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/init.h>
  23 #include <linux/export.h>
  24 #include <linux/efi.h>
  25 #include <linux/bcd.h>
  26 #include <linux/highmem.h>
  27 #include <linux/kprobes.h>
  28
  29 #include <asm/bug.h>
  30 #include <asm/paravirt.h>
  31 #include <asm/debugreg.h>
  32 #include <asm/desc.h>
  33 #include <asm/setup.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/time.h>
  36 #include <asm/pgalloc.h>
  37 #include <asm/irq.h>
  38 #include <asm/delay.h>
  39 #include <asm/fixmap.h>
  40 #include <asm/apic.h>
  41 #include <asm/tlbflush.h>
  42 #include <asm/timer.h>
  43 #include <asm/special_insns.h>
  44
  45 /*
  46  * nop stub, which must not clobber anything *including the stack* to
  47  * avoid confusing the entry prologues.
  48  */
  49 extern void _paravirt_nop(void);
  50 asm (".pushsection .entry.text, \"ax\"\n"
  51      ".global _paravirt_nop\n"
  52      "_paravirt_nop:\n\t"
  53      "ret\n\t"
  54      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  55      ".type _paravirt_nop, @function\n\t"
  56      ".popsection");
  57
  58 /* identity function, which can be inlined */
  59 u32 notrace _paravirt_ident_32(u32 x)
  60 {
  61         return x;
  62 }
  63
  64 u64 notrace _paravirt_ident_64(u64 x)
  65 {
  66         return x;
  67 }
  68
  69 void __init default_banner(void)
  70 {
  71         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  72                pv_info.name);
  73 }
  74
  75 /* Undefined instruction for dealing with missing ops pointers. */
  76 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  77
  78 struct branch {
  79         unsigned char opcode;
  80         u32 delta;
  81 } __attribute__((packed));
  82
  83 unsigned paravirt_patch_call(void *insnbuf,
  84                              const void *target, u16 tgt_clobbers,
  85                              unsigned long addr, u16 site_clobbers,
  86                              unsigned len)
  87 {
  88         struct branch *b = insnbuf;
  89         unsigned long delta = (unsigned long)target - (addr+5);
  90
  91         if (len < 5) {
  92 #ifdef CONFIG_RETPOLINE
  93                 WARN_ONCE("Failing to patch indirect CALL in %ps\n", (void *)addr);
  94 #endif
  95                 return len;     /* call too long for patch site */
  96         }
  97
  98         b->opcode = 0xe8; /* call */
  99         b->delta = delta;
 100         BUILD_BUG_ON(sizeof(*b) != 5);
 101
 102         return 5;
 103 }
 104
 105 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 106                             unsigned long addr, unsigned len)
 107 {
 108         struct branch *b = insnbuf;
 109         unsigned long delta = (unsigned long)target - (addr+5);
 110
 111         if (len < 5) {
 112 #ifdef CONFIG_RETPOLINE
 113                 WARN_ONCE("Failing to patch indirect JMP in %ps\n", (void *)addr);
 114 #endif
 115                 return len;     /* call too long for patch site */
 116         }
 117
 118         b->opcode = 0xe9;       /* jmp */
 119         b->delta = delta;
 120
 121         return 5;
 122 }
 123
 124 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
 125
 126 void __init native_pv_lock_init(void)
 127 {
 128         if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
 129                 static_branch_disable(&virt_spin_lock_key);
 130 }
 131
 132 /*
 133  * Neat trick to map patch type back to the call within the
 134  * corresponding structure.
 135  */
 136 static void *get_call_destination(u8 type)
 137 {
 138         struct paravirt_patch_template tmpl = {
 139                 .pv_init_ops = pv_init_ops,
 140                 .pv_time_ops = pv_time_ops,
 141                 .pv_cpu_ops = pv_cpu_ops,
 142                 .pv_irq_ops = pv_irq_ops,
 143                 .pv_mmu_ops = pv_mmu_ops,
 144 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 145                 .pv_lock_ops = pv_lock_ops,
 146 #endif
 147         };
 148         return *((void **)&tmpl + type);
 149 }
 150
 151 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 152                                 unsigned long addr, unsigned len)
 153 {
 154         void *opfunc = get_call_destination(type);
 155         unsigned ret;
 156
 157         if (opfunc == NULL)
 158                 /* If there's no function, patch it with a ud2a (BUG) */
 159                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 160         else if (opfunc == _paravirt_nop)
 161                 ret = 0;
 162
 163         /* identity functions just return their single argument */
 164         else if (opfunc == _paravirt_ident_32)
 165                 ret = paravirt_patch_ident_32(insnbuf, len);
 166         else if (opfunc == _paravirt_ident_64)
 167                 ret = paravirt_patch_ident_64(insnbuf, len);
 168
 169         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 170                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
 171                 /* If operation requires a jmp, then jmp */
 172                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 173         else
 174                 /* Otherwise call the function; assume target could
 175                    clobber any caller-save reg */
 176                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
 177                                           addr, clobbers, len);
 178
 179         return ret;
 180 }
 181
 182 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 183                               const char *start, const char *end)
 184 {
 185         unsigned insn_len = end - start;
 186
 187         if (insn_len > len || start == NULL)
 188                 insn_len = len;
 189         else
 190                 memcpy(insnbuf, start, insn_len);
 191
 192         return insn_len;
 193 }
 194
 195 static void native_flush_tlb(void)
 196 {
 197         __native_flush_tlb();
 198 }
 199
 200 /*
 201  * Global pages have to be flushed a bit differently. Not a real
 202  * performance problem because this does not happen often.
