Bootlin logo

Elixir Cross Referencer

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
/*
 * Machine specific setup for xen
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/memblock.h>
#include <linux/cpuidle.h>
#include <linux/cpufreq.h>

#include <asm/elf.h>
#include <asm/vdso.h>
#include <asm/e820.h>
#include <asm/setup.h>
#include <asm/acpi.h>
#include <asm/numa.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/page.h>
#include <xen/interface/callback.h>
#include <xen/interface/memory.h>
#include <xen/interface/physdev.h>
#include <xen/features.h>
#include <xen/hvc-console.h>
#include "xen-ops.h"
#include "vdso.h"
#include "mmu.h"

#define GB(x) ((uint64_t)(x) * 1024 * 1024 * 1024)

/* Amount of extra memory space we add to the e820 ranges */
struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;

/* Number of pages released from the initial allocation. */
unsigned long xen_released_pages;

/* E820 map used during setting up memory. */
static struct e820entry xen_e820_map[E820MAX] __initdata;
static u32 xen_e820_map_entries __initdata;

/*
 * Buffer used to remap identity mapped pages. We only need the virtual space.
 * The physical page behind this address is remapped as needed to different
 * buffer pages.
 */
#define REMAP_SIZE	(P2M_PER_PAGE - 3)
static struct {
	unsigned long	next_area_mfn;
	unsigned long	target_pfn;
	unsigned long	size;
	unsigned long	mfns[REMAP_SIZE];
} xen_remap_buf __initdata __aligned(PAGE_SIZE);
static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY;

/* 
 * The maximum amount of extra memory compared to the base size.  The
 * main scaling factor is the size of struct page.  At extreme ratios
 * of base:extra, all the base memory can be filled with page
 * structures for the extra memory, leaving no space for anything
 * else.
 * 
 * 10x seems like a reasonable balance between scaling flexibility and
 * leaving a practically usable system.
 */
#define EXTRA_MEM_RATIO		(10)

static bool xen_512gb_limit __initdata = IS_ENABLED(CONFIG_XEN_512GB);

static void __init xen_parse_512gb(void)
{
	bool val = false;
	char *arg;

	arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit");
	if (!arg)
		return;

	arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit=");
	if (!arg)
		val = true;
	else if (strtobool(arg + strlen("xen_512gb_limit="), &val))
		return;

	xen_512gb_limit = val;
}

static void __init xen_add_extra_mem(unsigned long start_pfn,
				     unsigned long n_pfns)
{
	int i;

	/*
	 * No need to check for zero size, should happen rarely and will only
	 * write a new entry regarded to be unused due to zero size.
	 */
	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		/* Add new region. */
		if (xen_extra_mem[i].n_pfns == 0) {
			xen_extra_mem[i].start_pfn = start_pfn;
			xen_extra_mem[i].n_pfns = n_pfns;
			break;
		}
		/* Append to existing region. */
		if (xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns ==
		    start_pfn) {
			xen_extra_mem[i].n_pfns += n_pfns;
			break;
		}
	}
	if (i == XEN_EXTRA_MEM_MAX_REGIONS)
		printk(KERN_WARNING "Warning: not enough extra memory regions\n");

	memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
}

static void __init xen_del_extra_mem(unsigned long start_pfn,
				     unsigned long n_pfns)
{
	int i;
	unsigned long start_r, size_r;

	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		start_r = xen_extra_mem[i].start_pfn;
		size_r = xen_extra_mem[i].n_pfns;

		/* Start of region. */
		if (start_r == start_pfn) {
			BUG_ON(n_pfns > size_r);
			xen_extra_mem[i].start_pfn += n_pfns;
			xen_extra_mem[i].n_pfns -= n_pfns;
			break;
		}
		/* End of region. */
		if (start_r + size_r == start_pfn + n_pfns) {
			BUG_ON(n_pfns > size_r);
			xen_extra_mem[i].n_pfns -= n_pfns;
			break;
		}
		/* Mid of region. */
		if (start_pfn > start_r && start_pfn < start_r + size_r) {
			BUG_ON(start_pfn + n_pfns > start_r + size_r);
			xen_extra_mem[i].n_pfns = start_pfn - start_r;
			/* Calling memblock_reserve() again is okay. */
			xen_add_extra_mem(start_pfn + n_pfns, start_r + size_r -
					  (start_pfn + n_pfns));
			break;
		}
	}
	memblock_free(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
}

