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
default_banner(void)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
paravirt_patch_call(void * insn_buff,const void * target,unsigned long addr,unsigned len)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 */
_paravirt_ident_64(u64 x)83 u64 notrace _paravirt_ident_64(u64 x)
84 {
85 return x;
86 }
87
paravirt_patch_jmp(void * insn_buff,const void * target,unsigned long addr,unsigned len)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
native_pv_lock_init(void)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
paravirt_patch_default(u8 type,void * insn_buff,unsigned long addr,unsigned len)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
paravirt_patch_insns(void * insn_buff,unsigned len,const char * start,const char * end)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
native_flush_tlb(void)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 */
native_flush_tlb_global(void)171 static void native_flush_tlb_global(void)
172 {
173 __native_flush_tlb_global();
174 }
175
native_flush_tlb_one_user(unsigned long addr)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
native_steal_clock(int cpu)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 */
paravirt_disable_iospace(void)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
enter_lazy(enum paravirt_lazy_mode mode)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
leave_lazy(enum paravirt_lazy_mode mode)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
paravirt_enter_lazy_mmu(void)228 void paravirt_enter_lazy_mmu(void)
229 {
230 enter_lazy(PARAVIRT_LAZY_MMU);
231 }
232
paravirt_leave_lazy_mmu(void)233 void paravirt_leave_lazy_mmu(void)
234 {
235 leave_lazy(PARAVIRT_LAZY_MMU);
236 }
237
paravirt_flush_lazy_mmu(void)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
paravirt_start_context_switch(struct task_struct * prev)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
paravirt_end_context_switch(struct task_struct * next)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
paravirt_get_lazy_mode(void)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 .cpu.wbinvd = native_wbinvd,
315 .cpu.read_msr = native_read_msr,
316 .cpu.write_msr = native_write_msr,
317 .cpu.read_msr_safe = native_read_msr_safe,
318 .cpu.write_msr_safe = native_write_msr_safe,
319 .cpu.read_pmc = native_read_pmc,
320 .cpu.load_tr_desc = native_load_tr_desc,
321 .cpu.set_ldt = native_set_ldt,
322 .cpu.load_gdt = native_load_gdt,
323 .cpu.load_idt = native_load_idt,
324 .cpu.store_tr = native_store_tr,
325 .cpu.load_tls = native_load_tls,
326 #ifdef CONFIG_X86_64
327 .cpu.load_gs_index = native_load_gs_index,
328 #endif
329 .cpu.write_ldt_entry = native_write_ldt_entry,
330 .cpu.write_gdt_entry = native_write_gdt_entry,
331 .cpu.write_idt_entry = native_write_idt_entry,
332
333 .cpu.alloc_ldt = paravirt_nop,
334 .cpu.free_ldt = paravirt_nop,
335
336 .cpu.load_sp0 = native_load_sp0,
337
338 #ifdef CONFIG_X86_64
339 .cpu.usergs_sysret64 = native_usergs_sysret64,
340 #endif
341 .cpu.iret = native_iret,
342 .cpu.swapgs = native_swapgs,
343
344 .cpu.set_iopl_mask = native_set_iopl_mask,
345
346 .cpu.start_context_switch = paravirt_nop,
347 .cpu.end_context_switch = paravirt_nop,
348
349 /* Irq ops. */
350 .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
