arch/x86/kernel/paravirt.c

   1 /*  Paravirtualization interfaces
   2     Copyright (C) 2006 Rusty Russell IBM Corporation
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17
  18     2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
  19 */
  20
  21 #include <linux/errno.h>
  22 #include <linux/module.h>
  23 #include <linux/efi.h>
  24 #include <linux/bcd.h>
  25 #include <linux/highmem.h>
  26 #include <linux/kprobes.h>
  27
  28 #include <asm/bug.h>
  29 #include <asm/paravirt.h>
  30 #include <asm/debugreg.h>
  31 #include <asm/desc.h>
  32 #include <asm/setup.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/time.h>
  35 #include <asm/pgalloc.h>
  36 #include <asm/irq.h>
  37 #include <asm/delay.h>
  38 #include <asm/fixmap.h>
  39 #include <asm/apic.h>
  40 #include <asm/tlbflush.h>
  41 #include <asm/timer.h>
  42 #include <asm/special_insns.h>
  43
  44 /*
  45  * nop stub, which must not clobber anything *including the stack* to
  46  * avoid confusing the entry prologues.
  47  */
  48 extern void _paravirt_nop(void);
  49 asm (".pushsection .entry.text, \"ax\"\n"
  50      ".global _paravirt_nop\n"
  51      "_paravirt_nop:\n\t"
  52      "ret\n\t"
  53      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  54      ".type _paravirt_nop, @function\n\t"
  55      ".popsection");
  56
  57 /* identity function, which can be inlined */
  58 u32 notrace _paravirt_ident_32(u32 x)
  59 {
  60         return x;
  61 }
  62
  63 u64 notrace _paravirt_ident_64(u64 x)
  64 {
  65         return x;
  66 }
  67
  68 void __init default_banner(void)
  69 {
  70         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  71                pv_info.name);
  72 }
  73
  74 /* Undefined instruction for dealing with missing ops pointers. */
  75 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  76
  77 unsigned paravirt_patch_nop(void)
  78 {
  79         return 0;
  80 }
  81
  82 unsigned paravirt_patch_ignore(unsigned len)
  83 {
  84         return len;
  85 }
  86
  87 struct branch {
  88         unsigned char opcode;
  89         u32 delta;
  90 } __attribute__((packed));
  91
  92 unsigned paravirt_patch_call(void *insnbuf,
  93                              const void *target, u16 tgt_clobbers,
  94                              unsigned long addr, u16 site_clobbers,
  95                              unsigned len)
  96 {
  97         struct branch *b = insnbuf;
  98         unsigned long delta = (unsigned long)target - (addr+5);
  99
 100         if (len < 5) {
 101 #ifdef CONFIG_RETPOLINE
 102                 WARN_ONCE("Failing to patch indirect CALL in %ps\n", (void *)addr);
 103 #endif
 104                 return len;     /* call too long for patch site */
 105         }
 106
 107         b->opcode = 0xe8; /* call */
 108         b->delta = delta;
 109         BUILD_BUG_ON(sizeof(*b) != 5);
 110
 111         return 5;
 112 }
 113
 114 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 115                             unsigned long addr, unsigned len)
 116 {
 117         struct branch *b = insnbuf;
 118         unsigned long delta = (unsigned long)target - (addr+5);
 119
 120         if (len < 5) {
 121 #ifdef CONFIG_RETPOLINE
 122                 WARN_ONCE("Failing to patch indirect JMP in %ps\n", (void *)addr);
 123 #endif
 124                 return len;     /* call too long for patch site */
 125         }
 126
 127         b->opcode = 0xe9;       /* jmp */
 128         b->delta = delta;
 129
 130         return 5;
 131 }
 132
 133 /* Neat trick to map patch type back to the call within the
 134  * corresponding structure. */
 135 static void *get_call_destination(u8 type)
 136 {
 137         struct paravirt_patch_template tmpl = {
 138                 .pv_init_ops = pv_init_ops,
