aboutsummaryrefslogtreecommitdiff
path: root/arch/i386/xen/enlighten.c
blob: 142e74891344d982a31eb0efc5bcf507f5278416 (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
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
/*
 * Core of Xen paravirt_ops implementation.
 *
 * This file contains the xen_paravirt_ops structure itself, and the
 * implementations for:
 * - privileged instructions
 * - interrupt flags
 * - segment operations
 * - booting and setup
 *
 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/preempt.h>
#include <linux/hardirq.h>
#include <linux/percpu.h>
#include <linux/delay.h>
#include <linux/start_kernel.h>
#include <linux/sched.h>
#include <linux/bootmem.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/highmem.h>
#include <linux/smp.h>

#include <xen/interface/xen.h>
#include <xen/interface/physdev.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/sched.h>
#include <xen/features.h>
#include <xen/page.h>

#include <asm/paravirt.h>
#include <asm/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <asm/fixmap.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/reboot.h>

#include "xen-ops.h"
#include "mmu.h"
#include "multicalls.h"

EXPORT_SYMBOL_GPL(hypercall_page);

DEFINE_PER_CPU(enum paravirt_lazy_mode, xen_lazy_mode);

DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
DEFINE_PER_CPU(unsigned long, xen_cr3);

struct start_info *xen_start_info;
EXPORT_SYMBOL_GPL(xen_start_info);

void xen_vcpu_setup(int cpu)
{
	per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
}

static void __init xen_banner(void)
{
	printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
	       paravirt_ops.name);
	printk(KERN_INFO "Hypervisor signature: %s\n", xen_start_info->magic);
}

static void xen_cpuid(unsigned int *eax, unsigned int *ebx,
		      unsigned int *ecx, unsigned int *edx)
{
	unsigned maskedx = ~0;

	/*
	 * Mask out inconvenient features, to try and disable as many
	 * unsupported kernel subsystems as possible.
	 */
	if (*eax == 1)
		maskedx = ~((1 << X86_FEATURE_APIC) |  /* disable APIC */
			    (1 << X86_FEATURE_ACPI) |  /* disable ACPI */
			    (1 << X86_FEATURE_ACC));   /* thermal monitoring */

	asm(XEN_EMULATE_PREFIX "cpuid"
		: "=a" (*eax),
		  "=b" (*ebx),
		  "=c" (*ecx),
		  "=d" (*edx)
		: "0" (*eax), "2" (*ecx));
	*edx &= maskedx;
}

static void xen_set_debugreg(int reg, unsigned long val)
{
	HYPERVISOR_set_debugreg(reg, val);
}

static unsigned long xen_get_debugreg(int reg)
{
	return HYPERVISOR_get_debugreg(reg);
}

static unsigned long xen_save_fl(void)
{
	struct vcpu_info *vcpu;
	unsigned long flags;

	vcpu = x86_read_percpu(xen_vcpu);

	/* flag has opposite sense of mask */
	flags = !vcpu->evtchn_upcall_mask;

	/* convert to IF type flag
	   -0 -> 0x00000000
	   -1 -> 0xffffffff
	*/
	return (-flags) & X86_EFLAGS_IF;
}

static void xen_restore_fl(unsigned long flags)
{
	struct vcpu_info *vcpu;

	/* convert from IF type flag */
	flags = !(flags & X86_EFLAGS_IF);

	/* There's a one instruction preempt window here.  We need to
	   make sure we're don't switch CPUs between getting the vcpu
	   pointer and updating the mask. */
	preempt_disable();
	vcpu = x86_read_percpu(xen_vcpu);
	vcpu->evtchn_upcall_mask = flags;
	preempt_enable_no_resched();

	/* Doesn't matter if we get preempted here, because any
	   pending event will get dealt with anyway. */

	if (flags == 0) {
		preempt_check_resched();
		barrier(); /* unmask then check (avoid races) */
		if (unlikely(vcpu->evtchn_upcall_pending))
			force_evtchn_callback();
	}
}

static void xen_irq_disable(void)
{
	/* There's a one instruction preempt window here.  We need to
	   make sure we're don't switch CPUs between getting the vcpu
	   pointer and updating the mask. */
	preempt_disable();
	x86_read_percpu(xen_vcpu)->evtchn_upcall_mask = 1;
	preempt_enable_no_resched();
}

static void xen_irq_enable(void)
{
	struct vcpu_info *vcpu;