351 .irq.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
352 .irq.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
353 .irq.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
354 .irq.safe_halt = native_safe_halt,
355 .irq.halt = native_halt,
356 #endif /* CONFIG_PARAVIRT_XXL */
357
358 /* Mmu ops. */
359 .mmu.flush_tlb_user = native_flush_tlb,
360 .mmu.flush_tlb_kernel = native_flush_tlb_global,
361 .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
362 .mmu.flush_tlb_others = native_flush_tlb_others,
363 .mmu.tlb_remove_table =
364 (void (*)(struct mmu_gather *, void *))tlb_remove_page,
365
366 .mmu.exit_mmap = paravirt_nop,
367
368 #ifdef CONFIG_PARAVIRT_XXL
369 .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2),
370 .mmu.write_cr2 = native_write_cr2,
371 .mmu.read_cr3 = __native_read_cr3,
372 .mmu.write_cr3 = native_write_cr3,
373
374 .mmu.pgd_alloc = __paravirt_pgd_alloc,
375 .mmu.pgd_free = paravirt_nop,
376
377 .mmu.alloc_pte = paravirt_nop,
378 .mmu.alloc_pmd = paravirt_nop,
379 .mmu.alloc_pud = paravirt_nop,
380 .mmu.alloc_p4d = paravirt_nop,
381 .mmu.release_pte = paravirt_nop,
382 .mmu.release_pmd = paravirt_nop,
383 .mmu.release_pud = paravirt_nop,
384 .mmu.release_p4d = paravirt_nop,
385
386 .mmu.set_pte = native_set_pte,
387 .mmu.set_pte_at = native_set_pte_at,
388 .mmu.set_pmd = native_set_pmd,
389
390 .mmu.ptep_modify_prot_start = __ptep_modify_prot_start,
391 .mmu.ptep_modify_prot_commit = __ptep_modify_prot_commit,
392
393 #if CONFIG_PGTABLE_LEVELS >= 3
394 #ifdef CONFIG_X86_PAE
395 .mmu.set_pte_atomic = native_set_pte_atomic,
396 .mmu.pte_clear = native_pte_clear,
397 .mmu.pmd_clear = native_pmd_clear,
398 #endif
399 .mmu.set_pud = native_set_pud,
400
401 .mmu.pmd_val = PTE_IDENT,
402 .mmu.make_pmd = PTE_IDENT,
403
404 #if CONFIG_PGTABLE_LEVELS >= 4
405 .mmu.pud_val = PTE_IDENT,
406 .mmu.make_pud = PTE_IDENT,
407
408 .mmu.set_p4d = native_set_p4d,
409
410 #if CONFIG_PGTABLE_LEVELS >= 5
411 .mmu.p4d_val = PTE_IDENT,
412 .mmu.make_p4d = PTE_IDENT,
413
414 .mmu.set_pgd = native_set_pgd,
415 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
416 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
417 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
418
419 .mmu.pte_val = PTE_IDENT,
420 .mmu.pgd_val = PTE_IDENT,
421
422 .mmu.make_pte = PTE_IDENT,
423 .mmu.make_pgd = PTE_IDENT,
424
425 .mmu.dup_mmap = paravirt_nop,
426 .mmu.activate_mm = paravirt_nop,
427
428 .mmu.lazy_mode = {
429 .enter = paravirt_nop,
430 .leave = paravirt_nop,
431 .flush = paravirt_nop,
432 },
433
434 .mmu.set_fixmap = native_set_fixmap,
435 #endif /* CONFIG_PARAVIRT_XXL */
436
437 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
438 /* Lock ops. */
439 #ifdef CONFIG_SMP
440 .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
441 .lock.queued_spin_unlock =
442 PV_CALLEE_SAVE(__native_queued_spin_unlock),
443 .lock.wait = paravirt_nop,
444 .lock.kick = paravirt_nop,
445 .lock.vcpu_is_preempted =
446 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
447 #endif /* SMP */
448 #endif
449 };
450
451 #ifdef CONFIG_PARAVIRT_XXL
452 /* At this point, native_get/set_debugreg has real function entries */
453 NOKPROBE_SYMBOL(native_get_debugreg);
454 NOKPROBE_SYMBOL(native_set_debugreg);
455 NOKPROBE_SYMBOL(native_load_idt);
456 #endif
457
458 EXPORT_SYMBOL(pv_ops);
459 EXPORT_SYMBOL_GPL(pv_info);
460
