aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/xen/setup.c
blob: 29834b3fd87f8eba807d5b969f09085f857ceeb9 (plain)
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
/*
 * Machine specific setup for xen
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 */

#include <linux/module.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-ops.h"
#include "vdso.h"
#include "p2m.h"

/* These are code, but not functions.  Defined in entry.S */
extern const char xen_hypervisor_callback[];
extern const char xen_failsafe_callback[];
#ifdef CONFIG_X86_64
extern asmlinkage void nmi(void);
#endif
extern void xen_sysenter_target(void);
extern void xen_syscall_target(void);
extern void xen_syscall32_target(void);

/* 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;

/* Buffer used to remap identity mapped pages */
unsigned long xen_remap_buf[P2M_PER_PAGE] __initdata;

/* 
 * 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 void __init xen_add_extra_mem(u64 start, u64 size)
{
	unsigned long pfn;
	int i;

	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		/* Add new region. */
		if (xen_extra_mem[i].size == 0) {
			xen_extra_mem[i].start = start;
			xen_extra_mem[i].size  = size;
			break;
		}
		/* Append to existing region. */
		if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) {
			xen_extra_mem[i].size += size;
			break;
		}
	}
	if (i == XEN_EXTRA_MEM_MAX_REGIONS)
		printk(KERN_WARNING "Warning: not enough extra memory regions\n");

	memblock_reserve(start, size);

	xen_max_p2m_pfn = PFN_DOWN(start + size);
	for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
		unsigned long mfn = pfn_to_mfn(pfn);

		if (WARN_ONCE(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
			continue;
		WARN_ONCE(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
			  pfn, mfn);

		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
	}
}

static unsigned long __init xen_do_chunk(unsigned long start,
					 unsigned long end, bool release)
{
	struct xen_memory_reservation reservation = {
		.address_bits = 0,
		.extent_order = 0,
		.domid        = DOMID_SELF
	};
	unsigned long len = 0;
	unsigned long pfn;
	int ret;

	for (pfn = start; pfn < end; pfn++) {
		unsigned long frame;
		unsigned long mfn = pfn_to_mfn(pfn);

		if (release) {
			/* Make sure pfn exists to start with */
			if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
				continue;
			frame = mfn;
		} else {
			if (mfn != INVALID_P2M_ENTRY)
				continue;
			frame = pfn;
		}
		set_xen_guest_handle(reservation.extent_start, &frame);
		reservation.nr_extents = 1;

		ret = HYPERVISOR_memory_op(release ? XENMEM_decrease_reservation : XENMEM_populate_physmap,
					   &reservation);
		WARN(ret != 1, "Failed to %s pfn %lx err=%d\n",
		     release ? "release" : "populate", pfn, ret);

		if (ret == 1) {
			if (!early_set_phys_to_machine(pfn, release ? INVALID_P2M_ENTRY : frame)) {
				if (release)
					break;
				set_xen_guest_handle(reservation.extent_start, &frame);
				reservation.nr_extents = 1;
				ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
							   &reservation);
				break;
			}
			len++;
		} else
			break;
	}
	if (len)
		printk(KERN_INFO "%s %lx-%lx pfn range: %lu pages %s\n",
		       release ? "Freeing" : "Populating",
		       start, end, len,
		       release ? "freed" : "added");

	return len;
}

/*
 * 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(
	const struct e820entry *list, size_t map_size,
	unsigned long *min_pfn)
{
	const struct e820entry *entry;
	unsigned int i;
	unsigned long done = 0;

	for (i = 0, entry = list; i < map_size; 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;
}

/*
 * This releases a chunk of memory and then does the identity map. It's used as
 * 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 *identity,
	unsigned long *released)
{
	WARN_ON(start_pfn > end_pfn);

	/* Need to release pages first */
	*released += xen_do_chunk(start_pfn, min(end_pfn, nr_pages), true);
	*identity += set_phys_range_identity(start_pfn, end_pfn);
}