	/* There's a one instruction preempt window here.  We need to
	   make sure we're don't switch CPUs between getting the vcpu
	   pointer and updating the mask. */
	preempt_disable();
	vcpu = x86_read_percpu(xen_vcpu);
	vcpu->evtchn_upcall_mask = 0;
	preempt_enable_no_resched();

	/* Doesn't matter if we get preempted here, because any
	   pending event will get dealt with anyway. */

	barrier(); /* unmask then check (avoid races) */
	if (unlikely(vcpu->evtchn_upcall_pending))
		force_evtchn_callback();
}

static void xen_safe_halt(void)
{
	/* Blocking includes an implicit local_irq_enable(). */
	if (HYPERVISOR_sched_op(SCHEDOP_block, 0) != 0)
		BUG();
}

static void xen_halt(void)
{
	if (irqs_disabled())
		HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
	else
		xen_safe_halt();
}

static void xen_set_lazy_mode(enum paravirt_lazy_mode mode)
{
	BUG_ON(preemptible());

	switch (mode) {
	case PARAVIRT_LAZY_NONE:
		BUG_ON(x86_read_percpu(xen_lazy_mode) == PARAVIRT_LAZY_NONE);
		break;

	case PARAVIRT_LAZY_MMU:
	case PARAVIRT_LAZY_CPU:
		BUG_ON(x86_read_percpu(xen_lazy_mode) != PARAVIRT_LAZY_NONE);
		break;

	case PARAVIRT_LAZY_FLUSH:
		/* flush if necessary, but don't change state */
		if (x86_read_percpu(xen_lazy_mode) != PARAVIRT_LAZY_NONE)
			xen_mc_flush();
		return;
	}

	xen_mc_flush();
	x86_write_percpu(xen_lazy_mode, mode);
}

static unsigned long xen_store_tr(void)
{
	return 0;
}

static void xen_set_ldt(const void *addr, unsigned entries)
{
	unsigned long linear_addr = (unsigned long)addr;
	struct mmuext_op *op;
	struct multicall_space mcs = xen_mc_entry(sizeof(*op));

	op = mcs.args;
	op->cmd = MMUEXT_SET_LDT;
	if (linear_addr) {
		/* ldt my be vmalloced, use arbitrary_virt_to_machine */
		xmaddr_t maddr;
		maddr = arbitrary_virt_to_machine((unsigned long)addr);
		linear_addr = (unsigned long)maddr.maddr;
	}
	op->arg1.linear_addr = linear_addr;
	op->arg2.nr_ents = entries;

	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

	xen_mc_issue(PARAVIRT_LAZY_CPU);
}

static void xen_load_gdt(const struct Xgt_desc_struct *dtr)
{
	unsigned long *frames;
	unsigned long va = dtr->address;
	unsigned int size = dtr->size + 1;
	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
	int f;
	struct multicall_space mcs;

	/* A GDT can be up to 64k in size, which corresponds to 8192
	   8-byte entries, or 16 4k pages.. */

	BUG_ON(size > 65536);
	BUG_ON(va & ~PAGE_MASK);

	mcs = xen_mc_entry(sizeof(*frames) * pages);
	frames = mcs.args;

	for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
		frames[f] = virt_to_mfn(va);
		make_lowmem_page_readonly((void *)va);
	}

	MULTI_set_gdt(mcs.mc, frames, size / sizeof(struct desc_struct));

	xen_mc_issue(PARAVIRT_LAZY_CPU);
}

static void load_TLS_descriptor(struct thread_struct *t,
				unsigned int cpu, unsigned int i)
{
	struct desc_struct *gdt = get_cpu_gdt_table(cpu);
	xmaddr_t maddr = virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]);
	struct multicall_space mc = __xen_mc_entry(0);

	MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]);
}

static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
{
	xen_mc_batch();

	load_TLS_descriptor(t, cpu, 0);
	load_TLS_descriptor(t, cpu, 1);
	load_TLS_descriptor(t, cpu, 2);

	xen_mc_issue(PARAVIRT_LAZY_CPU);

