nr_pages < MB2PAGES(8192))
1123		min_pages = MB2PAGES(232) + (nr_pages >> 4);
1124	else
1125		min_pages = MB2PAGES(488) + (nr_pages >> 5);
1126#undef MB2PAGES
1127	return min_pages;
1128}
1129
1130/*
1131 * Compute total committed memory pages
1132 */
1133
1134static unsigned long get_pages_committed(struct hv_dynmem_device *dm)
1135{
1136	return vm_memory_committed() +
1137		dm->num_pages_ballooned +
1138		(dm->num_pages_added > dm->num_pages_onlined ?
1139		 dm->num_pages_added - dm->num_pages_onlined : 0) +
1140		compute_balloon_floor();
1141}
1142
1143/*
1144 * Post our status as it relates memory pressure to the
1145 * host. Host expects the guests to post this status
1146 * periodically at 1 second intervals.
1147 *
1148 * The metrics specified in this protocol are very Windows
1149 * specific and so we cook up numbers here to convey our memory
1150 * pressure.
1151 */
1152
1153static void post_status(struct hv_dynmem_device *dm)
1154{
1155	struct dm_status status;
1156	unsigned long now = jiffies;
1157	unsigned long last_post = last_post_time;
1158	unsigned long num_pages_avail, num_pages_committed;
1159
1160	if (pressure_report_delay > 0) {
1161		--pressure_report_delay;
1162		return;
1163	}
1164
1165	if (!time_after(now, (last_post_time + HZ)))
1166		return;
1167
1168	memset(&status, 0, sizeof(struct dm_status));
1169	status.hdr.type = DM_STATUS_REPORT;
1170	status.hdr.size = sizeof(struct dm_status);
1171	status.hdr.trans_id = atomic_inc_return(&trans_id);
1172
1173	/*
1174	 * The host expects the guest to report free and committed memory.
1175	 * Furthermore, the host expects the pressure information to include
1176	 * the ballooned out pages. For a given amount of memory that we are
1177	 * managing we need to compute a floor below which we should not
1178	 * balloon. Compute this and add it to the pressure report.
1179	 * We also need to report all offline pages (num_pages_added -
1180	 * num_pages_onlined) as committed to the host, otherwise it can try
1181	 * asking us to balloon them out.
1182	 */
1183	num_pages_avail = si_mem_available();
1184	num_pages_committed = get_pages_committed(dm);
 
 
 
 
1185
1186	trace_balloon_status(num_pages_avail, num_pages_committed,
1187			     vm_memory_committed(), dm->num_pages_ballooned,
1188			     dm->num_pages_added, dm->num_pages_onlined);
1189
1190	/* Convert numbers of pages into numbers of HV_HYP_PAGEs. */
1191	status.num_avail = num_pages_avail * NR_HV_HYP_PAGES_IN_PAGE;
1192	status.num_committed = num_pages_committed * NR_HV_HYP_PAGES_IN_PAGE;
1193
1194	/*
1195	 * If our transaction ID is no longer current, just don't
1196	 * send the status. This can happen if we were interrupted
1197	 * after we picked our transaction ID.
1198	 */
1199	if (status.hdr.trans_id != atomic_read(&trans_id))
1200		return;
1201
1202	/*
1203	 * If the last post time that we sampled has changed,
1204	 * we have raced, don't post the status.
1205	 */
1206	if (last_post != last_post_time)
1207		return;
1208
1209	last_post_time = jiffies;
1210	vmbus_sendpacket(dm->dev->channel, &status,
1211				sizeof(struct dm_status),
1212				(unsigned long)NULL,
1213				VM_PKT_DATA_INBAND, 0);
1214
1215}
1216
1217static void free_balloon_pages(struct hv_dynmem_device *dm,
1218			 union dm_mem_page_range *range_array)
1219{
1220	int num_pages = range_array->finfo.page_cnt;
1221	__u64 start_frame = range_array->finfo.start_page;
1222	struct page *pg;
1223	int i;
1224
1225	for (i = 0; i < num_pages; i++) {
1226		pg = pfn_to_page(i + start_frame);
1227		__ClearPageOffline(pg);
1228		__free_page(pg);
1229		dm->num_pages_ballooned--;
1230		adjust_managed_page_count(pg, 1);
1231	}
1232}
1233
1234
1235
1236static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
1237					unsigned int num_pages,
1238					struct dm_balloon_response *bl_resp,
1239					int alloc_unit)
1240{
1241	unsigned int i, j;
1242	struct page *pg;
1243
1244	for (i = 0; i < num_pages / alloc_unit; i++) {
 
 
 
