Merge git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6
[linux-2.6] / arch / x86 / xen / enlighten.c
1 /*
2  * Core of Xen paravirt_ops implementation.
3  *
4  * This file contains the xen_paravirt_ops structure itself, and the
5  * implementations for:
6  * - privileged instructions
7  * - interrupt flags
8  * - segment operations
9  * - booting and setup
10  *
11  * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
12  */
13
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/smp.h>
17 #include <linux/preempt.h>
18 #include <linux/hardirq.h>
19 #include <linux/percpu.h>
20 #include <linux/delay.h>
21 #include <linux/start_kernel.h>
22 #include <linux/sched.h>
23 #include <linux/bootmem.h>
24 #include <linux/module.h>
25 #include <linux/mm.h>
26 #include <linux/page-flags.h>
27 #include <linux/highmem.h>
28 #include <linux/console.h>
29
30 #include <xen/interface/xen.h>
31 #include <xen/interface/version.h>
32 #include <xen/interface/physdev.h>
33 #include <xen/interface/vcpu.h>
34 #include <xen/features.h>
35 #include <xen/page.h>
36 #include <xen/hvc-console.h>
37
38 #include <asm/paravirt.h>
39 #include <asm/apic.h>
40 #include <asm/page.h>
41 #include <asm/xen/hypercall.h>
42 #include <asm/xen/hypervisor.h>
43 #include <asm/fixmap.h>
44 #include <asm/processor.h>
45 #include <asm/msr-index.h>
46 #include <asm/setup.h>
47 #include <asm/desc.h>
48 #include <asm/pgtable.h>
49 #include <asm/tlbflush.h>
50 #include <asm/reboot.h>
51
52 #include "xen-ops.h"
53 #include "mmu.h"
54 #include "multicalls.h"
55
56 EXPORT_SYMBOL_GPL(hypercall_page);
57
58 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
59 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
60
61 enum xen_domain_type xen_domain_type = XEN_NATIVE;
62 EXPORT_SYMBOL_GPL(xen_domain_type);
63
64 struct start_info *xen_start_info;
65 EXPORT_SYMBOL_GPL(xen_start_info);
66
67 struct shared_info xen_dummy_shared_info;
68
69 void *xen_initial_gdt;
70
71 /*
72  * Point at some empty memory to start with. We map the real shared_info
73  * page as soon as fixmap is up and running.
74  */
75 struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
76
77 /*
78  * Flag to determine whether vcpu info placement is available on all
79  * VCPUs.  We assume it is to start with, and then set it to zero on
80  * the first failure.  This is because it can succeed on some VCPUs
81  * and not others, since it can involve hypervisor memory allocation,
82  * or because the guest failed to guarantee all the appropriate
83  * constraints on all VCPUs (ie buffer can't cross a page boundary).
84  *
85  * Note that any particular CPU may be using a placed vcpu structure,
86  * but we can only optimise if the all are.
87  *
88  * 0: not available, 1: available
89  */
90 static int have_vcpu_info_placement = 1;
91
92 static void xen_vcpu_setup(int cpu)
93 {
94         struct vcpu_register_vcpu_info info;
95         int err;
96         struct vcpu_info *vcpup;
97
98         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
99         per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
100
101         if (!have_vcpu_info_placement)
102                 return;         /* already tested, not available */
103
104         vcpup = &per_cpu(xen_vcpu_info, cpu);
105
106         info.mfn = arbitrary_virt_to_mfn(vcpup);
107         info.offset = offset_in_page(vcpup);
108
109         printk(KERN_DEBUG "trying to map vcpu_info %d at %p, mfn %llx, offset %d\n",
110                cpu, vcpup, info.mfn, info.offset);
111
112         /* Check to see if the hypervisor will put the vcpu_info
113            structure where we want it, which allows direct access via
114            a percpu-variable. */
115         err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, cpu, &info);
116
117         if (err) {
118                 printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err);
119                 have_vcpu_info_placement = 0;
120         } else {
121                 /* This cpu is using the registered vcpu info, even if
122                    later ones fail to. */
123                 per_cpu(xen_vcpu, cpu) = vcpup;
124
125                 printk(KERN_DEBUG "cpu %d using vcpu_info at %p\n",
126                        cpu, vcpup);
127         }
128 }
129
130 /*
131  * On restore, set the vcpu placement up again.
