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 #include <asm/tlb.h>
  45
  46 /*
  47  * nop stub, which must not clobber anything *including the stack* to
  48  * avoid confusing the entry prologues.
  49  */
  50 extern void _paravirt_nop(void);
  51 asm (".pushsection .entry.text, \"ax\"\n"
  52      ".global _paravirt_nop\n"
  53      "_paravirt_nop:\n\t"
  54      "ret\n\t"
  55      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  56      ".type _paravirt_nop, @function\n\t"
  57      ".popsection");
  58
  59 void __init default_banner(void)
  60 {
  61         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  62                pv_info.name);
  63 }
  64
  65 /* Undefined instruction for dealing with missing ops pointers. */
  66 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  67
  68 struct branch {
  69         unsigned char opcode;
  70         u32 delta;
  71 } __attribute__((packed));
  72
  73 static unsigned paravirt_patch_call(void *insnbuf, const void *target,
  74                                     unsigned long addr, unsigned len)
  75 {
  76         struct branch *b = insnbuf;
  77         unsigned long delta = (unsigned long)target - (addr+5);
  78
  79         if (len < 5) {
  80 #ifdef CONFIG_RETPOLINE
  81                 WARN_ONCE(1, "Failing to patch indirect CALL in %ps\n", (void *)addr);
  82 #endif
  83                 return len;     /* call too long for patch site */
  84         }
  85
  86         b->opcode = 0xe8; /* call */
  87         b->delta = delta;
  88         BUILD_BUG_ON(sizeof(*b) != 5);
  89
  90         return 5;
  91 }
  92
  93 #ifdef CONFIG_PARAVIRT_XXL
  94 /* identity function, which can be inlined */
  95 u64 notrace _paravirt_ident_64(u64 x)
  96 {
  97         return x;
  98 }
  99
 100 static unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 101                                    unsigned long addr, unsigned len)
 102 {
 103         struct branch *b = insnbuf;
 104         unsigned long delta = (unsigned long)target - (addr+5);
 105
 106         if (len < 5) {
 107 #ifdef CONFIG_RETPOLINE
 108                 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
 109 #endif
 110                 return len;     /* call too long for patch site */
 111         }
 112
 113         b->opcode = 0xe9;       /* jmp */
 114         b->delta = delta;
 115
 116         return 5;
 117 }
 118 #endif
 119
 120 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
 121
 122 void __init native_pv_lock_init(void)
 123 {
 124         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 125                 static_branch_disable(&virt_spin_lock_key);
 126 }
 127
 128 unsigned paravirt_patch_default(u8 type, void *insnbuf,
 129                                 unsigned long addr, unsigned len)
 130 {
 131         /*
 132          * Neat trick to map patch type back to the call within the
 133          * corresponding structure.
 134          */
 135         void *opfunc = *((void **)&pv_ops + type);
 136         unsigned ret;
 137
 138         if (opfunc == NULL)
 139                 /* If there's no function, patch it with a ud2a (BUG) */
 140                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 141         else if (opfunc == _paravirt_nop)
 142                 ret = 0;
 143
 144 #ifdef CONFIG_PARAVIRT_XXL
 145         /* identity functions just return their single argument */
 146         else if (opfunc == _paravirt_ident_64)
 147                 ret = paravirt_patch_ident_64(insnbuf, len);
 148
 149         else if (type == PARAVIRT_PATCH(cpu.iret) ||
 150                  type == PARAVIRT_PATCH(cpu.usergs_sysret64))
 151                 /* If operation requires a jmp, then jmp */
 152                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 153 #endif
 154         else
 155                 /* Otherwise call the function. */
 156                 ret = paravirt_patch_call(insnbuf, opfunc, addr, len);
 157
 158         return ret;
 159 }
 160
 161 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 162                               const char *start, const char *end)
 163 {
 164         unsigned insn_len = end - start;
 165
 166         if (insn_len > len || start == NULL)
 167                 insn_len = len;
 168         else
 169                 memcpy(insnbuf, start, insn_len);
 170
 171         return insn_len;
 172 }
 173
 174 static void native_flush_tlb(void)
 175 {
 176         __native_flush_tlb();
 177 }
 178
 179 /*
 180  * Global pages have to be flushed a bit differently. Not a real
 181  * performance problem because this does not happen often.
