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
default_banner(void)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. */
paravirt_BUG(void)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
paravirt_patch_call(void * insn_buff,const void * target,unsigned long addr,unsigned len)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 */
_paravirt_ident_64(u64 x)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
native_pv_lock_init(void)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
paravirt_patch(u8 type,void * insn_buff,unsigned long addr,unsigned int len)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
native_steal_clock(int cpu)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
paravirt_set_sched_clock(u64 (* func)(void))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 */
paravirt_disable_iospace(void)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
enter_lazy(enum paravirt_lazy_mode mode)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
leave_lazy(enum paravirt_lazy_mode mode)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
paravirt_enter_lazy_mmu(void)178 void paravirt_enter_lazy_mmu(void)
179 {
180 enter_lazy(PARAVIRT_LAZY_MMU);
181 }
182
paravirt_leave_lazy_mmu(void)183 void paravirt_leave_lazy_mmu(void)
184 {
185 leave_lazy(PARAVIRT_LAZY_MMU);
186 }
187
paravirt_flush_lazy_mmu(void)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
paravirt_start_context_switch(struct task_struct * prev)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
paravirt_end_context_switch(struct task_struct * next)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
paravirt_get_lazy_mode(void)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