 139                 .pv_time_ops = pv_time_ops,
 140                 .pv_cpu_ops = pv_cpu_ops,
 141                 .pv_irq_ops = pv_irq_ops,
 142                 .pv_apic_ops = pv_apic_ops,
 143                 .pv_mmu_ops = pv_mmu_ops,
 144 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 145                 .pv_lock_ops = pv_lock_ops,
 146 #endif
 147         };
 148         return *((void **)&tmpl + type);
 149 }
 150
 151 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 152                                 unsigned long addr, unsigned len)
 153 {
 154         void *opfunc = get_call_destination(type);
 155         unsigned ret;
 156
 157         if (opfunc == NULL)
 158                 /* If there's no function, patch it with a ud2a (BUG) */
 159                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 160         else if (opfunc == _paravirt_nop)
 161                 /* If the operation is a nop, then nop the callsite */
 162                 ret = paravirt_patch_nop();
 163
 164         /* identity functions just return their single argument */
 165         else if (opfunc == _paravirt_ident_32)
 166                 ret = paravirt_patch_ident_32(insnbuf, len);
 167         else if (opfunc == _paravirt_ident_64)
 168                 ret = paravirt_patch_ident_64(insnbuf, len);
 169
 170         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 171                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
 172                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
 173                 /* If operation requires a jmp, then jmp */
 174                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 175         else
 176                 /* Otherwise call the function; assume target could
 177                    clobber any caller-save reg */
 178                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
 179                                           addr, clobbers, len);
 180
 181         return ret;
 182 }
 183
 184 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 185                               const char *start, const char *end)
 186 {
 187         unsigned insn_len = end - start;
 188
 189         if (insn_len > len || start == NULL)
 190                 insn_len = len;
 191         else
 192                 memcpy(insnbuf, start, insn_len);
 193
 194         return insn_len;
 195 }
 196
 197 static void native_flush_tlb(void)
 198 {
 199         __native_flush_tlb();
 200 }
 201
 202 /*
 203  * Global pages have to be flushed a bit differently. Not a real
 204  * performance problem because this does not happen often.
 205  */
 206 static void native_flush_tlb_global(void)
 207 {
 208         __native_flush_tlb_global();
 209 }
 210
 211 static void native_flush_tlb_single(unsigned long addr)
 212 {
 213         __native_flush_tlb_single(addr);
 214 }
 215
 216 struct static_key paravirt_steal_enabled;
 217 struct static_key paravirt_steal_rq_enabled;
 218
 219 static u64 native_steal_clock(int cpu)
 220 {
 221         return 0;
 222 }
 223
 224 /* These are in entry.S */
 225 extern void native_iret(void);
 226 extern void native_usergs_sysret32(void);
 227 extern void native_usergs_sysret64(void);
 228
 229 static struct resource reserve_ioports = {
 230         .start = 0,
 231         .end = IO_SPACE_LIMIT,
 232         .name = "paravirt-ioport",
 233         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 234 };
 235
 236 /*
 237  * Reserve the whole legacy IO space to prevent any legacy drivers
 238  * from wasting time probing for their hardware.  This is a fairly
 239  * brute-force approach to disabling all non-virtual drivers.
 240  *
 241  * Note that this must be called very early to have any effect.