 182  */
 183 static void native_flush_tlb_global(void)
 184 {
 185         __native_flush_tlb_global();
 186 }
 187
 188 static void native_flush_tlb_one_user(unsigned long addr)
 189 {
 190         __native_flush_tlb_one_user(addr);
 191 }
 192
 193 struct static_key paravirt_steal_enabled;
 194 struct static_key paravirt_steal_rq_enabled;
 195
 196 static u64 native_steal_clock(int cpu)
 197 {
 198         return 0;
 199 }
 200
 201 /* These are in entry.S */
 202 extern void native_iret(void);
 203 extern void native_usergs_sysret64(void);
 204
 205 static struct resource reserve_ioports = {
 206         .start = 0,
 207         .end = IO_SPACE_LIMIT,
 208         .name = "paravirt-ioport",
 209         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 210 };
 211
 212 /*
 213  * Reserve the whole legacy IO space to prevent any legacy drivers
 214  * from wasting time probing for their hardware.  This is a fairly
 215  * brute-force approach to disabling all non-virtual drivers.
 216  *
 217  * Note that this must be called very early to have any effect.
 218  */
 219 int paravirt_disable_iospace(void)
 220 {
 221         return request_resource(&ioport_resource, &reserve_ioports);
 222 }
 223
 224 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 225
 226 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 227 {
 228         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 229
 230         this_cpu_write(paravirt_lazy_mode, mode);
 231 }
 232
 233 static void leave_lazy(enum paravirt_lazy_mode mode)
 234 {
 235         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 236
 237         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 238 }
 239
 240 void paravirt_enter_lazy_mmu(void)
 241 {
 242         enter_lazy(PARAVIRT_LAZY_MMU);
 243 }
 244
 245 void paravirt_leave_lazy_mmu(void)
 246 {
 247         leave_lazy(PARAVIRT_LAZY_MMU);
 248 }
 249
 250 void paravirt_flush_lazy_mmu(void)
 251 {
 252         preempt_disable();
 253
 254         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 255                 arch_leave_lazy_mmu_mode();
 256                 arch_enter_lazy_mmu_mode();
 257         }
 258
 259         preempt_enable();
 260 }
 261
 262 #ifdef CONFIG_PARAVIRT_XXL
 263 void paravirt_start_context_switch(struct task_struct *prev)
 264 {
 265         BUG_ON(preemptible());
 266
 267         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 268                 arch_leave_lazy_mmu_mode();
 269                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 270         }
 271         enter_lazy(PARAVIRT_LAZY_CPU);
 272 }
 273
 274 void paravirt_end_context_switch(struct task_struct *next)
 275 {
 276         BUG_ON(preemptible());
 277
 278         leave_lazy(PARAVIRT_LAZY_CPU);
 279
 280         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 281                 arch_enter_lazy_mmu_mode();
 282 }
 283 #endif
 284
 285 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 286 {
 287         if (in_interrupt())
 288                 return PARAVIRT_LAZY_NONE;
 289
 290         return this_cpu_read(paravirt_lazy_mode);
 291 }
 292
 293 struct pv_info pv_info = {
 294         .name = "bare hardware",
 295 #ifdef CONFIG_PARAVIRT_XXL
 296         .kernel_rpl = 0,
 297         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 298
 299 #ifdef CONFIG_X86_64
 300         .extra_user_64bit_cs = __USER_CS,
 301 #endif
 302 #endif
 303 };
 304
 305 /* 64-bit pagetable entries */
 306 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 307
