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/kprobes.h>
  24 #include <linux/bootmem.h>
  25 #include <linux/module.h>
  26 #include <linux/mm.h>
  27 #include <linux/page-flags.h>
  28 #include <linux/highmem.h>
  29 #include <linux/console.h>
  30
  31 #include <xen/interface/xen.h>
  32 #include <xen/interface/version.h>
  33 #include <xen/interface/physdev.h>
  34 #include <xen/interface/vcpu.h>
  35 #include <xen/features.h>
  36 #include <xen/page.h>
  37 #include <xen/hvc-console.h>
  38
  39 #include <asm/paravirt.h>
  40 #include <asm/apic.h>
  41 #include <asm/page.h>
  42 #include <asm/xen/hypercall.h>
  43 #include <asm/xen/hypervisor.h>
  44 #include <asm/fixmap.h>
  45 #include <asm/processor.h>
  46 #include <asm/proto.h>
  47 #include <asm/msr-index.h>
  48 #include <asm/traps.h>
  49 #include <asm/setup.h>
  50 #include <asm/desc.h>
  51 #include <asm/pgtable.h>
  52 #include <asm/tlbflush.h>
  53 #include <asm/reboot.h>
  54
  55 #include "xen-ops.h"
  56 #include "mmu.h"
  57 #include "multicalls.h"
  58
  59 EXPORT_SYMBOL_GPL(hypercall_page);
  60
  61 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
  62 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
  63
  64 enum xen_domain_type xen_domain_type = XEN_NATIVE;
  65 EXPORT_SYMBOL_GPL(xen_domain_type);
  66
  67 struct start_info *xen_start_info;
  68 EXPORT_SYMBOL_GPL(xen_start_info);
  69
  70 struct shared_info xen_dummy_shared_info;
  71
  72 void *xen_initial_gdt;
  73
  74 /*
  75  * Point at some empty memory to start with. We map the real shared_info
  76  * page as soon as fixmap is up and running.
  77  */
  78 struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
  79
  80 /*
  81  * Flag to determine whether vcpu info placement is available on all
  82  * VCPUs.  We assume it is to start with, and then set it to zero on
  83  * the first failure.  This is because it can succeed on some VCPUs
  84  * and not others, since it can involve hypervisor memory allocation,
  85  * or because the guest failed to guarantee all the appropriate
  86  * constraints on all VCPUs (ie buffer can't cross a page boundary).
  87  *
  88  * Note that any particular CPU may be using a placed vcpu structure,
  89  * but we can only optimise if the all are.
  90  *
  91  * 0: not available, 1: available
  92  */
  93 static int have_vcpu_info_placement = 1;
  94
  95 static void xen_vcpu_setup(int cpu)
  96 {
  97         struct vcpu_register_vcpu_info info;
  98         int err;
  99         struct vcpu_info *vcpup;
 100
 101         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 102         per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
 103
 104         if (!have_vcpu_info_placement)
 105                 return;         /* already tested, not available */
 106
 107         vcpup = &per_cpu(xen_vcpu_info, cpu);
 108
 109         info.mfn = arbitrary_virt_to_mfn(vcpup);
 110         info.offset = offset_in_page(vcpup);
 111
 112         printk(KERN_DEBUG "trying to map vcpu_info %d at %p, mfn %llx, offset %d\n",
 113                cpu, vcpup, info.mfn, info.offset);
 114
 115         /* Check to see if the hypervisor will put the vcpu_info
 116            structure where we want it, which allows direct access via
 117            a percpu-variable. */
 118         err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, cpu, &info);
 119
 120         if (err) {
 121                 printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err);
 122                 have_vcpu_info_placement = 0;
 123         } else {
 124                 /* This cpu is using the registered vcpu info, even if
 125                    later ones fail to. */
 126                 per_cpu(xen_vcpu, cpu) = vcpup;
 127
 128                 printk(KERN_DEBUG "cpu %d using vcpu_info at %p\n",
 129                        cpu, vcpup);
 130         }
 131 }
 132
 133 /*
 134  * On restore, set the vcpu placement up again.
 135  * If it fails, then we're in a bad state, since
 136  * we can't back out from using it...