132  * If it fails, then we're in a bad state, since
133  * we can't back out from using it...
134  */
135 void xen_vcpu_restore(void)
136 {
137         if (have_vcpu_info_placement) {
138                 int cpu;
139
140                 for_each_online_cpu(cpu) {
141                         bool other_cpu = (cpu != smp_processor_id());
142
143                         if (other_cpu &&
144                             HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL))
145                                 BUG();
146
147                         xen_vcpu_setup(cpu);
148
149                         if (other_cpu &&
150                             HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL))
151                                 BUG();
152                 }
153
154                 BUG_ON(!have_vcpu_info_placement);
155         }
156 }
157
158 static void __init xen_banner(void)
159 {
160         unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
161         struct xen_extraversion extra;
162         HYPERVISOR_xen_version(XENVER_extraversion, &extra);
163
164         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
165                pv_info.name);
166         printk(KERN_INFO "Xen version: %d.%d%s%s\n",
167                version >> 16, version & 0xffff, extra.extraversion,
168                xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
169 }
170
171 static void xen_cpuid(unsigned int *ax, unsigned int *bx,
172                       unsigned int *cx, unsigned int *dx)
173 {
174         unsigned maskedx = ~0;
175
176         /*
177          * Mask out inconvenient features, to try and disable as many
178          * unsupported kernel subsystems as possible.
179          */
180         if (*ax == 1)
181                 maskedx = ~((1 << X86_FEATURE_APIC) |  /* disable APIC */
182                             (1 << X86_FEATURE_ACPI) |  /* disable ACPI */
183                             (1 << X86_FEATURE_MCE)  |  /* disable MCE */
184                             (1 << X86_FEATURE_MCA)  |  /* disable MCA */
185                             (1 << X86_FEATURE_ACC));   /* thermal monitoring */
186
187         asm(XEN_EMULATE_PREFIX "cpuid"
188                 : "=a" (*ax),
189                   "=b" (*bx),
190                   "=c" (*cx),
191                   "=d" (*dx)
192                 : "0" (*ax), "2" (*cx));
193         *dx &= maskedx;
194 }
195
196 static void xen_set_debugreg(int reg, unsigned long val)
197 {
198         HYPERVISOR_set_debugreg(reg, val);
199 }
200
201 static unsigned long xen_get_debugreg(int reg)
202 {
203         return HYPERVISOR_get_debugreg(reg);
204 }
205
206 void xen_leave_lazy(void)
207 {
208         paravirt_leave_lazy(paravirt_get_lazy_mode());
209         xen_mc_flush();
210 }
211
212 static unsigned long xen_store_tr(void)
213 {
214         return 0;
215 }
216
217 /*
218  * Set the page permissions for a particular virtual address.  If the
219  * address is a vmalloc mapping (or other non-linear mapping), then
220  * find the linear mapping of the page and also set its protections to
221  * match.
