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 _paravirt_ident_32(u32 x)
  59 {
  60         return x;
  61 }
  62
  63 u64 _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 (tgt_clobbers & ~site_clobbers)
 101                 return len;     /* target would clobber too much for this site */
 102         if (len < 5)
 103                 return len;     /* call too long for patch site */
 104
 105         b->opcode = 0xe8; /* call */
 106         b->delta = delta;
 107         BUILD_BUG_ON(sizeof(*b) != 5);
 108
 109         return 5;
 110 }
 111
 112 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 113                             unsigned long addr, unsigned len)
 114 {
 115         struct branch *b = insnbuf;
 116         unsigned long delta = (unsigned long)target - (addr+5);
 117
 118         if (len < 5)
 119                 return len;     /* call too long for patch site */
 120
 121         b->opcode = 0xe9;       /* jmp */
 122         b->delta = delta;
 123
 124         return 5;
 125 }
 126
 127 /* Neat trick to map patch type back to the call within the
 128  * corresponding structure. */
 129 static void *get_call_destination(u8 type)
 130 {
 131         struct paravirt_patch_template tmpl = {
 132                 .pv_init_ops = pv_init_ops,
 133                 .pv_time_ops = pv_time_ops,
 134                 .pv_cpu_ops = pv_cpu_ops,
 135                 .pv_irq_ops = pv_irq_ops,
 136                 .pv_apic_ops = pv_apic_ops,
 137                 .pv_mmu_ops = pv_mmu_ops,
 138 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 139                 .pv_lock_ops = pv_lock_ops,
 140 #endif
 141         };
 142         return *((void **)&tmpl + type);
 143 }
 144
 145 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 146                                 unsigned long addr, unsigned len)
 147 {
 148         void *opfunc = get_call_destination(type);
 149         unsigned ret;
 150
 151         if (opfunc == NULL)
 152                 /* If there's no function, patch it with a ud2a (BUG) */
 153                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 154         else if (opfunc == _paravirt_nop)
 155                 /* If the operation is a nop, then nop the callsite */
 156                 ret = paravirt_patch_nop();
 157
 158         /* identity functions just return their single argument */
 159         else if (opfunc == _paravirt_ident_32)
 160                 ret = paravirt_patch_ident_32(insnbuf, len);
 161         else if (opfunc == _paravirt_ident_64)
 162                 ret = paravirt_patch_ident_64(insnbuf, len);
 163
 164         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 165 #ifdef CONFIG_X86_32
 166                  type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
 167 #endif
 168                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
 169                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
 170                 /* If operation requires a jmp, then jmp */
 171                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 172         else
 173                 /* Otherwise call the function; assume target could
 174                    clobber any caller-save reg */
 175                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
 176                                           addr, clobbers, len);
 177
 178         return ret;
 179 }
 180
 181 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 182                               const char *start, const char *end)
 183 {
 184         unsigned insn_len = end - start;
 185
 186         if (insn_len > len || start == NULL)
 187                 insn_len = len;
 188         else
 189                 memcpy(insnbuf, start, insn_len);
 190
 191         return insn_len;
 192 }
 193
 194 static void native_flush_tlb(void)
 195 {
 196         __native_flush_tlb();
 197 }
 198
 199 /*
 200  * Global pages have to be flushed a bit differently. Not a real
 201  * performance problem because this does not happen often.
 202  */
 203 static void native_flush_tlb_global(void)
 204 {
 205         __native_flush_tlb_global();
 206 }
 207
 208 static void native_flush_tlb_single(unsigned long addr)
 209 {
 210         __native_flush_tlb_single(addr);
 211 }
 212
 213 struct static_key paravirt_steal_enabled;
 214 struct static_key paravirt_steal_rq_enabled;
 215
 216 static u64 native_steal_clock(int cpu)
 217 {
 218         return 0;
 219 }
 220
 221 /* These are in entry.S */
 222 extern void native_iret(void);
 223 extern void native_irq_enable_sysexit(void);
 224 extern void native_usergs_sysret32(void);
 225 extern void native_usergs_sysret64(void);
 226
 227 static struct resource reserve_ioports = {
 228         .start = 0,
 229         .end = IO_SPACE_LIMIT,
 230         .name = "paravirt-ioport",
 231         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 232 };
 233
 234 /*
 235  * Reserve the whole legacy IO space to prevent any legacy drivers
 236  * from wasting time probing for their hardware.  This is a fairly
 237  * brute-force approach to disabling all non-virtual drivers.
 238  *
 239  * Note that this must be called very early to have any effect.
