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