222  */
223 static void set_aliased_prot(void *v, pgprot_t prot)
224 {
225         int level;
226         pte_t *ptep;
227         pte_t pte;
228         unsigned long pfn;
229         struct page *page;
230
231         ptep = lookup_address((unsigned long)v, &level);
232         BUG_ON(ptep == NULL);
233
234         pfn = pte_pfn(*ptep);
235         page = pfn_to_page(pfn);
236
237         pte = pfn_pte(pfn, prot);
238
239         if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
240                 BUG();
241
242         if (!PageHighMem(page)) {
243                 void *av = __va(PFN_PHYS(pfn));
244
245                 if (av != v)
246                         if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
247                                 BUG();
248         } else
249                 kmap_flush_unused();
250 }
251
252 static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
253 {
254         const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
255         int i;
256
257         for(i = 0; i < entries; i += entries_per_page)
258                 set_aliased_prot(ldt + i, PAGE_KERNEL_RO);
259 }
260
261 static void xen_free_ldt(struct desc_struct *ldt, unsigned entries)
262 {
263         const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
264         int i;
265
266         for(i = 0; i < entries; i += entries_per_page)
267                 set_aliased_prot(ldt + i, PAGE_KERNEL);
268 }
269
270 static void xen_set_ldt(const void *addr, unsigned entries)
271 {
272         struct mmuext_op *op;
273         struct multicall_space mcs = xen_mc_entry(sizeof(*op));
274
275         op = mcs.args;
276         op->cmd = MMUEXT_SET_LDT;
277         op->arg1.linear_addr = (unsigned long)addr;
278         op->arg2.nr_ents = entries;
279
280         MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
281
282         xen_mc_issue(PARAVIRT_LAZY_CPU);
283 }
284
285 static void xen_load_gdt(const struct desc_ptr *dtr)
286 {
287         unsigned long *frames;
288         unsigned long va = dtr->address;
289         unsigned int size = dtr->size + 1;
290         unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
291         int f;
292         struct multicall_space mcs;
293
294         /* A GDT can be up to 64k in size, which corresponds to 8192
295            8-byte entries, or 16 4k pages.. */
296
297         BUG_ON(size > 65536);
298         BUG_ON(va & ~PAGE_MASK);
299
300         mcs = xen_mc_entry(sizeof(*frames) * pages);
301         frames = mcs.args;
302
303         for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
304                 frames[f] = arbitrary_virt_to_mfn((void *)va);
305
306                 make_lowmem_page_readonly((void *)va);
307                 make_lowmem_page_readonly(mfn_to_virt(frames[f]));
308         }
309
310         MULTI_set_gdt(mcs.mc, frames, size / sizeof(struct desc_struct));
311
312         xen_mc_issue(PARAVIRT_LAZY_CPU);
313 }
314
315 static void load_TLS_descriptor(struct thread_struct *t,
316                                 unsigned int cpu, unsigned int i)
317 {
318         struct desc_struct *gdt = get_cpu_gdt_table(cpu);
319         xmaddr_t maddr = arbitrary_virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]);
320         struct multicall_space mc = __xen_mc_entry(0);
321
322         MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]);
323 }
324
325 static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
326 {
327         /*
328          * XXX sleazy hack: If we're being called in a lazy-cpu zone
329          * and lazy gs handling is enabled, it means we're in a
330          * context switch, and %gs has just been saved.  This means we
331          * can zero it out to prevent faults on exit from the
332          * hypervisor if the next process has no %gs.  Either way, it
333          * has been saved, and the new value will get loaded properly.
334          * This will go away as soon as Xen has been modified to not
335          * save/restore %gs for normal hypercalls.
336          *
337          * On x86_64, this hack is not used for %gs, because gs points
338          * to KERNEL_GS_BASE (and uses it for PDA references), so we
339          * must not zero %gs on x86_64
340          *
341          * For x86_64, we need to zero %fs, otherwise we may get an
342          * exception between the new %fs descriptor being loaded and
343          * %fs being effectively cleared at __switch_to().
