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
default_banner(void)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. */
paravirt_BUG(void)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
paravirt_patch_call(void * insn_buff,const void * target,unsigned long addr,unsigned len)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 */
_paravirt_ident_64(u64 x)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
native_pv_lock_init(void)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
paravirt_patch(u8 type,void * insn_buff,unsigned long addr,unsigned int len)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
native_steal_clock(int cpu)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
paravirt_set_sched_clock(u64 (* func)(void))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 */
paravirt_disable_iospace(void)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
enter_lazy(enum paravirt_lazy_mode mode)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
leave_lazy(enum paravirt_lazy_mode mode)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
paravirt_enter_lazy_mmu(void)189 void paravirt_enter_lazy_mmu(void)
190 {
191 enter_lazy(PARAVIRT_LAZY_MMU);
192 }
193
paravirt_leave_lazy_mmu(void)194 void paravirt_leave_lazy_mmu(void)
195 {
196 leave_lazy(PARAVIRT_LAZY_MMU);
197 }
198
paravirt_flush_lazy_mmu(void)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
paravirt_start_context_switch(struct task_struct * prev)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
paravirt_end_context_switch(struct task_struct * next)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
pv_native_read_cr2(void)233 static noinstr unsigned long pv_native_read_cr2(void)
234 {
235 return native_read_cr2();
236 }
237
pv_native_write_cr2(unsigned long val)238 static noinstr void pv_native_write_cr2(unsigned long val)
239 {
240 native_write_cr2(val);
241 }
242
pv_native_get_debugreg(int regno)243 static noinstr unsigned long pv_native_get_debugreg(int regno)
244 {
245 return native_get_debugreg(regno);
246 }
247
pv_native_set_debugreg(int regno,unsigned long val)248 static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
249 {
250 native_set_debugreg(regno, val);
251 }
252
pv_native_irq_enable(void)253 static noinstr void pv_native_irq_enable(void)
254 {
255 native_irq_enable();
256 }
257
pv_native_irq_disable(void)258 static noinstr void pv_native_irq_disable(void)
259 {
260 native_irq_disable();
261 }
262 #endif
263
paravirt_get_lazy_mode(void)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