1245		if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
1246			HV_HYP_PAGE_SIZE)
1247			return i * alloc_unit;
1248
1249		/*
1250		 * We execute this code in a thread context. Furthermore,
1251		 * we don't want the kernel to try too hard.
1252		 */
1253		pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
1254				__GFP_NOMEMALLOC | __GFP_NOWARN,
1255				get_order(alloc_unit << PAGE_SHIFT));
1256
1257		if (!pg)
1258			return i * alloc_unit;
1259
1260		dm->num_pages_ballooned += alloc_unit;
1261
1262		/*
1263		 * If we allocatted 2M pages; split them so we
1264		 * can free them in any order we get.
1265		 */
1266
1267		if (alloc_unit != 1)
1268			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
1269
1270		/* mark all pages offline */
1271		for (j = 0; j < alloc_unit; j++) {
1272			__SetPageOffline(pg + j);
1273			adjust_managed_page_count(pg + j, -1);
1274		}
1275
1276		bl_resp->range_count++;
1277		bl_resp->range_array[i].finfo.start_page =
1278			page_to_pfn(pg);
1279		bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
1280		bl_resp->hdr.size += sizeof(union dm_mem_page_range);
1281
1282	}
1283
1284	return i * alloc_unit;
1285}
1286
1287static void balloon_up(struct work_struct *dummy)
1288{
1289	unsigned int num_pages = dm_device.balloon_wrk.num_pages;
1290	unsigned int num_ballooned = 0;
1291	struct dm_balloon_response *bl_resp;
1292	int alloc_unit;
1293	int ret;
1294	bool done = false;
1295	int i;
1296	long avail_pages;
1297	unsigned long floor;
1298
 
 
 
1299	/*
1300	 * We will attempt 2M allocations. However, if we fail to
1301	 * allocate 2M chunks, we will go back to PAGE_SIZE allocations.
1302	 */
1303	alloc_unit = PAGES_IN_2M;
1304
1305	avail_pages = si_mem_available();
1306	floor = compute_balloon_floor();
1307
1308	/* Refuse to balloon below the floor. */
1309	if (avail_pages < num_pages || avail_pages - num_pages < floor) {
1310		pr_info("Balloon request will be partially fulfilled. %s\n",
1311			avail_pages < num_pages ? "Not enough memory." :
1312			"Balloon floor reached.");
1313
1314		num_pages = avail_pages > floor ? (avail_pages - floor) : 0;
 