344          */
345         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
346 #ifdef CONFIG_X86_32
347                 lazy_load_gs(0);
348 #else
349                 loadsegment(fs, 0);
350 #endif
351         }
352
353         xen_mc_batch();
354
355         load_TLS_descriptor(t, cpu, 0);
356         load_TLS_descriptor(t, cpu, 1);
357         load_TLS_descriptor(t, cpu, 2);
358
359         xen_mc_issue(PARAVIRT_LAZY_CPU);
360 }
361
362 #ifdef CONFIG_X86_64
363 static void xen_load_gs_index(unsigned int idx)
364 {
365         if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx))
366                 BUG();
367 }
368 #endif
369
370 static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
371                                 const void *ptr)
372 {
373         xmaddr_t mach_lp = arbitrary_virt_to_machine(&dt[entrynum]);
374         u64 entry = *(u64 *)ptr;
375
376         preempt_disable();
377
378         xen_mc_flush();
379         if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry))
380                 BUG();
381
382         preempt_enable();
383 }
384
385 static int cvt_gate_to_trap(int vector, const gate_desc *val,
386                             struct trap_info *info)
387 {
388         if (val->type != 0xf && val->type != 0xe)
389                 return 0;
390
391         info->vector = vector;
392         info->address = gate_offset(*val);
393         info->cs = gate_segment(*val);
394         info->flags = val->dpl;
395         /* interrupt gates clear IF */
396         if (val->type == 0xe)
397                 info->flags |= 4;
398
399         return 1;
400 }
401
402 /* Locations of each CPU's IDT */
403 static DEFINE_PER_CPU(struct desc_ptr, idt_desc);
404
405 /* Set an IDT entry.  If the entry is part of the current IDT, then
406    also update Xen. */
407 static void xen_write_idt_entry(gate_desc *dt, int entrynum, const gate_desc *g)
408 {
409         unsigned long p = (unsigned long)&dt[entrynum];
410         unsigned long start, end;
411
412         preempt_disable();
413
414         start = __get_cpu_var(idt_desc).address;
415         end = start + __get_cpu_var(idt_desc).size + 1;
416
417         xen_mc_flush();
418
419         native_write_idt_entry(dt, entrynum, g);
420
421         if (p >= start && (p + 8) <= end) {
422                 struct trap_info info[2];
423
424                 info[1].address = 0;
425
426                 if (cvt_gate_to_trap(entrynum, g, &info[0]))
427                         if (HYPERVISOR_set_trap_table(info))
428                                 BUG();
429         }
430
431         preempt_enable();
432 }
433
434 static void xen_convert_trap_info(const struct desc_ptr *desc,
435                                   struct trap_info *traps)
436 {
437         unsigned in, out, count;
438
439         count = (desc->size+1) / sizeof(gate_desc);
440         BUG_ON(count > 256);
441
442         for (in = out = 0; in < count; in++) {
443                 gate_desc *entry = (gate_desc*)(desc->address) + in;
444
445                 if (cvt_gate_to_trap(in, entry, &traps[out]))
446                         out++;
447         }
448         traps[out].address = 0;
449 }
450
451 void xen_copy_trap_info(struct trap_info *traps)
452 {
453         const struct desc_ptr *desc = &__get_cpu_var(idt_desc);
454
455         xen_convert_trap_info(desc, traps);
456 }
457
458 /* Load a new IDT into Xen.  In principle this can be per-CPU, so we
459    hold a spinlock to protect the static traps[] array (static because
460    it avoids allocation, and saves stack space). */
461 static void xen_load_idt(const struct desc_ptr *desc)
462 {
463         static DEFINE_SPINLOCK(lock);
464         static struct trap_info traps[257];
465
466         spin_lock(&lock);
467
468         __get_cpu_var(idt_desc) = *desc;
469
470         xen_convert_trap_info(desc, traps);
471
472         xen_mc_flush();
473         if (HYPERVISOR_set_trap_table(traps))
474                 BUG();
475
476         spin_unlock(&lock);
477 }
478
479 /* Write a GDT descriptor entry.  Ignore LDT descriptors, since
480    they're handled differently. */
481 static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
482                                 const void *desc, int type)
483 {
