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
  27 #include <asm/bug.h>
  28 #include <asm/paravirt.h>
  29 #include <asm/desc.h>
  30 #include <asm/setup.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/time.h>
  33 #include <asm/pgalloc.h>
  34 #include <asm/irq.h>
  35 #include <asm/delay.h>
  36 #include <asm/fixmap.h>
  37 #include <asm/apic.h>
  38 #include <asm/tlbflush.h>
  39 #include <asm/timer.h>
  40
  41 /* nop stub */
  42 void _paravirt_nop(void)
  43 {
  44 }
  45
  46 /* identity function, which can be inlined */
  47 u32 _paravirt_ident_32(u32 x)
  48 {
  49         return x;
  50 }
  51
  52 u64 _paravirt_ident_64(u64 x)
  53 {
  54         return x;
  55 }
  56
  57 void __init default_banner(void)
  58 {
  59         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  60                pv_info.name);
  61 }
  62
  63 /* Simple instruction patching code. */
  64 #define DEF_NATIVE(ops, name, code)                                     \
  65         extern const char start_##ops##_##name[], end_##ops##_##name[]; \
  66         asm("start_" #ops "_" #name ": " code "; end_" #ops "_" #name ":")
  67
  68 /* Undefined instruction for dealing with missing ops pointers. */
  69 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  70
  71 unsigned paravirt_patch_nop(void)
  72 {
  73         return 0;
  74 }
  75
  76 unsigned paravirt_patch_ignore(unsigned len)
  77 {
  78         return len;
  79 }
  80
  81 struct branch {
  82         unsigned char opcode;
  83         u32 delta;
  84 } __attribute__((packed));
  85
  86 unsigned paravirt_patch_call(void *insnbuf,
  87                              const void *target, u16 tgt_clobbers,
  88                              unsigned long addr, u16 site_clobbers,
  89                              unsigned len)
  90 {
  91         struct branch *b = insnbuf;
  92         unsigned long delta = (unsigned long)target - (addr+5);
  93
  94         if (tgt_clobbers & ~site_clobbers)
  95                 return len;     /* target would clobber too much for this site */
  96         if (len < 5)
  97                 return len;     /* call too long for patch site */
  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                 return len;     /* call too long for patch site */
 114
 115         b->opcode = 0xe9;       /* jmp */
 116         b->delta = delta;
 117
 118         return 5;
 119 }
 120
 121 /* Neat trick to map patch type back to the call within the
 122  * corresponding structure. */
 123 static void *get_call_destination(u8 type)
 124 {
 125         struct paravirt_patch_template tmpl = {
 126                 .pv_init_ops = pv_init_ops,
 127                 .pv_time_ops = pv_time_ops,
 128                 .pv_cpu_ops = pv_cpu_ops,
 129                 .pv_irq_ops = pv_irq_ops,
 130                 .pv_apic_ops = pv_apic_ops,
 131                 .pv_mmu_ops = pv_mmu_ops,
 132 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 133                 .pv_lock_ops = pv_lock_ops,
 134 #endif
 135         };
 136         return *((void **)&tmpl + type);
 137 }
 138
 139 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 140                                 unsigned long addr, unsigned len)
 141 {
 142         void *opfunc = get_call_destination(type);
 143         unsigned ret;
 144
 145         if (opfunc == NULL)
 146                 /* If there's no function, patch it with a ud2a (BUG) */
 147                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 148         else if (opfunc == _paravirt_nop)
 149                 /* If the operation is a nop, then nop the callsite */
 150                 ret = paravirt_patch_nop();
 151
 152         /* identity functions just return their single argument */
 153         else if (opfunc == _paravirt_ident_32)
 154                 ret = paravirt_patch_ident_32(insnbuf, len);
 155         else if (opfunc == _paravirt_ident_64)
 156                 ret = paravirt_patch_ident_64(insnbuf, len);
 157
 158         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 159                  type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
 160                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
 161                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
 162                 /* If operation requires a jmp, then jmp */
 163                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
 164         else
 165                 /* Otherwise call the function; assume target could
 166                    clobber any caller-save reg */
 167                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
 168                                           addr, clobbers, len);
 169
 170         return ret;
 171 }
 172
 173 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
 174                               const char *start, const char *end)
 175 {
 176         unsigned insn_len = end - start;
 177
 178         if (insn_len > len || start == NULL)
 179                 insn_len = len;
 180         else
 181                 memcpy(insnbuf, start, insn_len);
 182
 183         return insn_len;
 184 }
 185
 186 static void native_flush_tlb(void)
 187 {
 188         __native_flush_tlb();
 189 }
 190
 191 /*
 192  * Global pages have to be flushed a bit differently. Not a real
 193  * performance problem because this does not happen often.
