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 /* identity function, which can be inlined */
  60 u32 notrace _paravirt_ident_32(u32 x)
  61 {
  62         return x;
  63 }
  64
  65 u64 notrace _paravirt_ident_64(u64 x)
  66 {
  67         return x;
  68 }
  69
  70 void __init default_banner(void)
  71 {
  72         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  73                pv_info.name);
  74 }
  75
  76 /* Undefined instruction for dealing with missing ops pointers. */
  77 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  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 (len < 5) {
  93 #ifdef CONFIG_RETPOLINE
  94                 WARN_ONCE(1, "Failing to patch indirect CALL in %ps\n", (void *)addr);
  95 #endif
  96                 return len;     /* call too long for patch site */
  97         }
  98
  99         b->opcode = 0xe8; /* call */
 100         b->delta = delta;
 101         BUILD_BUG_ON(sizeof(*b) != 5);
 102
 103         return 5;
 104 }
 105
 106 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 107                             unsigned long addr, unsigned len)
 108 {
 109         struct branch *b = insnbuf;
 110         unsigned long delta = (unsigned long)target - (addr+5);
 111
 112         if (len < 5) {
 113 #ifdef CONFIG_RETPOLINE
 114                 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
 115 #endif
 116                 return len;     /* call too long for patch site */
 117         }
 118
 119         b->opcode = 0xe9;       /* jmp */
 120         b->delta = delta;
 121
 122         return 5;
 123 }
 124
 125 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
 126
 127 void __init native_pv_lock_init(void)
 128 {
 129         if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
 130                 static_branch_disable(&virt_spin_lock_key);
 131 }
 132
 133 /*
 134  * Neat trick to map patch type back to the call within the
 135  * corresponding structure.
 136  */
 137 static void *get_call_destination(u8 type)
 138 {
 139         struct paravirt_patch_template tmpl = {
 140                 .pv_init_ops = pv_init_ops,
 141                 .pv_time_ops = pv_time_ops,
 142                 .pv_cpu_ops = pv_cpu_ops,
 143                 .pv_irq_ops = pv_irq_ops,
 144                 .pv_mmu_ops = pv_mmu_ops,
 145 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 146                 .pv_lock_ops = pv_lock_ops,
 147 #endif
 148         };
 149         return *((void **)&tmpl + type);
 150 }
 151
 152 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 153                                 unsigned long addr, unsigned len)
 154 {
 155         void *opfunc = get_call_destination(type);
 156         unsigned ret;
 157
 158         if (opfunc == NULL)
 159                 /* If there's no function, patch it with a ud2a (BUG) */
 160                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 161         else if (opfunc == _paravirt_nop)
 162                 ret = 0;
 163
 164         /* identity functions just return their single argument */
 165         else if (opfunc == _paravirt_ident_32)
 166                 ret = paravirt_patch_ident_32(insnbuf, len);
 167         else if (opfunc == _paravirt_ident_64)
 168                 ret = paravirt_patch_ident_64(insnbuf, len);
 169
 170         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 171                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
 172                 /* If operation requires a jmp, then jmp */
 173                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 174         else
 175                 /* Otherwise call the function; assume target could
 176                    clobber any caller-save reg */
 177                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
 178                                           addr, clobbers, len);
 179
 180         return ret;
 181 }
 182
 183 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 184                               const char *start, const char *end)
 185 {
 186         unsigned insn_len = end - start;
 187
 188         if (insn_len > len || start == NULL)
 189                 insn_len = len;
 190         else
 191                 memcpy(insnbuf, start, insn_len);
 192
 193         return insn_len;
 194 }
 195
 196 static void native_flush_tlb(void)
 197 {
 198         __native_flush_tlb();
 199 }
 200
 201 /*
 202  * Global pages have to be flushed a bit differently. Not a real
 203  * performance problem because this does not happen often.