1315	}
1316
1317	while (!done) {
1318		memset(balloon_up_send_buffer, 0, HV_HYP_PAGE_SIZE);
1319		bl_resp = (struct dm_balloon_response *)balloon_up_send_buffer;
1320		bl_resp->hdr.type = DM_BALLOON_RESPONSE;
1321		bl_resp->hdr.size = sizeof(struct dm_balloon_response);
1322		bl_resp->more_pages = 1;
1323
1324		num_pages -= num_ballooned;
1325		num_ballooned = alloc_balloon_pages(&dm_device, num_pages,
1326						    bl_resp, alloc_unit);
1327
1328		if (alloc_unit != 1 && num_ballooned == 0) {
1329			alloc_unit = 1;
1330			continue;
1331		}
1332
1333		if (num_ballooned == 0 || num_ballooned == num_pages) {
1334			pr_debug("Ballooned %u out of %u requested pages.\n",
1335				num_pages, dm_device.balloon_wrk.num_pages);
1336
1337			bl_resp->more_pages = 0;
1338			done = true;
1339			dm_device.state = DM_INITIALIZED;
1340		}
1341
1342		/*
1343		 * We are pushing a lot of data through the channel;
1344		 * deal with transient failures caused because of the
1345		 * lack of space in the ring buffer.
1346		 */
1347
1348		do {
1349			bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
1350			ret = vmbus_sendpacket(dm_device.dev->channel,
1351						bl_resp,
1352						bl_resp->hdr.size,
1353						(unsigned long)NULL,
1354						VM_PKT_DATA_INBAND, 0);
1355
1356			if (ret == -EAGAIN)
1357				msleep(20);
1358			post_status(&dm_device);
1359		} while (ret == -EAGAIN);
1360
1361		if (ret) {
1362			/*
1363			 * Free up the memory we allocatted.
1364			 */
1365			pr_err("Balloon response failed\n");
1366
1367			for (i = 0; i < bl_resp->range_count; i++)
1368				free_balloon_pages(&dm_device,
1369						 &bl_resp->range_array[i]);
1370
1371			done = true;
1372		}
1373	}
1374
1375}
1376
1377static void balloon_down(struct hv_dynmem_device *dm,
1378			struct dm_unballoon_request *req)
1379{
1380	union dm_mem_page_range *range_array = req->range_array;
1381	int range_count = req->range_count;
1382	struct dm_unballoon_response resp;
1383	int i;
1384	unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
1385
1386	for (i = 0; i < range_count; i++) {
1387		free_balloon_pages(dm, &range_array[i]);
1388		complete(&dm_device.config_event);
1389	}
1390
1391	pr_debug("Freed %u ballooned pages.\n",
1392		prev_pages_ballooned - dm->num_pages_ballooned);
1393
1394	if (req->more_pages == 1)
1395		return;
1396
1397	memset(&resp, 0, sizeof(struct dm_unballoon_response));
1398	resp.hdr.type = DM_UNBALLOON_RESPONSE;
1399	resp.hdr.trans_id = atomic_inc_return(&trans_id);
1400	resp.hdr.size = sizeof(struct dm_unballoon_response);
1401
1402	vmbus_sendpacket(dm_device.dev->channel, &resp,
1403				sizeof(struct dm_unballoon_response),
1404				(unsigned long)NULL,
1405				VM_PKT_DATA_INBAND, 0);
1406
1407	dm->state = DM_INITIALIZED;
1408}
1409
1410static void balloon_onchannelcallback(void *context);
1411
1412static int dm_thread_func(void *dm_dev)
1413{
1414	struct hv_dynmem_device *dm = dm_dev;
1415
1416	while (!kthread_should_stop()) {
1417		wait_for_completion_interruptible_timeout(
1418						&dm_device.config_event, 1*HZ);
1419		/*
1420		 * The host expects us to post information on the memory
1421		 * pressure every second.
1422		 */
1423		reinit_completion(&dm_device.config_event);
1424		post_status(dm);
1425		/*
1426		 * disable free page reporting if multiple hypercall
1427		 * failure flag set. It is not done in the page_reporting
1428		 * callback context as that causes a deadlock between
1429		 * page_reporting_process() and page_reporting_unregister()
1430		 */
1431		if (hv_hypercall_multi_failure >= HV_MAX_FAILURES) {
1432			pr_err("Multiple failures in cold memory discard hypercall, disabling page reporting\n");
1433			disable_page_reporting();
1434			/* Reset the flag after disabling reporting */
1435			hv_hypercall_multi_failure = 0;
1436		}
1437	}
1438
1439	return 0;
1440}
1441
1442
1443static void version_resp(struct hv_dynmem_device *dm,
1444			struct dm_version_response *vresp)
1445{
1446	struct dm_version_request version_req;
1447	int ret;
1448
1449	if (vresp->is_accepted) {
1450		/*
1451		 * We are done; wakeup the
1452		 * context waiting for version
1453		 * negotiation.
1454		 */
1455		complete(&dm->host_event);
1456		return;
1457	}
1458	/*
1459	 * If there are more versions to try, continue
1460	 * with negotiations; if not
1461	 * shutdown the service since we are not able
1462	 * to negotiate a suitable version number
1463	 * with the host.
1464	 */
1465	if (dm->next_version == 0)
1466		goto version_error;
1467
1468	memset(&version_req, 0, sizeof(struct dm_version_request));
1469	version_req.hdr.type = DM_VERSION_REQUEST;
1470	version_req.hdr.size = sizeof(struct dm_version_request);
1471	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1472	version_req.version.version = dm->next_version;
1473	dm->version = version_req.version.version;
1474
1475	/*
1476	 * Set the next version to try in case current version fails.
1477	 * Win7 protocol ought to be the last one to try.
1478	 */
1479	switch (version_req.version.version) {
1480	case DYNMEM_PROTOCOL_VERSION_WIN8:
1481		dm->next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
1482		version_req.is_last_attempt = 0;
1483		break;
1484	default:
1485		dm->next_version = 0;
1486		version_req.is_last_attempt = 1;
1487	}
1488
1489	ret = vmbus_sendpacket(dm->dev->channel, &version_req,
1490				sizeof(struct dm_version_request),
1491				(unsigned long)NULL,
1492				VM_PKT_DATA_INBAND, 0);
1493
1494	if (ret)
1495		goto version_error;
1496
1497	return;
1498
1499version_error:
1500	dm->state = DM_INIT_ERROR;
1501	complete(&dm->host_event);
1502}
1503
1504static void cap_resp(struct hv_dynmem_device *dm,
1505			struct dm_capabilities_resp_msg *cap_resp)
1506{
1507	if (!cap_resp->is_accepted) {
1508		pr_err("Capabilities not accepted by host\n");