 240  */
 241 int paravirt_disable_iospace(void)
 242 {
 243         return request_resource(&ioport_resource, &reserve_ioports);
 244 }
 245
 246 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 247
 248 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 249 {
 250         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 251
 252         this_cpu_write(paravirt_lazy_mode, mode);
 253 }
 254
 255 static void leave_lazy(enum paravirt_lazy_mode mode)
 256 {
 257         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 258
 259         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 260 }
 261
 262 void paravirt_enter_lazy_mmu(void)
 263 {
 264         enter_lazy(PARAVIRT_LAZY_MMU);
 265 }
 266
 267 void paravirt_leave_lazy_mmu(void)
 268 {
 269         leave_lazy(PARAVIRT_LAZY_MMU);
 270 }
 271
 272 void paravirt_flush_lazy_mmu(void)
 273 {
 274         preempt_disable();
 275
 276         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 277                 arch_leave_lazy_mmu_mode();
 278                 arch_enter_lazy_mmu_mode();
 279         }
 280
 281         preempt_enable();
 282 }
 283
 284 void paravirt_start_context_switch(struct task_struct *prev)
 285 {
 286         BUG_ON(preemptible());
 287
 288         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 289                 arch_leave_lazy_mmu_mode();
 290                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 291         }
 292         enter_lazy(PARAVIRT_LAZY_CPU);
 293 }
 294
 295 void paravirt_end_context_switch(struct task_struct *next)
 296 {
 297         BUG_ON(preemptible());
 298
 299         leave_lazy(PARAVIRT_LAZY_CPU);
 300
 301         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 302                 arch_enter_lazy_mmu_mode();
 303 }
 304
 305 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 306 {
 307         if (in_interrupt())
 308                 return PARAVIRT_LAZY_NONE;
 309
 310         return this_cpu_read(paravirt_lazy_mode);
 311 }
 312
 313 struct pv_info pv_info = {
 314         .name = "bare hardware",
 315         .paravirt_enabled = 0,
 316         .kernel_rpl = 0,
 317         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 318
 319 #ifdef CONFIG_X86_64
 320         .extra_user_64bit_cs = __USER_CS,
 321 #endif
 322 };
 323
 324 struct pv_init_ops pv_init_ops = {
 325         .patch = native_patch,
 326 };
 327
 328 struct pv_time_ops pv_time_ops = {
 329         .sched_clock = native_sched_clock,
 330         .steal_clock = native_steal_clock,
 331 };
 332
 333 __visible struct pv_irq_ops pv_irq_ops = {
 334         .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
 335         .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
 336         .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
 337         .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
 338         .safe_halt = native_safe_halt,
 339         .halt = native_halt,
 340 #ifdef CONFIG_X86_64
 341         .adjust_exception_frame = paravirt_nop,
 342 #endif
 343 };
 344
 345 __visible struct pv_cpu_ops pv_cpu_ops = {
 346         .cpuid = native_cpuid,
 347         .get_debugreg = native_get_debugreg,
 348         .set_debugreg = native_set_debugreg,
 349         .clts = native_clts,
 350         .read_cr0 = native_read_cr0,
 351         .write_cr0 = native_write_cr0,
 352         .read_cr4 = native_read_cr4,
 353         .read_cr4_safe = native_read_cr4_safe,
 354         .write_cr4 = native_write_cr4,
 355 #ifdef CONFIG_X86_64
 356         .read_cr8 = native_read_cr8,
 357         .write_cr8 = native_write_cr8,
 358 #endif
 359         .wbinvd = native_wbinvd,
 360         .read_msr = native_read_msr_safe,
 361         .write_msr = native_write_msr_safe,
 362         .read_pmc = native_read_pmc,
 363         .load_tr_desc = native_load_tr_desc,
 364         .set_ldt = native_set_ldt,
 365         .load_gdt = native_load_gdt,
 366         .load_idt = native_load_idt,
 367         .store_idt = native_store_idt,
 368         .store_tr = native_store_tr,
 369         .load_tls = native_load_tls,
 370 #ifdef CONFIG_X86_64