	/*
	 * XXX sleazy hack: If we're being called in a lazy-cpu zone,
	 * it means we're in a context switch, and %gs has just been
	 * saved.  This means we can zero it out to prevent faults on
	 * exit from the hypervisor if the next process has no %gs.
	 * Either way, it has been saved, and the new value will get
	 * loaded properly.  This will go away as soon as Xen has been
	 * modified to not save/restore %gs for normal hypercalls.
	 */
	if (xen_get_lazy_mode() == PARAVIRT_LAZY_CPU)
		loadsegment(gs, 0);
}

static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
				u32 low, u32 high)
{
	unsigned long lp = (unsigned long)&dt[entrynum];
	xmaddr_t mach_lp = virt_to_machine(lp);
	u64 entry = (u64)high << 32 | low;

	preempt_disable();

	xen_mc_flush();
	if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry))
		BUG();

	preempt_enable();
}

static int cvt_gate_to_trap(int vector, u32 low, u32 high,
			    struct trap_info *info)
{
	u8 type, dpl;

	type = (high >> 8) & 0x1f;
	dpl = (high >> 13) & 3;

	if (type != 0xf && type != 0xe)
		return 0;

	info->vector = vector;
	info->address = (high & 0xffff0000) | (low & 0x0000ffff);
	info->cs = low >> 16;
	info->flags = dpl;
	/* interrupt gates clear IF */
	if (type == 0xe)
		info->flags |= 4;

	return 1;
}

/* Locations of each CPU's IDT */
static DEFINE_PER_CPU(struct Xgt_desc_struct, idt_desc);

/* Set an IDT entry.  If the entry is part of the current IDT, then
   also update Xen. */
static void xen_write_idt_entry(struct desc_struct *dt, int entrynum,
				u32 low, u32 high)
{
	unsigned long p = (unsigned long)&dt[entrynum];
	unsigned long start, end;

	preempt_disable();

	start = __get_cpu_var(idt_desc).address;
	end = start + __get_cpu_var(idt_desc).size + 1;

	xen_mc_flush();

	write_dt_entry(dt, entrynum, low, high);

	if (p >= start && (p + 8) <= end) {
		struct trap_info info[2];

		info[1].address = 0;

		if (cvt_gate_to_trap(entrynum, low, high, &info[0]))
			if (HYPERVISOR_set_trap_table(info))
				BUG();
	}

	preempt_enable();
}

static void xen_convert_trap_info(const struct Xgt_desc_struct *desc,
				  struct trap_info *traps)
{
	unsigned in, out, count;

	count = (desc->size+1) / 8;
	BUG_ON(count > 256);

	for (in = out = 0; in < count; in++) {
		const u32 *entry = (u32 *)(desc->address + in * 8);

		if (cvt_gate_to_trap(in, entry[0], entry[1], &traps[out]))
			out++;
	}
	traps[out].address = 0;
}

void xen_copy_trap_info(struct trap_info *traps)
{
	const struct Xgt_desc_struct *desc = &__get_cpu_var(idt_desc);

	xen_convert_trap_info(desc, traps);
}

/* Load a new IDT into Xen.  In principle this can be per-CPU, so we
   hold a spinlock to protect the static traps[] array (static because
   it avoids allocation, and saves stack space). */
static void xen_load_idt(const struct Xgt_desc_struct *desc)
{
	static DEFINE_SPINLOCK(lock);
	static struct trap_info traps[257];

	spin_lock(&lock);

	__get_cpu_var(idt_desc) = *desc;

	xen_convert_trap_info(desc, traps);

	xen_mc_flush();
	if (HYPERVISOR_set_trap_table(traps))
		BUG();

	spin_unlock(&lock);
}

/* Write a GDT descriptor entry.  Ignore LDT descriptors, since
   they're handled differently. */
static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
				u32 low, u32 high)
{
	preempt_disable();

	switch ((high >> 8) & 0xff) {
	case DESCTYPE_LDT:
	case DESCTYPE_TSS:
		/* ignore */
		break;

	default: {
		xmaddr_t maddr = virt_to_machine(&dt[entry]);
		u64 desc = (u64)high << 32 | low;

		xen_mc_flush();
		if (HYPERVISOR_update_descriptor(maddr.maddr, desc))
			BUG();
	}