1509		dm->state = DM_INIT_ERROR;
1510	}
1511	complete(&dm->host_event);
1512}
1513
1514static void balloon_onchannelcallback(void *context)
1515{
1516	struct hv_device *dev = context;
1517	u32 recvlen;
1518	u64 requestid;
1519	struct dm_message *dm_msg;
1520	struct dm_header *dm_hdr;
1521	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
1522	struct dm_balloon *bal_msg;
1523	struct dm_hot_add *ha_msg;
1524	union dm_mem_page_range *ha_pg_range;
1525	union dm_mem_page_range *ha_region;
1526
1527	memset(recv_buffer, 0, sizeof(recv_buffer));
1528	vmbus_recvpacket(dev->channel, recv_buffer,
1529			 HV_HYP_PAGE_SIZE, &recvlen, &requestid);
1530
1531	if (recvlen > 0) {
1532		dm_msg = (struct dm_message *)recv_buffer;
1533		dm_hdr = &dm_msg->hdr;
1534
1535		switch (dm_hdr->type) {
1536		case DM_VERSION_RESPONSE:
1537			version_resp(dm,
1538				 (struct dm_version_response *)dm_msg);
1539			break;
1540
1541		case DM_CAPABILITIES_RESPONSE:
1542			cap_resp(dm,
1543				 (struct dm_capabilities_resp_msg *)dm_msg);
1544			break;
1545
1546		case DM_BALLOON_REQUEST:
1547			if (allow_hibernation) {
1548				pr_info("Ignore balloon-up request!\n");
1549				break;
1550			}
1551
1552			if (dm->state == DM_BALLOON_UP)
1553				pr_warn("Currently ballooning\n");
1554			bal_msg = (struct dm_balloon *)recv_buffer;
1555			dm->state = DM_BALLOON_UP;
1556			dm_device.balloon_wrk.num_pages = bal_msg->num_pages;
1557			schedule_work(&dm_device.balloon_wrk.wrk);
1558			break;
1559
1560		case DM_UNBALLOON_REQUEST:
1561			if (allow_hibernation) {
1562				pr_info("Ignore balloon-down request!\n");
1563				break;
1564			}
1565
1566			dm->state = DM_BALLOON_DOWN;
1567			balloon_down(dm,
1568				 (struct dm_unballoon_request *)recv_buffer);
1569			break;
1570
1571		case DM_MEM_HOT_ADD_REQUEST:
1572			if (dm->state == DM_HOT_ADD)
1573				pr_warn("Currently hot-adding\n");
1574			dm->state = DM_HOT_ADD;
1575			ha_msg = (struct dm_hot_add *)recv_buffer;
1576			if (ha_msg->hdr.size == sizeof(struct dm_hot_add)) {
1577				/*
1578				 * This is a normal hot-add request specifying
1579				 * hot-add memory.
1580				 */
1581				dm->host_specified_ha_region = false;
1582				ha_pg_range = &ha_msg->range;
1583				dm->ha_wrk.ha_page_range = *ha_pg_range;
1584				dm->ha_wrk.ha_region_range.page_range = 0;
1585			} else {
1586				/*
1587				 * Host is specifying that we first hot-add
1588				 * a region and then partially populate this
1589				 * region.
1590				 */
1591				dm->host_specified_ha_region = true;
1592				ha_pg_range = &ha_msg->range;
1593				ha_region = &ha_pg_range[1];
1594				dm->ha_wrk.ha_page_range = *ha_pg_range;
1595				dm->ha_wrk.ha_region_range = *ha_region;
1596			}
1597			schedule_work(&dm_device.ha_wrk.wrk);
1598			break;
1599
1600		case DM_INFO_MESSAGE:
1601			process_info(dm, (struct dm_info_msg *)dm_msg);
1602			break;
1603
1604		default:
1605			pr_warn_ratelimited("Unhandled message: type: %d\n", dm_hdr->type);
1606
1607		}
1608	}
1609
1610}
1611
1612#define HV_LARGE_REPORTING_ORDER	9
1613#define HV_LARGE_REPORTING_LEN (HV_HYP_PAGE_SIZE << \
1614		HV_LARGE_REPORTING_ORDER)
1615static int hv_free_page_report(struct page_reporting_dev_info *pr_dev_info,
1616		    struct scatterlist *sgl, unsigned int nents)
1617{
1618	unsigned long flags;
1619	struct hv_memory_hint *hint;
1620	int i, order;
1621	u64 status;
1622	struct scatterlist *sg;
1623
1624	WARN_ON_ONCE(nents > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
1625	WARN_ON_ONCE(sgl->length < (HV_HYP_PAGE_SIZE << page_reporting_order));
1626	local_irq_save(flags);
1627	hint = *this_cpu_ptr(hyperv_pcpu_input_arg);
1628	if (!hint) {
1629		local_irq_restore(flags);
1630		return -ENOSPC;
1631	}
1632
1633	hint->type = HV_EXT_MEMORY_HEAT_HINT_TYPE_COLD_DISCARD;
1634	hint->reserved = 0;
1635	for_each_sg(sgl, sg, nents, i) {
1636		union hv_gpa_page_range *range;
1637
1638		range = &hint->ranges[i];
1639		range->address_space = 0;
1640		order = get_order(sg->length);
1641		/*
1642		 * Hyper-V expects the additional_pages field in the units
1643		 * of one of these 3 sizes, 4Kbytes, 2Mbytes or 1Gbytes.
1644		 * This is dictated by the values of the fields page.largesize
1645		 * and page_size.
1646		 * This code however, only uses 4Kbytes and 2Mbytes units
1647		 * and not 1Gbytes unit.
1648		 */
1649
1650		/* page reporting for pages 2MB or higher */
1651		if (order >= HV_LARGE_REPORTING_ORDER ) {
1652			range->page.largepage = 1;
1653			range->page_size = HV_GPA_PAGE_RANGE_PAGE_SIZE_2MB;
1654			range->base_large_pfn = page_to_hvpfn(
1655					sg_page(sg)) >> HV_LARGE_REPORTING_ORDER;
1656			range->page.additional_pages =
1657				(sg->length / HV_LARGE_REPORTING_LEN) - 1;
1658		} else {
1659			/* Page reporting for pages below 2MB */
1660			range->page.basepfn = page_to_hvpfn(sg_page(sg));
1661			range->page.largepage = false;
1662			range->page.additional_pages =
1663				(sg->length / HV_HYP_PAGE_SIZE) - 1;
1664		}
1665
1666	}
1667
1668	status = hv_do_rep_hypercall(HV_EXT_CALL_MEMORY_HEAT_HINT, nents, 0,
1669				     hint, NULL);
1670	local_irq_restore(flags);
1671	if (!hv_result_success(status)) {
1672
1673		pr_err("Cold memory discard hypercall failed with status %llx\n",
1674				status);
1675		if (hv_hypercall_multi_failure > 0)
1676			hv_hypercall_multi_failure++;
1677
1678		if (hv_result(status) == HV_STATUS_INVALID_PARAMETER) {
1679			pr_err("Underlying Hyper-V does not support order less than 9. Hypercall failed\n");
1680			pr_err("Defaulting to page_reporting_order %d\n",
1681					pageblock_order);
1682			page_reporting_order = pageblock_order;
1683			hv_hypercall_multi_failure++;
1684			return -EINVAL;
1685		}
1686
1687		return -EINVAL;
1688	}
1689
1690	return 0;
1691}
1692
1693static void enable_page_reporting(void)
 
