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