 204  */
 205 static void native_flush_tlb_global(void)
 206 {
 207         __native_flush_tlb_global();
 208 }
 209
 210 static void native_flush_tlb_one_user(unsigned long addr)
 211 {
 212         __native_flush_tlb_one_user(addr);
 213 }
 214
 215 struct static_key paravirt_steal_enabled;
 216 struct static_key paravirt_steal_rq_enabled;
 217
 218 static u64 native_steal_clock(int cpu)
 219 {
 220         return 0;
 221 }
 222
 223 /* These are in entry.S */
 224 extern void native_iret(void);
 225 extern void native_usergs_sysret64(void);
 226
 227 static struct resource reserve_ioports = {
 228         .start = 0,
 229         .end = IO_SPACE_LIMIT,
 230         .name = "paravirt-ioport",
 231         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 232 };
 233
 234 /*
 235  * Reserve the whole legacy IO space to prevent any legacy drivers
 236  * from wasting time probing for their hardware.  This is a fairly
 237  * brute-force approach to disabling all non-virtual drivers.
 238  *
 239  * Note that this must be called very early to have any effect.
 240  */
 241 int paravirt_disable_iospace(void)
 242 {
 243         return request_resource(&ioport_resource, &reserve_ioports);
 244 }
 245
 246 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 247
 248 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 249 {
 250         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 251
 252         this_cpu_write(paravirt_lazy_mode, mode);
 253 }
 254
 255 static void leave_lazy(enum paravirt_lazy_mode mode)
 256 {
 257         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 258
 259         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 260 }
 261
 262 void paravirt_enter_lazy_mmu(void)
 263 {
 264         enter_lazy(PARAVIRT_LAZY_MMU);
 265 }
 266
 267 void paravirt_leave_lazy_mmu(void)
 268 {
 269         leave_lazy(PARAVIRT_LAZY_MMU);
 270 }
 271
 272 void paravirt_flush_lazy_mmu(void)
 273 {
 274         preempt_disable();
 275
 276         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 277                 arch_leave_lazy_mmu_mode();
 278                 arch_enter_lazy_mmu_mode();
 279         }
 280
 281         preempt_enable();
 282 }
 283
 284 void paravirt_start_context_switch(struct task_struct *prev)
 285 {
 286         BUG_ON(preemptible());
 287
 288         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 289                 arch_leave_lazy_mmu_mode();
 290                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 291         }
 292         enter_lazy(PARAVIRT_LAZY_CPU);
 293 }
 294
 295 void paravirt_end_context_switch(struct task_struct *next)
 296 {
 297         BUG_ON(preemptible());
 298
 299         leave_lazy(PARAVIRT_LAZY_CPU);
 300
 301         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 302                 arch_enter_lazy_mmu_mode();
 303 }
 304
 305 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 306 {
 307         if (in_interrupt())
 308                 return PARAVIRT_LAZY_NONE;
 309
 310         return this_cpu_read(paravirt_lazy_mode);
 311 }
 312
 313 struct pv_info pv_info = {
 314         .name = "bare hardware",
 315         .kernel_rpl = 0,
 316         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 317
 318 #ifdef CONFIG_X86_64
 319         .extra_user_64bit_cs = __USER_CS,
 320 #endif
 321 };
 322
 323 struct pv_init_ops pv_init_ops = {
 324         .patch = native_patch,
 325 };
 326
 327 struct pv_time_ops pv_time_ops = {
 328         .sched_clock = native_sched_clock,
 329         .steal_clock = native_steal_clock,
 330 };
 331
 332 __visible struct pv_irq_ops pv_irq_ops = {
 333         .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
 334         .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
 335         .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
 336         .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
 337         .safe_halt = native_safe_halt,
