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