	}

	preempt_enable();
}

static void xen_load_esp0(struct tss_struct *tss,
			  struct thread_struct *thread)
{
	struct multicall_space mcs = xen_mc_entry(0);
	MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->esp0);
	xen_mc_issue(PARAVIRT_LAZY_CPU);
}

static void xen_set_iopl_mask(unsigned mask)
{
	struct physdev_set_iopl set_iopl;

	/* Force the change at ring 0. */
	set_iopl.iopl = (mask == 0) ? 1 : (mask >> 12) & 3;
	HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
}

static void xen_io_delay(void)
{
}

#ifdef CONFIG_X86_LOCAL_APIC
static unsigned long xen_apic_read(unsigned long reg)
{
	return 0;
}

static void xen_apic_write(unsigned long reg, unsigned long val)
{
	/* Warn to see if there's any stray references */
	WARN_ON(1);
}
#endif

static void xen_flush_tlb(void)
{
	struct mmuext_op *op;
	struct multicall_space mcs = xen_mc_entry(sizeof(*op));

	op = mcs.args;
	op->cmd = MMUEXT_TLB_FLUSH_LOCAL;
	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

	xen_mc_issue(PARAVIRT_LAZY_MMU);
}

static void xen_flush_tlb_single(unsigned long addr)
{
	struct mmuext_op *op;
	struct multicall_space mcs = xen_mc_entry(sizeof(*op));

	op = mcs.args;
	op->cmd = MMUEXT_INVLPG_LOCAL;
	op->arg1.linear_addr = addr & PAGE_MASK;
	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

	xen_mc_issue(PARAVIRT_LAZY_MMU);
}

static void xen_flush_tlb_others(const cpumask_t *cpus, struct mm_struct *mm,
				 unsigned long va)
{
	struct {
		struct mmuext_op op;
		cpumask_t mask;
	} *args;
	cpumask_t cpumask = *cpus;
	struct multicall_space mcs;

	/*
	 * A couple of (to be removed) sanity checks:
	 *
	 * - current CPU must not be in mask
	 * - mask must exist :)
	 */
	BUG_ON(cpus_empty(cpumask));
	BUG_ON(cpu_isset(smp_processor_id(), cpumask));
	BUG_ON(!mm);

	/* If a CPU which we ran on has gone down, OK. */
	cpus_and(cpumask, cpumask, cpu_online_map);
	if (cpus_empty(cpumask))
		return;

	mcs = xen_mc_entry(sizeof(*args));
	args = mcs.args;
	args->mask = cpumask;
	args->op.arg2.vcpumask = &args->mask;

	if (va == TLB_FLUSH_ALL) {
		args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
	} else {
		args->op.cmd = MMUEXT_INVLPG_MULTI;
		args->op.arg1.linear_addr = va;
	}

	MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF);

	xen_mc_issue(PARAVIRT_LAZY_MMU);
}

static unsigned long xen_read_cr2(void)
{
	return x86_read_percpu(xen_vcpu)->arch.cr2;
}

static void xen_write_cr4(unsigned long cr4)
{
	/* never allow TSC to be disabled */
	native_write_cr4(cr4 & ~X86_CR4_TSD);
}

static unsigned long xen_read_cr3(void)
{
	return x86_read_percpu(xen_cr3);
}

static void xen_write_cr3(unsigned long cr3)
{
	BUG_ON(preemptible());

	if (cr3 == x86_read_percpu(xen_cr3)) {
		/* just a simple tlb flush */
		xen_flush_tlb();
		return;
	}

	x86_write_percpu(xen_cr3, cr3);


	{
		struct mmuext_op *op;
		struct multicall_space mcs = xen_mc_entry(sizeof(*op));
		unsigned long mfn = pfn_to_mfn(PFN_DOWN(cr3));

		op = mcs.args;
		op->cmd = MMUEXT_NEW_BASEPTR;
		op->arg1.mfn = mfn;

		MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

		xen_mc_issue(PARAVIRT_LAZY_CPU);
	}
}

/* Early in boot, while setting up the initial pagetable, assume
   everything is pinned. */
static __init void xen_alloc_pt_init(struct mm_struct *mm, u32 pfn)
{
	BUG_ON(mem_map);	/* should only be used early */
	make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
}