/*
 * Called during boot before the p2m list can take entries beyond the
 * hypervisor supplied p2m list. Entries in extra mem are to be regarded as
 * invalid.
 */
unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
{
	int i;

	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		if (pfn >= xen_extra_mem[i].start_pfn &&
		    pfn < xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns)
			return INVALID_P2M_ENTRY;
	}

	return IDENTITY_FRAME(pfn);
}

/*
 * Mark all pfns of extra mem as invalid in p2m list.
 */
void __init xen_inv_extra_mem(void)
{
	unsigned long pfn, pfn_s, pfn_e;
	int i;

	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		if (!xen_extra_mem[i].n_pfns)
			continue;
		pfn_s = xen_extra_mem[i].start_pfn;
		pfn_e = pfn_s + xen_extra_mem[i].n_pfns;
		for (pfn = pfn_s; pfn < pfn_e; pfn++)
			set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
	}
}

/*
 * Finds the next RAM pfn available in the E820 map after min_pfn.
 * This function updates min_pfn with the pfn found and returns
 * the size of that range or zero if not found.
 */
static unsigned long __init xen_find_pfn_range(unsigned long *min_pfn)
{
	const struct e820entry *entry = xen_e820_map;
	unsigned int i;
	unsigned long done = 0;

	for (i = 0; i < xen_e820_map_entries; i++, entry++) {
		unsigned long s_pfn;
		unsigned long e_pfn;

		if (entry->type != E820_RAM)
			continue;

		e_pfn = PFN_DOWN(entry->addr + entry->size);

		/* We only care about E820 after this */
		if (e_pfn <= *min_pfn)
			continue;

		s_pfn = PFN_UP(entry->addr);

		/* If min_pfn falls within the E820 entry, we want to start
		 * at the min_pfn PFN.
		 */
		if (s_pfn <= *min_pfn) {
			done = e_pfn - *min_pfn;
		} else {
			done = e_pfn - s_pfn;
			*min_pfn = s_pfn;
		}
		break;
	}

	return done;
}

static int __init xen_free_mfn(unsigned long mfn)
{
	struct xen_memory_reservation reservation = {
		.address_bits = 0,
		.extent_order = 0,
		.domid        = DOMID_SELF
	};

	set_xen_guest_handle(reservation.extent_start, &mfn);
	reservation.nr_extents = 1;

	return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
}

/*
 * This releases a chunk of memory and then does the identity map. It's used
 * as a fallback if the remapping fails.
 */
static void __init xen_set_identity_and_release_chunk(unsigned long start_pfn,
			unsigned long end_pfn, unsigned long nr_pages)
{
	unsigned long pfn, end;
	int ret;

	WARN_ON(start_pfn > end_pfn);

	/* Release pages first. */
	end = min(end_pfn, nr_pages);
	for (pfn = start_pfn; pfn < end; pfn++) {
		unsigned long mfn = pfn_to_mfn(pfn);

		/* Make sure pfn exists to start with */
		if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
			continue;

		ret = xen_free_mfn(mfn);
		WARN(ret != 1, "Failed to release pfn %lx err=%d\n", pfn, ret);

		if (ret == 1) {
			xen_released_pages++;
			if (!__set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
				break;
		} else
			break;
	}

	set_phys_range_identity(start_pfn, end_pfn);
}

/*
 * Helper function to update the p2m and m2p tables and kernel mapping.
 */
static void __init xen_update_mem_tables(unsigned long pfn, unsigned long mfn)
{
	struct mmu_update update = {
		.ptr = ((uint64_t)mfn << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE,
		.val = pfn
	};

	/* Update p2m */
	if (!set_phys_to_machine(pfn, mfn)) {
		WARN(1, "Failed to set p2m mapping for pfn=%ld mfn=%ld\n",
		     pfn, mfn);
		BUG();
	}