1694{
1695	int ret;
 
 
 
1696
1697	if (!hv_query_ext_cap(HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT)) {
1698		pr_debug("Cold memory discard hint not supported by Hyper-V\n");
1699		return;
1700	}
1701
1702	BUILD_BUG_ON(PAGE_REPORTING_CAPACITY > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES);
1703	dm_device.pr_dev_info.report = hv_free_page_report;
1704	/*
1705	 * We let the page_reporting_order parameter decide the order
1706	 * in the page_reporting code
1707	 */
1708	dm_device.pr_dev_info.order = 0;
1709	ret = page_reporting_register(&dm_device.pr_dev_info);
1710	if (ret < 0) {
1711		dm_device.pr_dev_info.report = NULL;
1712		pr_err("Failed to enable cold memory discard: %d\n", ret);
1713	} else {
1714		pr_info("Cold memory discard hint enabled with order %d\n",
1715				page_reporting_order);
1716	}
1717}
1718
1719static void disable_page_reporting(void)
1720{
1721	if (dm_device.pr_dev_info.report) {
1722		page_reporting_unregister(&dm_device.pr_dev_info);
1723		dm_device.pr_dev_info.report = NULL;
1724	}
1725}
1726
1727static int ballooning_enabled(void)
1728{
1729	/*
1730	 * Disable ballooning if the page size is not 4k (HV_HYP_PAGE_SIZE),
1731	 * since currently it's unclear to us whether an unballoon request can
1732	 * make sure all page ranges are guest page size aligned.
1733	 */
1734	if (PAGE_SIZE != HV_HYP_PAGE_SIZE) {
1735		pr_info("Ballooning disabled because page size is not 4096 bytes\n");
1736		return 0;
1737	}
1738
1739	return 1;
1740}
 
1741
1742static int hot_add_enabled(void)
1743{
1744	/*
1745	 * Disable hot add on ARM64, because we currently rely on
1746	 * memory_add_physaddr_to_nid() to get a node id of a hot add range,
1747	 * however ARM64's memory_add_physaddr_to_nid() always return 0 and
1748	 * DM_MEM_HOT_ADD_REQUEST doesn't have the NUMA node information for
1749	 * add_memory().
1750	 */
1751	if (IS_ENABLED(CONFIG_ARM64)) {
1752		pr_info("Memory hot add disabled on ARM64\n");
1753		return 0;
1754	}
1755
1756	return 1;
1757}
1758
1759static int balloon_connect_vsp(struct hv_device *dev)
1760{
1761	struct dm_version_request version_req;
1762	struct dm_capabilities cap_msg;
1763	unsigned long t;
1764	int ret;
 