 194  */
 195 static void native_flush_tlb_global(void)
 196 {
 197         __native_flush_tlb_global();
 198 }
 199
 200 static void native_flush_tlb_single(unsigned long addr)
 201 {
 202         __native_flush_tlb_single(addr);
 203 }
 204
 205 /* These are in entry.S */
 206 extern void native_iret(void);
 207 extern void native_irq_enable_sysexit(void);
 208 extern void native_usergs_sysret32(void);
 209 extern void native_usergs_sysret64(void);
 210
 211 static struct resource reserve_ioports = {
 212         .start = 0,
 213         .end = IO_SPACE_LIMIT,
 214         .name = "paravirt-ioport",
 215         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 216 };
 217
 218 /*
 219  * Reserve the whole legacy IO space to prevent any legacy drivers
 220  * from wasting time probing for their hardware.  This is a fairly
 221  * brute-force approach to disabling all non-virtual drivers.
 222  *
 223  * Note that this must be called very early to have any effect.
 224  */
 225 int paravirt_disable_iospace(void)
 226 {
 227         return request_resource(&ioport_resource, &reserve_ioports);
 228 }
 229
 230 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 231
 232 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 233 {
 234         BUG_ON(percpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 235
 236         percpu_write(paravirt_lazy_mode, mode);
 237 }
 238
 239 static void leave_lazy(enum paravirt_lazy_mode mode)
 240 {
 241         BUG_ON(percpu_read(paravirt_lazy_mode) != mode);
 242
 243         percpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 244 }
 245
 246 void paravirt_enter_lazy_mmu(void)
 247 {
 248         enter_lazy(PARAVIRT_LAZY_MMU);
 249 }
 250
 251 void paravirt_leave_lazy_mmu(void)
 252 {
 253         leave_lazy(PARAVIRT_LAZY_MMU);
 254 }
 255
 256 void paravirt_start_context_switch(struct task_struct *prev)
 257 {
 258         BUG_ON(preemptible());
 259
 260         if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 261                 arch_leave_lazy_mmu_mode();
 262                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 263         }
 264         enter_lazy(PARAVIRT_LAZY_CPU);
 265 }
 266
 267 void paravirt_end_context_switch(struct task_struct *next)
 268 {
 269         BUG_ON(preemptible());
 270
 271         leave_lazy(PARAVIRT_LAZY_CPU);
 272
 273         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 274                 arch_enter_lazy_mmu_mode();
 275 }
 276
 277 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 278 {
 279         if (in_interrupt())
 280                 return PARAVIRT_LAZY_NONE;
 281
 282         return percpu_read(paravirt_lazy_mode);
 283 }
 284
 285 void arch_flush_lazy_mmu_mode(void)
 286 {
 287         preempt_disable();
 288
 289         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 290                 arch_leave_lazy_mmu_mode();
 291                 arch_enter_lazy_mmu_mode();
 292         }
 293
 294         preempt_enable();
 295 }
 296
 297 struct pv_info pv_info = {
 298         .name = "bare hardware",
 299         .paravirt_enabled = 0,
 300         .kernel_rpl = 0,
 301         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 302 };
 303
 304 struct pv_init_ops pv_init_ops = {
 305         .patch = native_patch,
 306 };
 307
 308 struct pv_time_ops pv_time_ops = {
 309         .sched_clock = native_sched_clock,
 310 };
 311
 312 struct pv_irq_ops pv_irq_ops = {
 313         .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
 314         .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
 315         .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
 316         .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
 317         .safe_halt = native_safe_halt,
 318         .halt = native_halt,
 319 #ifdef CONFIG_X86_64
 320         .adjust_exception_frame = paravirt_nop,
 321 #endif
 322 };
 323
 324 struct pv_cpu_ops pv_cpu_ops = {
 325         .cpuid = native_cpuid,
 326         .get_debugreg = native_get_debugreg,
 327         .set_debugreg = native_set_debugreg,
 328         .clts = native_clts,
 329         .read_cr0 = native_read_cr0,
 330         .write_cr0 = native_write_cr0,
 331         .read_cr4 = native_read_cr4,
 332         .read_cr4_safe = native_read_cr4_safe,
 333         .write_cr4 = native_write_cr4,
 334 #ifdef CONFIG_X86_64
 335         .read_cr8 = native_read_cr8,
 336         .write_cr8 = native_write_cr8,
 337 #endif
 338         .wbinvd = native_wbinvd,