	/* Update m2p */
	if (HYPERVISOR_mmu_update(&update, 1, NULL, DOMID_SELF) < 0) {
		WARN(1, "Failed to set m2p mapping for mfn=%ld pfn=%ld\n",
		     mfn, pfn);
		BUG();
	}

	/* Update kernel mapping, but not for highmem. */
	if (pfn >= PFN_UP(__pa(high_memory - 1)))
		return;

	if (HYPERVISOR_update_va_mapping((unsigned long)__va(pfn << PAGE_SHIFT),
					 mfn_pte(mfn, PAGE_KERNEL), 0)) {
		WARN(1, "Failed to update kernel mapping for mfn=%ld pfn=%ld\n",
		      mfn, pfn);
		BUG();
	}
}

/*
 * This function updates the p2m and m2p tables with an identity map from
 * start_pfn to start_pfn+size and prepares remapping the underlying RAM of the
 * original allocation at remap_pfn. The information needed for remapping is
 * saved in the memory itself to avoid the need for allocating buffers. The
 * complete remap information is contained in a list of MFNs each containing
 * up to REMAP_SIZE MFNs and the start target PFN for doing the remap.
 * This enables us to preserve the original mfn sequence while doing the
 * remapping at a time when the memory management is capable of allocating
 * virtual and physical memory in arbitrary amounts, see 'xen_remap_memory' and
 * its callers.
 */
static void __init xen_do_set_identity_and_remap_chunk(
        unsigned long start_pfn, unsigned long size, unsigned long remap_pfn)
{
	unsigned long buf = (unsigned long)&xen_remap_buf;
	unsigned long mfn_save, mfn;
	unsigned long ident_pfn_iter, remap_pfn_iter;
	unsigned long ident_end_pfn = start_pfn + size;
	unsigned long left = size;
	unsigned int i, chunk;

	WARN_ON(size == 0);

	BUG_ON(xen_feature(XENFEAT_auto_translated_physmap));

	mfn_save = virt_to_mfn(buf);

	for (ident_pfn_iter = start_pfn, remap_pfn_iter = remap_pfn;
	     ident_pfn_iter < ident_end_pfn;
	     ident_pfn_iter += REMAP_SIZE, remap_pfn_iter += REMAP_SIZE) {
		chunk = (left < REMAP_SIZE) ? left : REMAP_SIZE;

		/* Map first pfn to xen_remap_buf */
		mfn = pfn_to_mfn(ident_pfn_iter);
		set_pte_mfn(buf, mfn, PAGE_KERNEL);

		/* Save mapping information in page */
		xen_remap_buf.next_area_mfn = xen_remap_mfn;
		xen_remap_buf.target_pfn = remap_pfn_iter;
		xen_remap_buf.size = chunk;
		for (i = 0; i < chunk; i++)
			xen_remap_buf.mfns[i] = pfn_to_mfn(ident_pfn_iter + i);

		/* Put remap buf into list. */
		xen_remap_mfn = mfn;

		/* Set identity map */
		set_phys_range_identity(ident_pfn_iter, ident_pfn_iter + chunk);

		left -= chunk;
	}

	/* Restore old xen_remap_buf mapping */
	set_pte_mfn(buf, mfn_save, PAGE_KERNEL);
}

/*
 * This function takes a contiguous pfn range that needs to be identity mapped
 * and:
 *
 *  1) Finds a new range of pfns to use to remap based on E820 and remap_pfn.
 *  2) Calls the do_ function to actually do the mapping/remapping work.
 *
 * The goal is to not allocate additional memory but to remap the existing
 * pages. In the case of an error the underlying memory is simply released back
 * to Xen and not remapped.
 */
static unsigned long __init xen_set_identity_and_remap_chunk(
	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
	unsigned long remap_pfn)
{
	unsigned long pfn;
	unsigned long i = 0;
	unsigned long n = end_pfn - start_pfn;

	if (remap_pfn == 0)
		remap_pfn = nr_pages;

	while (i < n) {
		unsigned long cur_pfn = start_pfn + i;
		unsigned long left = n - i;
		unsigned long size = left;
		unsigned long remap_range_size;