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

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

	/* 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);
		return false;
	}

	return true;
}

/*
 * This function updates the p2m and m2p tables with an identity map from
 * start_pfn to start_pfn+size and remaps the underlying RAM of the original
 * allocation at remap_pfn. It must do so carefully in P2M_PER_PAGE sized blocks
 * to not exhaust the reserved brk space. Doing it in properly aligned blocks
 * ensures we only allocate the minimum required leaf pages in the p2m table. It
 * copies the existing mfns from the p2m table under the 1:1 map, overwrites
 * them with the identity map and then updates the p2m and m2p tables with the
 * remapped memory.
 */
static unsigned long __init xen_do_set_identity_and_remap_chunk(
        unsigned long start_pfn, unsigned long size, unsigned long remap_pfn)
{
	unsigned long ident_pfn_iter, remap_pfn_iter;
	unsigned long ident_start_pfn_align, remap_start_pfn_align;
	unsigned long ident_end_pfn_align, remap_end_pfn_align;
	unsigned long ident_boundary_pfn, remap_boundary_pfn;
	unsigned long ident_cnt = 0;
	unsigned long remap_cnt = 0;
	unsigned long left = size;
	unsigned long mod;
	int i;

	WARN_ON(size == 0);

	BUG_ON(xen_feature(XENFEAT_auto_translated_physmap));

	/*
	 * Determine the proper alignment to remap memory in P2M_PER_PAGE sized
	 * blocks. We need to keep track of both the existing pfn mapping and
	 * the new pfn remapping.
	 */
	mod = start_pfn % P2M_PER_PAGE;
	ident_start_pfn_align =
		mod ? (start_pfn - mod + P2M_PER_PAGE) : start_pfn;
	mod = remap_pfn % P2M_PER_PAGE;
	remap_start_pfn_align =
		mod ? (remap_pfn - mod + P2M_PER_PAGE) : remap_pfn;
	mod = (start_pfn + size) % P2M_PER_PAGE;
	ident_end_pfn_align = start_pfn + size - mod;
	mod = (remap_pfn + size) % P2M_PER_PAGE;
	remap_end_pfn_align = remap_pfn + size - mod;

	/* Iterate over each p2m leaf node in each range */
	for (ident_pfn_iter = ident_start_pfn_align, remap_pfn_iter = remap_start_pfn_align;
	     ident_pfn_iter < ident_end_pfn_align && remap_pfn_iter < remap_end_pfn_align;
	     ident_pfn_iter += P2M_PER_PAGE, remap_pfn_iter += P2M_PER_PAGE) {
		/* Check we aren't past the end */
		BUG_ON(ident_pfn_iter + P2M_PER_PAGE > start_pfn + size);
		BUG_ON(remap_pfn_iter + P2M_PER_PAGE > remap_pfn + size);

		/* Save p2m mappings */
		for (i = 0; i < P2M_PER_PAGE; i++)
			xen_remap_buf[i] = pfn_to_mfn(ident_pfn_iter + i);

		/* Set identity map which will free a p2m leaf */
		ident_cnt += set_phys_range_identity(ident_pfn_iter,
			ident_pfn_iter + P2M_PER_PAGE);

#ifdef DEBUG
		/* Helps verify a p2m leaf has been freed */
		for (i = 0; i < P2M_PER_PAGE; i++) {
			unsigned int pfn = ident_pfn_iter + i;
			BUG_ON(pfn_to_mfn(pfn) != pfn);
		}
#endif
		/* Now remap memory */
		for (i = 0; i < P2M_PER_PAGE; i++) {
			unsigned long mfn = xen_remap_buf[i];

			/* This will use the p2m leaf freed above */
			if (!xen_update_mem_tables(remap_pfn_iter + i, mfn)) {
				WARN(1, "Failed to update mem mapping for pfn=%ld mfn=%ld\n",
					remap_pfn_iter + i, mfn);
				return 0;
			}

			remap_cnt++;
		}

		left -= P2M_PER_PAGE;
	}

	/* Max boundary space possible */
	BUG_ON(left > (P2M_PER_PAGE - 1) * 2);

	/* Now handle the boundary conditions */
	ident_boundary_pfn = start_pfn;
	remap_boundary_pfn = remap_pfn;
	for (i = 0; i < left; i++) {
		unsigned long mfn;

		/* These two checks move from the start to end boundaries */
		if (ident_boundary_pfn == ident_start_pfn_align)
			ident_boundary_pfn = ident_pfn_iter;
		if (remap_boundary_pfn == remap_start_pfn_align)
			remap_boundary_pfn = remap_pfn_iter;

