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 #include <linux/pgtable.h>
  17
  18 #include <asm/bug.h>
  19 #include <asm/paravirt.h>
  20 #include <asm/debugreg.h>
  21 #include <asm/desc.h>
  22 #include <asm/setup.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 struct static_key paravirt_steal_enabled;
 164 struct static_key paravirt_steal_rq_enabled;
 165
 166 static u64 native_steal_clock(int cpu)
 167 {
 168         return 0;
 169 }
 170
 171 /* These are in entry.S */
 172 extern void native_iret(void);
 173 extern void native_usergs_sysret64(void);
 174
 175 static struct resource reserve_ioports = {
 176         .start = 0,
 177         .end = IO_SPACE_LIMIT,
 178         .name = "paravirt-ioport",
 179         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 180 };
 181
 182 /*
 183  * Reserve the whole legacy IO space to prevent any legacy drivers
 184  * from wasting time probing for their hardware.  This is a fairly
 185  * brute-force approach to disabling all non-virtual drivers.
 186  *
 187  * Note that this must be called very early to have any effect.
 188  */
 189 int paravirt_disable_iospace(void)
 190 {
 191         return request_resource(&ioport_resource, &reserve_ioports);
 192 }
 193
 194 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 195
 196 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 197 {
 198         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 199
 200         this_cpu_write(paravirt_lazy_mode, mode);
 201 }
 202
 203 static void leave_lazy(enum paravirt_lazy_mode mode)
 204 {
 205         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 206
 207         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 208 }
 209
 210 void paravirt_enter_lazy_mmu(void)
 211 {
 212         enter_lazy(PARAVIRT_LAZY_MMU);
 213 }
 214
 215 void paravirt_leave_lazy_mmu(void)
 216 {
 217         leave_lazy(PARAVIRT_LAZY_MMU);
 218 }
 219
 220 void paravirt_flush_lazy_mmu(void)
 221 {
 222         preempt_disable();
 223
 224         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 225                 arch_leave_lazy_mmu_mode();
 226                 arch_enter_lazy_mmu_mode();
 227         }
 228
 229         preempt_enable();
 230 }
 231
 232 #ifdef CONFIG_PARAVIRT_XXL
 233 void paravirt_start_context_switch(struct task_struct *prev)
 234 {
 235         BUG_ON(preemptible());
 236
 237         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 238                 arch_leave_lazy_mmu_mode();
 239                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 240         }
 241         enter_lazy(PARAVIRT_LAZY_CPU);
 242 }
 243
 244 void paravirt_end_context_switch(struct task_struct *next)
 245 {
 246         BUG_ON(preemptible());
 247
 248         leave_lazy(PARAVIRT_LAZY_CPU);
 249
 250         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 251                 arch_enter_lazy_mmu_mode();
 252 }
 253 #endif
 254
 255 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 256 {
 257         if (in_interrupt())
 258                 return PARAVIRT_LAZY_NONE;
 259
 260         return this_cpu_read(paravirt_lazy_mode);
 261 }
 262
 263 struct pv_info pv_info = {
 264         .name = "bare hardware",
 265 #ifdef CONFIG_PARAVIRT_XXL
 266         .kernel_rpl = 0,
 267         .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
 268
 269 #ifdef CONFIG_X86_64
 270         .extra_user_64bit_cs = __USER_CS,
 271 #endif
 272 #endif
 273 };
 274
 275 /* 64-bit pagetable entries */
 276 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 277
 278 struct paravirt_patch_template pv_ops = {
 279         /* Init ops. */
 280         .init.patch             = native_patch,
 281
 282         /* Time ops. */
 283         .time.sched_clock       = native_sched_clock,
 284         .time.steal_clock       = native_steal_clock,
 285
 286         /* Cpu ops. */
 287         .cpu.io_delay           = native_io_delay,
 288
 289 #ifdef CONFIG_PARAVIRT_XXL
 290         .cpu.cpuid              = native_cpuid,
 291         .cpu.get_debugreg       = native_get_debugreg,
 292         .cpu.set_debugreg       = native_set_debugreg,
 293         .cpu.read_cr0           = native_read_cr0,
 294         .cpu.write_cr0          = native_write_cr0,
 295         .cpu.write_cr4          = native_write_cr4,
 296         .cpu.wbinvd             = native_wbinvd,
 297         .cpu.read_msr           = native_read_msr,
 298         .cpu.write_msr          = native_write_msr,
 299         .cpu.read_msr_safe      = native_read_msr_safe,
 300         .cpu.write_msr_safe     = native_write_msr_safe,
 301         .cpu.read_pmc           = native_read_pmc,
 302         .cpu.load_tr_desc       = native_load_tr_desc,
 303         .cpu.set_ldt            = native_set_ldt,
 304         .cpu.load_gdt           = native_load_gdt,
 305         .cpu.load_idt           = native_load_idt,
 306         .cpu.store_tr           = native_store_tr,
 307         .cpu.load_tls           = native_load_tls,
 308 #ifdef CONFIG_X86_64
 309         .cpu.load_gs_index      = native_load_gs_index,
 310 #endif
 311         .cpu.write_ldt_entry    = native_write_ldt_entry,
 312         .cpu.write_gdt_entry    = native_write_gdt_entry,
 313         .cpu.write_idt_entry    = native_write_idt_entry,