		/* Do not remap pages beyond the current allocation */
		if (cur_pfn >= nr_pages) {
			/* Identity map remaining pages */
			set_phys_range_identity(cur_pfn, cur_pfn + size);
			break;
		}
		if (cur_pfn + size > nr_pages)
			size = nr_pages - cur_pfn;

		remap_range_size = xen_find_pfn_range(&remap_pfn);
		if (!remap_range_size) {
			pr_warning("Unable to find available pfn range, not remapping identity pages\n");
			xen_set_identity_and_release_chunk(cur_pfn,
						cur_pfn + left, nr_pages);
			break;
		}
		/* Adjust size to fit in current e820 RAM region */
		if (size > remap_range_size)
			size = remap_range_size;

		xen_do_set_identity_and_remap_chunk(cur_pfn, size, remap_pfn);

		/* Update variables to reflect new mappings. */
		i += size;
		remap_pfn += size;
	}

	/*
	 * If the PFNs are currently mapped, the VA mapping also needs
	 * to be updated to be 1:1.
	 */
	for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
		(void)HYPERVISOR_update_va_mapping(
			(unsigned long)__va(pfn << PAGE_SHIFT),
			mfn_pte(pfn, PAGE_KERNEL_IO), 0);

	return remap_pfn;
}

static unsigned long __init xen_count_remap_pages(
	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
	unsigned long remap_pages)
{
	if (start_pfn >= nr_pages)
		return remap_pages;

	return remap_pages + min(end_pfn, nr_pages) - start_pfn;
}

static unsigned long __init xen_foreach_remap_area(unsigned long nr_pages,
	unsigned long (*func)(unsigned long start_pfn, unsigned long end_pfn,
			      unsigned long nr_pages, unsigned long last_val))
{
	phys_addr_t start = 0;
	unsigned long ret_val = 0;
	const struct e820entry *entry = xen_e820_map;
	int i;

	/*
	 * Combine non-RAM regions and gaps until a RAM region (or the
	 * end of the map) is reached, then call the provided function
	 * to perform its duty on the non-RAM region.
	 *
	 * The combined non-RAM regions are rounded to a whole number
	 * of pages so any partial pages are accessible via the 1:1
	 * mapping.  This is needed for some BIOSes that put (for
	 * example) the DMI tables in a reserved region that begins on
	 * a non-page boundary.
	 */
	for (i = 0; i < xen_e820_map_entries; i++, entry++) {
		phys_addr_t end = entry->addr + entry->size;
		if (entry->type == E820_RAM || i == xen_e820_map_entries - 1) {
			unsigned long start_pfn = PFN_DOWN(start);
			unsigned long end_pfn = PFN_UP(end);

			if (entry->type == E820_RAM)
				end_pfn = PFN_UP(entry->addr);

			if (start_pfn < end_pfn)
				ret_val = func(start_pfn, end_pfn, nr_pages,
					       ret_val);
			start = end;
		}
	}

	return ret_val;
}

/*
 * Remap the memory prepared in xen_do_set_identity_and_remap_chunk().
 * The remap information (which mfn remap to which pfn) is contained in the
 * to be remapped memory itself in a linked list anchored at xen_remap_mfn.
 * This scheme allows to remap the different chunks in arbitrary order while
 * the resulting mapping will be independant from the order.
 */
void __init xen_remap_memory(void)
{
	unsigned long buf = (unsigned long)&xen_remap_buf;
	unsigned long mfn_save, mfn, pfn;
	unsigned long remapped = 0;
	unsigned int i;
	unsigned long pfn_s = ~0UL;
	unsigned long len = 0;

	mfn_save = virt_to_mfn(buf);

	while (xen_remap_mfn != INVALID_P2M_ENTRY) {
		/* Map the remap information */
		set_pte_mfn(buf, xen_remap_mfn, PAGE_KERNEL);

