1 /* Paravirtualization interfaces
2 Copyright (C) 2006 Rusty Russell IBM Corporation
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17
18 2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
19 */
20
21 #include <linux/errno.h>
22 #include <linux/module.h>
23 #include <linux/efi.h>
24 #include <linux/bcd.h>
25 #include <linux/highmem.h>
26 #include <linux/kprobes.h>
27
28 #include <asm/bug.h>
29 #include <asm/paravirt.h>
30 #include <asm/debugreg.h>
31 #include <asm/desc.h>
32 #include <asm/setup.h>
33 #include <asm/pgtable.h>
34 #include <asm/time.h>
35 #include <asm/pgalloc.h>
36 #include <asm/irq.h>
37 #include <asm/delay.h>
38 #include <asm/fixmap.h>
39 #include <asm/apic.h>
40 #include <asm/tlbflush.h>
41 #include <asm/timer.h>
42 #include <asm/special_insns.h>
43
44 /*
45 * nop stub, which must not clobber anything *including the stack* to
46 * avoid confusing the entry prologues.
47 */
48 extern void _paravirt_nop(void);
49 asm (".pushsection .entry.text, \"ax\"\n"
50 ".global _paravirt_nop\n"
51 "_paravirt_nop:\n\t"
52 "ret\n\t"
53 ".size _paravirt_nop, . - _paravirt_nop\n\t"
54 ".type _paravirt_nop, @function\n\t"
55 ".popsection");
56
57 /* identity function, which can be inlined */
_paravirt_ident_32(u32 x)58 u32 notrace _paravirt_ident_32(u32 x)
59 {
60 return x;
61 }
62
_paravirt_ident_64(u64 x)63 u64 notrace _paravirt_ident_64(u64 x)
64 {
65 return x;
66 }
67
default_banner(void)68 void __init default_banner(void)
69 {
70 printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
71 pv_info.name);
72 }
73
74 /* Undefined instruction for dealing with missing ops pointers. */
75 static const unsigned char ud2a[] = { 0x0f, 0x0b };
76
paravirt_patch_nop(void)77 unsigned paravirt_patch_nop(void)
78 {
79 return 0;
80 }
81
paravirt_patch_ignore(unsigned len)82 unsigned paravirt_patch_ignore(unsigned len)
83 {
84 return len;
85 }
86
87 struct branch {
88 unsigned char opcode;
89 u32 delta;
90 } __attribute__((packed));
91
paravirt_patch_call(void * insnbuf,const void * target,u16 tgt_clobbers,unsigned long addr,u16 site_clobbers,unsigned len)92 unsigned paravirt_patch_call(void *insnbuf,
93 const void *target, u16 tgt_clobbers,
94 unsigned long addr, u16 site_clobbers,
95 unsigned len)
96 {
97 struct branch *b = insnbuf;
98 unsigned long delta = (unsigned long)target - (addr+5);
99
100 if (len < 5) {
101 #ifdef CONFIG_RETPOLINE
102 WARN_ONCE("Failing to patch indirect CALL in %ps\n", (void *)addr);
103 #endif
104 return len; /* call too long for patch site */
105 }
106
107 b->opcode = 0xe8; /* call */
108 b->delta = delta;
109 BUILD_BUG_ON(sizeof(*b) != 5);
110
111 return 5;
112 }
113
paravirt_patch_jmp(void * insnbuf,const void * target,unsigned long addr,unsigned len)114 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
115 unsigned long addr, unsigned len)
116 {
117 struct branch *b = insnbuf;
118 unsigned long delta = (unsigned long)target - (addr+5);
119
120 if (len < 5) {
121 #ifdef CONFIG_RETPOLINE
122 WARN_ONCE("Failing to patch indirect JMP in %ps\n", (void *)addr);
123 #endif
124 return len; /* call too long for patch site */
125 }
126
127 b->opcode = 0xe9; /* jmp */
128 b->delta = delta;
129
130 return 5;
131 }
132
133 /* Neat trick to map patch type back to the call within the
134 * corresponding structure. */
get_call_destination(u8 type)135 static void *get_call_destination(u8 type)