 314
 315         .cpu.alloc_ldt          = paravirt_nop,
 316         .cpu.free_ldt           = paravirt_nop,
 317
 318         .cpu.load_sp0           = native_load_sp0,
 319
 320 #ifdef CONFIG_X86_64
 321         .cpu.usergs_sysret64    = native_usergs_sysret64,
 322 #endif
 323         .cpu.iret               = native_iret,
 324         .cpu.swapgs             = native_swapgs,
 325
 326 #ifdef CONFIG_X86_IOPL_IOPERM
 327         .cpu.update_io_bitmap   = native_tss_update_io_bitmap,
 328 #endif
 329
 330         .cpu.start_context_switch       = paravirt_nop,
 331         .cpu.end_context_switch         = paravirt_nop,
 332
 333         /* Irq ops. */
 334         .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
 335         .irq.restore_fl         = __PV_IS_CALLEE_SAVE(native_restore_fl),
 336         .irq.irq_disable        = __PV_IS_CALLEE_SAVE(native_irq_disable),
 337         .irq.irq_enable         = __PV_IS_CALLEE_SAVE(native_irq_enable),
 338         .irq.safe_halt          = native_safe_halt,
 339         .irq.halt               = native_halt,
 340 #endif /* CONFIG_PARAVIRT_XXL */
 341
 342         /* Mmu ops. */
 343         .mmu.flush_tlb_user     = native_flush_tlb_local,
 344         .mmu.flush_tlb_kernel   = native_flush_tlb_global,
 345         .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
 346         .mmu.flush_tlb_others   = native_flush_tlb_others,
 347         .mmu.tlb_remove_table   =
 348                         (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 349
 350         .mmu.exit_mmap          = paravirt_nop,
 351
 352 #ifdef CONFIG_PARAVIRT_XXL
 353         .mmu.read_cr2           = __PV_IS_CALLEE_SAVE(native_read_cr2),
 354         .mmu.write_cr2          = native_write_cr2,
 355         .mmu.read_cr3           = __native_read_cr3,
 356         .mmu.write_cr3          = native_write_cr3,
 357
 358         .mmu.pgd_alloc          = __paravirt_pgd_alloc,
 359         .mmu.pgd_free           = paravirt_nop,
 360
 361         .mmu.alloc_pte          = paravirt_nop,
 362         .mmu.alloc_pmd          = paravirt_nop,
 363         .mmu.alloc_pud          = paravirt_nop,
 364         .mmu.alloc_p4d          = paravirt_nop,
 365         .mmu.release_pte        = paravirt_nop,
 366         .mmu.release_pmd        = paravirt_nop,
 367         .mmu.release_pud        = paravirt_nop,
 368         .mmu.release_p4d        = paravirt_nop,
 369
 370         .mmu.set_pte            = native_set_pte,
 371         .mmu.set_pte_at         = native_set_pte_at,
 372         .mmu.set_pmd            = native_set_pmd,
 373
 374         .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
 375         .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,
 376
 377 #if CONFIG_PGTABLE_LEVELS >= 3
 378 #ifdef CONFIG_X86_PAE
 379         .mmu.set_pte_atomic     = native_set_pte_atomic,
 380         .mmu.pte_clear          = native_pte_clear,
 381         .mmu.pmd_clear          = native_pmd_clear,
 382 #endif
 383         .mmu.set_pud            = native_set_pud,
 384
 385         .mmu.pmd_val            = PTE_IDENT,
 386         .mmu.make_pmd           = PTE_IDENT,
 387
 388 #if CONFIG_PGTABLE_LEVELS >= 4
 389         .mmu.pud_val            = PTE_IDENT,
 390         .mmu.make_pud           = PTE_IDENT,
 391
 392         .mmu.set_p4d            = native_set_p4d,
 393
 394 #if CONFIG_PGTABLE_LEVELS >= 5
 395         .mmu.p4d_val            = PTE_IDENT,
 396         .mmu.make_p4d           = PTE_IDENT,
 397
 398         .mmu.set_pgd            = native_set_pgd,
 399 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 400 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
 401 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
 402
 403         .mmu.pte_val            = PTE_IDENT,
 404         .mmu.pgd_val            = PTE_IDENT,
 405
 406         .mmu.make_pte           = PTE_IDENT,
 407         .mmu.make_pgd           = PTE_IDENT,
 408
 409         .mmu.dup_mmap           = paravirt_nop,
 410         .mmu.activate_mm        = paravirt_nop,
 411
 412         .mmu.lazy_mode = {
 413                 .enter          = paravirt_nop,
 414                 .leave          = paravirt_nop,
 415                 .flush          = paravirt_nop,
 416         },
 417
 418         .mmu.set_fixmap         = native_set_fixmap,
 419 #endif /* CONFIG_PARAVIRT_XXL */
 420
 421 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
 422         /* Lock ops. */
 423 #ifdef CONFIG_SMP
 424         .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
 425         .lock.queued_spin_unlock        =
 426                                 PV_CALLEE_SAVE(__native_queued_spin_unlock),
 427         .lock.wait                      = paravirt_nop,
 428         .lock.kick                      = paravirt_nop,
 429         .lock.vcpu_is_preempted         =
 430                                 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
 431 #endif /* SMP */
 432 #endif
 433 };
 434
 435 #ifdef CONFIG_PARAVIRT_XXL
 436 /* At this point, native_get/set_debugreg has real function entries */
 437 NOKPROBE_SYMBOL(native_get_debugreg);
 438 NOKPROBE_SYMBOL(native_set_debugreg);
 439 NOKPROBE_SYMBOL(native_load_idt);
 440 #endif
 441
 442 EXPORT_SYMBOL(pv_ops);
 443 EXPORT_SYMBOL_GPL(pv_info);