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/debugreg.h>
  30 #include <asm/desc.h>
  31 #include <asm/setup.h>
  32 #include <asm/pgtable.h>
  33 #include <asm/time.h>
  34 #include <asm/pgalloc.h>
  35 #include <asm/irq.h>
  36 #include <asm/delay.h>
  37 #include <asm/fixmap.h>
  38 #include <asm/apic.h>
  39 #include <asm/tlbflush.h>
  40 #include <asm/timer.h>
  41 #include <asm/special_insns.h>
  42
  43 /* nop stub */
  44 void _paravirt_nop(void)
  45 {
  46 }
  47
  48 /* identity function, which can be inlined */
  49 u32 _paravirt_ident_32(u32 x)
  50 {
  51         return x;
  52 }
  53
  54 u64 _paravirt_ident_64(u64 x)
  55 {
  56         return x;
  57 }
  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 unsigned paravirt_patch_nop(void)
  69 {
  70         return 0;
  71 }
  72
  73 unsigned paravirt_patch_ignore(unsigned len)
  74 {
  75         return len;
  76 }
  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 (tgt_clobbers & ~site_clobbers)
  92                 return len;     /* target would clobber too much for this site */
  93         if (len < 5)
  94                 return len;     /* call too long for patch site */
  95
  96         b->opcode = 0xe8; /* call */
  97         b->delta = delta;
  98         BUILD_BUG_ON(sizeof(*b) != 5);
  99
 100         return 5;
 101 }
 102
 103 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 104                             unsigned long addr, unsigned len)
 105 {
 106         struct branch *b = insnbuf;
 107         unsigned long delta = (unsigned long)target - (addr+5);
 108
 109         if (len < 5)
 110                 return len;     /* call too long for patch site */
 111
 112         b->opcode = 0xe9;       /* jmp */
 113         b->delta = delta;
 114
 115         return 5;
 116 }
 117
 118 /* Neat trick to map patch type back to the call within the
 119  * corresponding structure. */
 120 static void *get_call_destination(u8 type)
 121 {
 122         struct paravirt_patch_template tmpl = {
 123                 .pv_init_ops = pv_init_ops,
 124                 .pv_time_ops = pv_time_ops,
 125                 .pv_cpu_ops = pv_cpu_ops,
 126                 .pv_irq_ops = pv_irq_ops,
 127                 .pv_apic_ops = pv_apic_ops,
 128                 .pv_mmu_ops = pv_mmu_ops,
 129 #ifdef CONFIG_PARAVIRT_SPINLOCKS
 130                 .pv_lock_ops = pv_lock_ops,
 131 #endif
 132         };
 133         return *((void **)&tmpl + type);
 134 }
 135
 136 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
 137                                 unsigned long addr, unsigned len)
 138 {
 139         void *opfunc = get_call_destination(type);
 140         unsigned ret;
 141
 142         if (opfunc == NULL)
 143                 /* If there's no function, patch it with a ud2a (BUG) */
 144                 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 145         else if (opfunc == _paravirt_nop)
 146                 /* If the operation is a nop, then nop the callsite */
 147                 ret = paravirt_patch_nop();
 148
 149         /* identity functions just return their single argument */
 150         else if (opfunc == _paravirt_ident_32)
 151                 ret = paravirt_patch_ident_32(insnbuf, len);
 152         else if (opfunc == _paravirt_ident_64)
 153                 ret = paravirt_patch_ident_64(insnbuf, len);
 154
 155         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
 156                  type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
 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_tsc = native_read_tsc,
 352         .read_pmc = native_read_pmc,
 353         .read_tscp = native_read_tscp,
 354         .load_tr_desc = native_load_tr_desc,
 355         .set_ldt = native_set_ldt,
 356         .load_gdt = native_load_gdt,
 357         .load_idt = native_load_idt,
 358         .store_idt = native_store_idt,
 359         .store_tr = native_store_tr,
 360         .load_tls = native_load_tls,