136 {
137 struct paravirt_patch_template tmpl = {
138 .pv_init_ops = pv_init_ops,
139 .pv_time_ops = pv_time_ops,
140 .pv_cpu_ops = pv_cpu_ops,
141 .pv_irq_ops = pv_irq_ops,
142 .pv_apic_ops = pv_apic_ops,
143 .pv_mmu_ops = pv_mmu_ops,
144 #ifdef CONFIG_PARAVIRT_SPINLOCKS
145 .pv_lock_ops = pv_lock_ops,
146 #endif
147 };
148 return *((void **)&tmpl + type);
149 }
150
paravirt_patch_default(u8 type,u16 clobbers,void * insnbuf,unsigned long addr,unsigned len)151 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
152 unsigned long addr, unsigned len)
153 {
154 void *opfunc = get_call_destination(type);
155 unsigned ret;
156
157 if (opfunc == NULL)
158 /* If there's no function, patch it with a ud2a (BUG) */
159 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
160 else if (opfunc == _paravirt_nop)
161 /* If the operation is a nop, then nop the callsite */
162 ret = paravirt_patch_nop();
163
164 /* identity functions just return their single argument */
165 else if (opfunc == _paravirt_ident_32)
166 ret = paravirt_patch_ident_32(insnbuf, len);
167 else if (opfunc == _paravirt_ident_64)
168 ret = paravirt_patch_ident_64(insnbuf, len);
169
170 else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
171 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
172 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
173 /* If operation requires a jmp, then jmp */
174 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
175 else
176 /* Otherwise call the function; assume target could
177 clobber any caller-save reg */
178 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
179 addr, clobbers, len);
180
181 return ret;
182 }
183
paravirt_patch_insns(void * insnbuf,unsigned len,const char * start,const char * end)184 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
185 const char *start, const char *end)
186 {
187 unsigned insn_len = end - start;
188
189 if (insn_len > len || start == NULL)
190 insn_len = len;
191 else
192 memcpy(insnbuf, start, insn_len);
193
194 return insn_len;
195 }
196
native_flush_tlb(void)197 static void native_flush_tlb(void)
198 {
199 __native_flush_tlb();
200 }
201
202 /*
203 * Global pages have to be flushed a bit differently. Not a real
204 * performance problem because this does not happen often.
205 */
native_flush_tlb_global(void)206 static void native_flush_tlb_global(void)
207 {
208 __native_flush_tlb_global();
209 }
210
native_flush_tlb_single(unsigned long addr)211 static void native_flush_tlb_single(unsigned long addr)
212 {
213 __native_flush_tlb_single(addr);
214 }
215
216 struct static_key paravirt_steal_enabled;
217 struct static_key paravirt_steal_rq_enabled;
218
native_steal_clock(int cpu)219 static u64 native_steal_clock(int cpu)
220 {
221 return 0;
222 }
223
224 /* These are in entry.S */
225 extern void native_iret(void);
226 extern void native_usergs_sysret32(void);
227 extern void native_usergs_sysret64(void);
228
229 static struct resource reserve_ioports = {
230 .start = 0,
231 .end = IO_SPACE_LIMIT,
232 .name = "paravirt-ioport",
233 .flags = IORESOURCE_IO | IORESOURCE_BUSY,
234 };
235
236 /*
237 * Reserve the whole legacy IO space to prevent any legacy drivers
238 * from wasting time probing for their hardware. This is a fairly
239 * brute-force approach to disabling all non-virtual drivers.
240 *
241 * Note that this must be called very early to have any effect.