 338         .halt = native_halt,
 339 };
 340
 341 __visible struct pv_cpu_ops pv_cpu_ops = {
 342         .cpuid = native_cpuid,
 343         .get_debugreg = native_get_debugreg,
 344         .set_debugreg = native_set_debugreg,
 345         .read_cr0 = native_read_cr0,
 346         .write_cr0 = native_write_cr0,
 347         .write_cr4 = native_write_cr4,
 348 #ifdef CONFIG_X86_64
 349         .read_cr8 = native_read_cr8,
 350         .write_cr8 = native_write_cr8,
 351 #endif
 352         .wbinvd = native_wbinvd,
 353         .read_msr = native_read_msr,
 354         .write_msr = native_write_msr,
 355         .read_msr_safe = native_read_msr_safe,
 356         .write_msr_safe = native_write_msr_safe,
 357         .read_pmc = native_read_pmc,
 358         .load_tr_desc = native_load_tr_desc,
 359         .set_ldt = native_set_ldt,
 360         .load_gdt = native_load_gdt,
 361         .load_idt = native_load_idt,
 362         .store_tr = native_store_tr,
 363         .load_tls = native_load_tls,
 364 #ifdef CONFIG_X86_64
 365         .load_gs_index = native_load_gs_index,
 366 #endif
 367         .write_ldt_entry = native_write_ldt_entry,
 368         .write_gdt_entry = native_write_gdt_entry,
 369         .write_idt_entry = native_write_idt_entry,
 370
 371         .alloc_ldt = paravirt_nop,
 372         .free_ldt = paravirt_nop,
 373
 374         .load_sp0 = native_load_sp0,
 375
 376 #ifdef CONFIG_X86_64
 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 __ro_after_init = {
 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_one_user = native_flush_tlb_one_user,
 412         .flush_tlb_others = native_flush_tlb_others,
 413         .tlb_remove_table = (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 414
 415         .pgd_alloc = __paravirt_pgd_alloc,
 416         .pgd_free = paravirt_nop,
 417
 418         .alloc_pte = paravirt_nop,
 419         .alloc_pmd = paravirt_nop,
 420         .alloc_pud = paravirt_nop,
 421         .alloc_p4d = paravirt_nop,
 422         .release_pte = paravirt_nop,
 423         .release_pmd = paravirt_nop,
 424         .release_pud = paravirt_nop,
 425         .release_p4d = paravirt_nop,
 426
 427         .set_pte = native_set_pte,
 428         .set_pte_at = native_set_pte_at,
 429         .set_pmd = native_set_pmd,
 430
 431         .ptep_modify_prot_start = __ptep_modify_prot_start,
 432         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 433
 434 #if CONFIG_PGTABLE_LEVELS >= 3
 435 #ifdef CONFIG_X86_PAE
 436         .set_pte_atomic = native_set_pte_atomic,
 437         .pte_clear = native_pte_clear,
 438         .pmd_clear = native_pmd_clear,
 439 #endif
 440         .set_pud = native_set_pud,
 441
 442         .pmd_val = PTE_IDENT,
 443         .make_pmd = PTE_IDENT,
 444
 445 #if CONFIG_PGTABLE_LEVELS >= 4
 446         .pud_val = PTE_IDENT,
 447         .make_pud = PTE_IDENT,
 448
 449         .set_p4d = native_set_p4d,
 450
 451 #if CONFIG_PGTABLE_LEVELS >= 5
 452         .p4d_val = PTE_IDENT,
 453         .make_p4d = PTE_IDENT,
 454
 455         .set_pgd = native_set_pgd,
 456 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 457 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
 458 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 459
 460         .pte_val = PTE_IDENT,
 461         .pgd_val = PTE_IDENT,
 462
 463         .make_pte = PTE_IDENT,
 464         .make_pgd = PTE_IDENT,
 465
 466         .dup_mmap = paravirt_nop,
 467         .exit_mmap = paravirt_nop,
 468         .activate_mm = paravirt_nop,
 469
 470         .lazy_mode = {
 471                 .enter = paravirt_nop,
 472                 .leave = paravirt_nop,
 473                 .flush = paravirt_nop,
 474         },
 475
 476         .set_fixmap = native_set_fixmap,
 477 };
 478
 479 EXPORT_SYMBOL_GPL(pv_time_ops);
 480 EXPORT_SYMBOL    (pv_cpu_ops);
 481 EXPORT_SYMBOL    (pv_mmu_ops);
 482 EXPORT_SYMBOL_GPL(pv_info);
 483 EXPORT_SYMBOL    (pv_irq_ops);