 242  */
 243 int paravirt_disable_iospace(void)
 244 {
 245         return request_resource(&ioport_resource, &reserve_ioports);
 246 }
 247
 248 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 249
 250 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 251 {
 252         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 253
 254         this_cpu_write(paravirt_lazy_mode, mode);
 255 }
 256
 257 static void leave_lazy(enum paravirt_lazy_mode mode)
 258 {
 259         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 260
 261         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 262 }
 263
 264 void paravirt_enter_lazy_mmu(void)
 265 {
 266         enter_lazy(PARAVIRT_LAZY_MMU);
 267 }
 268
 269 void paravirt_leave_lazy_mmu(void)
 270 {
 271         leave_lazy(PARAVIRT_LAZY_MMU);
 272 }
 273
 274 void paravirt_flush_lazy_mmu(void)
 275 {
 276         preempt_disable();
 277
 278         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 279                 arch_leave_lazy_mmu_mode();
 280                 arch_enter_lazy_mmu_mode();
 281         }
 282
 283         preempt_enable();
 284 }
 285
 286 void paravirt_start_context_switch(struct task_struct *prev)
 287 {
 288         BUG_ON(preemptible());
 289
 290         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 291                 arch_leave_lazy_mmu_mode();
 292                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 293         }
 294         enter_lazy(PARAVIRT_LAZY_CPU);
 295 }
 296
 297 void paravirt_end_context_switch(struct task_struct *next)
 298 {
 299         BUG_ON(preemptible());
 300
 301         leave_lazy(PARAVIRT_LAZY_CPU);
 302
 303         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 304                 arch_enter_lazy_mmu_mode();
 305 }
 306
 307 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 308 {
 309         if (in_interrupt())
 310                 return PARAVIRT_LAZY_NONE;
 311
 312         return this_cpu_read(paravirt_lazy_mode);
 313 }
 314
 315 struct pv_info pv_info = {
 316         .name = "bare hardware",
 317         .paravirt_enabled = 0,
 318         .kernel_rpl = 0,
 319         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 320
 321 #ifdef CONFIG_X86_64
 322         .extra_user_64bit_cs = __USER_CS,
 323 #endif
 324 };
 325
 326 struct pv_init_ops pv_init_ops = {
 327         .patch = native_patch,
 328 };
 329
 330 struct pv_time_ops pv_time_ops = {
 331         .sched_clock = native_sched_clock,
 332         .steal_clock = native_steal_clock,
 333 };
 334
 335 __visible struct pv_irq_ops pv_irq_ops = {
 336         .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
 337         .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
 338         .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
 339         .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
 340         .safe_halt = native_safe_halt,
 341         .halt = native_halt,
 342 #ifdef CONFIG_X86_64
 343         .adjust_exception_frame = paravirt_nop,
 344 #endif
 345 };
 346
 347 __visible struct pv_cpu_ops pv_cpu_ops = {
 348         .cpuid = native_cpuid,
 349         .get_debugreg = native_get_debugreg,
 350         .set_debugreg = native_set_debugreg,
 351         .clts = native_clts,
 352         .read_cr0 = native_read_cr0,
 353         .write_cr0 = native_write_cr0,
 354         .read_cr4 = native_read_cr4,
 355         .read_cr4_safe = native_read_cr4_safe,
 356         .write_cr4 = native_write_cr4,
 357 #ifdef CONFIG_X86_64
 358         .read_cr8 = native_read_cr8,
 359         .write_cr8 = native_write_cr8,
 360 #endif
 361         .wbinvd = native_wbinvd,
 362         .read_msr = native_read_msr_safe,
 363         .write_msr = native_write_msr_safe,
 364         .read_pmc = native_read_pmc,
 365         .load_tr_desc = native_load_tr_desc,
 366         .set_ldt = native_set_ldt,
 367         .load_gdt = native_load_gdt,
 368         .load_idt = native_load_idt,
 369         .store_idt = native_store_idt,
 370         .store_tr = native_store_tr,
 371         .load_tls = native_load_tls,