 203  */
 204 static void native_flush_tlb_global(void)
 205 {
 206         __native_flush_tlb_global();
 207 }
 208
 209 static void native_flush_tlb_one_user(unsigned long addr)
 210 {
 211         __native_flush_tlb_one_user(addr);
 212 }
 213
 214 struct static_key paravirt_steal_enabled;
 215 struct static_key paravirt_steal_rq_enabled;
 216
 217 static u64 native_steal_clock(int cpu)
 218 {
 219         return 0;
 220 }
 221
 222 /* These are in entry.S */
 223 extern void native_iret(void);
 224 extern void native_usergs_sysret64(void);
 225
 226 static struct resource reserve_ioports = {
 227         .start = 0,
 228         .end = IO_SPACE_LIMIT,
 229         .name = "paravirt-ioport",
 230         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 231 };
 232
 233 /*
 234  * Reserve the whole legacy IO space to prevent any legacy drivers
 235  * from wasting time probing for their hardware.  This is a fairly
 236  * brute-force approach to disabling all non-virtual drivers.
 237  *
 238  * Note that this must be called very early to have any effect.
 239  */
 240 int paravirt_disable_iospace(void)
 241 {
 242         return request_resource(&ioport_resource, &reserve_ioports);
 243 }
 244
 245 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 246
 247 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 248 {
 249         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 250
 251         this_cpu_write(paravirt_lazy_mode, mode);
 252 }
 253
 254 static void leave_lazy(enum paravirt_lazy_mode mode)
 255 {
 256         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 257
 258         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 259 }
 260
 261 void paravirt_enter_lazy_mmu(void)
 262 {
 263         enter_lazy(PARAVIRT_LAZY_MMU);
 264 }
 265
 266 void paravirt_leave_lazy_mmu(void)
 267 {
 268         leave_lazy(PARAVIRT_LAZY_MMU);
 269 }
 270
 271 void paravirt_flush_lazy_mmu(void)
 272 {
 273         preempt_disable();
 274
 275         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 276                 arch_leave_lazy_mmu_mode();
 277                 arch_enter_lazy_mmu_mode();
 278         }
 279
 280         preempt_enable();
 281 }
 282
 283 void paravirt_start_context_switch(struct task_struct *prev)
 284 {
 285         BUG_ON(preemptible());
 286
 287         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 288                 arch_leave_lazy_mmu_mode();
 289                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 290         }
 291         enter_lazy(PARAVIRT_LAZY_CPU);
 292 }
 293
 294 void paravirt_end_context_switch(struct task_struct *next)
 295 {
 296         BUG_ON(preemptible());
 297
 298         leave_lazy(PARAVIRT_LAZY_CPU);
 299
 300         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 301                 arch_enter_lazy_mmu_mode();
 302 }
 303
 304 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 305 {
 306         if (in_interrupt())
 307                 return PARAVIRT_LAZY_NONE;
 308
 309         return this_cpu_read(paravirt_lazy_mode);
 310 }
 311
 312 struct pv_info pv_info = {
 313         .name = "bare hardware",
 314         .kernel_rpl = 0,
 315         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 316
 317 #ifdef CONFIG_X86_64
 318         .extra_user_64bit_cs = __USER_CS,
 319 #endif
 320 };
 321
 322 struct pv_init_ops pv_init_ops = {
 323         .patch = native_patch,
 324 };
 325
 326 struct pv_time_ops pv_time_ops = {
 327         .sched_clock = native_sched_clock,
 328         .steal_clock = native_steal_clock,
 329 };
 330
 331 __visible struct pv_irq_ops pv_irq_ops = {
 332         .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
 333         .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
 334         .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
 335         .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
 336         .safe_halt = native_safe_halt,
 337         .halt = native_halt,
 338 };
 339
 340 __visible struct pv_cpu_ops pv_cpu_ops = {
 341         .cpuid = native_cpuid,
 342         .get_debugreg = native_get_debugreg,
 343         .set_debugreg = native_set_debugreg,
 344         .read_cr0 = native_read_cr0,
 345         .write_cr0 = native_write_cr0,
