arch/x86/kernel/paravirt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*  Paravirtualization interfaces
   3     Copyright (C) 2006 Rusty Russell IBM Corporation
   4
   5
   6     2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
   7 */
   8
   9 #include <linux/errno.h>
  10 #include <linux/init.h>
  11 #include <linux/export.h>
  12 #include <linux/efi.h>
  13 #include <linux/bcd.h>
  14 #include <linux/highmem.h>
  15 #include <linux/kprobes.h>
  16
  17 #include <asm/bug.h>
  18 #include <asm/paravirt.h>
  19 #include <asm/debugreg.h>
  20 #include <asm/desc.h>
  21 #include <asm/setup.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/time.h>
  24 #include <asm/pgalloc.h>
  25 #include <asm/irq.h>
  26 #include <asm/delay.h>
  27 #include <asm/fixmap.h>
  28 #include <asm/apic.h>
  29 #include <asm/tlbflush.h>
  30 #include <asm/timer.h>
  31 #include <asm/special_insns.h>
  32 #include <asm/tlb.h>
  33 #include <asm/io_bitmap.h>
  34
  35 /*
  36  * nop stub, which must not clobber anything *including the stack* to
  37  * avoid confusing the entry prologues.
  38  */
  39 extern void _paravirt_nop(void);
  40 asm (".pushsection .entry.text, \"ax\"\n"
  41      ".global _paravirt_nop\n"
  42      "_paravirt_nop:\n\t"
  43      "ret\n\t"
  44      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  45      ".type _paravirt_nop, @function\n\t"
  46      ".popsection");
  47
  48 void __init default_banner(void)
  49 {
  50         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  51                pv_info.name);
  52 }
  53
  54 /* Undefined instruction for dealing with missing ops pointers. */
  55 static const unsigned char ud2a[] = { 0x0f, 0x0b };
  56
  57 struct branch {
  58         unsigned char opcode;
  59         u32 delta;
  60 } __attribute__((packed));
  61
  62 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
  63                                     unsigned long addr, unsigned len)
  64 {
  65         const int call_len = 5;
  66         struct branch *b = insn_buff;
  67         unsigned long delta = (unsigned long)target - (addr+call_len);
  68
  69         if (len < call_len) {
  70                 pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
  71                 /* Kernel might not be viable if patching fails, bail out: */
  72                 BUG_ON(1);
  73         }
  74
  75         b->opcode = 0xe8; /* call */
  76         b->delta = delta;
  77         BUILD_BUG_ON(sizeof(*b) != call_len);
  78
  79         return call_len;
  80 }
  81
  82 #ifdef CONFIG_PARAVIRT_XXL
  83 /* identity function, which can be inlined */
  84 u64 notrace _paravirt_ident_64(u64 x)
  85 {
  86         return x;
  87 }
  88
  89 static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
  90                                    unsigned long addr, unsigned len)
  91 {
  92         struct branch *b = insn_buff;
  93         unsigned long delta = (unsigned long)target - (addr+5);
  94
  95         if (len < 5) {
  96 #ifdef CONFIG_RETPOLINE
  97                 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
  98 #endif
  99                 return len;     /* call too long for patch site */
 100         }
 101
 102         b->opcode = 0xe9;       /* jmp */
 103         b->delta = delta;
 104
 105         return 5;
 106 }
 107 #endif
 108
 109 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
 110
 111 void __init native_pv_lock_init(void)
 112 {
 113         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 114                 static_branch_disable(&virt_spin_lock_key);
 115 }
 116
 117 unsigned paravirt_patch_default(u8 type, void *insn_buff,
 118                                 unsigned long addr, unsigned len)
 119 {
 120         /*
 121          * Neat trick to map patch type back to the call within the
 122          * corresponding structure.