484         preempt_disable();
485
486         switch (type) {
487         case DESC_LDT:
488         case DESC_TSS:
489                 /* ignore */
490                 break;
491
492         default: {
493                 xmaddr_t maddr = arbitrary_virt_to_machine(&dt[entry]);
494
495                 xen_mc_flush();
496                 if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
497                         BUG();
498         }
499
500         }
501
502         preempt_enable();
503 }
504
505 static void xen_load_sp0(struct tss_struct *tss,
506                          struct thread_struct *thread)
507 {
508         struct multicall_space mcs = xen_mc_entry(0);
509         MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0);
510         xen_mc_issue(PARAVIRT_LAZY_CPU);
511 }
512
513 static void xen_set_iopl_mask(unsigned mask)
514 {
515         struct physdev_set_iopl set_iopl;
516
517         /* Force the change at ring 0. */
518         set_iopl.iopl = (mask == 0) ? 1 : (mask >> 12) & 3;
519         HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
520 }
521
522 static void xen_io_delay(void)
523 {
524 }
525
526 #ifdef CONFIG_X86_LOCAL_APIC
527 static u32 xen_apic_read(u32 reg)
528 {
529         return 0;
530 }
531
532 static void xen_apic_write(u32 reg, u32 val)
533 {
534         /* Warn to see if there's any stray references */
535         WARN_ON(1);
536 }
537
538 static u64 xen_apic_icr_read(void)
539 {
540         return 0;
541 }
542
543 static void xen_apic_icr_write(u32 low, u32 id)
544 {
545         /* Warn to see if there's any stray references */
546         WARN_ON(1);
547 }
548
549 static void xen_apic_wait_icr_idle(void)
550 {
551         return;
552 }
553
554 static u32 xen_safe_apic_wait_icr_idle(void)
555 {
556         return 0;
557 }
558
559 static void set_xen_basic_apic_ops(void)
560 {
561         apic->read = xen_apic_read;
562         apic->write = xen_apic_write;
563         apic->icr_read = xen_apic_icr_read;
564         apic->icr_write = xen_apic_icr_write;
565         apic->wait_icr_idle = xen_apic_wait_icr_idle;
566         apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
567 }
568
569 #endif
570
571
572 static void xen_clts(void)
573 {
574         struct multicall_space mcs;
575
576         mcs = xen_mc_entry(0);
577
578         MULTI_fpu_taskswitch(mcs.mc, 0);
579
580         xen_mc_issue(PARAVIRT_LAZY_CPU);
581 }
582
583 static void xen_write_cr0(unsigned long cr0)
584 {
585         struct multicall_space mcs;
586
587         /* Only pay attention to cr0.TS; everything else is
588            ignored. */
589         mcs = xen_mc_entry(0);
590
591         MULTI_fpu_taskswitch(mcs.mc, (cr0 & X86_CR0_TS) != 0);
592
593         xen_mc_issue(PARAVIRT_LAZY_CPU);
594 }
595
596 static void xen_write_cr4(unsigned long cr4)
597 {
598         cr4 &= ~X86_CR4_PGE;
599         cr4 &= ~X86_CR4_PSE;
600
601         native_write_cr4(cr4);
602 }
603
604 static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
605 {
606         int ret;
607
608         ret = 0;
609
610         switch (msr) {
611 #ifdef CONFIG_X86_64
612                 unsigned which;
613                 u64 base;
614
615         case MSR_FS_BASE:               which = SEGBASE_FS; goto set;
616         case MSR_KERNEL_GS_BASE:        which = SEGBASE_GS_USER; goto set;
617         case MSR_GS_BASE:               which = SEGBASE_GS_KERNEL; goto set;
618
619         set:
620                 base = ((u64)high << 32) | low;
621                 if (HYPERVISOR_set_segment_base(which, base) != 0)
622                         ret = -EFAULT;
623                 break;
624 #endif
625
626         case MSR_STAR:
627         case MSR_CSTAR:
628         case MSR_LSTAR:
629         case MSR_SYSCALL_MASK:
630         case MSR_IA32_SYSENTER_CS:
631         case MSR_IA32_SYSENTER_ESP:
632         case MSR_IA32_SYSENTER_EIP:
633                 /* Fast syscall setup is all done in hypercalls, so
634                    these are all ignored.  Stub them out here to stop
635                    Xen console noise. */
636                 break;
637
638         default:
639                 ret = native_write_msr_safe(msr, low, high);
640         }
641
642         return ret;
643 }
644
