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 #include <linux/static_call.h>
  18
  19 #include <asm/bug.h>
  20 #include <asm/paravirt.h>
  21 #include <asm/debugreg.h>
  22 #include <asm/desc.h>
  23 #include <asm/setup.h>
  24 #include <asm/time.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/irq.h>
  27 #include <asm/delay.h>
  28 #include <asm/fixmap.h>
  29 #include <asm/apic.h>
  30 #include <asm/tlbflush.h>
  31 #include <asm/timer.h>
  32 #include <asm/special_insns.h>
  33 #include <asm/tlb.h>
  34 #include <asm/io_bitmap.h>
  35
  36 /*
  37  * nop stub, which must not clobber anything *including the stack* to
  38  * avoid confusing the entry prologues.
  39  */
  40 extern void _paravirt_nop(void);
  41 asm (".pushsection .entry.text, \"ax\"\n"
  42      ".global _paravirt_nop\n"
  43      "_paravirt_nop:\n\t"
  44      ASM_RET
  45      ".size _paravirt_nop, . - _paravirt_nop\n\t"
  46      ".type _paravirt_nop, @function\n\t"
  47      ".popsection");
  48
  49 /* stub always returning 0. */
  50 asm (".pushsection .entry.text, \"ax\"\n"
  51      ".global paravirt_ret0\n"
  52      "paravirt_ret0:\n\t"
  53      "xor %" _ASM_AX ", %" _ASM_AX ";\n\t"
  54      ASM_RET
  55      ".size paravirt_ret0, . - paravirt_ret0\n\t"
  56      ".type paravirt_ret0, @function\n\t"
  57      ".popsection");
  58
  59
  60 void __init default_banner(void)
  61 {
  62         printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
  63                pv_info.name);
  64 }
  65
  66 /* Undefined instruction for dealing with missing ops pointers. */
  67 noinstr void paravirt_BUG(void)
  68 {
  69         BUG();
  70 }
  71
  72 struct branch {
  73         unsigned char opcode;
  74         u32 delta;
  75 } __attribute__((packed));
  76
  77 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
  78                                     unsigned long addr, unsigned len)
  79 {
  80         const int call_len = 5;
  81         struct branch *b = insn_buff;
  82         unsigned long delta = (unsigned long)target - (addr+call_len);
  83
  84         if (len < call_len) {
  85                 pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
  86                 /* Kernel might not be viable if patching fails, bail out: */
  87                 BUG_ON(1);
  88         }
  89
  90         b->opcode = 0xe8; /* call */
  91         b->delta = delta;
  92         BUILD_BUG_ON(sizeof(*b) != call_len);
  93
  94         return call_len;
  95 }
  96
  97 #ifdef CONFIG_PARAVIRT_XXL
  98 /* identity function, which can be inlined */
  99 u64 notrace _paravirt_ident_64(u64 x)
 100 {
 101         return x;
 102 }
 103 #endif
 104
 105 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
 106
 107 void __init native_pv_lock_init(void)
 108 {
 109         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 110                 static_branch_disable(&virt_spin_lock_key);
 111 }
 112
 113 unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr,
 114                             unsigned int len)
 115 {
 116         /*
 117          * Neat trick to map patch type back to the call within the
 118          * corresponding structure.
 119          */
 120         void *opfunc = *((void **)&pv_ops + type);
 121         unsigned ret;
 122
 123         if (opfunc == NULL)
 124                 /* If there's no function, patch it with paravirt_BUG() */
 125                 ret = paravirt_patch_call(insn_buff, paravirt_BUG, addr, len);
 126         else if (opfunc == _paravirt_nop)
 127                 ret = 0;
 128         else
 129                 /* Otherwise call the function. */
 130                 ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
 131
 132         return ret;
 133 }
 134
 135 struct static_key paravirt_steal_enabled;
 136 struct static_key paravirt_steal_rq_enabled;
 137
 138 static u64 native_steal_clock(int cpu)
 139 {
 140         return 0;
 141 }
 142
 143 DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
 144 DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock);
 145
 146 void paravirt_set_sched_clock(u64 (*func)(void))
 147 {
 148         static_call_update(pv_sched_clock, func);
 149 }
 150
 151 /* These are in entry.S */
 152 extern void native_iret(void);
 153
 154 static struct resource reserve_ioports = {
 155         .start = 0,
 156         .end = IO_SPACE_LIMIT,
 157         .name = "paravirt-ioport",
 158         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
 159 };
 160
 161 /*
 162  * Reserve the whole legacy IO space to prevent any legacy drivers
 163  * from wasting time probing for their hardware.  This is a fairly
 164  * brute-force approach to disabling all non-virtual drivers.
 165  *
 166  * Note that this must be called very early to have any effect.