 123          */
 124         void *opfunc = *((void **)&pv_ops + type);
 125         unsigned ret;
 126
 127         if (opfunc == NULL)
 128                 /* If there's no function, patch it with a ud2a (BUG) */
 129                 ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
 130         else if (opfunc == _paravirt_nop)
 131                 ret = 0;
 132
 133 #ifdef CONFIG_PARAVIRT_XXL
 134         /* identity functions just return their single argument */
 135         else if (opfunc == _paravirt_ident_64)
 136                 ret = paravirt_patch_ident_64(insn_buff, len);
 137
 138         else if (type == PARAVIRT_PATCH(cpu.iret) ||
 139                  type == PARAVIRT_PATCH(cpu.usergs_sysret64))
 140                 /* If operation requires a jmp, then jmp */
 141                 ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
 142 #endif
 143         else
 144                 /* Otherwise call the function. */
 145                 ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
 146
 147         return ret;
 148 }
 149
 150 unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
 151                               const char *start, const char *end)
 152 {
 153         unsigned insn_len = end - start;
 154
 155         /* Alternative instruction is too large for the patch site and we cannot continue: */
 156         BUG_ON(insn_len > len || start == NULL);
 157
 158         memcpy(insn_buff, start, insn_len);
 159
 160         return insn_len;
 161 }
 162
 163 static void native_flush_tlb(void)
 164 {
 165         __native_flush_tlb();
 166 }
 167
 168 /*
 169  * Global pages have to be flushed a bit differently. Not a real
 170  * performance problem because this does not happen often.
 171  */
 172 static void native_flush_tlb_global(void)
 173 {
 174         __native_flush_tlb_global();
 175 }
 176
 177 static void native_flush_tlb_one_user(unsigned long addr)
 178 {
 179         __native_flush_tlb_one_user(addr);
 180 }
 181
 182 struct static_key paravirt_steal_enabled;
 183 struct static_key paravirt_steal_rq_enabled;
 184
 185 static u64 native_steal_clock(int cpu)
 186 {
 187         return 0;
 188 }
 189
 190 /* These are in entry.S */
 191 extern void native_iret(void);
 192 extern void native_usergs_sysret64(void);
 193
 194 static struct resource reserve_ioports = {
 195         .start = 0,
 196         .end = IO_SPACE_LIMIT,
 197         .name = "paravirt-ioport",
 198         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 199 };
 200
 201 /*
 202  * Reserve the whole legacy IO space to prevent any legacy drivers
 203  * from wasting time probing for their hardware.  This is a fairly
 204  * brute-force approach to disabling all non-virtual drivers.
 205  *
 206  * Note that this must be called very early to have any effect.
 207  */
 208 int paravirt_disable_iospace(void)
 209 {
 210         return request_resource(&ioport_resource, &reserve_ioports);
 211 }
 212
 213 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 214
 215 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 216 {
 217         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 218
 219         this_cpu_write(paravirt_lazy_mode, mode);
 220 }
 221
 222 static void leave_lazy(enum paravirt_lazy_mode mode)
 223 {
 224         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 225
 226         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 227 }
 228
 229 void paravirt_enter_lazy_mmu(void)
 230 {
 231         enter_lazy(PARAVIRT_LAZY_MMU);
 232 }
 233
 234 void paravirt_leave_lazy_mmu(void)
 235 {
 236         leave_lazy(PARAVIRT_LAZY_MMU);
 237 }
 238
 239 void paravirt_flush_lazy_mmu(void)
 240 {
 241         preempt_disable();
 242
 243         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 244                 arch_leave_lazy_mmu_mode();
 245                 arch_enter_lazy_mmu_mode();
 246         }
 247
 248         preempt_enable();
 249 }
 250
 251 #ifdef CONFIG_PARAVIRT_XXL
 252 void paravirt_start_context_switch(struct task_struct *prev)
 253 {
 254         BUG_ON(preemptible());