645 void xen_setup_shared_info(void)
646 {
647         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
648                 set_fixmap(FIX_PARAVIRT_BOOTMAP,
649                            xen_start_info->shared_info);
650
651                 HYPERVISOR_shared_info =
652                         (struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
653         } else
654                 HYPERVISOR_shared_info =
655                         (struct shared_info *)__va(xen_start_info->shared_info);
656
657 #ifndef CONFIG_SMP
658         /* In UP this is as good a place as any to set up shared info */
659         xen_setup_vcpu_info_placement();
660 #endif
661
662         xen_setup_mfn_list_list();
663 }
664
665 /* This is called once we have the cpu_possible_map */
666 void xen_setup_vcpu_info_placement(void)
667 {
668         int cpu;
669
670         for_each_possible_cpu(cpu)
671                 xen_vcpu_setup(cpu);
672
673         /* xen_vcpu_setup managed to place the vcpu_info within the
674            percpu area for all cpus, so make use of it */
675         if (have_vcpu_info_placement) {
676                 printk(KERN_INFO "Xen: using vcpu_info placement\n");
677
678                 pv_irq_ops.save_fl = __PV_IS_CALLEE_SAVE(xen_save_fl_direct);
679                 pv_irq_ops.restore_fl = __PV_IS_CALLEE_SAVE(xen_restore_fl_direct);
680                 pv_irq_ops.irq_disable = __PV_IS_CALLEE_SAVE(xen_irq_disable_direct);
681                 pv_irq_ops.irq_enable = __PV_IS_CALLEE_SAVE(xen_irq_enable_direct);
682                 pv_mmu_ops.read_cr2 = xen_read_cr2_direct;
683         }
684 }
685
686 static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
687                           unsigned long addr, unsigned len)
688 {
689         char *start, *end, *reloc;
690         unsigned ret;
691
692         start = end = reloc = NULL;
693
694 #define SITE(op, x)                                                     \
695         case PARAVIRT_PATCH(op.x):                                      \
696         if (have_vcpu_info_placement) {                                 \
697                 start = (char *)xen_##x##_direct;                       \
698                 end = xen_##x##_direct_end;                             \
699                 reloc = xen_##x##_direct_reloc;                         \
700         }                                                               \
701         goto patch_site
702
703         switch (type) {
704                 SITE(pv_irq_ops, irq_enable);
705                 SITE(pv_irq_ops, irq_disable);
706                 SITE(pv_irq_ops, save_fl);
707                 SITE(pv_irq_ops, restore_fl);
708 #undef SITE
709
710         patch_site:
711                 if (start == NULL || (end-start) > len)
712                         goto default_patch;
713
714                 ret = paravirt_patch_insns(insnbuf, len, start, end);
715
716                 /* Note: because reloc is assigned from something that
717                    appears to be an array, gcc assumes it's non-null,
718                    but doesn't know its relationship with start and
719                    end. */
720                 if (reloc > start && reloc < end) {
721                         int reloc_off = reloc - start;
722                         long *relocp = (long *)(insnbuf + reloc_off);
723                         long delta = start - (char *)addr;
724
725                         *relocp += delta;
726                 }
727                 break;
728
729         default_patch:
730         default:
731                 ret = paravirt_patch_default(type, clobbers, insnbuf,
732                                              addr, len);
733                 break;
734         }
735
736         return ret;
737 }
738
739 static const struct pv_info xen_info __initdata = {
740         .paravirt_enabled = 1,
741         .shared_kernel_pmd = 0,
742
743         .name = "Xen",
744 };
745
746 static const struct pv_init_ops xen_init_ops __initdata = {
747         .patch = xen_patch,
748
749         .banner = xen_banner,
750         .memory_setup = xen_memory_setup,
751         .arch_setup = xen_arch_setup,
752         .post_allocator_init = xen_post_allocator_init,
753 };
754