 137  */
 138 void xen_vcpu_restore(void)
 139 {
 140         if (have_vcpu_info_placement) {
 141                 int cpu;
 142
 143                 for_each_online_cpu(cpu) {
 144                         bool other_cpu = (cpu != smp_processor_id());
 145
 146                         if (other_cpu &&
 147                             HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL))
 148                                 BUG();
 149
 150                         xen_vcpu_setup(cpu);
 151
 152                         if (other_cpu &&
 153                             HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL))
 154                                 BUG();
 155                 }
 156
 157                 BUG_ON(!have_vcpu_info_placement);
 158         }
 159 }
 160
 161 static void __init xen_banner(void)
 162 {
 163         unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
 164         struct xen_extraversion extra;
 165         HYPERVISOR_xen_version(XENVER_extraversion, &extra);
 166
 167         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
 168                pv_info.name);
 169         printk(KERN_INFO "Xen version: %d.%d%s%s\n",
 170                version >> 16, version & 0xffff, extra.extraversion,
 171                xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
 172 }
 173
 174 static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
 175 static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
 176
 177 static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 178                       unsigned int *cx, unsigned int *dx)
 179 {
 180         unsigned maskecx = ~0;
 181         unsigned maskedx = ~0;
 182
 183         /*
 184          * Mask out inconvenient features, to try and disable as many
 185          * unsupported kernel subsystems as possible.
 186          */
 187         if (*ax == 1) {
 188                 maskecx = cpuid_leaf1_ecx_mask;
 189                 maskedx = cpuid_leaf1_edx_mask;
 190         }
 191
 192         asm(XEN_EMULATE_PREFIX "cpuid"
 193                 : "=a" (*ax),
 194                   "=b" (*bx),
 195                   "=c" (*cx),
 196                   "=d" (*dx)
 197                 : "0" (*ax), "2" (*cx));
 198
 199         *cx &= maskecx;
 200         *dx &= maskedx;
 201 }
 202
 203 static __init void xen_init_cpuid_mask(void)
 204 {
 205         unsigned int ax, bx, cx, dx;
 206
 207         cpuid_leaf1_edx_mask =
 208                 ~((1 << X86_FEATURE_MCE)  |  /* disable MCE */
 209                   (1 << X86_FEATURE_MCA)  |  /* disable MCA */
 210                   (1 << X86_FEATURE_ACC));   /* thermal monitoring */
 211
 212         if (!xen_initial_domain())
 213                 cpuid_leaf1_edx_mask &=
 214                         ~((1 << X86_FEATURE_APIC) |  /* disable local APIC */
 215                           (1 << X86_FEATURE_ACPI));  /* disable ACPI */
 216
 217         ax = 1;
 218         cx = 0;
 219         xen_cpuid(&ax, &bx, &cx, &dx);
 220
 221         /* cpuid claims we support xsave; try enabling it to see what happens */
 222         if (cx & (1 << (X86_FEATURE_XSAVE % 32))) {
 223                 unsigned long cr4;
 224
 225                 set_in_cr4(X86_CR4_OSXSAVE);
 226
 227                 cr4 = read_cr4();
 228
 229                 if ((cr4 & X86_CR4_OSXSAVE) == 0)
 230                         cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_XSAVE % 32));
 231
 232                 clear_in_cr4(X86_CR4_OSXSAVE);
 233         }
 234 }
 235
 236 static void xen_set_debugreg(int reg, unsigned long val)
 237 {
 238         HYPERVISOR_set_debugreg(reg, val);
 239 }
 240
 241 static unsigned long xen_get_debugreg(int reg)
 242 {
 243         return HYPERVISOR_get_debugreg(reg);
 244 }
 245
 246 static void xen_end_context_switch(struct task_struct *next)
 247 {
 248         xen_mc_flush();
 249         paravirt_end_context_switch(next);
 250 }
 251
 252 static unsigned long xen_store_tr(void)
 253 {
 254         return 0;
 255 }
 256
 257 /*
 258  * Set the page permissions for a particular virtual address.  If the
 259  * address is a vmalloc mapping (or other non-linear mapping), then
 260  * find the linear mapping of the page and also set its protections to
 261  * match.
