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