755 static const struct pv_time_ops xen_time_ops __initdata = {
756         .time_init = xen_time_init,
757
758         .set_wallclock = xen_set_wallclock,
759         .get_wallclock = xen_get_wallclock,
760         .get_tsc_khz = xen_tsc_khz,
761         .sched_clock = xen_sched_clock,
762 };
763
764 static const struct pv_cpu_ops xen_cpu_ops __initdata = {
765         .cpuid = xen_cpuid,
766
767         .set_debugreg = xen_set_debugreg,
768         .get_debugreg = xen_get_debugreg,
769
770         .clts = xen_clts,
771
772         .read_cr0 = native_read_cr0,
773         .write_cr0 = xen_write_cr0,
774
775         .read_cr4 = native_read_cr4,
776         .read_cr4_safe = native_read_cr4_safe,
777         .write_cr4 = xen_write_cr4,
778
779         .wbinvd = native_wbinvd,
780
781         .read_msr = native_read_msr_safe,
782         .write_msr = xen_write_msr_safe,
783         .read_tsc = native_read_tsc,
784         .read_pmc = native_read_pmc,
785
786         .iret = xen_iret,
787         .irq_enable_sysexit = xen_sysexit,
788 #ifdef CONFIG_X86_64
789         .usergs_sysret32 = xen_sysret32,
790         .usergs_sysret64 = xen_sysret64,
791 #endif
792
793         .load_tr_desc = paravirt_nop,
794         .set_ldt = xen_set_ldt,
795         .load_gdt = xen_load_gdt,
796         .load_idt = xen_load_idt,
797         .load_tls = xen_load_tls,
798 #ifdef CONFIG_X86_64
799         .load_gs_index = xen_load_gs_index,
800 #endif
801
802         .alloc_ldt = xen_alloc_ldt,
803         .free_ldt = xen_free_ldt,
804
805         .store_gdt = native_store_gdt,
806         .store_idt = native_store_idt,
807         .store_tr = xen_store_tr,
808
809         .write_ldt_entry = xen_write_ldt_entry,
810         .write_gdt_entry = xen_write_gdt_entry,
811         .write_idt_entry = xen_write_idt_entry,
812         .load_sp0 = xen_load_sp0,
813
814         .set_iopl_mask = xen_set_iopl_mask,
815         .io_delay = xen_io_delay,
816
817         /* Xen takes care of %gs when switching to usermode for us */
818         .swapgs = paravirt_nop,
819
820         .lazy_mode = {
821                 .enter = paravirt_enter_lazy_cpu,
822                 .leave = xen_leave_lazy,
823         },
824 };
825
826 static const struct pv_apic_ops xen_apic_ops __initdata = {
827 #ifdef CONFIG_X86_LOCAL_APIC
828         .setup_boot_clock = paravirt_nop,
829         .setup_secondary_clock = paravirt_nop,
830         .startup_ipi_hook = paravirt_nop,
831 #endif
832 };
833
834 static void xen_reboot(int reason)
835 {
836         struct sched_shutdown r = { .reason = reason };
837
838 #ifdef CONFIG_SMP
839         smp_send_stop();
840 #endif
841
842         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
843                 BUG();
844 }
845
846 static void xen_restart(char *msg)
847 {
848         xen_reboot(SHUTDOWN_reboot);
849 }
850
851 static void xen_emergency_restart(void)
852 {
853         xen_reboot(SHUTDOWN_reboot);
854 }
855
856 static void xen_machine_halt(void)
857 {
858         xen_reboot(SHUTDOWN_poweroff);
859 }
860
861 static void xen_crash_shutdown(struct pt_regs *regs)
862 {
863         xen_reboot(SHUTDOWN_crash);
864 }
865
866 static const struct machine_ops __initdata xen_machine_ops = {
867         .restart = xen_restart,
868         .halt = xen_machine_halt,
869         .power_off = xen_machine_halt,
870         .shutdown = xen_machine_halt,
871         .crash_shutdown = xen_crash_shutdown,
872         .emergency_restart = xen_emergency_restart,
873 };
874
875
876 /* First C function to be called on Xen boot */
877 asmlinkage void __init xen_start_kernel(void)
878 {
879         pgd_t *pgd;
880
881         if (!xen_start_info)
882                 return;
883
884         xen_domain_type = XEN_PV_DOMAIN;
885
886         BUG_ON(memcmp(xen_start_info->magic, "xen-3", 5) != 0);
887
888         xen_setup_features();
889
890         /* Install Xen paravirt ops */
891         pv_info = xen_info;
892         pv_init_ops = xen_init_ops;
893         pv_time_ops = xen_time_ops;
894         pv_cpu_ops = xen_cpu_ops;
895         pv_apic_ops = xen_apic_ops;
896         pv_mmu_ops = xen_mmu_ops;
897
898         xen_init_irq_ops();
899
900 #ifdef CONFIG_X86_LOCAL_APIC
901         /*
902          * set up the basic apic ops.