/* This needs to make sure the new pte page is pinned iff its being
   attached to a pinned pagetable. */
static void xen_alloc_pt(struct mm_struct *mm, u32 pfn)
{
	struct page *page = pfn_to_page(pfn);

	if (PagePinned(virt_to_page(mm->pgd))) {
		SetPagePinned(page);

		if (!PageHighMem(page))
			make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
		else
			/* make sure there are no stray mappings of
			   this page */
			kmap_flush_unused();
	}
}

/* This should never happen until we're OK to use struct page */
static void xen_release_pt(u32 pfn)
{
	struct page *page = pfn_to_page(pfn);

	if (PagePinned(page)) {
		if (!PageHighMem(page))
			make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
	}
}

#ifdef CONFIG_HIGHPTE
static void *xen_kmap_atomic_pte(struct page *page, enum km_type type)
{
	pgprot_t prot = PAGE_KERNEL;

	if (PagePinned(page))
		prot = PAGE_KERNEL_RO;

	if (0 && PageHighMem(page))
		printk("mapping highpte %lx type %d prot %s\n",
		       page_to_pfn(page), type,
		       (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" : "READ");

	return kmap_atomic_prot(page, type, prot);
}
#endif

static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
{
	/* If there's an existing pte, then don't allow _PAGE_RW to be set */
	if (pte_val_ma(*ptep) & _PAGE_PRESENT)
		pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
			       pte_val_ma(pte));

	return pte;
}

/* Init-time set_pte while constructing initial pagetables, which
   doesn't allow RO pagetable pages to be remapped RW */
static __init void xen_set_pte_init(pte_t *ptep, pte_t pte)
{
	pte = mask_rw_pte(ptep, pte);

	xen_set_pte(ptep, pte);
}

static __init void xen_pagetable_setup_start(pgd_t *base)
{
	pgd_t *xen_pgd = (pgd_t *)xen_start_info->pt_base;

	/* special set_pte for pagetable initialization */
	paravirt_ops.set_pte = xen_set_pte_init;

	init_mm.pgd = base;
	/*
	 * copy top-level of Xen-supplied pagetable into place.	 For
	 * !PAE we can use this as-is, but for PAE it is a stand-in
	 * while we copy the pmd pages.
	 */
	memcpy(base, xen_pgd, PTRS_PER_PGD * sizeof(pgd_t));

	if (PTRS_PER_PMD > 1) {
		int i;
		/*
		 * For PAE, need to allocate new pmds, rather than
		 * share Xen's, since Xen doesn't like pmd's being
		 * shared between address spaces.
		 */
		for (i = 0; i < PTRS_PER_PGD; i++) {
			if (pgd_val_ma(xen_pgd[i]) & _PAGE_PRESENT) {
				pmd_t *pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);

				memcpy(pmd, (void *)pgd_page_vaddr(xen_pgd[i]),
				       PAGE_SIZE);

				make_lowmem_page_readonly(pmd);

				set_pgd(&base[i], __pgd(1 + __pa(pmd)));
			} else
				pgd_clear(&base[i]);
		}
	}

	/* make sure zero_page is mapped RO so we can use it in pagetables */
	make_lowmem_page_readonly(empty_zero_page);
	make_lowmem_page_readonly(base);
	/*
	 * Switch to new pagetable.  This is done before
	 * pagetable_init has done anything so that the new pages
	 * added to the table can be prepared properly for Xen.
	 */
	xen_write_cr3(__pa(base));
}

static __init void xen_pagetable_setup_done(pgd_t *base)
{
	/* This will work as long as patching hasn't happened yet
	   (which it hasn't) */
	paravirt_ops.alloc_pt = xen_alloc_pt;
	paravirt_ops.set_pte = xen_set_pte;

	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
		/*
		 * Create a mapping for the shared info page.
		 * Should be set_fixmap(), but shared_info is a machine
		 * address with no corresponding pseudo-phys address.
		 */
		set_pte_mfn(fix_to_virt(FIX_PARAVIRT_BOOTMAP),
			    PFN_DOWN(xen_start_info->shared_info),
			    PAGE_KERNEL);

		HYPERVISOR_shared_info =
			(struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);

	} else
		HYPERVISOR_shared_info =
			(struct shared_info *)__va(xen_start_info->shared_info);