 372 #ifdef CONFIG_X86_64
 373         .load_gs_index = native_load_gs_index,
 374 #endif
 375         .write_ldt_entry = native_write_ldt_entry,
 376         .write_gdt_entry = native_write_gdt_entry,
 377         .write_idt_entry = native_write_idt_entry,
 378
 379         .alloc_ldt = paravirt_nop,
 380         .free_ldt = paravirt_nop,
 381
 382         .load_sp0 = native_load_sp0,
 383
 384 #ifdef CONFIG_X86_64
 385 #ifdef CONFIG_IA32_EMULATION
 386         .usergs_sysret32 = native_usergs_sysret32,
 387 #endif
 388         .usergs_sysret64 = native_usergs_sysret64,
 389 #endif
 390         .iret = native_iret,
 391         .swapgs = native_swapgs,
 392
 393         .set_iopl_mask = native_set_iopl_mask,
 394         .io_delay = native_io_delay,
 395
 396         .start_context_switch = paravirt_nop,
 397         .end_context_switch = paravirt_nop,
 398 };
 399
 400 /* At this point, native_get/set_debugreg has real function entries */
 401 NOKPROBE_SYMBOL(native_get_debugreg);
 402 NOKPROBE_SYMBOL(native_set_debugreg);
 403 NOKPROBE_SYMBOL(native_load_idt);
 404
 405 struct pv_apic_ops pv_apic_ops = {
 406 #ifdef CONFIG_X86_LOCAL_APIC
 407         .startup_ipi_hook = paravirt_nop,
 408 #endif
 409 };
 410
 411 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
 412 /* 32-bit pagetable entries */
 413 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
 414 #else
 415 /* 64-bit pagetable entries */
 416 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 417 #endif
 418
 419 struct pv_mmu_ops pv_mmu_ops = {
 420
 421         .read_cr2 = native_read_cr2,
 422         .write_cr2 = native_write_cr2,
 423         .read_cr3 = native_read_cr3,
 424         .write_cr3 = native_write_cr3,
 425
 426         .flush_tlb_user = native_flush_tlb,
 427         .flush_tlb_kernel = native_flush_tlb_global,
 428         .flush_tlb_single = native_flush_tlb_single,
 429         .flush_tlb_others = native_flush_tlb_others,
 430
 431         .pgd_alloc = __paravirt_pgd_alloc,
 432         .pgd_free = paravirt_nop,
 433
 434         .alloc_pte = paravirt_nop,
 435         .alloc_pmd = paravirt_nop,
 436         .alloc_pud = paravirt_nop,
 437         .release_pte = paravirt_nop,
 438         .release_pmd = paravirt_nop,
 439         .release_pud = paravirt_nop,
 440
 441         .set_pte = native_set_pte,
 442         .set_pte_at = native_set_pte_at,
 443         .set_pmd = native_set_pmd,
 444         .set_pmd_at = native_set_pmd_at,
 445         .pte_update = paravirt_nop,
 446         .pte_update_defer = paravirt_nop,
 447         .pmd_update = paravirt_nop,
 448         .pmd_update_defer = paravirt_nop,
 449
 450         .ptep_modify_prot_start = __ptep_modify_prot_start,
 451         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 452
 453 #if CONFIG_PGTABLE_LEVELS >= 3
 454 #ifdef CONFIG_X86_PAE
 455         .set_pte_atomic = native_set_pte_atomic,
 456         .pte_clear = native_pte_clear,
 457         .pmd_clear = native_pmd_clear,
 458 #endif
 459         .set_pud = native_set_pud,
 460
 461         .pmd_val = PTE_IDENT,
 462         .make_pmd = PTE_IDENT,
 463
 464 #if CONFIG_PGTABLE_LEVELS == 4
 465         .pud_val = PTE_IDENT,
 466         .make_pud = PTE_IDENT,
 467
 468         .set_pgd = native_set_pgd,
 469 #endif
 470 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 471
 472         .pte_val = PTE_IDENT,
 473         .pgd_val = PTE_IDENT,
 474
 475         .make_pte = PTE_IDENT,
 476         .make_pgd = PTE_IDENT,
 477
 478         .dup_mmap = paravirt_nop,
 479         .exit_mmap = paravirt_nop,
 480         .activate_mm = paravirt_nop,
 481
 482         .lazy_mode = {
 483                 .enter = paravirt_nop,
 484                 .leave = paravirt_nop,
 485                 .flush = paravirt_nop,
 486         },
 487
 488         .set_fixmap = native_set_fixmap,
 489 };
 490
 491 EXPORT_SYMBOL_GPL(pv_time_ops);
 492 EXPORT_SYMBOL    (pv_cpu_ops);
 493 EXPORT_SYMBOL    (pv_mmu_ops);
 494 EXPORT_SYMBOL_GPL(pv_apic_ops);
 495 EXPORT_SYMBOL_GPL(pv_info);
 496 EXPORT_SYMBOL    (pv_irq_ops);