 255
 256         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 257                 arch_leave_lazy_mmu_mode();
 258                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 259         }
 260         enter_lazy(PARAVIRT_LAZY_CPU);
 261 }
 262
 263 void paravirt_end_context_switch(struct task_struct *next)
 264 {
 265         BUG_ON(preemptible());
 266
 267         leave_lazy(PARAVIRT_LAZY_CPU);
 268
 269         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 270                 arch_enter_lazy_mmu_mode();
 271 }
 272 #endif
 273
 274 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 275 {
 276         if (in_interrupt())
 277                 return PARAVIRT_LAZY_NONE;
 278
 279         return this_cpu_read(paravirt_lazy_mode);
 280 }
 281
 282 struct pv_info pv_info = {
 283         .name = "bare hardware",
 284 #ifdef CONFIG_PARAVIRT_XXL
 285         .kernel_rpl = 0,
 286         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 287
 288 #ifdef CONFIG_X86_64
 289         .extra_user_64bit_cs = __USER_CS,
 290 #endif
 291 #endif
 292 };
 293
 294 /* 64-bit pagetable entries */
 295 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 296
 297 struct paravirt_patch_template pv_ops = {
 298         /* Init ops. */
 299         .init.patch             = native_patch,
 300
 301         /* Time ops. */
 302         .time.sched_clock       = native_sched_clock,
 303         .time.steal_clock       = native_steal_clock,
 304
 305         /* Cpu ops. */
 306         .cpu.io_delay           = native_io_delay,
 307
 308 #ifdef CONFIG_PARAVIRT_XXL
 309         .cpu.cpuid              = native_cpuid,
 310         .cpu.get_debugreg       = native_get_debugreg,
 311         .cpu.set_debugreg       = native_set_debugreg,
 312         .cpu.read_cr0           = native_read_cr0,
 313         .cpu.write_cr0          = native_write_cr0,
 314         .cpu.write_cr4          = native_write_cr4,
 315         .cpu.wbinvd             = native_wbinvd,
 316         .cpu.read_msr           = native_read_msr,
 317         .cpu.write_msr          = native_write_msr,
 318         .cpu.read_msr_safe      = native_read_msr_safe,
 319         .cpu.write_msr_safe     = native_write_msr_safe,
 320         .cpu.read_pmc           = native_read_pmc,
 321         .cpu.load_tr_desc       = native_load_tr_desc,
 322         .cpu.set_ldt            = native_set_ldt,
 323         .cpu.load_gdt           = native_load_gdt,
 324         .cpu.load_idt           = native_load_idt,
 325         .cpu.store_tr           = native_store_tr,
 326         .cpu.load_tls           = native_load_tls,
 327 #ifdef CONFIG_X86_64
 328         .cpu.load_gs_index      = native_load_gs_index,
 329 #endif
 330         .cpu.write_ldt_entry    = native_write_ldt_entry,
 331         .cpu.write_gdt_entry    = native_write_gdt_entry,
 332         .cpu.write_idt_entry    = native_write_idt_entry,
 333
 334         .cpu.alloc_ldt          = paravirt_nop,
 335         .cpu.free_ldt           = paravirt_nop,
 336
 337         .cpu.load_sp0           = native_load_sp0,
 338
 339 #ifdef CONFIG_X86_64
 340         .cpu.usergs_sysret64    = native_usergs_sysret64,
 341 #endif
 342         .cpu.iret               = native_iret,
 343         .cpu.swapgs             = native_swapgs,
 344
 345 #ifdef CONFIG_X86_IOPL_IOPERM
 346         .cpu.update_io_bitmap   = native_tss_update_io_bitmap,
 347 #endif
 348
 349         .cpu.start_context_switch       = paravirt_nop,
 350         .cpu.end_context_switch         = paravirt_nop,
 351
 352         /* Irq ops. */
 353         .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
 354         .irq.restore_fl         = __PV_IS_CALLEE_SAVE(native_restore_fl),
 355         .irq.irq_disable        = __PV_IS_CALLEE_SAVE(native_irq_disable),
 356         .irq.irq_enable         = __PV_IS_CALLEE_SAVE(native_irq_enable),
 357         .irq.safe_halt          = native_safe_halt,
 358         .irq.halt               = native_halt,
 359 #endif /* CONFIG_PARAVIRT_XXL */
 360
 361         /* Mmu ops. */
 362         .mmu.flush_tlb_user     = native_flush_tlb,