		BUG_ON(xen_remap_mfn != xen_remap_buf.mfns[0]);

		pfn = xen_remap_buf.target_pfn;
		for (i = 0; i < xen_remap_buf.size; i++) {
			mfn = xen_remap_buf.mfns[i];
			xen_update_mem_tables(pfn, mfn);
			remapped++;
			pfn++;
		}
		if (pfn_s == ~0UL || pfn == pfn_s) {
			pfn_s = xen_remap_buf.target_pfn;
			len += xen_remap_buf.size;
		} else if (pfn_s + len == xen_remap_buf.target_pfn) {
			len += xen_remap_buf.size;
		} else {
			xen_del_extra_mem(pfn_s, len);
			pfn_s = xen_remap_buf.target_pfn;
			len = xen_remap_buf.size;
		}

		mfn = xen_remap_mfn;
		xen_remap_mfn = xen_remap_buf.next_area_mfn;
	}

	if (pfn_s != ~0UL && len)
		xen_del_extra_mem(pfn_s, len);

	set_pte_mfn(buf, mfn_save, PAGE_KERNEL);

	pr_info("Remapped %ld page(s)\n", remapped);
}

static unsigned long __init xen_get_pages_limit(void)
{
	unsigned long limit;

#ifdef CONFIG_X86_32
	limit = GB(64) / PAGE_SIZE;
#else
	limit = MAXMEM / PAGE_SIZE;
	if (!xen_initial_domain() && xen_512gb_limit)
		limit = GB(512) / PAGE_SIZE;
#endif
	return limit;
}

static unsigned long __init xen_get_max_pages(void)
{
	unsigned long max_pages, limit;
	domid_t domid = DOMID_SELF;
	long ret;

	limit = xen_get_pages_limit();
	max_pages = limit;

	/*
	 * For the initial domain we use the maximum reservation as
	 * the maximum page.
	 *
	 * For guest domains the current maximum reservation reflects
	 * the current maximum rather than the static maximum. In this
	 * case the e820 map provided to us will cover the static
	 * maximum region.
	 */
	if (xen_initial_domain()) {
		ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
		if (ret > 0)
			max_pages = ret;
	}

	return min(max_pages, limit);
}

static void __init xen_align_and_add_e820_region(phys_addr_t start,
						 phys_addr_t size, int type)
{
	phys_addr_t end = start + size;

	/* Align RAM regions to page boundaries. */
	if (type == E820_RAM) {
		start = PAGE_ALIGN(start);
		end &= ~((phys_addr_t)PAGE_SIZE - 1);
	}

	e820_add_region(start, end - start, type);
}

static void __init xen_ignore_unusable(void)
{
	struct e820entry *entry = xen_e820_map;
	unsigned int i;

	for (i = 0; i < xen_e820_map_entries; i++, entry++) {
		if (entry->type == E820_UNUSABLE)
			entry->type = E820_RAM;
	}
}

bool __init xen_is_e820_reserved(phys_addr_t start, phys_addr_t size)
{
	struct e820entry *entry;
	unsigned mapcnt;
	phys_addr_t end;

	if (!size)
		return false;

	end = start + size;
	entry = xen_e820_map;

	for (mapcnt = 0; mapcnt < xen_e820_map_entries; mapcnt++) {
		if (entry->type == E820_RAM && entry->addr <= start &&
		    (entry->addr + entry->size) >= end)
			return false;

		entry++;
	}

	return true;
}

/*
 * Find a free area in physical memory not yet reserved and compliant with
 * E820 map.
 * Used to relocate pre-allocated areas like initrd or p2m list which are in
 * conflict with the to be used E820 map.
 * In case no area is found, return 0. Otherwise return the physical address
 * of the area which is already reserved for convenience.
 */
phys_addr_t __init xen_find_free_area(phys_addr_t size)
{
	unsigned mapcnt;
	phys_addr_t addr, start;
	struct e820entry *entry = xen_e820_map;

	for (mapcnt = 0; mapcnt < xen_e820_map_entries; mapcnt++, entry++) {
		if (entry->type != E820_RAM || entry->size < size)
			continue;
		start = entry->addr;
		for (addr = start; addr < start + size; addr += PAGE_SIZE) {
			if (!memblock_is_reserved(addr))
				continue;
			start = addr + PAGE_SIZE;
			if (start + size > entry->addr + entry->size)
				break;
		}
		if (addr >= start + size) {
			memblock_reserve(start, size);
			return start;
		}
	}