 339         .read_msr = native_read_msr_safe,
 340         .rdmsr_regs = native_rdmsr_safe_regs,
 341         .write_msr = native_write_msr_safe,
 342         .wrmsr_regs = native_wrmsr_safe_regs,
 343         .read_tsc = native_read_tsc,
 344         .read_pmc = native_read_pmc,
 345         .read_tscp = native_read_tscp,
 346         .load_tr_desc = native_load_tr_desc,
 347         .set_ldt = native_set_ldt,
 348         .load_gdt = native_load_gdt,
 349         .load_idt = native_load_idt,
 350         .store_gdt = native_store_gdt,
 351         .store_idt = native_store_idt,
 352         .store_tr = native_store_tr,
 353         .load_tls = native_load_tls,
 354 #ifdef CONFIG_X86_64
 355         .load_gs_index = native_load_gs_index,
 356 #endif
 357         .write_ldt_entry = native_write_ldt_entry,
 358         .write_gdt_entry = native_write_gdt_entry,
 359         .write_idt_entry = native_write_idt_entry,
 360
 361         .alloc_ldt = paravirt_nop,
 362         .free_ldt = paravirt_nop,
 363
 364         .load_sp0 = native_load_sp0,
 365
 366 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 367         .irq_enable_sysexit = native_irq_enable_sysexit,
 368 #endif
 369 #ifdef CONFIG_X86_64
 370 #ifdef CONFIG_IA32_EMULATION
 371         .usergs_sysret32 = native_usergs_sysret32,
 372 #endif
 373         .usergs_sysret64 = native_usergs_sysret64,
 374 #endif
 375         .iret = native_iret,
 376         .swapgs = native_swapgs,
 377
 378         .set_iopl_mask = native_set_iopl_mask,
 379         .io_delay = native_io_delay,
 380
 381         .start_context_switch = paravirt_nop,
 382         .end_context_switch = paravirt_nop,
 383 };
 384
 385 struct pv_apic_ops pv_apic_ops = {
 386 #ifdef CONFIG_X86_LOCAL_APIC
 387         .startup_ipi_hook = paravirt_nop,
 388 #endif
 389 };
 390
 391 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
 392 /* 32-bit pagetable entries */
 393 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
 394 #else
 395 /* 64-bit pagetable entries */
 396 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 397 #endif
 398
 399 struct pv_mmu_ops pv_mmu_ops = {
 400
 401         .read_cr2 = native_read_cr2,
 402         .write_cr2 = native_write_cr2,
 403         .read_cr3 = native_read_cr3,
 404         .write_cr3 = native_write_cr3,
 405
 406         .flush_tlb_user = native_flush_tlb,
 407         .flush_tlb_kernel = native_flush_tlb_global,
 408         .flush_tlb_single = native_flush_tlb_single,
 409         .flush_tlb_others = native_flush_tlb_others,
 410
 411         .pgd_alloc = __paravirt_pgd_alloc,
 412         .pgd_free = paravirt_nop,
 413
 414         .alloc_pte = paravirt_nop,
 415         .alloc_pmd = paravirt_nop,
 416         .alloc_pmd_clone = paravirt_nop,
 417         .alloc_pud = paravirt_nop,
 418         .release_pte = paravirt_nop,
 419         .release_pmd = paravirt_nop,
 420         .release_pud = paravirt_nop,
 421
 422         .set_pte = native_set_pte,
 423         .set_pte_at = native_set_pte_at,
 424         .set_pmd = native_set_pmd,
 425         .pte_update = paravirt_nop,
 426         .pte_update_defer = paravirt_nop,
 427
 428         .ptep_modify_prot_start = __ptep_modify_prot_start,
 429         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 430
 431 #if PAGETABLE_LEVELS >= 3
 432 #ifdef CONFIG_X86_PAE
 433         .set_pte_atomic = native_set_pte_atomic,
 434         .pte_clear = native_pte_clear,
 435         .pmd_clear = native_pmd_clear,
 436 #endif
 437         .set_pud = native_set_pud,
 438
 439         .pmd_val = PTE_IDENT,
 440         .make_pmd = PTE_IDENT,
 441
 442 #if PAGETABLE_LEVELS == 4
 443         .pud_val = PTE_IDENT,
 444         .make_pud = PTE_IDENT,
 445
 446         .set_pgd = native_set_pgd,
 447 #endif
 448 #endif /* PAGETABLE_LEVELS >= 3 */
 449
 450         .pte_val = PTE_IDENT,
 451         .pgd_val = PTE_IDENT,
 452
 453         .make_pte = PTE_IDENT,
 454         .make_pgd = PTE_IDENT,
 455
 456         .dup_mmap = paravirt_nop,
 457         .exit_mmap = paravirt_nop,
 458         .activate_mm = paravirt_nop,
 459
 460         .lazy_mode = {
 461                 .enter = paravirt_nop,
 462                 .leave = paravirt_nop,
 463         },
 464
 465         .set_fixmap = native_set_fixmap,
 466 };
 467
 468 EXPORT_SYMBOL_GPL(pv_time_ops);
 469 EXPORT_SYMBOL    (pv_cpu_ops);
 470 EXPORT_SYMBOL    (pv_mmu_ops);
 471 EXPORT_SYMBOL_GPL(pv_apic_ops);
 472 EXPORT_SYMBOL_GPL(pv_info);
 473 EXPORT_SYMBOL    (pv_irq_ops);