	/* Actually pin the pagetable down, but we can't set PG_pinned
	   yet because the page structures don't exist yet. */
	{
		struct mmuext_op op;
#ifdef CONFIG_X86_PAE
		op.cmd = MMUEXT_PIN_L3_TABLE;
#else
		op.cmd = MMUEXT_PIN_L3_TABLE;
#endif
		op.arg1.mfn = pfn_to_mfn(PFN_DOWN(__pa(base)));
		if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
			BUG();
	}

	xen_vcpu_setup(smp_processor_id());
}

static const struct paravirt_ops xen_paravirt_ops __initdata = {
	.paravirt_enabled = 1,
	.shared_kernel_pmd = 0,

	.name = "Xen",
	.banner = xen_banner,

	.patch = paravirt_patch_default,

	.memory_setup = xen_memory_setup,
	.arch_setup = xen_arch_setup,
	.init_IRQ = xen_init_IRQ,
	.post_allocator_init = xen_mark_init_mm_pinned,

	.time_init = xen_time_init,
	.set_wallclock = xen_set_wallclock,
	.get_wallclock = xen_get_wallclock,
	.get_cpu_khz = xen_cpu_khz,
	.sched_clock = xen_sched_clock,

	.cpuid = xen_cpuid,

	.set_debugreg = xen_set_debugreg,
	.get_debugreg = xen_get_debugreg,

	.clts = native_clts,

	.read_cr0 = native_read_cr0,
	.write_cr0 = native_write_cr0,

	.read_cr2 = xen_read_cr2,
	.write_cr2 = native_write_cr2,

	.read_cr3 = xen_read_cr3,
	.write_cr3 = xen_write_cr3,

	.read_cr4 = native_read_cr4,
	.read_cr4_safe = native_read_cr4_safe,
	.write_cr4 = xen_write_cr4,

	.save_fl = xen_save_fl,
	.restore_fl = xen_restore_fl,
	.irq_disable = xen_irq_disable,
	.irq_enable = xen_irq_enable,
	.safe_halt = xen_safe_halt,
	.halt = xen_halt,
	.wbinvd = native_wbinvd,

	.read_msr = native_read_msr_safe,
	.write_msr = native_write_msr_safe,
	.read_tsc = native_read_tsc,
	.read_pmc = native_read_pmc,

	.iret = (void *)&hypercall_page[__HYPERVISOR_iret],
	.irq_enable_sysexit = NULL,  /* never called */

	.load_tr_desc = paravirt_nop,
	.set_ldt = xen_set_ldt,
	.load_gdt = xen_load_gdt,
	.load_idt = xen_load_idt,
	.load_tls = xen_load_tls,

	.store_gdt = native_store_gdt,
	.store_idt = native_store_idt,
	.store_tr = xen_store_tr,

	.write_ldt_entry = xen_write_ldt_entry,
	.write_gdt_entry = xen_write_gdt_entry,
	.write_idt_entry = xen_write_idt_entry,
	.load_esp0 = xen_load_esp0,

	.set_iopl_mask = xen_set_iopl_mask,
	.io_delay = xen_io_delay,

#ifdef CONFIG_X86_LOCAL_APIC
	.apic_write = xen_apic_write,
	.apic_write_atomic = xen_apic_write,
	.apic_read = xen_apic_read,
	.setup_boot_clock = paravirt_nop,
	.setup_secondary_clock = paravirt_nop,
	.startup_ipi_hook = paravirt_nop,
#endif

	.flush_tlb_user = xen_flush_tlb,
	.flush_tlb_kernel = xen_flush_tlb,
	.flush_tlb_single = xen_flush_tlb_single,
	.flush_tlb_others = xen_flush_tlb_others,

	.pte_update = paravirt_nop,
	.pte_update_defer = paravirt_nop,

	.pagetable_setup_start = xen_pagetable_setup_start,
	.pagetable_setup_done = xen_pagetable_setup_done,

	.alloc_pt = xen_alloc_pt_init,
	.release_pt = xen_release_pt,
	.alloc_pd = paravirt_nop,
	.alloc_pd_clone = paravirt_nop,
	.release_pd = paravirt_nop,

#ifdef CONFIG_HIGHPTE
	.kmap_atomic_pte = xen_kmap_atomic_pte,
#endif

	.set_pte = NULL,	/* see xen_pagetable_setup_* */
	.set_pte_at = xen_set_pte_at,
	.set_pmd = xen_set_pmd,

