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