 262  */
 263 static void set_aliased_prot(void *v, pgprot_t prot)
 264 {
 265         int level;
 266         pte_t *ptep;
 267         pte_t pte;
 268         unsigned long pfn;
 269         struct page *page;
 270
 271         ptep = lookup_address((unsigned long)v, &level);
 272         BUG_ON(ptep == NULL);
 273
 274         pfn = pte_pfn(*ptep);
 275         page = pfn_to_page(pfn);
 276
 277         pte = pfn_pte(pfn, prot);
 278
 279         if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
 280                 BUG();
 281
 282         if (!PageHighMem(page)) {
 283                 void *av = __va(PFN_PHYS(pfn));
 284
 285                 if (av != v)
 286                         if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
 287                                 BUG();
 288         } else
 289                 kmap_flush_unused();
 290 }
 291
 292 static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
 293 {
 294         const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
 295         int i;
 296
 297         for(i = 0; i < entries; i += entries_per_page)
 298                 set_aliased_prot(ldt + i, PAGE_KERNEL_RO);
 299 }
 300
 301 static void xen_free_ldt(struct desc_struct *ldt, unsigned entries)
 302 {
 303         const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
 304         int i;
 305
 306         for(i = 0; i < entries; i += entries_per_page)
 307                 set_aliased_prot(ldt + i, PAGE_KERNEL);
 308 }
 309
 310 static void xen_set_ldt(const void *addr, unsigned entries)
 311 {
 312         struct mmuext_op *op;
 313         struct multicall_space mcs = xen_mc_entry(sizeof(*op));
 314
 315         op = mcs.args;
 316         op->cmd = MMUEXT_SET_LDT;
 317         op->arg1.linear_addr = (unsigned long)addr;
 318         op->arg2.nr_ents = entries;
 319
 320         MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
 321
 322         xen_mc_issue(PARAVIRT_LAZY_CPU);
 323 }
 324
 325 static void xen_load_gdt(const struct desc_ptr *dtr)
 326 {
 327         unsigned long va = dtr->address;
 328         unsigned int size = dtr->size + 1;
 329         unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
 330         unsigned long frames[pages];
 331         int f;
 332
 333         /* A GDT can be up to 64k in size, which corresponds to 8192
 334            8-byte entries, or 16 4k pages.. */
 335
 336         BUG_ON(size > 65536);
 337         BUG_ON(va & ~PAGE_MASK);
 338
 339         for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
 340                 int level;
 341                 pte_t *ptep = lookup_address(va, &level);
 342                 unsigned long pfn, mfn;
 343                 void *virt;
 344
 345                 BUG_ON(ptep == NULL);
 346
 347                 pfn = pte_pfn(*ptep);
 348                 mfn = pfn_to_mfn(pfn);
 349                 virt = __va(PFN_PHYS(pfn));
 350
 351                 frames[f] = mfn;
 352
 353                 make_lowmem_page_readonly((void *)va);
 354                 make_lowmem_page_readonly(virt);
 355         }
 356
 357         if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
 358                 BUG();
 359 }
 360
 361 static void load_TLS_descriptor(struct thread_struct *t,
 362                                 unsigned int cpu, unsigned int i)
 363 {
 364         struct desc_struct *gdt = get_cpu_gdt_table(cpu);
 365         xmaddr_t maddr = arbitrary_virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]);
 366         struct multicall_space mc = __xen_mc_entry(0);
 367
 368         MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]);
 369 }
 370
 371 static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
 372 {
 373         /*
 374          * XXX sleazy hack: If we're being called in a lazy-cpu zone
 375          * and lazy gs handling is enabled, it means we're in a
 376          * context switch, and %gs has just been saved.  This means we
 377          * can zero it out to prevent faults on exit from the
 378          * hypervisor if the next process has no %gs.  Either way, it
 379          * has been saved, and the new value will get loaded properly.
 380          * This will go away as soon as Xen has been modified to not
 381          * save/restore %gs for normal hypercalls.
 382          *
 383          * On x86_64, this hack is not used for %gs, because gs points
 384          * to KERNEL_GS_BASE (and uses it for PDA references), so we
 385          * must not zero %gs on x86_64
 386          *
 387          * For x86_64, we need to zero %fs, otherwise we may get an
 388          * exception between the new %fs descriptor being loaded and
 389          * %fs being effectively cleared at __switch_to().
 390          */
 391         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
 392 #ifdef CONFIG_X86_32
 393                 lazy_load_gs(0);
 394 #else
 395                 loadsegment(fs, 0);
 396 #endif
 397         }
 398
 399         xen_mc_batch();
 400
 401         load_TLS_descriptor(t, cpu, 0);
 402         load_TLS_descriptor(t, cpu, 1);
 403         load_TLS_descriptor(t, cpu, 2);
 404
 405         xen_mc_issue(PARAVIRT_LAZY_CPU);
 406 }
 407
 408 #ifdef CONFIG_X86_64
 409 static void xen_load_gs_index(unsigned int idx)
 410 {
 411         if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx))
 412                 BUG();
 413 }
 414 #endif
 415
 416 static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
 417                                 const void *ptr)
 418 {
 419         xmaddr_t mach_lp = arbitrary_virt_to_machine(&dt[entrynum]);
 420         u64 entry = *(u64 *)ptr;
 421
 422         preempt_disable();
 423
 424         xen_mc_flush();
 425         if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry))
 426                 BUG();
 427
 428         preempt_enable();
 429 }
 430
 431 static int cvt_gate_to_trap(int vector, const gate_desc *val,
 432                             struct trap_info *info)
 433 {
 434         unsigned long addr;
 435
 436         if (val->type != GATE_TRAP && val->type != GATE_INTERRUPT)
 437                 return 0;
 438
 439         info->vector = vector;
 440
 441         addr = gate_offset(*val);
 442 #ifdef CONFIG_X86_64
 443         /*
 444          * Look for known traps using IST, and substitute them
 445          * appropriately.  The debugger ones are the only ones we care
 446          * about.  Xen will handle faults like double_fault and
 447          * machine_check, so we should never see them.  Warn if
 448          * there's an unexpected IST-using fault handler.