 361 #ifdef CONFIG_X86_64
 362         .load_gs_index = native_load_gs_index,
 363 #endif
 364         .write_ldt_entry = native_write_ldt_entry,
 365         .write_gdt_entry = native_write_gdt_entry,
 366         .write_idt_entry = native_write_idt_entry,
 367
 368         .alloc_ldt = paravirt_nop,
 369         .free_ldt = paravirt_nop,
 370
 371         .load_sp0 = native_load_sp0,
 372
 373 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 374         .irq_enable_sysexit = native_irq_enable_sysexit,
 375 #endif
 376 #ifdef CONFIG_X86_64
 377 #ifdef CONFIG_IA32_EMULATION
 378         .usergs_sysret32 = native_usergs_sysret32,
 379 #endif
 380         .usergs_sysret64 = native_usergs_sysret64,
 381 #endif
 382         .iret = native_iret,
 383         .swapgs = native_swapgs,
 384
 385         .set_iopl_mask = native_set_iopl_mask,
 386         .io_delay = native_io_delay,
 387
 388         .start_context_switch = paravirt_nop,
 389         .end_context_switch = paravirt_nop,
 390 };
 391
 392 struct pv_apic_ops pv_apic_ops = {
 393 #ifdef CONFIG_X86_LOCAL_APIC
 394         .startup_ipi_hook = paravirt_nop,
 395 #endif
 396 };
 397
 398 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
 399 /* 32-bit pagetable entries */
 400 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
 401 #else
 402 /* 64-bit pagetable entries */
 403 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 404 #endif
 405
 406 struct pv_mmu_ops pv_mmu_ops = {
 407
 408         .read_cr2 = native_read_cr2,
 409         .write_cr2 = native_write_cr2,
 410         .read_cr3 = native_read_cr3,
 411         .write_cr3 = native_write_cr3,
 412
 413         .flush_tlb_user = native_flush_tlb,
 414         .flush_tlb_kernel = native_flush_tlb_global,
 415         .flush_tlb_single = native_flush_tlb_single,
 416         .flush_tlb_others = native_flush_tlb_others,
 417
 418         .pgd_alloc = __paravirt_pgd_alloc,
 419         .pgd_free = paravirt_nop,
 420
 421         .alloc_pte = paravirt_nop,
 422         .alloc_pmd = paravirt_nop,
 423         .alloc_pud = paravirt_nop,
 424         .release_pte = paravirt_nop,
 425         .release_pmd = paravirt_nop,
 426         .release_pud = paravirt_nop,
 427
 428         .set_pte = native_set_pte,
 429         .set_pte_at = native_set_pte_at,
 430         .set_pmd = native_set_pmd,
 431         .set_pmd_at = native_set_pmd_at,
 432         .pte_update = paravirt_nop,
 433         .pte_update_defer = paravirt_nop,
 434         .pmd_update = paravirt_nop,
 435         .pmd_update_defer = paravirt_nop,
 436
 437         .ptep_modify_prot_start = __ptep_modify_prot_start,
 438         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
 439
 440 #if PAGETABLE_LEVELS >= 3
 441 #ifdef CONFIG_X86_PAE
 442         .set_pte_atomic = native_set_pte_atomic,
 443         .pte_clear = native_pte_clear,
 444         .pmd_clear = native_pmd_clear,
 445 #endif
 446         .set_pud = native_set_pud,
 447
 448         .pmd_val = PTE_IDENT,
 449         .make_pmd = PTE_IDENT,
 450
 451 #if PAGETABLE_LEVELS == 4
 452         .pud_val = PTE_IDENT,
 453         .make_pud = PTE_IDENT,
 454
 455         .set_pgd = native_set_pgd,
 456 #endif
 457 #endif /* PAGETABLE_LEVELS >= 3 */
 458
 459         .pte_val = PTE_IDENT,
 460         .pgd_val = PTE_IDENT,
 461
 462         .make_pte = PTE_IDENT,
 463         .make_pgd = PTE_IDENT,
 464
 465         .dup_mmap = paravirt_nop,
 466         .exit_mmap = paravirt_nop,
 467         .activate_mm = paravirt_nop,
 468
 469         .lazy_mode = {
 470                 .enter = paravirt_nop,
 471                 .leave = paravirt_nop,
 472                 .flush = paravirt_nop,
 473         },
 474
 475         .set_fixmap = native_set_fixmap,
 476 };
 477
 478 EXPORT_SYMBOL_GPL(pv_time_ops);
 479 EXPORT_SYMBOL    (pv_cpu_ops);
 480 EXPORT_SYMBOL    (pv_mmu_ops);
 481 EXPORT_SYMBOL_GPL(pv_apic_ops);
 482 EXPORT_SYMBOL_GPL(pv_info);
 483 EXPORT_SYMBOL    (pv_irq_ops);