242 */
paravirt_disable_iospace(void)243 int paravirt_disable_iospace(void)
244 {
245 return request_resource(&ioport_resource, &reserve_ioports);
246 }
247
248 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
249
enter_lazy(enum paravirt_lazy_mode mode)250 static inline void enter_lazy(enum paravirt_lazy_mode mode)
251 {
252 BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
253
254 this_cpu_write(paravirt_lazy_mode, mode);
255 }
256
leave_lazy(enum paravirt_lazy_mode mode)257 static void leave_lazy(enum paravirt_lazy_mode mode)
258 {
259 BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
260
261 this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
262 }
263
paravirt_enter_lazy_mmu(void)264 void paravirt_enter_lazy_mmu(void)
265 {
266 enter_lazy(PARAVIRT_LAZY_MMU);
267 }
268
paravirt_leave_lazy_mmu(void)269 void paravirt_leave_lazy_mmu(void)
270 {
271 leave_lazy(PARAVIRT_LAZY_MMU);
272 }
273
paravirt_flush_lazy_mmu(void)274 void paravirt_flush_lazy_mmu(void)
275 {
276 preempt_disable();
277
278 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
279 arch_leave_lazy_mmu_mode();
280 arch_enter_lazy_mmu_mode();
281 }
282
283 preempt_enable();
284 }
285
paravirt_start_context_switch(struct task_struct * prev)286 void paravirt_start_context_switch(struct task_struct *prev)
287 {
288 BUG_ON(preemptible());
289
290 if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
291 arch_leave_lazy_mmu_mode();
292 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
293 }
294 enter_lazy(PARAVIRT_LAZY_CPU);
295 }
296
paravirt_end_context_switch(struct task_struct * next)297 void paravirt_end_context_switch(struct task_struct *next)
298 {
299 BUG_ON(preemptible());
300
301 leave_lazy(PARAVIRT_LAZY_CPU);
302
303 if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
304 arch_enter_lazy_mmu_mode();
305 }
306
paravirt_get_lazy_mode(void)307 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
308 {
309 if (in_interrupt())
310 return PARAVIRT_LAZY_NONE;
311
312 return this_cpu_read(paravirt_lazy_mode);
313 }
314
315 struct pv_info pv_info = {
316 .name = "bare hardware",
317 .paravirt_enabled = 0,
318 .kernel_rpl = 0,
319 .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
320
321 #ifdef CONFIG_X86_64
322 .extra_user_64bit_cs = __USER_CS,
323 #endif
324 };
325
326 struct pv_init_ops pv_init_ops = {
327 .patch = native_patch,
328 };
329
330 struct pv_time_ops pv_time_ops = {
331 .sched_clock = native_sched_clock,
332 .steal_clock = native_steal_clock,
333 };
334
335 __visible struct pv_irq_ops pv_irq_ops = {
336 .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
337 .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
338 .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
339 .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
340 .safe_halt = native_safe_halt,
341 .halt = native_halt,
342 #ifdef CONFIG_X86_64
343 .adjust_exception_frame = paravirt_nop,
344 #endif
345 };
346
347 __visible struct pv_cpu_ops pv_cpu_ops = {
348 .cpuid = native_cpuid,
349 .get_debugreg = native_get_debugreg,
350 .set_debugreg = native_set_debugreg,
351 .clts = native_clts,
352 .read_cr0 = native_read_cr0,
353 .write_cr0 = native_write_cr0,
354 .read_cr4 = native_read_cr4,
355 .read_cr4_safe = native_read_cr4_safe,
356 .write_cr4 = native_write_cr4,
357 #ifdef CONFIG_X86_64
358 .read_cr8 = native_read_cr8,
359 .write_cr8 = native_write_cr8,
360 #endif
361 .wbinvd = native_wbinvd,
362 .read_msr = native_read_msr_safe,
363 .write_msr = native_write_msr_safe,
364 .read_pmc = native_read_pmc,
365 .load_tr_desc = native_load_tr_desc,