 363         .mmu.flush_tlb_kernel   = native_flush_tlb_global,
 364         .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
 365         .mmu.flush_tlb_others   = native_flush_tlb_others,
 366         .mmu.tlb_remove_table   =
 367                         (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 368
 369         .mmu.exit_mmap          = paravirt_nop,
 370
 371 #ifdef CONFIG_PARAVIRT_XXL
 372         .mmu.read_cr2           = __PV_IS_CALLEE_SAVE(native_read_cr2),
 373         .mmu.write_cr2          = native_write_cr2,
 374         .mmu.read_cr3           = __native_read_cr3,
 375         .mmu.write_cr3          = native_write_cr3,
 376
 377         .mmu.pgd_alloc          = __paravirt_pgd_alloc,
 378         .mmu.pgd_free           = paravirt_nop,
 379
 380         .mmu.alloc_pte          = paravirt_nop,
 381         .mmu.alloc_pmd          = paravirt_nop,
 382         .mmu.alloc_pud          = paravirt_nop,
 383         .mmu.alloc_p4d          = paravirt_nop,
 384         .mmu.release_pte        = paravirt_nop,
 385         .mmu.release_pmd        = paravirt_nop,
 386         .mmu.release_pud        = paravirt_nop,
 387         .mmu.release_p4d        = paravirt_nop,
 388
 389         .mmu.set_pte            = native_set_pte,
 390         .mmu.set_pte_at         = native_set_pte_at,
 391         .mmu.set_pmd            = native_set_pmd,
 392
 393         .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
 394         .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,
 395
 396 #if CONFIG_PGTABLE_LEVELS >= 3
 397 #ifdef CONFIG_X86_PAE
 398         .mmu.set_pte_atomic     = native_set_pte_atomic,
 399         .mmu.pte_clear          = native_pte_clear,
 400         .mmu.pmd_clear          = native_pmd_clear,
 401 #endif
 402         .mmu.set_pud            = native_set_pud,
 403
 404         .mmu.pmd_val            = PTE_IDENT,
 405         .mmu.make_pmd           = PTE_IDENT,
 406
 407 #if CONFIG_PGTABLE_LEVELS >= 4
 408         .mmu.pud_val            = PTE_IDENT,
 409         .mmu.make_pud           = PTE_IDENT,
 410
 411         .mmu.set_p4d            = native_set_p4d,
 412
 413 #if CONFIG_PGTABLE_LEVELS >= 5
 414         .mmu.p4d_val            = PTE_IDENT,
 415         .mmu.make_p4d           = PTE_IDENT,
 416
 417         .mmu.set_pgd            = native_set_pgd,
 418 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 419 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
 420 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 421
 422         .mmu.pte_val            = PTE_IDENT,
 423         .mmu.pgd_val            = PTE_IDENT,
 424
 425         .mmu.make_pte           = PTE_IDENT,
 426         .mmu.make_pgd           = PTE_IDENT,
 427
 428         .mmu.dup_mmap           = paravirt_nop,
 429         .mmu.activate_mm        = paravirt_nop,
 430
 431         .mmu.lazy_mode = {
 432                 .enter          = paravirt_nop,
 433                 .leave          = paravirt_nop,
 434                 .flush          = paravirt_nop,
 435         },
 436
 437         .mmu.set_fixmap         = native_set_fixmap,
 438 #endif /* CONFIG_PARAVIRT_XXL */
 439
 440 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
 441         /* Lock ops. */
 442 #ifdef CONFIG_SMP
 443         .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
 444         .lock.queued_spin_unlock        =
 445                                 PV_CALLEE_SAVE(__native_queued_spin_unlock),
 446         .lock.wait                      = paravirt_nop,
 447         .lock.kick                      = paravirt_nop,
 448         .lock.vcpu_is_preempted         =
 449                                 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
 450 #endif /* SMP */
 451 #endif
 452 };
 453
 454 #ifdef CONFIG_PARAVIRT_XXL
 455 /* At this point, native_get/set_debugreg has real function entries */
 456 NOKPROBE_SYMBOL(native_get_debugreg);
 457 NOKPROBE_SYMBOL(native_set_debugreg);
 458 NOKPROBE_SYMBOL(native_load_idt);
 459 #endif
 460
 461 EXPORT_SYMBOL(pv_ops);
 462 EXPORT_SYMBOL_GPL(pv_info);