	return 0;
}

/*
 * Like memcpy, but with physical addresses for dest and src.
 */
static void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src,
				   phys_addr_t n)
{
	phys_addr_t dest_off, src_off, dest_len, src_len, len;
	void *from, *to;

	while (n) {
		dest_off = dest & ~PAGE_MASK;
		src_off = src & ~PAGE_MASK;
		dest_len = n;
		if (dest_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off)
			dest_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off;
		src_len = n;
		if (src_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off)
			src_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off;
		len = min(dest_len, src_len);
		to = early_memremap(dest - dest_off, dest_len + dest_off);
		from = early_memremap(src - src_off, src_len + src_off);
		memcpy(to, from, len);
		early_memunmap(to, dest_len + dest_off);
		early_memunmap(from, src_len + src_off);
		n -= len;
		dest += len;
		src += len;
	}
}

/*
 * Reserve Xen mfn_list.
 */
static void __init xen_reserve_xen_mfnlist(void)
{
	phys_addr_t start, size;

	if (xen_start_info->mfn_list >= __START_KERNEL_map) {
		start = __pa(xen_start_info->mfn_list);
		size = PFN_ALIGN(xen_start_info->nr_pages *
				 sizeof(unsigned long));
	} else {
		start = PFN_PHYS(xen_start_info->first_p2m_pfn);
		size = PFN_PHYS(xen_start_info->nr_p2m_frames);
	}

	if (!xen_is_e820_reserved(start, size)) {
		memblock_reserve(start, size);
		return;
	}

#ifdef CONFIG_X86_32
	/*
	 * Relocating the p2m on 32 bit system to an arbitrary virtual address
	 * is not supported, so just give up.
	 */
	xen_raw_console_write("Xen hypervisor allocated p2m list conflicts with E820 map\n");
	BUG();
#else
	xen_relocate_p2m();
#endif
}

/**
 * machine_specific_memory_setup - Hook for machine specific memory setup.
 **/
char * __init xen_memory_setup(void)
{
	unsigned long max_pfn, pfn_s, n_pfns;
	phys_addr_t mem_end, addr, size, chunk_size;
	u32 type;
	int rc;
	struct xen_memory_map memmap;
	unsigned long max_pages;
	unsigned long extra_pages = 0;
	int i;
	int op;

	xen_parse_512gb();
	max_pfn = xen_get_pages_limit();
	max_pfn = min(max_pfn, xen_start_info->nr_pages);
	mem_end = PFN_PHYS(max_pfn);

	memmap.nr_entries = E820MAX;
	set_xen_guest_handle(memmap.buffer, xen_e820_map);

	op = xen_initial_domain() ?
		XENMEM_machine_memory_map :
		XENMEM_memory_map;
	rc = HYPERVISOR_memory_op(op, &memmap);
	if (rc == -ENOSYS) {
		BUG_ON(xen_initial_domain());
		memmap.nr_entries = 1;
		xen_e820_map[0].addr = 0ULL;
		xen_e820_map[0].size = mem_end;
		/* 8MB slack (to balance backend allocations). */
		xen_e820_map[0].size += 8ULL << 20;
		xen_e820_map[0].type = E820_RAM;
		rc = 0;
	}
	BUG_ON(rc);
	BUG_ON(memmap.nr_entries == 0);
	xen_e820_map_entries = memmap.nr_entries;

	/*
	 * Xen won't allow a 1:1 mapping to be created to UNUSABLE
	 * regions, so if we're using the machine memory map leave the
	 * region as RAM as it is in the pseudo-physical map.
	 *
	 * UNUSABLE regions in domUs are not handled and will need
	 * a patch in the future.
	 */
	if (xen_initial_domain())
		xen_ignore_unusable();

	/* Make sure the Xen-supplied memory map is well-ordered. */
	sanitize_e820_map(xen_e820_map, ARRAY_SIZE(xen_e820_map),
			  &xen_e820_map_entries);

	max_pages = xen_get_max_pages();

