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 34 /* 35 * nop stub, which must not clobber anything *including the stack* to 36 * avoid confusing the entry prologues. 37 */ 38 extern void _paravirt_nop(void); 39 asm (".pushsection .entry.text, \"ax\"\n" 40 ".global _paravirt_nop\n" 41 "_paravirt_nop:\n\t" 42 "ret\n\t" 43 ".size _paravirt_nop, . - _paravirt_nop\n\t" 44 ".type _paravirt_nop, @function\n\t" 45 ".popsection"); 46 47 void __init default_banner(void) 48 { 49 printk(KERN_INFO "Booting paravirtualized kernel on %s\n", 50 pv_info.name); 51 } 52 53 /* Undefined instruction for dealing with missing ops pointers. */ 54 static const unsigned char ud2a[] = { 0x0f, 0x0b }; 55 56 struct branch { 57 unsigned char opcode; 58 u32 delta; 59 } __attribute__((packed)); 60 61 static unsigned paravirt_patch_call(void *insn_buff, const void *target, 62 unsigned long addr, unsigned len) 63 { 64 const int call_len = 5; 65 struct branch *b = insn_buff; 66 unsigned long delta = (unsigned long)target - (addr+call_len); 67 68 if (len < call_len) { 69 pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr); 70 /* Kernel might not be viable if patching fails, bail out: */ 71 BUG_ON(1); 72 } 73 74 b->opcode = 0xe8; /* call */ 75 b->delta = delta; 76 BUILD_BUG_ON(sizeof(*b) != call_len); 77 78 return call_len; 79 } 80 81 #ifdef CONFIG_PARAVIRT_XXL 82 /* identity function, which can be inlined */ 83 u64 notrace _paravirt_ident_64(u64 x) 84 { 85 return x; 86 } 87 88 static unsigned paravirt_patch_jmp(void *insn_buff, const void *target, 89 unsigned long addr, unsigned len) 90 { 91 struct branch *b = insn_buff; 92 unsigned long delta = (unsigned long)target - (addr+5); 93 94 if (len < 5) { 95 #ifdef CONFIG_RETPOLINE 96 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr); 97 #endif 98 return len; /* call too long for patch site */ 99 } 100 101 b->opcode = 0xe9; /* jmp */ 102 b->delta = delta; 103 104 return 5; 105 } 106 #endif 107 108 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); 109 110 void __init native_pv_lock_init(void) 111 { 112 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) 113 static_branch_disable(&virt_spin_lock_key); 114 } 115 116 unsigned paravirt_patch_default(u8 type, void *insn_buff, 117 unsigned long addr, unsigned len) 118 { 119 /* 120 * Neat trick to map patch type back to the call within the 121 * corresponding structure. 122 */ 123 void *opfunc = *((void **)&pv_ops + type); 124 unsigned ret; 125 126 if (opfunc == NULL) 127 /* If there's no function, patch it with a ud2a (BUG) */ 128 ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a)); 129 else if (opfunc == _paravirt_nop) 130 ret = 0; 131 132 #ifdef CONFIG_PARAVIRT_XXL 133 /* identity functions just return their single argument */ 134 else if (opfunc == _paravirt_ident_64) 135 ret = paravirt_patch_ident_64(insn_buff, len); 136 137 else if (type == PARAVIRT_PATCH(cpu.iret) || 138 type == PARAVIRT_PATCH(cpu.usergs_sysret64)) 139 /* If operation requires a jmp, then jmp */ 140 ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len); 141 #endif 142 else 143 /* Otherwise call the function. */ 144 ret = paravirt_patch_call(insn_buff, opfunc, addr, len); 145 146 return ret; 147 } 148 149 unsigned paravirt_patch_insns(void *insn_buff, unsigned len, 150 const char *start, const char *end) 151 { 152 unsigned insn_len = end - start; 153 154 /* Alternative instruction is too large for the patch site and we cannot continue: */ 155 BUG_ON(insn_len > len || start == NULL); 156 157 memcpy(insn_buff, start, insn_len); 158 159 return insn_len; 160 } 161 162 static void native_flush_tlb(void) 163 { 164 __native_flush_tlb(); 165 } 166 167 /* 168 * Global pages have to be flushed a bit differently. Not a real 169 * performance problem because this does not happen often. 