		/* Check we aren't past the end */
		BUG_ON(ident_boundary_pfn >= start_pfn + size);
		BUG_ON(remap_boundary_pfn >= remap_pfn + size);

		mfn = pfn_to_mfn(ident_boundary_pfn);

		if (!xen_update_mem_tables(remap_boundary_pfn, mfn)) {
			WARN(1, "Failed to update mem mapping for pfn=%ld mfn=%ld\n",
				remap_pfn_iter + i, mfn);
			return 0;
		}
		remap_cnt++;

		ident_boundary_pfn++;
		remap_boundary_pfn++;
	}

	/* Finish up the identity map */
	if (ident_start_pfn_align >= ident_end_pfn_align) {
		/*
                 * In this case we have an identity range which does not span an
                 * aligned block so everything needs to be identity mapped here.
                 * If we didn't check this we might remap too many pages since
                 * the align boundaries are not meaningful in this case.
	         */
		ident_cnt += set_phys_range_identity(start_pfn,
			start_pfn + size);
	} else {
		/* Remapped above so check each end of the chunk */
		if (start_pfn < ident_start_pfn_align)
			ident_cnt += set_phys_range_identity(start_pfn,
				ident_start_pfn_align);
		if (start_pfn + size > ident_pfn_iter)
			ident_cnt += set_phys_range_identity(ident_pfn_iter,
				start_pfn + size);
	}

	BUG_ON(ident_cnt != size);
	BUG_ON(remap_cnt != size);

	return size;
}

/*
 * 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(
        const struct e820entry *list, size_t map_size, unsigned long start_pfn,
	unsigned long end_pfn, unsigned long nr_pages, unsigned long remap_pfn,
	unsigned long *identity, unsigned long *remapped,
	unsigned long *released)
{
	unsigned long pfn;
	unsigned long i = 0;
	unsigned long n = end_pfn - start_pfn;

	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 */
			*identity += 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(list, map_size,
						      &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, identity, released);
			break;
		}
		/* Adjust size to fit in current e820 RAM region */
		if (size > remap_range_size)
			size = remap_range_size;

		if (!xen_do_set_identity_and_remap_chunk(cur_pfn, size, remap_pfn)) {
			WARN(1, "Failed to remap 1:1 memory cur_pfn=%ld size=%ld remap_pfn=%ld\n",
				cur_pfn, size, remap_pfn);
			xen_set_identity_and_release_chunk(cur_pfn,
				cur_pfn + left, nr_pages, identity, released);
			break;
		}

		/* Update variables to reflect new mappings. */
		i += size;
		remap_pfn += size;
		*identity += size;
		*remapped += 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_set_identity_and_remap(
	const struct e820entry *list, size_t map_size, unsigned long nr_pages,
	unsigned long *released)
{
	phys_addr_t start = 0;
	unsigned long identity = 0;
	unsigned long remapped = 0;
	unsigned long last_pfn = nr_pages;
	const struct e820entry *entry;
	unsigned long num_released = 0;
	int i;

	/*
	 * Combine non-RAM regions and gaps until a RAM region (or the
	 * end of the map) is reached, then set the 1:1 map and
	 * remap the memory in those non-RAM regions.
	 *
	 * 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, entry = list; i < map_size; i++, entry++) {
		phys_addr_t end = entry->addr + entry->size;
		if (entry->type == E820_RAM || i == map_size - 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)
				last_pfn = xen_set_identity_and_remap_chunk(
						list, map_size, start_pfn,
						end_pfn, nr_pages, last_pfn,
						&identity, &remapped,
						&num_released);
			start = end;
		}
	}

	*released = num_released;

	pr_info("Set %ld page(s) to 1-1 mapping\n", identity);
	pr_info("Remapped %ld page(s), last_pfn=%ld\n", remapped,
		last_pfn);
	pr_info("Released %ld page(s)\n", num_released);

	return last_pfn;
}
static unsigned long __init xen_get_max_pages(void)
{
	unsigned long max_pages = MAX_DOMAIN_PAGES;
	domid_t domid = DOMID_SELF;
	int ret;

	/*
	 * 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, MAX_DOMAIN_PAGES);
}

static void xen_align_and_add_e820_region(u64 start, u64 size, int type)
{
	u64 end = start + size;

	/* Align RAM regions to page boundaries. */
	if (type == E820_RAM) {
		start = PAGE_ALIGN(start);
		end &= ~((u64)PAGE_SIZE - 1);
	}

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

void xen_ignore_unusable(struct e820entry *list, size_t map_size)
{
	struct e820entry *entry;
	unsigned int i;