	/* How many extra pages do we need due to remapping? */
	max_pages += xen_foreach_remap_area(max_pfn, xen_count_remap_pages);

	if (max_pages > max_pfn)
		extra_pages += max_pages - max_pfn;

	/*
	 * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
	 * factor the base size.  On non-highmem systems, the base
	 * size is the full initial memory allocation; on highmem it
	 * is limited to the max size of lowmem, so that it doesn't
	 * get completely filled.
	 *
	 * Make sure we have no memory above max_pages, as this area
	 * isn't handled by the p2m management.
	 *
	 * In principle there could be a problem in lowmem systems if
	 * the initial memory is also very large with respect to
	 * lowmem, but we won't try to deal with that here.
	 */
	extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
			   extra_pages, max_pages - max_pfn);
	i = 0;
	addr = xen_e820_map[0].addr;
	size = xen_e820_map[0].size;
	while (i < xen_e820_map_entries) {
		bool discard = false;

		chunk_size = size;
		type = xen_e820_map[i].type;

		if (type == E820_RAM) {
			if (addr < mem_end) {
				chunk_size = min(size, mem_end - addr);
			} else if (extra_pages) {
				chunk_size = min(size, PFN_PHYS(extra_pages));
				pfn_s = PFN_UP(addr);
				n_pfns = PFN_DOWN(addr + chunk_size) - pfn_s;
				extra_pages -= n_pfns;
				xen_add_extra_mem(pfn_s, n_pfns);
				xen_max_p2m_pfn = pfn_s + n_pfns;
			} else
				discard = true;
		}

		if (!discard)
			xen_align_and_add_e820_region(addr, chunk_size, type);

		addr += chunk_size;
		size -= chunk_size;
		if (size == 0) {
			i++;
			if (i < xen_e820_map_entries) {
				addr = xen_e820_map[i].addr;
				size = xen_e820_map[i].size;
			}
		}
	}

	/*
	 * Set the rest as identity mapped, in case PCI BARs are
	 * located here.
	 */
	set_phys_range_identity(addr / PAGE_SIZE, ~0ul);

	/*
	 * In domU, the ISA region is normal, usable memory, but we
	 * reserve ISA memory anyway because too many things poke
	 * about in there.
	 */
	e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
			E820_RESERVED);

	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

	/*
	 * Check whether the kernel itself conflicts with the target E820 map.
	 * Failing now is better than running into weird problems later due
	 * to relocating (and even reusing) pages with kernel text or data.
	 */
	if (xen_is_e820_reserved(__pa_symbol(_text),
			__pa_symbol(__bss_stop) - __pa_symbol(_text))) {
		xen_raw_console_write("Xen hypervisor allocated kernel memory conflicts with E820 map\n");
		BUG();
	}

	/*
	 * Check for a conflict of the hypervisor supplied page tables with
	 * the target E820 map.
	 */
	xen_pt_check_e820();

	xen_reserve_xen_mfnlist();

	/* Check for a conflict of the initrd with the target E820 map. */
	if (xen_is_e820_reserved(boot_params.hdr.ramdisk_image,
				 boot_params.hdr.ramdisk_size)) {
		phys_addr_t new_area, start, size;

		new_area = xen_find_free_area(boot_params.hdr.ramdisk_size);
		if (!new_area) {
			xen_raw_console_write("Can't find new memory area for initrd needed due to E820 map conflict\n");
			BUG();
		}

		start = boot_params.hdr.ramdisk_image;
		size = boot_params.hdr.ramdisk_size;
		xen_phys_memcpy(new_area, start, size);
		pr_info("initrd moved from [mem %#010llx-%#010llx] to [mem %#010llx-%#010llx]\n",
			start, start + size, new_area, new_area + size);
		memblock_free(start, size);
		boot_params.hdr.ramdisk_image = new_area;
		boot_params.ext_ramdisk_image = new_area >> 32;
	}