	.pte_val = xen_pte_val,
	.pgd_val = xen_pgd_val,

	.make_pte = xen_make_pte,
	.make_pgd = xen_make_pgd,

#ifdef CONFIG_X86_PAE
	.set_pte_atomic = xen_set_pte_atomic,
	.set_pte_present = xen_set_pte_at,
	.set_pud = xen_set_pud,
	.pte_clear = xen_pte_clear,
	.pmd_clear = xen_pmd_clear,

	.make_pmd = xen_make_pmd,
	.pmd_val = xen_pmd_val,
#endif	/* PAE */

	.activate_mm = xen_activate_mm,
	.dup_mmap = xen_dup_mmap,
	.exit_mmap = xen_exit_mmap,

	.set_lazy_mode = xen_set_lazy_mode,
};

#ifdef CONFIG_SMP
static const struct smp_ops xen_smp_ops __initdata = {
	.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
	.smp_prepare_cpus = xen_smp_prepare_cpus,
	.cpu_up = xen_cpu_up,
	.smp_cpus_done = xen_smp_cpus_done,

	.smp_send_stop = xen_smp_send_stop,
	.smp_send_reschedule = xen_smp_send_reschedule,
	.smp_call_function_mask = xen_smp_call_function_mask,
};
#endif	/* CONFIG_SMP */

static void xen_reboot(int reason)
{
#ifdef CONFIG_SMP
	smp_send_stop();
#endif

	if (HYPERVISOR_sched_op(SCHEDOP_shutdown, reason))
		BUG();
}

static void xen_restart(char *msg)
{
	xen_reboot(SHUTDOWN_reboot);
}

static void xen_emergency_restart(void)
{
	xen_reboot(SHUTDOWN_reboot);
}

static void xen_machine_halt(void)
{
	xen_reboot(SHUTDOWN_poweroff);
}

static void xen_crash_shutdown(struct pt_regs *regs)
{
	xen_reboot(SHUTDOWN_crash);
}

static const struct machine_ops __initdata xen_machine_ops = {
	.restart = xen_restart,
	.halt = xen_machine_halt,
	.power_off = xen_machine_halt,
	.shutdown = xen_machine_halt,
	.crash_shutdown = xen_crash_shutdown,
	.emergency_restart = xen_emergency_restart,
};

/* First C function to be called on Xen boot */
asmlinkage void __init xen_start_kernel(void)
{
	pgd_t *pgd;

	if (!xen_start_info)
		return;

	BUG_ON(memcmp(xen_start_info->magic, "xen-3.0", 7) != 0);

	/* Install Xen paravirt ops */
	paravirt_ops = xen_paravirt_ops;
	machine_ops = xen_machine_ops;

#ifdef CONFIG_SMP
	smp_ops = xen_smp_ops;
#endif

	xen_setup_features();

	/* Get mfn list */
	if (!xen_feature(XENFEAT_auto_translated_physmap))
		phys_to_machine_mapping = (unsigned long *)xen_start_info->mfn_list;

	pgd = (pgd_t *)xen_start_info->pt_base;

	init_pg_tables_end = __pa(pgd) + xen_start_info->nr_pt_frames*PAGE_SIZE;

	init_mm.pgd = pgd; /* use the Xen pagetables to start */

	/* keep using Xen gdt for now; no urgent need to change it */

	x86_write_percpu(xen_cr3, __pa(pgd));
	xen_vcpu_setup(0);

	paravirt_ops.kernel_rpl = 1;
	if (xen_feature(XENFEAT_supervisor_mode_kernel))
		paravirt_ops.kernel_rpl = 0;

	/* set the limit of our address space */
	reserve_top_address(-HYPERVISOR_VIRT_START + 2 * PAGE_SIZE);

	/* set up basic CPUID stuff */
	cpu_detect(&new_cpu_data);
	new_cpu_data.hard_math = 1;
	new_cpu_data.x86_capability[0] = cpuid_edx(1);

	/* Poke various useful things into boot_params */
	LOADER_TYPE = (9 << 4) | 0;
	INITRD_START = xen_start_info->mod_start ? __pa(xen_start_info->mod_start) : 0;
	INITRD_SIZE = xen_start_info->mod_len;

	/* Start the world */
	start_kernel();
}