 449          */
 450         if (addr == (unsigned long)debug)
 451                 addr = (unsigned long)xen_debug;
 452         else if (addr == (unsigned long)int3)
 453                 addr = (unsigned long)xen_int3;
 454         else if (addr == (unsigned long)stack_segment)
 455                 addr = (unsigned long)xen_stack_segment;
 456         else if (addr == (unsigned long)double_fault ||
 457                  addr == (unsigned long)nmi) {
 458                 /* Don't need to handle these */
 459                 return 0;
 460 #ifdef CONFIG_X86_MCE
 461         } else if (addr == (unsigned long)machine_check) {
 462                 return 0;
 463 #endif
 464         } else {
 465                 /* Some other trap using IST? */
 466                 if (WARN_ON(val->ist != 0))
 467                         return 0;
 468         }
 469 #endif  /* CONFIG_X86_64 */
 470         info->address = addr;
 471
 472         info->cs = gate_segment(*val);
 473         info->flags = val->dpl;
 474         /* interrupt gates clear IF */
 475         if (val->type == GATE_INTERRUPT)
 476                 info->flags |= 1 << 2;
 477
 478         return 1;
 479 }
 480
 481 /* Locations of each CPU's IDT */
 482 static DEFINE_PER_CPU(struct desc_ptr, idt_desc);
 483
 484 /* Set an IDT entry.  If the entry is part of the current IDT, then
 485    also update Xen. */
 486 static void xen_write_idt_entry(gate_desc *dt, int entrynum, const gate_desc *g)
 487 {
 488         unsigned long p = (unsigned long)&dt[entrynum];
 489         unsigned long start, end;
 490
 491         preempt_disable();
 492
 493         start = __get_cpu_var(idt_desc).address;
 494         end = start + __get_cpu_var(idt_desc).size + 1;
 495
 496         xen_mc_flush();
 497
 498         native_write_idt_entry(dt, entrynum, g);
 499
 500         if (p >= start && (p + 8) <= end) {
 501                 struct trap_info info[2];
 502
 503                 info[1].address = 0;
 504
 505                 if (cvt_gate_to_trap(entrynum, g, &info[0]))
 506                         if (HYPERVISOR_set_trap_table(info))
 507                                 BUG();
 508         }
 509
 510         preempt_enable();
 511 }
 512
 513 static void xen_convert_trap_info(const struct desc_ptr *desc,
 514                                   struct trap_info *traps)
 515 {
 516         unsigned in, out, count;
 517
 518         count = (desc->size+1) / sizeof(gate_desc);
 519         BUG_ON(count > 256);
 520
 521         for (in = out = 0; in < count; in++) {
 522                 gate_desc *entry = (gate_desc*)(desc->address) + in;
 523
 524                 if (cvt_gate_to_trap(in, entry, &traps[out]))
 525                         out++;
 526         }
 527         traps[out].address = 0;
 528 }
 529
 530 void xen_copy_trap_info(struct trap_info *traps)
 531 {
 532         const struct desc_ptr *desc = &__get_cpu_var(idt_desc);
 533
 534         xen_convert_trap_info(desc, traps);
 535 }
 536
 537 /* Load a new IDT into Xen.  In principle this can be per-CPU, so we
 538    hold a spinlock to protect the static traps[] array (static because
 539    it avoids allocation, and saves stack space). */
 540 static void xen_load_idt(const struct desc_ptr *desc)
 541 {
 542         static DEFINE_SPINLOCK(lock);
 543         static struct trap_info traps[257];
 544
 545         spin_lock(&lock);
 546
 547         __get_cpu_var(idt_desc) = *desc;
 548
 549         xen_convert_trap_info(desc, traps);
 550
 551         xen_mc_flush();
 552         if (HYPERVISOR_set_trap_table(traps))
 553                 BUG();
 554
 555         spin_unlock(&lock);
 556 }
 557
 558 /* Write a GDT descriptor entry.  Ignore LDT descriptors, since
 559    they're handled differently. */
 560 static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
 561                                 const void *desc, int type)
 562 {
 563         preempt_disable();
 564
 565         switch (type) {
 566         case DESC_LDT:
 567         case DESC_TSS:
 568                 /* ignore */
 569                 break;
 570
 571         default: {
 572                 xmaddr_t maddr = arbitrary_virt_to_machine(&dt[entry]);
 573
 574                 xen_mc_flush();
 575                 if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
 576                         BUG();
