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