903          */
904         set_xen_basic_apic_ops();
905 #endif
906
907         if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
908                 pv_mmu_ops.ptep_modify_prot_start = xen_ptep_modify_prot_start;
909                 pv_mmu_ops.ptep_modify_prot_commit = xen_ptep_modify_prot_commit;
910         }
911
912         machine_ops = xen_machine_ops;
913
914 #ifdef CONFIG_X86_64
915         /*
916          * Setup percpu state.  We only need to do this for 64-bit
917          * because 32-bit already has %fs set properly.
918          */
919         load_percpu_segment(0);
920 #endif
921         /*
922          * The only reliable way to retain the initial address of the
923          * percpu gdt_page is to remember it here, so we can go and
924          * mark it RW later, when the initial percpu area is freed.
925          */
926         xen_initial_gdt = &per_cpu(gdt_page, 0);
927
928         xen_smp_init();
929
930         /* Get mfn list */
931         if (!xen_feature(XENFEAT_auto_translated_physmap))
932                 xen_build_dynamic_phys_to_machine();
933
934         pgd = (pgd_t *)xen_start_info->pt_base;
935
936         /* Prevent unwanted bits from being set in PTEs. */
937         __supported_pte_mask &= ~_PAGE_GLOBAL;
938         if (!xen_initial_domain())
939                 __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
940
941         /* Don't do the full vcpu_info placement stuff until we have a
942            possible map and a non-dummy shared_info. */
943         per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
944
945         local_irq_disable();
946         early_boot_irqs_off();
947
948         xen_raw_console_write("mapping kernel into physical memory\n");
949         pgd = xen_setup_kernel_pagetable(pgd, xen_start_info->nr_pages);
950
951         init_mm.pgd = pgd;
952
953         /* keep using Xen gdt for now; no urgent need to change it */
954
955         pv_info.kernel_rpl = 1;
956         if (xen_feature(XENFEAT_supervisor_mode_kernel))
957                 pv_info.kernel_rpl = 0;
958
959         /* set the limit of our address space */
960         xen_reserve_top();
961
962 #ifdef CONFIG_X86_32
963         /* set up basic CPUID stuff */
964         cpu_detect(&new_cpu_data);
965         new_cpu_data.hard_math = 1;
966         new_cpu_data.x86_capability[0] = cpuid_edx(1);
967 #endif
968
969         /* Poke various useful things into boot_params */
970         boot_params.hdr.type_of_loader = (9 << 4) | 0;
971         boot_params.hdr.ramdisk_image = xen_start_info->mod_start
972                 ? __pa(xen_start_info->mod_start) : 0;
973         boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
974         boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
975
976         if (!xen_initial_domain()) {
977                 add_preferred_console("xenboot", 0, NULL);
978                 add_preferred_console("tty", 0, NULL);
979                 add_preferred_console("hvc", 0, NULL);
980         }
981
982         xen_raw_console_write("about to get started...\n");
983
984         /* Start the world */
985 #ifdef CONFIG_X86_32
986         i386_start_kernel();
987 #else
988         x86_64_start_reservations((char *)__pa_symbol(&boot_params));
989 #endif
990 }