 167  */
 168 int paravirt_disable_iospace(void)
 169 {
 170         return request_resource(&ioport_resource, &reserve_ioports);
 171 }
 172
 173 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
 174
 175 static inline void enter_lazy(enum paravirt_lazy_mode mode)
 176 {
 177         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
 178
 179         this_cpu_write(paravirt_lazy_mode, mode);
 180 }
 181
 182 static void leave_lazy(enum paravirt_lazy_mode mode)
 183 {
 184         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
 185
 186         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
 187 }
 188
 189 void paravirt_enter_lazy_mmu(void)
 190 {
 191         enter_lazy(PARAVIRT_LAZY_MMU);
 192 }
 193
 194 void paravirt_leave_lazy_mmu(void)
 195 {
 196         leave_lazy(PARAVIRT_LAZY_MMU);
 197 }
 198
 199 void paravirt_flush_lazy_mmu(void)
 200 {
 201         preempt_disable();
 202
 203         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
 204                 arch_leave_lazy_mmu_mode();
 205                 arch_enter_lazy_mmu_mode();
 206         }
 207
 208         preempt_enable();
 209 }
 210
 211 #ifdef CONFIG_PARAVIRT_XXL
 212 void paravirt_start_context_switch(struct task_struct *prev)
 213 {
 214         BUG_ON(preemptible());
 215
 216         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
 217                 arch_leave_lazy_mmu_mode();
 218                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
 219         }
 220         enter_lazy(PARAVIRT_LAZY_CPU);
 221 }
 222
 223 void paravirt_end_context_switch(struct task_struct *next)
 224 {
 225         BUG_ON(preemptible());
 226
 227         leave_lazy(PARAVIRT_LAZY_CPU);
 228
 229         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
 230                 arch_enter_lazy_mmu_mode();
 231 }
 232
 233 static noinstr unsigned long pv_native_read_cr2(void)
 234 {
 235         return native_read_cr2();
 236 }
 237
 238 static noinstr void pv_native_write_cr2(unsigned long val)
 239 {
 240         native_write_cr2(val);
 241 }
 242
 243 static noinstr unsigned long pv_native_get_debugreg(int regno)
 244 {
 245         return native_get_debugreg(regno);
 246 }
 247
 248 static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
 249 {
 250         native_set_debugreg(regno, val);
 251 }
 252
 253 static noinstr void pv_native_irq_enable(void)
 254 {
 255         native_irq_enable();
 256 }
 257
 258 static noinstr void pv_native_irq_disable(void)
 259 {
 260         native_irq_disable();
 261 }
 262 #endif
 263
 264 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 265 {
 266         if (in_interrupt())
 267                 return PARAVIRT_LAZY_NONE;
 268
 269         return this_cpu_read(paravirt_lazy_mode);
 270 }
 271
 272 struct pv_info pv_info = {
 273         .name = "bare hardware",
 274 #ifdef CONFIG_PARAVIRT_XXL
 275         .extra_user_64bit_cs = __USER_CS,
 276 #endif
 277 };
 278
 279 /* 64-bit pagetable entries */
 280 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
 281
 282 struct paravirt_patch_template pv_ops = {
 283         /* Cpu ops. */
 284         .cpu.io_delay           = native_io_delay,
 285
 286 #ifdef CONFIG_PARAVIRT_XXL
 287         .cpu.cpuid              = native_cpuid,
 288         .cpu.get_debugreg       = pv_native_get_debugreg,
 289         .cpu.set_debugreg       = pv_native_set_debugreg,
 290         .cpu.read_cr0           = native_read_cr0,
 291         .cpu.write_cr0          = native_write_cr0,
 292         .cpu.write_cr4          = native_write_cr4,
 293         .cpu.wbinvd             = native_wbinvd,
 294         .cpu.read_msr           = native_read_msr,
 295         .cpu.write_msr          = native_write_msr,
 296         .cpu.read_msr_safe      = native_read_msr_safe,
 297         .cpu.write_msr_safe     = native_write_msr_safe,
 298         .cpu.read_pmc           = native_read_pmc,
 299         .cpu.load_tr_desc       = native_load_tr_desc,
 300         .cpu.set_ldt            = native_set_ldt,
 301         .cpu.load_gdt           = native_load_gdt,
 302         .cpu.load_idt           = native_load_idt,
 303         .cpu.store_tr           = native_store_tr,
 304         .cpu.load_tls           = native_load_tls,
 305         .cpu.load_gs_index      = native_load_gs_index,
 306         .cpu.write_ldt_entry    = native_write_ldt_entry,
 307         .cpu.write_gdt_entry    = native_write_gdt_entry,
 308         .cpu.write_idt_entry    = native_write_idt_entry,
 309
 310         .cpu.alloc_ldt          = paravirt_nop,