 
 
 
1765
1766	/*
1767	 * max_pkt_size should be large enough for one vmbus packet header plus
1768	 * our receive buffer size. Hyper-V sends messages up to
1769	 * HV_HYP_PAGE_SIZE bytes long on balloon channel.
1770	 */
1771	dev->channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
1772
1773	ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
1774			 balloon_onchannelcallback, dev);
1775	if (ret)
1776		return ret;
1777
 
1778	/*
1779	 * Initiate the hand shake with the host and negotiate
1780	 * a version that the host can support. We start with the
1781	 * highest version number and go down if the host cannot
1782	 * support it.
1783	 */
1784	memset(&version_req, 0, sizeof(struct dm_version_request));
1785	version_req.hdr.type = DM_VERSION_REQUEST;
1786	version_req.hdr.size = sizeof(struct dm_version_request);
1787	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
1788	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
1789	version_req.is_last_attempt = 0;
1790	dm_device.version = version_req.version.version;
1791
1792	ret = vmbus_sendpacket(dev->channel, &version_req,
1793			       sizeof(struct dm_version_request),
1794			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
 
1795	if (ret)
1796		goto out;
1797
1798	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1799	if (t == 0) {
1800		ret = -ETIMEDOUT;
1801		goto out;
1802	}
1803
1804	/*
1805	 * If we could not negotiate a compatible version with the host
1806	 * fail the probe function.
1807	 */
1808	if (dm_device.state == DM_INIT_ERROR) {
1809		ret = -EPROTO;
1810		goto out;
1811	}
1812
1813	pr_info("Using Dynamic Memory protocol version %u.%u\n",
1814		DYNMEM_MAJOR_VERSION(dm_device.version),
1815		DYNMEM_MINOR_VERSION(dm_device.version));
1816
1817	/*
1818	 * Now submit our capabilities to the host.
1819	 */
1820	memset(&cap_msg, 0, sizeof(struct dm_capabilities));
1821	cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
1822	cap_msg.hdr.size = sizeof(struct dm_capabilities);
1823	cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);
1824
1825	/*
1826	 * When hibernation (i.e. virtual ACPI S4 state) is enabled, the host
1827	 * currently still requires the bits to be set, so we have to add code
1828	 * to fail the host's hot-add and balloon up/down requests, if any.
1829	 */
1830	cap_msg.caps.cap_bits.balloon = ballooning_enabled();
1831	cap_msg.caps.cap_bits.hot_add = hot_add_enabled();
1832
1833	/*
1834	 * Specify our alignment requirements as it relates
1835	 * memory hot-add. Specify 128MB alignment.
1836	 */
1837	cap_msg.caps.cap_bits.hot_add_alignment = 7;
1838
1839	/*
1840	 * Currently the host does not use these
1841	 * values and we set them to what is done in the
1842	 * Windows driver.
1843	 */
1844	cap_msg.min_page_cnt = 0;
1845	cap_msg.max_page_number = -1;
1846
1847	ret = vmbus_sendpacket(dev->channel, &cap_msg,
1848			       sizeof(struct dm_capabilities),
1849			       (unsigned long)NULL, VM_PKT_DATA_INBAND, 0);
 