 308 struct paravirt_patch_template pv_ops = {
 309         /* Init ops. */
 310         .init.patch             = native_patch,
 311
 312         /* Time ops. */
 313         .time.sched_clock       = native_sched_clock,
 314         .time.steal_clock       = native_steal_clock,
 315
 316         /* Cpu ops. */
 317         .cpu.io_delay           = native_io_delay,
 318
 319 #ifdef CONFIG_PARAVIRT_XXL
 320         .cpu.cpuid              = native_cpuid,
 321         .cpu.get_debugreg       = native_get_debugreg,
 322         .cpu.set_debugreg       = native_set_debugreg,
 323         .cpu.read_cr0           = native_read_cr0,
 324         .cpu.write_cr0          = native_write_cr0,
 325         .cpu.write_cr4          = native_write_cr4,
 326 #ifdef CONFIG_X86_64
 327         .cpu.read_cr8           = native_read_cr8,
 328         .cpu.write_cr8          = native_write_cr8,
 329 #endif
 330         .cpu.wbinvd             = native_wbinvd,
 331         .cpu.read_msr           = native_read_msr,
 332         .cpu.write_msr          = native_write_msr,
 333         .cpu.read_msr_safe      = native_read_msr_safe,
 334         .cpu.write_msr_safe     = native_write_msr_safe,
 335         .cpu.read_pmc           = native_read_pmc,
 336         .cpu.load_tr_desc       = native_load_tr_desc,
 337         .cpu.set_ldt            = native_set_ldt,
 338         .cpu.load_gdt           = native_load_gdt,
 339         .cpu.load_idt           = native_load_idt,
 340         .cpu.store_tr           = native_store_tr,
 341         .cpu.load_tls           = native_load_tls,
 342 #ifdef CONFIG_X86_64
 343         .cpu.load_gs_index      = native_load_gs_index,
 344 #endif
 345         .cpu.write_ldt_entry    = native_write_ldt_entry,
 346         .cpu.write_gdt_entry    = native_write_gdt_entry,
 347         .cpu.write_idt_entry    = native_write_idt_entry,
 348
 349         .cpu.alloc_ldt          = paravirt_nop,
 350         .cpu.free_ldt           = paravirt_nop,
 351
 352         .cpu.load_sp0           = native_load_sp0,
 353
 354 #ifdef CONFIG_X86_64
 355         .cpu.usergs_sysret64    = native_usergs_sysret64,
 356 #endif
 357         .cpu.iret               = native_iret,
 358         .cpu.swapgs             = native_swapgs,
 359
 360         .cpu.set_iopl_mask      = native_set_iopl_mask,
 361
 362         .cpu.start_context_switch       = paravirt_nop,
 363         .cpu.end_context_switch         = paravirt_nop,
 364
 365         /* Irq ops. */
 366         .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
 367         .irq.restore_fl         = __PV_IS_CALLEE_SAVE(native_restore_fl),
 368         .irq.irq_disable        = __PV_IS_CALLEE_SAVE(native_irq_disable),
 369         .irq.irq_enable         = __PV_IS_CALLEE_SAVE(native_irq_enable),
 370         .irq.safe_halt          = native_safe_halt,
 371         .irq.halt               = native_halt,
 372 #endif /* CONFIG_PARAVIRT_XXL */
 373
 374         /* Mmu ops. */
 375         .mmu.flush_tlb_user     = native_flush_tlb,
 376         .mmu.flush_tlb_kernel   = native_flush_tlb_global,
 377         .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
 378         .mmu.flush_tlb_others   = native_flush_tlb_others,
 379         .mmu.tlb_remove_table   =
 380                         (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 381
 382         .mmu.exit_mmap          = paravirt_nop,
 383
 384 #ifdef CONFIG_PARAVIRT_XXL
 385         .mmu.read_cr2           = native_read_cr2,
 386         .mmu.write_cr2          = native_write_cr2,