 577         }
 578
 579         }
 580
 581         preempt_enable();
 582 }
 583
 584 static void xen_load_sp0(struct tss_struct *tss,
 585                          struct thread_struct *thread)
 586 {
 587         struct multicall_space mcs = xen_mc_entry(0);
 588         MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0);
 589         xen_mc_issue(PARAVIRT_LAZY_CPU);
 590 }
 591
 592 static void xen_set_iopl_mask(unsigned mask)
 593 {
 594         struct physdev_set_iopl set_iopl;
 595
 596         /* Force the change at ring 0. */
 597         set_iopl.iopl = (mask == 0) ? 1 : (mask >> 12) & 3;
 598         HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
 599 }
 600
 601 static void xen_io_delay(void)
 602 {
 603 }
 604
 605 #ifdef CONFIG_X86_LOCAL_APIC
 606 static u32 xen_apic_read(u32 reg)
 607 {
 608         return 0;
 609 }
 610
 611 static void xen_apic_write(u32 reg, u32 val)
 612 {
 613         /* Warn to see if there's any stray references */
 614         WARN_ON(1);
 615 }
 616
 617 static u64 xen_apic_icr_read(void)
 618 {
 619         return 0;
 620 }
 621
 622 static void xen_apic_icr_write(u32 low, u32 id)
 623 {
 624         /* Warn to see if there's any stray references */
 625         WARN_ON(1);
 626 }
 627
 628 static void xen_apic_wait_icr_idle(void)
 629 {
 630         return;
 631 }
 632
 633 static u32 xen_safe_apic_wait_icr_idle(void)
 634 {
 635         return 0;
 636 }
 637
 638 static void set_xen_basic_apic_ops(void)
 639 {
 640         apic->read = xen_apic_read;
 641         apic->write = xen_apic_write;
 642         apic->icr_read = xen_apic_icr_read;
 643         apic->icr_write = xen_apic_icr_write;
 644         apic->wait_icr_idle = xen_apic_wait_icr_idle;
 645         apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
 646 }
 647
 648 #endif
 649
 650
 651 static void xen_clts(void)
 652 {
 653         struct multicall_space mcs;
 654
 655         mcs = xen_mc_entry(0);
 656
 657         MULTI_fpu_taskswitch(mcs.mc, 0);
 658
 659         xen_mc_issue(PARAVIRT_LAZY_CPU);
 660 }
 661
 662 static DEFINE_PER_CPU(unsigned long, xen_cr0_value);
 663
 664 static unsigned long xen_read_cr0(void)
 665 {
 666         unsigned long cr0 = percpu_read(xen_cr0_value);
 667
 668         if (unlikely(cr0 == 0)) {
 669                 cr0 = native_read_cr0();
 670                 percpu_write(xen_cr0_value, cr0);
 671         }
 672
 673         return cr0;
 674 }
 675
 676 static void xen_write_cr0(unsigned long cr0)
 677 {
 678         struct multicall_space mcs;
 679
 680         percpu_write(xen_cr0_value, cr0);
 681
 682         /* Only pay attention to cr0.TS; everything else is
 683            ignored. */
 684         mcs = xen_mc_entry(0);
 685
 686         MULTI_fpu_taskswitch(mcs.mc, (cr0 & X86_CR0_TS) != 0);
 687
 688         xen_mc_issue(PARAVIRT_LAZY_CPU);
 689 }
 690
 691 static void xen_write_cr4(unsigned long cr4)
 692 {
 693         cr4 &= ~X86_CR4_PGE;
 694         cr4 &= ~X86_CR4_PSE;
 695
 696         native_write_cr4(cr4);
 697 }
 698
 699 static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
 700 {
 701         int ret;
 702
 703         ret = 0;
 704
 705         switch (msr) {
 706 #ifdef CONFIG_X86_64
 707                 unsigned which;
 708                 u64 base;
 709
 710         case MSR_FS_BASE:               which = SEGBASE_FS; goto set;
 711         case MSR_KERNEL_GS_BASE:        which = SEGBASE_GS_USER; goto set;
 712         case MSR_GS_BASE:               which = SEGBASE_GS_KERNEL; goto set;
 713
 714         set:
 715                 base = ((u64)high << 32) | low;
 716                 if (HYPERVISOR_set_segment_base(which, base) != 0)
 717                         ret = -EFAULT;
 718                 break;
 719 #endif
 720
 721         case MSR_STAR:
 722         case MSR_CSTAR:
 723         case MSR_LSTAR:
 724         case MSR_SYSCALL_MASK:
 725         case MSR_IA32_SYSENTER_CS:
 726         case MSR_IA32_SYSENTER_ESP:
 727         case MSR_IA32_SYSENTER_EIP:
 728                 /* Fast syscall setup is all done in hypercalls, so
 729                    these are all ignored.  Stub them out here to stop
 730                    Xen console noise. */
 731                 break;
 732
 733         default:
 734                 ret = native_write_msr_safe(msr, low, high);
 735         }
 736