 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,
 353         .write_msr = native_write_msr,
 354         .read_msr_safe = native_read_msr_safe,
 355         .write_msr_safe = native_write_msr_safe,
 356         .read_pmc = native_read_pmc,
 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_tr = native_store_tr,
 362         .load_tls = native_load_tls,
 363 #ifdef CONFIG_X86_64
 364         .load_gs_index = native_load_gs_index,
 365 #endif
 366         .write_ldt_entry = native_write_ldt_entry,
 367         .write_gdt_entry = native_write_gdt_entry,
 368         .write_idt_entry = native_write_idt_entry,
 369
 370         .alloc_ldt = paravirt_nop,
 371         .free_ldt = paravirt_nop,
 372
 373         .load_sp0 = native_load_sp0,
 374
 375 #ifdef CONFIG_X86_64
 376         .usergs_sysret64 = native_usergs_sysret64,
 377 #endif
 378         .iret = native_iret,
 379         .swapgs = native_swapgs,
 380
 381         .set_iopl_mask = native_set_iopl_mask,
 382         .io_delay = native_io_delay,
 383
 384         .start_context_switch = paravirt_nop,
 385         .end_context_switch = paravirt_nop,
 386 };
 387
 388 /* At this point, native_get/set_debugreg has real function entries */
 389 NOKPROBE_SYMBOL(native_get_debugreg);
 390 NOKPROBE_SYMBOL(native_set_debugreg);
 391 NOKPROBE_SYMBOL(native_load_idt);
 392
 393 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
 394 /* 32-bit pagetable entries */
 395 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
 396 #else
 397 /* 64-bit pagetable entries */
 398 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 399 #endif
 400
 401 struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
 402
 403         .read_cr2 = native_read_cr2,
 404         .write_cr2 = native_write_cr2,
 405         .read_cr3 = __native_read_cr3,
 406         .write_cr3 = native_write_cr3,
 407
 408         .flush_tlb_user = native_flush_tlb,
 409         .flush_tlb_kernel = native_flush_tlb_global,
 410         .flush_tlb_one_user = native_flush_tlb_one_user,
 411         .flush_tlb_others = native_flush_tlb_others,
 412
 413         .pgd_alloc = __paravirt_pgd_alloc,
 414         .pgd_free = paravirt_nop,
 415
 416         .alloc_pte = paravirt_nop,
 417         .alloc_pmd = paravirt_nop,
 418         .alloc_pud = paravirt_nop,
 419         .alloc_p4d = paravirt_nop,
 420         .release_pte = paravirt_nop,
 421         .release_pmd = paravirt_nop,
 422         .release_pud = paravirt_nop,
 423         .release_p4d = paravirt_nop,
 424
 425         .set_pte = native_set_pte,
 426         .set_pte_at = native_set_pte_at,
 427         .set_pmd = native_set_pmd,
 428
 429         .ptep_modify_prot_start = __ptep_modify_prot_start,
 430         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 431
 432 #if CONFIG_PGTABLE_LEVELS >= 3
 433 #ifdef CONFIG_X86_PAE
 434         .set_pte_atomic = native_set_pte_atomic,
 435         .pte_clear = native_pte_clear,
 436         .pmd_clear = native_pmd_clear,
 437 #endif
 438         .set_pud = native_set_pud,
 439
 440         .pmd_val = PTE_IDENT,
 441         .make_pmd = PTE_IDENT,
 442
 443 #if CONFIG_PGTABLE_LEVELS >= 4
 444         .pud_val = PTE_IDENT,
 445         .make_pud = PTE_IDENT,
 446
 447         .set_p4d = native_set_p4d,
 448
 449 #if CONFIG_PGTABLE_LEVELS >= 5
 450         .p4d_val = PTE_IDENT,
 451         .make_p4d = PTE_IDENT,
 452
 453         .set_pgd = native_set_pgd,
 454 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 455 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
 456 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 457
 458         .pte_val = PTE_IDENT,
 459         .pgd_val = PTE_IDENT,
 460
 461         .make_pte = PTE_IDENT,
 462         .make_pgd = PTE_IDENT,
 463
 464         .dup_mmap = paravirt_nop,
 465         .exit_mmap = paravirt_nop,
 466         .activate_mm = paravirt_nop,
 467
 468         .lazy_mode = {
 469                 .enter = paravirt_nop,
 470                 .leave = paravirt_nop,
 471                 .flush = paravirt_nop,
 472         },
 473
 474         .set_fixmap = native_set_fixmap,
 475 };
 476
 477 EXPORT_SYMBOL_GPL(pv_time_ops);
 478 EXPORT_SYMBOL    (pv_cpu_ops);
 479 EXPORT_SYMBOL    (pv_mmu_ops);
 480 EXPORT_SYMBOL_GPL(pv_info);
 481 EXPORT_SYMBOL    (pv_irq_ops);