 371         .load_gs_index = native_load_gs_index,
 372 #endif
 373         .write_ldt_entry = native_write_ldt_entry,
 374         .write_gdt_entry = native_write_gdt_entry,
 375         .write_idt_entry = native_write_idt_entry,
 376
 377         .alloc_ldt = paravirt_nop,
 378         .free_ldt = paravirt_nop,
 379
 380         .load_sp0 = native_load_sp0,
 381
 382 #if defined(CONFIG_X86_32)
 383         .irq_enable_sysexit = native_irq_enable_sysexit,
 384 #endif
 385 #ifdef CONFIG_X86_64
 386 #ifdef CONFIG_IA32_EMULATION
 387         .usergs_sysret32 = native_usergs_sysret32,
 388 #endif
 389         .usergs_sysret64 = native_usergs_sysret64,
 390 #endif
 391         .iret = native_iret,
 392         .swapgs = native_swapgs,
 393
 394         .set_iopl_mask = native_set_iopl_mask,
 395         .io_delay = native_io_delay,
 396
 397         .start_context_switch = paravirt_nop,
 398         .end_context_switch = paravirt_nop,
 399 };
 400
 401 /* At this point, native_get/set_debugreg has real function entries */
 402 NOKPROBE_SYMBOL(native_get_debugreg);
 403 NOKPROBE_SYMBOL(native_set_debugreg);
 404 NOKPROBE_SYMBOL(native_load_idt);
 405
 406 struct pv_apic_ops pv_apic_ops = {
 407 #ifdef CONFIG_X86_LOCAL_APIC
 408         .startup_ipi_hook = paravirt_nop,
 409 #endif
 410 };
 411
 412 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
 413 /* 32-bit pagetable entries */
 414 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
 415 #else
 416 /* 64-bit pagetable entries */
 417 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 418 #endif
 419
 420 struct pv_mmu_ops pv_mmu_ops = {
 421
 422         .read_cr2 = native_read_cr2,
 423         .write_cr2 = native_write_cr2,
 424         .read_cr3 = native_read_cr3,
 425         .write_cr3 = native_write_cr3,
 426
 427         .flush_tlb_user = native_flush_tlb,
 428         .flush_tlb_kernel = native_flush_tlb_global,
 429         .flush_tlb_single = native_flush_tlb_single,
 430         .flush_tlb_others = native_flush_tlb_others,
 431
 432         .pgd_alloc = __paravirt_pgd_alloc,
 433         .pgd_free = paravirt_nop,
 434
 435         .alloc_pte = paravirt_nop,
 436         .alloc_pmd = paravirt_nop,
 437         .alloc_pud = paravirt_nop,
 438         .release_pte = paravirt_nop,
 439         .release_pmd = paravirt_nop,
 440         .release_pud = paravirt_nop,
 441
 442         .set_pte = native_set_pte,
 443         .set_pte_at = native_set_pte_at,
 444         .set_pmd = native_set_pmd,
 445         .set_pmd_at = native_set_pmd_at,
 446         .pte_update = paravirt_nop,
 447         .pte_update_defer = paravirt_nop,
 448         .pmd_update = paravirt_nop,
 449         .pmd_update_defer = paravirt_nop,
 450
 451         .ptep_modify_prot_start = __ptep_modify_prot_start,
 452         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 453
 454 #if CONFIG_PGTABLE_LEVELS >= 3
 455 #ifdef CONFIG_X86_PAE
 456         .set_pte_atomic = native_set_pte_atomic,
 457         .pte_clear = native_pte_clear,
 458         .pmd_clear = native_pmd_clear,
 459 #endif
 460         .set_pud = native_set_pud,
 461
 462         .pmd_val = PTE_IDENT,
 463         .make_pmd = PTE_IDENT,
 464
 465 #if CONFIG_PGTABLE_LEVELS == 4
 466         .pud_val = PTE_IDENT,
 467         .make_pud = PTE_IDENT,
 468
 469         .set_pgd = native_set_pgd,
 470 #endif
 471 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 472
 473         .pte_val = PTE_IDENT,
 474         .pgd_val = PTE_IDENT,
 475
 476         .make_pte = PTE_IDENT,
 477         .make_pgd = PTE_IDENT,
 478
 479         .dup_mmap = paravirt_nop,
 480         .exit_mmap = paravirt_nop,
 481         .activate_mm = paravirt_nop,
 482
 483         .lazy_mode = {
 484                 .enter = paravirt_nop,
 485                 .leave = paravirt_nop,
 486                 .flush = paravirt_nop,
 487         },
 488
 489         .set_fixmap = native_set_fixmap,
 490 };
 491
 492 EXPORT_SYMBOL_GPL(pv_time_ops);
 493 EXPORT_SYMBOL    (pv_cpu_ops);
 494 EXPORT_SYMBOL    (pv_mmu_ops);
 495 EXPORT_SYMBOL_GPL(pv_apic_ops);
 496 EXPORT_SYMBOL_GPL(pv_info);
 497 EXPORT_SYMBOL    (pv_irq_ops);