 737         return ret;
 738 }
 739
 740 void xen_setup_shared_info(void)
 741 {
 742         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 743                 set_fixmap(FIX_PARAVIRT_BOOTMAP,
 744                            xen_start_info->shared_info);
 745
 746                 HYPERVISOR_shared_info =
 747                         (struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
 748         } else
 749                 HYPERVISOR_shared_info =
 750                         (struct shared_info *)__va(xen_start_info->shared_info);
 751
 752 #ifndef CONFIG_SMP
 753         /* In UP this is as good a place as any to set up shared info */
 754         xen_setup_vcpu_info_placement();
 755 #endif
 756
 757         xen_setup_mfn_list_list();
 758 }
 759
 760 /* This is called once we have the cpu_possible_map */
 761 void xen_setup_vcpu_info_placement(void)
 762 {
 763         int cpu;
 764
 765         for_each_possible_cpu(cpu)
 766                 xen_vcpu_setup(cpu);
 767
 768         /* xen_vcpu_setup managed to place the vcpu_info within the
 769            percpu area for all cpus, so make use of it */
 770         if (have_vcpu_info_placement) {
 771                 printk(KERN_INFO "Xen: using vcpu_info placement\n");
 772
 773                 pv_irq_ops.save_fl = __PV_IS_CALLEE_SAVE(xen_save_fl_direct);
 774                 pv_irq_ops.restore_fl = __PV_IS_CALLEE_SAVE(xen_restore_fl_direct);
 775                 pv_irq_ops.irq_disable = __PV_IS_CALLEE_SAVE(xen_irq_disable_direct);
 776                 pv_irq_ops.irq_enable = __PV_IS_CALLEE_SAVE(xen_irq_enable_direct);
 777                 pv_mmu_ops.read_cr2 = xen_read_cr2_direct;
 778         }
 779 }
 780
 781 static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
 782                           unsigned long addr, unsigned len)
 783 {
 784         char *start, *end, *reloc;
 785         unsigned ret;
 786
 787         start = end = reloc = NULL;
 788
 789 #define SITE(op, x)                                                     \
 790         case PARAVIRT_PATCH(op.x):                                      \
 791         if (have_vcpu_info_placement) {                                 \
 792                 start = (char *)xen_##x##_direct;                       \
 793                 end = xen_##x##_direct_end;                             \
 794                 reloc = xen_##x##_direct_reloc;                         \
 795         }                                                               \
 796         goto patch_site
 797
 798         switch (type) {
 799                 SITE(pv_irq_ops, irq_enable);
 800                 SITE(pv_irq_ops, irq_disable);
 801                 SITE(pv_irq_ops, save_fl);
 802                 SITE(pv_irq_ops, restore_fl);
 803 #undef SITE
 804
 805         patch_site:
 806                 if (start == NULL || (end-start) > len)
 807                         goto default_patch;
 808
 809                 ret = paravirt_patch_insns(insnbuf, len, start, end);
 810
 811                 /* Note: because reloc is assigned from something that
 812                    appears to be an array, gcc assumes it's non-null,
 813                    but doesn't know its relationship with start and
 814                    end. */
 815                 if (reloc > start && reloc < end) {
 816                         int reloc_off = reloc - start;
 817                         long *relocp = (long *)(insnbuf + reloc_off);
 818                         long delta = start - (char *)addr;
 819
 820                         *relocp += delta;
 821                 }
 822                 break;
 823
 824         default_patch:
 825         default:
 826                 ret = paravirt_patch_default(type, clobbers, insnbuf,
 827                                              addr, len);
 828                 break;
 829         }
 830
 831         return ret;
 832 }
 833
 834 static const struct pv_info xen_info __initdata = {
 835         .paravirt_enabled = 1,
 836         .shared_kernel_pmd = 0,
 837
 838         .name = "Xen",
 839 };
 840
 841 static const struct pv_init_ops xen_init_ops __initdata = {
 842         .patch = xen_patch,
 843
 844         .banner = xen_banner,
 845         .memory_setup = xen_memory_setup,
 846         .arch_setup = xen_arch_setup,
 847         .post_allocator_init = xen_post_allocator_init,