	/*
	 * Set identity map on non-RAM pages and prepare remapping the
	 * underlying RAM.
	 */
	xen_foreach_remap_area(max_pfn, xen_set_identity_and_remap_chunk);

	pr_info("Released %ld page(s)\n", xen_released_pages);

	return "Xen";
}

/*
 * Machine specific memory setup for auto-translated guests.
 */
char * __init xen_auto_xlated_memory_setup(void)
{
	struct xen_memory_map memmap;
	int i;
	int rc;

	memmap.nr_entries = E820MAX;
	set_xen_guest_handle(memmap.buffer, xen_e820_map);

	rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);
	if (rc < 0)
		panic("No memory map (%d)\n", rc);

	xen_e820_map_entries = memmap.nr_entries;

	sanitize_e820_map(xen_e820_map, ARRAY_SIZE(xen_e820_map),
			  &xen_e820_map_entries);

	for (i = 0; i < xen_e820_map_entries; i++)
		e820_add_region(xen_e820_map[i].addr, xen_e820_map[i].size,
				xen_e820_map[i].type);

	/* Remove p2m info, it is not needed. */
	xen_start_info->mfn_list = 0;
	xen_start_info->first_p2m_pfn = 0;
	xen_start_info->nr_p2m_frames = 0;

	return "Xen";
}

/*
 * Set the bit indicating "nosegneg" library variants should be used.
 * We only need to bother in pure 32-bit mode; compat 32-bit processes
 * can have un-truncated segments, so wrapping around is allowed.
 */
static void __init fiddle_vdso(void)
{
#ifdef CONFIG_X86_32
	u32 *mask = vdso_image_32.data +
		vdso_image_32.sym_VDSO32_NOTE_MASK;
	*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
#endif
}

static int register_callback(unsigned type, const void *func)
{
	struct callback_register callback = {
		.type = type,
		.address = XEN_CALLBACK(__KERNEL_CS, func),
		.flags = CALLBACKF_mask_events,
	};

	return HYPERVISOR_callback_op(CALLBACKOP_register, &callback);
}

void xen_enable_sysenter(void)
{
	int ret;
	unsigned sysenter_feature;

#ifdef CONFIG_X86_32
	sysenter_feature = X86_FEATURE_SEP;
#else
	sysenter_feature = X86_FEATURE_SYSENTER32;
#endif

	if (!boot_cpu_has(sysenter_feature))
		return;

	ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target);
	if(ret != 0)
		setup_clear_cpu_cap(sysenter_feature);
}

void xen_enable_syscall(void)
{
#ifdef CONFIG_X86_64
	int ret;

	ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);
	if (ret != 0) {
		printk(KERN_ERR "Failed to set syscall callback: %d\n", ret);
		/* Pretty fatal; 64-bit userspace has no other
		   mechanism for syscalls. */
	}

	if (boot_cpu_has(X86_FEATURE_SYSCALL32)) {
		ret = register_callback(CALLBACKTYPE_syscall32,
					xen_syscall32_target);
		if (ret != 0)
			setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
	}
#endif /* CONFIG_X86_64 */
}

void __init xen_pvmmu_arch_setup(void)
{
	HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments);
	HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_writable_pagetables);

	HYPERVISOR_vm_assist(VMASST_CMD_enable,
			     VMASST_TYPE_pae_extended_cr3);

	if (register_callback(CALLBACKTYPE_event, xen_hypervisor_callback) ||
	    register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback))
		BUG();

	xen_enable_sysenter();
	xen_enable_syscall();
}

/* This function is not called for HVM domains */
void __init xen_arch_setup(void)
{
	xen_panic_handler_init();
	if (!xen_feature(XENFEAT_auto_translated_physmap))
		xen_pvmmu_arch_setup();

#ifdef CONFIG_ACPI
	if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
		printk(KERN_INFO "ACPI in unprivileged domain disabled\n");
		disable_acpi();
	}
#endif

	memcpy(boot_command_line, xen_start_info->cmd_line,
	       MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ?
	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);

	/* Set up idle, making sure it calls safe_halt() pvop */
	disable_cpuidle();
	disable_cpufreq();
	WARN_ON(xen_set_default_idle());
	fiddle_vdso();
#ifdef CONFIG_NUMA
	numa_off = 1;
#endif
}