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 "ret\n\t" 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 "ret\n\t" 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); 423