 848 };
 849
 850 static const struct pv_time_ops xen_time_ops __initdata = {
 851         .time_init = xen_time_init,
 852
 853         .set_wallclock = xen_set_wallclock,
 854         .get_wallclock = xen_get_wallclock,
 855         .get_tsc_khz = xen_tsc_khz,
 856         .sched_clock = xen_sched_clock,
 857 };
 858
 859 static const struct pv_cpu_ops xen_cpu_ops __initdata = {
 860         .cpuid = xen_cpuid,
 861
 862         .set_debugreg = xen_set_debugreg,
 863         .get_debugreg = xen_get_debugreg,
 864
 865         .clts = xen_clts,
 866
 867         .read_cr0 = xen_read_cr0,
 868         .write_cr0 = xen_write_cr0,
 869
 870         .read_cr4 = native_read_cr4,
 871         .read_cr4_safe = native_read_cr4_safe,
 872         .write_cr4 = xen_write_cr4,
 873
 874         .wbinvd = native_wbinvd,
 875
 876         .read_msr = native_read_msr_safe,
 877         .write_msr = xen_write_msr_safe,
 878         .read_tsc = native_read_tsc,
 879         .read_pmc = native_read_pmc,
 880
 881         .iret = xen_iret,
 882         .irq_enable_sysexit = xen_sysexit,
 883 #ifdef CONFIG_X86_64
 884         .usergs_sysret32 = xen_sysret32,
 885         .usergs_sysret64 = xen_sysret64,
 886 #endif
 887
 888         .load_tr_desc = paravirt_nop,
 889         .set_ldt = xen_set_ldt,
 890         .load_gdt = xen_load_gdt,
 891         .load_idt = xen_load_idt,
 892         .load_tls = xen_load_tls,
 893 #ifdef CONFIG_X86_64
 894         .load_gs_index = xen_load_gs_index,
 895 #endif
 896
 897         .alloc_ldt = xen_alloc_ldt,
 898         .free_ldt = xen_free_ldt,
 899
 900         .store_gdt = native_store_gdt,
 901         .store_idt = native_store_idt,
 902         .store_tr = xen_store_tr,
 903
 904         .write_ldt_entry = xen_write_ldt_entry,
 905         .write_gdt_entry = xen_write_gdt_entry,
 906         .write_idt_entry = xen_write_idt_entry,
 907         .load_sp0 = xen_load_sp0,
 908
 909         .set_iopl_mask = xen_set_iopl_mask,
 910         .io_delay = xen_io_delay,
 911
 912         /* Xen takes care of %gs when switching to usermode for us */
 913         .swapgs = paravirt_nop,
 914
 915         .start_context_switch = paravirt_start_context_switch,
 916         .end_context_switch = xen_end_context_switch,
 917 };
 918
 919 static const struct pv_apic_ops xen_apic_ops __initdata = {
 920 #ifdef CONFIG_X86_LOCAL_APIC
 921         .setup_boot_clock = paravirt_nop,
 922         .setup_secondary_clock = paravirt_nop,
 923         .startup_ipi_hook = paravirt_nop,
 924 #endif
 925 };
 926
 927 static void xen_reboot(int reason)
 928 {
 929         struct sched_shutdown r = { .reason = reason };
 930
 931 #ifdef CONFIG_SMP
 932         smp_send_stop();
 933 #endif
 934
 935         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
 936                 BUG();
 937 }
 938
 939 static void xen_restart(char *msg)
 940 {
 941         xen_reboot(SHUTDOWN_reboot);
 942 }
 943
 944 static void xen_emergency_restart(void)
 945 {
 946         xen_reboot(SHUTDOWN_reboot);
 947 }
 948
 949 static void xen_machine_halt(void)
 950 {
 951         xen_reboot(SHUTDOWN_poweroff);
 952 }
 953
 954 static void xen_crash_shutdown(struct pt_regs *regs)
 955 {
 956         xen_reboot(SHUTDOWN_crash);
 957 }
 958
 959 static const struct machine_ops __initdata xen_machine_ops = {
 960         .restart = xen_restart,
 961         .halt = xen_machine_halt,
 962         .power_off = xen_machine_halt,
 963         .shutdown = xen_machine_halt,
 964         .crash_shutdown = xen_crash_shutdown,
 965         .emergency_restart = xen_emergency_restart,
 966 };
 967
 968 /* First C function to be called on Xen boot */
 969 asmlinkage void __init xen_start_kernel(void)
 970 {
 971         pgd_t *pgd;
 972
 973         if (!xen_start_info)
 974                 return;
 975
 976         xen_domain_type = XEN_PV_DOMAIN;
 977
 978         /* Install Xen paravirt ops */
 979         pv_info = xen_info;
 980         pv_init_ops = xen_init_ops;
 981         pv_time_ops = xen_time_ops;
 982         pv_cpu_ops = xen_cpu_ops;
 983         pv_apic_ops = xen_apic_ops;
 984         pv_mmu_ops = xen_mmu_ops;
 985
 986 #ifdef CONFIG_X86_64
 987         /*
 988          * Setup percpu state.  We only need to do this for 64-bit
 989          * because 32-bit already has %fs set properly.