 387         .mmu.read_cr3           = __native_read_cr3,
 388         .mmu.write_cr3          = native_write_cr3,
 389
 390         .mmu.pgd_alloc          = __paravirt_pgd_alloc,
 391         .mmu.pgd_free           = paravirt_nop,
 392
 393         .mmu.alloc_pte          = paravirt_nop,
 394         .mmu.alloc_pmd          = paravirt_nop,
 395         .mmu.alloc_pud          = paravirt_nop,
 396         .mmu.alloc_p4d          = paravirt_nop,
 397         .mmu.release_pte        = paravirt_nop,
 398         .mmu.release_pmd        = paravirt_nop,
 399         .mmu.release_pud        = paravirt_nop,
 400         .mmu.release_p4d        = paravirt_nop,
 401
 402         .mmu.set_pte            = native_set_pte,
 403         .mmu.set_pte_at         = native_set_pte_at,
 404         .mmu.set_pmd            = native_set_pmd,
 405
 406         .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
 407         .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,
 408
 409 #if CONFIG_PGTABLE_LEVELS >= 3
 410 #ifdef CONFIG_X86_PAE
 411         .mmu.set_pte_atomic     = native_set_pte_atomic,
 412         .mmu.pte_clear          = native_pte_clear,
 413         .mmu.pmd_clear          = native_pmd_clear,
 414 #endif
 415         .mmu.set_pud            = native_set_pud,
 416
 417         .mmu.pmd_val            = PTE_IDENT,
 418         .mmu.make_pmd           = PTE_IDENT,
 419
 420 #if CONFIG_PGTABLE_LEVELS >= 4
 421         .mmu.pud_val            = PTE_IDENT,
 422         .mmu.make_pud           = PTE_IDENT,
 423
 424         .mmu.set_p4d            = native_set_p4d,
 425
 426 #if CONFIG_PGTABLE_LEVELS >= 5
 427         .mmu.p4d_val            = PTE_IDENT,
 428         .mmu.make_p4d           = PTE_IDENT,
 429
 430         .mmu.set_pgd            = native_set_pgd,
 431 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 432 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
 433 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 434
 435         .mmu.pte_val            = PTE_IDENT,
 436         .mmu.pgd_val            = PTE_IDENT,
 437
 438         .mmu.make_pte           = PTE_IDENT,
 439         .mmu.make_pgd           = PTE_IDENT,
 440
 441         .mmu.dup_mmap           = paravirt_nop,
 442         .mmu.activate_mm        = paravirt_nop,
 443
 444         .mmu.lazy_mode = {
 445                 .enter          = paravirt_nop,
 446                 .leave          = paravirt_nop,
 447                 .flush          = paravirt_nop,
 448         },
 449
 450         .mmu.set_fixmap         = native_set_fixmap,
 451 #endif /* CONFIG_PARAVIRT_XXL */
 452
 453 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
 454         /* Lock ops. */
 455 #ifdef CONFIG_SMP
 456         .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
 457         .lock.queued_spin_unlock        =
 458                                 PV_CALLEE_SAVE(__native_queued_spin_unlock),
 459         .lock.wait                      = paravirt_nop,
 460         .lock.kick                      = paravirt_nop,
 461         .lock.vcpu_is_preempted         =
 462                                 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
 463 #endif /* SMP */
 464 #endif
 465 };
 466
 467 #ifdef CONFIG_PARAVIRT_XXL
 468 /* At this point, native_get/set_debugreg has real function entries */
 469 NOKPROBE_SYMBOL(native_get_debugreg);
 470 NOKPROBE_SYMBOL(native_set_debugreg);
 471 NOKPROBE_SYMBOL(native_load_idt);
 472 #endif
 473
 474 EXPORT_SYMBOL(pv_ops);
 475 EXPORT_SYMBOL_GPL(pv_info);