170 */ 171 static void native_flush_tlb_global(void) 172 { 173 __native_flush_tlb_global(); 174 } 175 176 static void native_flush_tlb_one_user(unsigned long addr) 177 { 178 __native_flush_tlb_one_user(addr); 179 } 180 181 struct static_key paravirt_steal_enabled; 182 struct static_key paravirt_steal_rq_enabled; 183 184 static u64 native_steal_clock(int cpu) 185 { 186 return 0; 187 } 188 189 /* These are in entry.S */ 190 extern void native_iret(void); 191 extern void native_usergs_sysret64(void); 192 193 static struct resource reserve_ioports = { 194 .start = 0, 195 .end = IO_SPACE_LIMIT, 196 .name = "paravirt-ioport", 197 .flags = IORESOURCE_IO | IORESOURCE_BUSY, 198 }; 199 200 /* 201 * Reserve the whole legacy IO space to prevent any legacy drivers 202 * from wasting time probing for their hardware. This is a fairly 203 * brute-force approach to disabling all non-virtual drivers. 204 * 205 * Note that this must be called very early to have any effect. 206 */ 207 int paravirt_disable_iospace(void) 208 { 209 return request_resource(&ioport_resource, &reserve_ioports); 210 } 211 212 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE; 213 214 static inline void enter_lazy(enum paravirt_lazy_mode mode) 215 { 216 BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE); 217 218 this_cpu_write(paravirt_lazy_mode, mode); 219 } 220 221 static void leave_lazy(enum paravirt_lazy_mode mode) 222 { 223 BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode); 224 225 this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE); 226 } 227 228 void paravirt_enter_lazy_mmu(void) 229 { 230 enter_lazy(PARAVIRT_LAZY_MMU); 231 } 232 233 void paravirt_leave_lazy_mmu(void) 234 { 235 leave_lazy(PARAVIRT_LAZY_MMU); 236 } 237 238 void paravirt_flush_lazy_mmu(void) 239 { 240 preempt_disable(); 241 242 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { 243 arch_leave_lazy_mmu_mode(); 244 arch_enter_lazy_mmu_mode(); 245 } 246 247 preempt_enable(); 248 } 249 250 #ifdef CONFIG_PARAVIRT_XXL 251 void paravirt_start_context_switch(struct task_struct *prev) 252 { 253 BUG_ON(preemptible()); 254 255 if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) { 256 arch_leave_lazy_mmu_mode(); 257 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES); 258 } 259 enter_lazy(PARAVIRT_LAZY_CPU); 260 } 261 262 void paravirt_end_context_switch(struct task_struct *next) 263 { 264 BUG_ON(preemptible()); 265 266 leave_lazy(PARAVIRT_LAZY_CPU); 267 268 if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES)) 269 arch_enter_lazy_mmu_mode(); 270 } 271 #endif 272 273 enum paravirt_lazy_mode paravirt_get_lazy_mode(void) 274 { 275 if (in_interrupt()) 276 return PARAVIRT_LAZY_NONE; 277 278 return this_cpu_read(paravirt_lazy_mode); 279 } 280 281 struct pv_info pv_info = { 282 .name = "bare hardware", 283 #ifdef CONFIG_PARAVIRT_XXL 284 .kernel_rpl = 0, 285 .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */ 286 287 #ifdef CONFIG_X86_64 288 .extra_user_64bit_cs = __USER_CS, 289 #endif 290 #endif 291 }; 292 293 /* 64-bit pagetable entries */ 294 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64) 295 296 struct paravirt_patch_template pv_ops = { 297 /* Init ops. */ 298 .init.patch = native_patch, 299 300 /* Time ops. */ 301 .time.sched_clock = native_sched_clock, 302 .time.steal_clock = native_steal_clock, 303 304 /* Cpu ops. */ 305 .cpu.io_delay = native_io_delay, 306 307 #ifdef CONFIG_PARAVIRT_XXL 308 .cpu.cpuid = native_cpuid, 309 .cpu.get_debugreg = native_get_debugreg, 310 .cpu.set_debugreg = native_set_debugreg, 311 .cpu.read_cr0 = native_read_cr0, 312 .cpu.write_cr0 = native_write_cr0, 313 .cpu.write_cr4 = native_write_cr4, 314 #ifdef CONFIG_X86_64 315 .cpu.read_cr8 = native_read_cr8, 316 .cpu.write_cr8 = native_write_cr8, 317 #endif 318 .cpu.wbinvd = native_wbinvd, 319 .cpu.read_msr = native_read_msr, 320 .cpu.write_msr = native_write_msr, 321 .cpu.read_msr_safe = native_read_msr_safe, 322 .cpu.write_msr_safe = native_write_msr_safe, 323 .cpu.read_pmc = native_read_pmc, 324 .cpu.load_tr_desc = native_load_tr_desc, 325 .cpu.set_ldt = native_set_ldt, 326 .cpu.load_gdt = native_load_gdt, 327 .cpu.load_idt = native_load_idt, 328 .cpu.store_tr = native_store_tr, 329 .cpu.load_tls = native_load_tls, 330 #ifdef CONFIG_X86_64 331 .cpu.load_gs_index = native_load_gs_index, 332 #endif 333 .cpu.write_ldt_entry = native_write_ldt_entry, 334 .cpu.write_gdt_entry = native_write_gdt_entry, 335 .cpu.write_idt_entry = native_write_idt_entry, 336 337 .cpu.alloc_ldt = paravirt_nop, 338 .cpu.free_ldt = paravirt_nop, 339 340 .cpu.load_sp0 = native_load_sp0, 341 342 #ifdef CONFIG_X86_64 343 .cpu.usergs_sysret64 = native_usergs_sysret64, 344 #endif 345 .cpu.iret = native_iret, 346 .cpu.swapgs = native_swapgs, 347 348 .cpu.set_iopl_mask = native_set_iopl_mask, 349 350 .cpu.start_context_switch = paravirt_nop, 351 .cpu.end_context_switch = paravirt_nop, 352 353 /* Irq ops. */ 354 .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl), 355 .irq.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl), 356 .irq.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable), 357 .irq.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable), 358 .irq.safe_halt = native_safe_halt, 359 .irq.halt = native_halt, 360 #endif /* CONFIG_PARAVIRT_XXL */ 361 362 /* Mmu ops. */ 363 .mmu.flush_tlb_user = native_flush_tlb, 364 .mmu.flush_tlb_kernel = native_flush_tlb_global, 365 .mmu.flush_tlb_one_user = native_flush_tlb_one_user, 366 .mmu.flush_tlb_others = native_flush_tlb_others, 367 .mmu.tlb_remove_table = 368 (void (*)(struct mmu_gather *, void *))tlb_remove_page, 369 370 .mmu.exit_mmap = paravirt_nop, 371 372 #ifdef CONFIG_PARAVIRT_XXL 373 .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2), 374 .mmu.write_cr2 = native_write_cr2, 375 .mmu.read_cr3 = __native_read_cr3, 376 .mmu.write_cr3 = native_write_cr3, 377 378 .mmu.pgd_alloc = __paravirt_pgd_alloc, 379 .mmu.pgd_free = paravirt_nop, 380 381 .mmu.alloc_pte = paravirt_nop, 382 .mmu.alloc_pmd = paravirt_nop, 383 .mmu.alloc_pud = paravirt_nop, 384 .mmu.alloc_p4d = paravirt_nop, 385 .mmu.release_pte = paravirt_nop, 386 .mmu.release_pmd = paravirt_nop, 387 .mmu.release_pud = paravirt_nop, 388 .mmu.release_p4d = paravirt_nop, 389 390 .mmu.set_pte = native_set_pte, 391 .mmu.set_pte_at = native_set_pte_at, 392 .mmu.set_pmd = native_set_pmd, 393 394 .mmu.ptep_modify_prot_start = __ptep_modify_prot_start, 395 .mmu.ptep_modify_prot_commit = __ptep_modify_prot_commit, 396 397 #if CONFIG_PGTABLE_LEVELS >= 3 398 #ifdef CONFIG_X86_PAE 399 .mmu.set_pte_atomic = native_set_pte_atomic, 400 .mmu.pte_clear = native_pte_clear, 401 .mmu.pmd_clear = native_pmd_clear, 402 #endif 403 .mmu.set_pud = native_set_pud, 404 405 .mmu.pmd_val = PTE_IDENT, 406 .mmu.make_pmd = PTE_IDENT, 407 408 #if CONFIG_PGTABLE_LEVELS >= 4 409 .mmu.pud_val = PTE_IDENT, 410 .mmu.make_pud = PTE_IDENT, 411 412 .mmu.set_p4d = native_set_p4d, 413 414 #if CONFIG_PGTABLE_LEVELS >= 5 415 .mmu.p4d_val = PTE_IDENT, 416 .mmu.make_p4d = PTE_IDENT, 417 418 .mmu.set_pgd = native_set_pgd, 419 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */ 420 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */ 421 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */ 422 423 .mmu.pte_val = PTE_IDENT, 424 .mmu.pgd_val = PTE_IDENT, 425 426 .mmu.make_pte = PTE_IDENT, 427 .mmu.make_pgd = PTE_IDENT, 428 429 .mmu.dup_mmap = paravirt_nop, 430 .mmu.activate_mm = paravirt_nop, 431 432 .mmu.lazy_mode = { 433 .enter = paravirt_nop, 434 .leave = paravirt_nop, 435 .flush = paravirt_nop, 436 }, 437 438 .mmu.set_fixmap = native_set_fixmap, 439 #endif /* CONFIG_PARAVIRT_XXL */ 440 441 #if defined(CONFIG_PARAVIRT_SPINLOCKS) 442 /* Lock ops. */ 443 #ifdef CONFIG_SMP 444 .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath, 445 .lock.queued_spin_unlock = 446 PV_CALLEE_SAVE(__native_queued_spin_unlock), 447 .lock.wait = paravirt_nop, 448 .lock.kick = paravirt_nop, 449 .lock.vcpu_is_preempted = 450 PV_CALLEE_SAVE(__native_vcpu_is_preempted), 451 #endif /* SMP */ 452 #endif 453 }; 454 455 #ifdef CONFIG_PARAVIRT_XXL 456 /* At this point, native_get/set_debugreg has real function entries */ 457 NOKPROBE_SYMBOL(native_get_debugreg); 458 NOKPROBE_SYMBOL(native_set_debugreg); 459 NOKPROBE_SYMBOL(native_load_idt); 460 #endif 461 462 EXPORT_SYMBOL(pv_ops); 463 EXPORT_SYMBOL_GPL(pv_info); 464