1850	if (ret)
1851		goto out;
1852
1853	t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
1854	if (t == 0) {
1855		ret = -ETIMEDOUT;
1856		goto out;
1857	}
1858
1859	/*
1860	 * If the host does not like our capabilities,
1861	 * fail the probe function.
1862	 */
1863	if (dm_device.state == DM_INIT_ERROR) {
1864		ret = -EPROTO;
1865		goto out;
1866	}
1867
1868	return 0;
1869out:
1870	vmbus_close(dev->channel);
1871	return ret;
1872}
1873
1874/*
1875 * DEBUGFS Interface
1876 */
1877#ifdef CONFIG_DEBUG_FS
1878
1879/**
1880 * hv_balloon_debug_show - shows statistics of balloon operations.
1881 * @f: pointer to the &struct seq_file.
1882 * @offset: ignored.
1883 *
1884 * Provides the statistics that can be accessed in hv-balloon in the debugfs.
1885 *
1886 * Return: zero on success or an error code.
1887 */
1888static int hv_balloon_debug_show(struct seq_file *f, void *offset)
1889{
1890	struct hv_dynmem_device *dm = f->private;
1891	char *sname;
1892
1893	seq_printf(f, "%-22s: %u.%u\n", "host_version",
1894				DYNMEM_MAJOR_VERSION(dm->version),
1895				DYNMEM_MINOR_VERSION(dm->version));
1896
1897	seq_printf(f, "%-22s:", "capabilities");
1898	if (ballooning_enabled())
1899		seq_puts(f, " enabled");
1900
1901	if (hot_add_enabled())
1902		seq_puts(f, " hot_add");
1903
1904	seq_puts(f, "\n");
1905
1906	seq_printf(f, "%-22s: %u", "state", dm->state);
1907	switch (dm->state) {
1908	case DM_INITIALIZING:
1909			sname = "Initializing";
1910			break;
1911	case DM_INITIALIZED:
1912			sname = "Initialized";
1913			break;
1914	case DM_BALLOON_UP:
1915			sname = "Balloon Up";
1916			break;
1917	case DM_BALLOON_DOWN:
1918			sname = "Balloon Down";
1919			break;
1920	case DM_HOT_ADD:
1921			sname = "Hot Add";
1922			break;
1923	case DM_INIT_ERROR:
1924			sname = "Error";
1925			break;
1926	default:
1927			sname = "Unknown";
1928	}
1929	seq_printf(f, " (%s)\n", sname);
1930
1931	/* HV Page Size */
1932	seq_printf(f, "%-22s: %ld\n", "page_size", HV_HYP_PAGE_SIZE);
1933
1934	/* Pages added with hot_add */
1935	seq_printf(f, "%-22s: %u\n", "pages_added", dm->num_pages_added);
1936
1937	/* pages that are "onlined"/used from pages_added */
1938	seq_printf(f, "%-22s: %u\n", "pages_onlined", dm->num_pages_onlined);
1939
1940	/* pages we have given back to host */
1941	seq_printf(f, "%-22s: %u\n", "pages_ballooned", dm->num_pages_ballooned);
1942
1943	seq_printf(f, "%-22s: %lu\n", "total_pages_committed",
1944				get_pages_committed(dm));
1945
1946	seq_printf(f, "%-22s: %llu\n", "max_dynamic_page_count",
1947				dm->max_dynamic_page_count);
1948
1949	return 0;
1950}
1951
1952DEFINE_SHOW_ATTRIBUTE(hv_balloon_debug);
1953
1954static void  hv_balloon_debugfs_init(struct hv_dynmem_device *b)
1955{
1956	debugfs_create_file("hv-balloon", 0444, NULL, b,
1957			&hv_balloon_debug_fops);
1958}
1959
1960static void  hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
1961{
1962	debugfs_lookup_and_remove("hv-balloon", NULL);
1963}
1964
1965#else
1966
1967static inline void hv_balloon_debugfs_init(struct hv_dynmem_device  *b)
1968{
1969}
1970
1971static inline void hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
1972{
1973}
1974
1975#endif	/* CONFIG_DEBUG_FS */
1976
1977static int balloon_probe(struct hv_device *dev,
1978			 const struct hv_vmbus_device_id *dev_id)
1979{
1980	int ret;
1981
1982	allow_hibernation = hv_is_hibernation_supported();
1983	if (allow_hibernation)
1984		hot_add = false;
1985
1986#ifdef CONFIG_MEMORY_HOTPLUG
1987	do_hot_add = hot_add;
1988#else
1989	do_hot_add = false;
1990#endif
1991	dm_device.dev = dev;
1992	dm_device.state = DM_INITIALIZING;
1993	dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN8;
1994	init_completion(&dm_device.host_event);
1995	init_completion(&dm_device.config_event);
1996	INIT_LIST_HEAD(&dm_device.ha_region_list);
1997	spin_lock_init(&dm_device.ha_lock);
1998	INIT_WORK(&dm_device.balloon_wrk.wrk, balloon_up);
1999	INIT_WORK(&dm_device.ha_wrk.wrk, hot_add_req);
2000	dm_device.host_specified_ha_region = false;
2001
2002#ifdef CONFIG_MEMORY_HOTPLUG
2003	set_online_page_callback(&hv_online_page);
2004	init_completion(&dm_device.ol_waitevent);
2005	register_memory_notifier(&hv_memory_nb);
2006#endif
2007
2008	hv_set_drvdata(dev, &dm_device);
2009
2010	ret = balloon_connect_vsp(dev);
2011	if (ret != 0)
2012		goto connect_error;
2013
2014	enable_page_reporting();
2015	dm_device.state = DM_INITIALIZED;
2016
2017	dm_device.thread =
2018		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
2019	if (IS_ERR(dm_device.thread)) {
2020		ret = PTR_ERR(dm_device.thread);
2021		goto probe_error;
2022	}
2023
2024	hv_balloon_debugfs_init(&dm_device);
2025
2026	return 0;
2027
2028probe_error:
2029	dm_device.state = DM_INIT_ERROR;
2030	dm_device.thread  = NULL;
2031	disable_page_reporting();
2032	vmbus_close(dev->channel);
2033connect_error:
2034#ifdef CONFIG_MEMORY_HOTPLUG
2035	unregister_memory_notifier(&hv_memory_nb);
2036	restore_online_page_callback(&hv_online_page);
2037#endif
 