366 .set_ldt = native_set_ldt,
367 .load_gdt = native_load_gdt,
368 .load_idt = native_load_idt,
369 .store_idt = native_store_idt,
370 .store_tr = native_store_tr,
371 .load_tls = native_load_tls,
372 #ifdef CONFIG_X86_64
373 .load_gs_index = native_load_gs_index,
374 #endif
375 .write_ldt_entry = native_write_ldt_entry,
376 .write_gdt_entry = native_write_gdt_entry,
377 .write_idt_entry = native_write_idt_entry,
378
379 .alloc_ldt = paravirt_nop,
380 .free_ldt = paravirt_nop,
381
382 .load_sp0 = native_load_sp0,
383
384 #ifdef CONFIG_X86_64
385 #ifdef CONFIG_IA32_EMULATION
386 .usergs_sysret32 = native_usergs_sysret32,
387 #endif
388 .usergs_sysret64 = native_usergs_sysret64,
389 #endif
390 .iret = native_iret,
391 .swapgs = native_swapgs,
392
393 .set_iopl_mask = native_set_iopl_mask,
394 .io_delay = native_io_delay,
395
396 .start_context_switch = paravirt_nop,
397 .end_context_switch = paravirt_nop,
398 };
399
400 /* At this point, native_get/set_debugreg has real function entries */
401 NOKPROBE_SYMBOL(native_get_debugreg);
402 NOKPROBE_SYMBOL(native_set_debugreg);
403 NOKPROBE_SYMBOL(native_load_idt);
404
405 struct pv_apic_ops pv_apic_ops = {
406 #ifdef CONFIG_X86_LOCAL_APIC
407 .startup_ipi_hook = paravirt_nop,
408 #endif
409 };
410
411 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
412 /* 32-bit pagetable entries */
413 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
414 #else
415 /* 64-bit pagetable entries */
416 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
417 #endif
418
419 struct pv_mmu_ops pv_mmu_ops = {
420
421 .read_cr2 = native_read_cr2,
422 .write_cr2 = native_write_cr2,
423 .read_cr3 = native_read_cr3,
424 .write_cr3 = native_write_cr3,
425
426 .flush_tlb_user = native_flush_tlb,
427 .flush_tlb_kernel = native_flush_tlb_global,
428 .flush_tlb_single = native_flush_tlb_single,
429 .flush_tlb_others = native_flush_tlb_others,
430
431 .pgd_alloc = __paravirt_pgd_alloc,
432 .pgd_free = paravirt_nop,
433
434 .alloc_pte = paravirt_nop,
435 .alloc_pmd = paravirt_nop,
436 .alloc_pud = paravirt_nop,
437 .release_pte = paravirt_nop,
438 .release_pmd = paravirt_nop,
439 .release_pud = paravirt_nop,
440
441 .set_pte = native_set_pte,
442 .set_pte_at = native_set_pte_at,
443 .set_pmd = native_set_pmd,
444 .set_pmd_at = native_set_pmd_at,
445 .pte_update = paravirt_nop,
446 .pte_update_defer = paravirt_nop,
447 .pmd_update = paravirt_nop,
448 .pmd_update_defer = paravirt_nop,
449
450 .ptep_modify_prot_start = __ptep_modify_prot_start,
451 .ptep_modify_prot_commit = __ptep_modify_prot_commit,
452
453 #if CONFIG_PGTABLE_LEVELS >= 3
454 #ifdef CONFIG_X86_PAE
455 .set_pte_atomic = native_set_pte_atomic,
456 .pte_clear = native_pte_clear,
457 .pmd_clear = native_pmd_clear,
458 #endif
459 .set_pud = native_set_pud,
460
461 .pmd_val = PTE_IDENT,
462 .make_pmd = PTE_IDENT,
463
464 #if CONFIG_PGTABLE_LEVELS == 4
465 .pud_val = PTE_IDENT,
466 .make_pud = PTE_IDENT,
467
468 .set_pgd = native_set_pgd,
469 #endif
470 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
471
472 .pte_val = PTE_IDENT,
473 .pgd_val = PTE_IDENT,
474
475 .make_pte = PTE_IDENT,
476 .make_pgd = PTE_IDENT,
477
478 .dup_mmap = paravirt_nop,
479 .exit_mmap = paravirt_nop,
480 .activate_mm = paravirt_nop,
481
482 .lazy_mode = {
483 .enter = paravirt_nop,
484 .leave = paravirt_nop,
485 .flush = paravirt_nop,
486 },
487
488 .set_fixmap = native_set_fixmap,
489 };
490
491 EXPORT_SYMBOL_GPL(pv_time_ops);
492 EXPORT_SYMBOL (pv_cpu_ops);
493 EXPORT_SYMBOL (pv_mmu_ops);
494 EXPORT_SYMBOL_GPL(pv_apic_ops);
495 EXPORT_SYMBOL_GPL(pv_info);
496 EXPORT_SYMBOL (pv_irq_ops);
497