 990          */
 991         load_percpu_segment(0);
 992 #endif
 993
 994         xen_init_irq_ops();
 995         xen_init_cpuid_mask();
 996
 997 #ifdef CONFIG_X86_LOCAL_APIC
 998         /*
 999          * set up the basic apic ops.
1000          */
1001         set_xen_basic_apic_ops();
1002 #endif
1003
1004         xen_setup_features();
1005
1006         if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
1007                 pv_mmu_ops.ptep_modify_prot_start = xen_ptep_modify_prot_start;
1008                 pv_mmu_ops.ptep_modify_prot_commit = xen_ptep_modify_prot_commit;
1009         }
1010
1011         machine_ops = xen_machine_ops;
1012
1013         /*
1014          * The only reliable way to retain the initial address of the
1015          * percpu gdt_page is to remember it here, so we can go and
1016          * mark it RW later, when the initial percpu area is freed.
1017          */
1018         xen_initial_gdt = &per_cpu(gdt_page, 0);
1019
1020         xen_smp_init();
1021
1022         /* Get mfn list */
1023         if (!xen_feature(XENFEAT_auto_translated_physmap))
1024                 xen_build_dynamic_phys_to_machine();
1025
1026         pgd = (pgd_t *)xen_start_info->pt_base;
1027
1028         /* Prevent unwanted bits from being set in PTEs. */
1029         __supported_pte_mask &= ~_PAGE_GLOBAL;
1030         if (!xen_initial_domain())
1031                 __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
1032
1033 #ifdef CONFIG_X86_64
1034         /* Work out if we support NX */
1035         check_efer();
1036 #endif
1037
1038         /* Don't do the full vcpu_info placement stuff until we have a
1039            possible map and a non-dummy shared_info. */
1040         per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
1041
1042         local_irq_disable();
1043         early_boot_irqs_off();
1044
1045         xen_raw_console_write("mapping kernel into physical memory\n");
1046         pgd = xen_setup_kernel_pagetable(pgd, xen_start_info->nr_pages);
1047
1048         init_mm.pgd = pgd;
1049
1050         /* keep using Xen gdt for now; no urgent need to change it */
1051
1052         pv_info.kernel_rpl = 1;
1053         if (xen_feature(XENFEAT_supervisor_mode_kernel))
1054                 pv_info.kernel_rpl = 0;
1055
1056         /* set the limit of our address space */
1057         xen_reserve_top();
1058
1059 #ifdef CONFIG_X86_32
1060         /* set up basic CPUID stuff */
1061         cpu_detect(&new_cpu_data);
1062         new_cpu_data.hard_math = 1;
1063         new_cpu_data.wp_works_ok = 1;
1064         new_cpu_data.x86_capability[0] = cpuid_edx(1);
1065 #endif
1066
1067         /* Poke various useful things into boot_params */
1068         boot_params.hdr.type_of_loader = (9 << 4) | 0;
1069         boot_params.hdr.ramdisk_image = xen_start_info->mod_start
1070                 ? __pa(xen_start_info->mod_start) : 0;
1071         boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
1072         boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
1073
1074         if (!xen_initial_domain()) {
1075                 add_preferred_console("xenboot", 0, NULL);
1076                 add_preferred_console("tty", 0, NULL);
1077                 add_preferred_console("hvc", 0, NULL);
1078         }
1079
1080         xen_raw_console_write("about to get started...\n");
1081
1082         /* Start the world */
1083 #ifdef CONFIG_X86_32
1084         i386_start_kernel();
1085 #else
1086         x86_64_start_reservations((char *)__pa_symbol(&boot_params));
1087 #endif
1088 }