 311         .cpu.free_ldt           = paravirt_nop,
 312
 313         .cpu.load_sp0           = native_load_sp0,
 314
 315 #ifdef CONFIG_X86_IOPL_IOPERM
 316         .cpu.invalidate_io_bitmap       = native_tss_invalidate_io_bitmap,
 317         .cpu.update_io_bitmap           = native_tss_update_io_bitmap,
 318 #endif
 319
 320         .cpu.start_context_switch       = paravirt_nop,
 321         .cpu.end_context_switch         = paravirt_nop,
 322
 323         /* Irq ops. */
 324         .irq.save_fl            = __PV_IS_CALLEE_SAVE(native_save_fl),
 325         .irq.irq_disable        = __PV_IS_CALLEE_SAVE(pv_native_irq_disable),
 326         .irq.irq_enable         = __PV_IS_CALLEE_SAVE(pv_native_irq_enable),
 327         .irq.safe_halt          = native_safe_halt,
 328         .irq.halt               = native_halt,
 329 #endif /* CONFIG_PARAVIRT_XXL */
 330
 331         /* Mmu ops. */
 332         .mmu.flush_tlb_user     = native_flush_tlb_local,
 333         .mmu.flush_tlb_kernel   = native_flush_tlb_global,
 334         .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
 335         .mmu.flush_tlb_multi    = native_flush_tlb_multi,
 336         .mmu.tlb_remove_table   =
 337                         (void (*)(struct mmu_gather *, void *))tlb_remove_page,
 338
 339         .mmu.exit_mmap          = paravirt_nop,
 340         .mmu.notify_page_enc_status_changed     = paravirt_nop,
 341
 342 #ifdef CONFIG_PARAVIRT_XXL
 343         .mmu.read_cr2           = __PV_IS_CALLEE_SAVE(pv_native_read_cr2),
 344         .mmu.write_cr2          = pv_native_write_cr2,
 345         .mmu.read_cr3           = __native_read_cr3,
 346         .mmu.write_cr3          = native_write_cr3,
 347
 348         .mmu.pgd_alloc          = __paravirt_pgd_alloc,
 349         .mmu.pgd_free           = paravirt_nop,
 350
 351         .mmu.alloc_pte          = paravirt_nop,
 352         .mmu.alloc_pmd          = paravirt_nop,
 353         .mmu.alloc_pud          = paravirt_nop,
 354         .mmu.alloc_p4d          = paravirt_nop,
 355         .mmu.release_pte        = paravirt_nop,
 356         .mmu.release_pmd        = paravirt_nop,
 357         .mmu.release_pud        = paravirt_nop,
 358         .mmu.release_p4d        = paravirt_nop,
 359
 360         .mmu.set_pte            = native_set_pte,
 361         .mmu.set_pmd            = native_set_pmd,
 362
 363         .mmu.ptep_modify_prot_start     = __ptep_modify_prot_start,
 364         .mmu.ptep_modify_prot_commit    = __ptep_modify_prot_commit,
 365
 366         .mmu.set_pud            = native_set_pud,
 367
 368         .mmu.pmd_val            = PTE_IDENT,
 369         .mmu.make_pmd           = PTE_IDENT,
 370
 371         .mmu.pud_val            = PTE_IDENT,
 372         .mmu.make_pud           = PTE_IDENT,
 373
 374         .mmu.set_p4d            = native_set_p4d,
 375
 376 #if CONFIG_PGTABLE_LEVELS >= 5
 377         .mmu.p4d_val            = PTE_IDENT,
 378         .mmu.make_p4d           = PTE_IDENT,
 379
 380         .mmu.set_pgd            = native_set_pgd,
 381 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 382
 383         .mmu.pte_val            = PTE_IDENT,
 384         .mmu.pgd_val            = PTE_IDENT,
 385
 386         .mmu.make_pte           = PTE_IDENT,
 387         .mmu.make_pgd           = PTE_IDENT,
 388
 389         .mmu.dup_mmap           = paravirt_nop,
 390         .mmu.activate_mm        = paravirt_nop,
 391
 392         .mmu.lazy_mode = {
 393                 .enter          = paravirt_nop,
 394                 .leave          = paravirt_nop,
 395                 .flush          = paravirt_nop,
 396         },
 397
 398         .mmu.set_fixmap         = native_set_fixmap,
 399 #endif /* CONFIG_PARAVIRT_XXL */
 400
 401 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
 402         /* Lock ops. */
 403 #ifdef CONFIG_SMP
 404         .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
 405         .lock.queued_spin_unlock        =
 406                                 PV_CALLEE_SAVE(__native_queued_spin_unlock),
 407         .lock.wait                      = paravirt_nop,
 408         .lock.kick                      = paravirt_nop,
 409         .lock.vcpu_is_preempted         =
 410                                 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
 411 #endif /* SMP */
 412 #endif
 413 };
 414
 415 #ifdef CONFIG_PARAVIRT_XXL
 416 NOKPROBE_SYMBOL(native_load_idt);
 417
 418 void (*paravirt_iret)(void) = native_iret;
 419 #endif
 420
 421 EXPORT_SYMBOL(pv_ops);
 422 EXPORT_SYMBOL_GPL(pv_info);