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

/**
 * machine_specific_memory_setup - Hook for machine specific memory setup.
 **/
char * __init xen_memory_setup(void)
{
	static struct e820entry map[E820MAX] __initdata;

	unsigned long max_pfn = xen_start_info->nr_pages;
	unsigned long long mem_end;
	int rc;
	struct xen_memory_map memmap;
	unsigned long max_pages;
	unsigned long last_pfn = 0;
	unsigned long extra_pages = 0;
	int i;
	int op;

	max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
	mem_end = PFN_PHYS(max_pfn);

	memmap.nr_entries = E820MAX;
	set_xen_guest_handle(memmap.buffer, 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;
		map[0].addr = 0ULL;
		map[0].size = mem_end;
		/* 8MB slack (to balance backend allocations). */
		map[0].size += 8ULL << 20;
		map[0].type = E820_RAM;
		rc = 0;
	}
	BUG_ON(rc);
	BUG_ON(memmap.nr_entries == 0);

	/*
	 * 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(map, memmap.nr_entries);

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

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

	/*
	 * Set identity map on non-RAM pages and remap the underlying RAM.
	 */
	last_pfn = xen_set_identity_and_remap(map, memmap.nr_entries, max_pfn,
					      &xen_released_pages);

	extra_pages += xen_released_pages;

	if (last_pfn > max_pfn) {
		max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);
		mem_end = PFN_PHYS(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.
	 *
	 * 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 = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
			  extra_pages);
	i = 0;
	while (i < memmap.nr_entries) {
		u64 addr = map[i].addr;
		u64 size = map[i].size;
		u32 type = map[i].type;

		if (type == E820_RAM) {
			if (addr < mem_end) {
				size = min(size, mem_end - addr);
			} else if (extra_pages) {
				size = min(size, (u64)extra_pages * PAGE_SIZE);
				extra_pages -= size / PAGE_SIZE;
				xen_add_extra_mem(addr, size);
			} else
				type = E820_UNUSABLE;
		}

		xen_align_and_add_e820_region(addr, size, type);

		map[i].addr += size;
		map[i].size -= size;
		if (map[i].size == 0)
			i++;
	}

	/*
	 * Set the rest as identity mapped, in case PCI BARs are
	 * located here.
	 *
	 * PFNs above MAX_P2M_PFN are considered identity mapped as
	 * well.
	 */
	set_phys_range_identity(map[i-1].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);

	/*
	 * Reserve Xen bits:
	 *  - mfn_list
	 *  - xen_start_info
	 * See comment above "struct start_info" in <xen/interface/xen.h>
	 * We tried to make the the memblock_reserve more selective so
	 * that it would be clear what region is reserved. Sadly we ran
	 * in the problem wherein on a 64-bit hypervisor with a 32-bit
	 * initial domain, the pt_base has the cr3 value which is not
	 * neccessarily where the pagetable starts! As Jan put it: "
	 * Actually, the adjustment turns out to be correct: The page
	 * tables for a 32-on-64 dom0 get allocated in the order "first L1",
	 * "first L2", "first L3", so the offset to the page table base is
	 * indeed 2. When reading xen/include/public/xen.h's comment
	 * very strictly, this is not a violation (since there nothing is said
	 * that the first thing in the page table space is pointed to by
	 * pt_base; I admit that this seems to be implied though, namely
	 * do I think that it is implied that the page table space is the
	 * range [pt_base, pt_base + nt_pt_frames), whereas that
	 * range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames),
	 * which - without a priori knowledge - the kernel would have
	 * difficulty to figure out)." - so lets just fall back to the
	 * easy way and reserve the whole region.
	 */
	memblock_reserve(__pa(xen_start_info->mfn_list),
			 xen_start_info->pt_base - xen_start_info->mfn_list);

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

	return "Xen";
}

/*
 * Machine specific memory setup for auto-translated guests.
 */
char * __init xen_auto_xlated_memory_setup(void)
{
	static struct e820entry map[E820MAX] __initdata;

	struct xen_memory_map memmap;
	int i;
	int rc;

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

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

	sanitize_e820_map(map, ARRAY_SIZE(map), &memmap.nr_entries);

	for (i = 0; i < memmap.nr_entries; i++)
		e820_add_region(map[i].addr, map[i].size, map[i].type);

	memblock_reserve(__pa(xen_start_info->mfn_list),
			 xen_start_info->pt_base - xen_start_info->mfn_list);

	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
	/*
	 * This could be called before selected_vdso32 is initialized, so
	 * just fiddle with both possible images.  vdso_image_32_syscall
	 * can't be selected, since it only exists on 64-bit systems.
	 */
	u32 *mask;
	mask = vdso_image_32_int80.data +
		vdso_image_32_int80.sym_VDSO32_NOTE_MASK;
	*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
	mask = vdso_image_32_sysenter.data +
		vdso_image_32_sysenter.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
}