 
 
 
 
 
2038	return ret;
2039}
2040
2041static void balloon_remove(struct hv_device *dev)
2042{
2043	struct hv_dynmem_device *dm = hv_get_drvdata(dev);
2044	struct hv_hotadd_state *has, *tmp;
2045	struct hv_hotadd_gap *gap, *tmp_gap;
 
2046
2047	if (dm->num_pages_ballooned != 0)
2048		pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);
2049
2050	hv_balloon_debugfs_exit(dm);
2051
2052	cancel_work_sync(&dm->balloon_wrk.wrk);
2053	cancel_work_sync(&dm->ha_wrk.wrk);
2054
 
2055	kthread_stop(dm->thread);
2056
2057	/*
2058	 * This is to handle the case when balloon_resume()
2059	 * call has failed and some cleanup has been done as
2060	 * a part of the error handling.
2061	 */
2062	if (dm_device.state != DM_INIT_ERROR) {
2063		disable_page_reporting();
2064		vmbus_close(dev->channel);
2065#ifdef CONFIG_MEMORY_HOTPLUG
2066		unregister_memory_notifier(&hv_memory_nb);
2067		restore_online_page_callback(&hv_online_page);
2068#endif
2069	}
2070
2071	guard(spinlock_irqsave)(&dm_device.ha_lock);
2072	list_for_each_entry_safe(has, tmp, &dm->ha_region_list, list) {
2073		list_for_each_entry_safe(gap, tmp_gap, &has->gap_list, list) {
2074			list_del(&gap->list);
2075			kfree(gap);
2076		}
2077		list_del(&has->list);
2078		kfree(has);
2079	}
2080}
2081
2082static int balloon_suspend(struct hv_device *hv_dev)
2083{
2084	struct hv_dynmem_device *dm = hv_get_drvdata(hv_dev);
2085
2086	tasklet_disable(&hv_dev->channel->callback_event);
2087
2088	cancel_work_sync(&dm->balloon_wrk.wrk);
2089	cancel_work_sync(&dm->ha_wrk.wrk);
2090
2091	if (dm->thread) {
2092		kthread_stop(dm->thread);
2093		dm->thread = NULL;
2094		vmbus_close(hv_dev->channel);
2095	}
2096
2097	tasklet_enable(&hv_dev->channel->callback_event);
2098
2099	return 0;
2100
2101}
2102
2103static int balloon_resume(struct hv_device *dev)
2104{
2105	int ret;
2106
2107	dm_device.state = DM_INITIALIZING;
2108
2109	ret = balloon_connect_vsp(dev);
2110
2111	if (ret != 0)
2112		goto out;
2113
2114	dm_device.thread =
2115		 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
2116	if (IS_ERR(dm_device.thread)) {
2117		ret = PTR_ERR(dm_device.thread);
2118		dm_device.thread = NULL;
2119		goto close_channel;
2120	}
2121
2122	dm_device.state = DM_INITIALIZED;
2123	return 0;
2124close_channel:
2125	vmbus_close(dev->channel);
2126out:
2127	dm_device.state = DM_INIT_ERROR;
2128	disable_page_reporting();
2129#ifdef CONFIG_MEMORY_HOTPLUG
2130	unregister_memory_notifier(&hv_memory_nb);
2131	restore_online_page_callback(&hv_online_page);
2132#endif
2133	return ret;
2134}
2135
2136static const struct hv_vmbus_device_id id_table[] = {
2137	/* Dynamic Memory Class ID */
2138	/* 525074DC-8985-46e2-8057-A307DC18A502 */
2139	{ HV_DM_GUID, },
2140	{ },
2141};
2142
2143MODULE_DEVICE_TABLE(vmbus, id_table);
2144
2145static  struct hv_driver balloon_drv = {
2146	.name = "hv_balloon",
2147	.id_table = id_table,
2148	.probe =  balloon_probe,
2149	.remove =  balloon_remove,
2150	.suspend = balloon_suspend,
2151	.resume = balloon_resume,
2152	.driver = {
2153		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
2154	},
2155};
2156
2157static int __init init_balloon_drv(void)
2158{
2159
2160	return vmbus_driver_register(&balloon_drv);
2161}
2162
2163module_init(init_balloon_drv);
2164
2165MODULE_DESCRIPTION("Hyper-V Balloon");
2166MODULE_LICENSE("GPL");