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/init.h>
23 #include <linux/export.h>
24 #include <linux/efi.h>
25 #include <linux/bcd.h>
26 #include <linux/highmem.h>
27 #include <linux/kprobes.h>
28
29 #include <asm/bug.h>
30 #include <asm/paravirt.h>
31 #include <asm/debugreg.h>
32 #include <asm/desc.h>
33 #include <asm/setup.h>
34 #include <asm/pgtable.h>
35 #include <asm/time.h>
36 #include <asm/pgalloc.h>
37 #include <asm/irq.h>
38 #include <asm/delay.h>
39 #include <asm/fixmap.h>
40 #include <asm/apic.h>
41 #include <asm/tlbflush.h>
42 #include <asm/timer.h>
43 #include <asm/special_insns.h>
44
45 /*
46 * nop stub, which must not clobber anything *including the stack* to
47 * avoid confusing the entry prologues.
48 */
49 extern void _paravirt_nop(void);
50 asm (".pushsection .entry.text, \"ax\"\n"
51 ".global _paravirt_nop\n"
52 "_paravirt_nop:\n\t"
53 "ret\n\t"
54 ".size _paravirt_nop, . - _paravirt_nop\n\t"
55 ".type _paravirt_nop, @function\n\t"
56 ".popsection");
57
58 /* identity function, which can be inlined */
_paravirt_ident_32(u32 x)59 u32 notrace _paravirt_ident_32(u32 x)
60 {
61 return x;
62 }
63
_paravirt_ident_64(u64 x)64 u64 notrace _paravirt_ident_64(u64 x)
65 {
66 return x;
67 }
68
default_banner(void)69 void __init default_banner(void)
70 {
71 printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
72 pv_info.name);
73 }
74
75 /* Undefined instruction for dealing with missing ops pointers. */
76 static const unsigned char ud2a[] = { 0x0f, 0x0b };
77
78 struct branch {
79 unsigned char opcode;
80 u32 delta;
81 } __attribute__((packed));
82
paravirt_patch_call(void * insnbuf,const void * target,u16 tgt_clobbers,unsigned long addr,u16 site_clobbers,unsigned len)83 unsigned paravirt_patch_call(void *insnbuf,
84 const void *target, u16 tgt_clobbers,
85 unsigned long addr, u16 site_clobbers,
86 unsigned len)
87 {
88 struct branch *b = insnbuf;
89 unsigned long delta = (unsigned long)target - (addr+5);
90
91 if (len < 5) {
92 #ifdef CONFIG_RETPOLINE
93 WARN_ONCE(1, "Failing to patch indirect CALL in %ps\n", (void *)addr);
94 #endif
95 return len; /* call too long for patch site */
96 }
97
98 b->opcode = 0xe8; /* call */
99 b->delta = delta;
100 BUILD_BUG_ON(sizeof(*b) != 5);
101
102 return 5;
103 }
104
paravirt_patch_jmp(void * insnbuf,const void * target,unsigned long addr,unsigned len)105 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
106 unsigned long addr, unsigned len)
107 {
108 struct branch *b = insnbuf;
109 unsigned long delta = (unsigned long)target - (addr+5);
110
111 if (len < 5) {
112 #ifdef CONFIG_RETPOLINE
113 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
114 #endif
115 return len; /* call too long for patch site */
116 }
117
118 b->opcode = 0xe9; /* jmp */
119 b->delta = delta;
120
121 return 5;
122 }
123
124 /* Neat trick to map patch type back to the call within the
125 * corresponding structure. */
get_call_destination(u8 type)126 static void *get_call_destination(u8 type)
127 {
128 struct paravirt_patch_template tmpl = {
129 .pv_init_ops = pv_init_ops,
130 .pv_time_ops = pv_time_ops,
131 .pv_cpu_ops = pv_cpu_ops,
132 .pv_irq_ops = pv_irq_ops,
133 .pv_mmu_ops = pv_mmu_ops,
134 #ifdef CONFIG_PARAVIRT_SPINLOCKS
135 .pv_lock_ops = pv_lock_ops,
136 #endif
137 };
138 return *((void **)&tmpl + type);
139 }
140
paravirt_patch_default(u8 type,u16 clobbers,void * insnbuf,unsigned long addr,unsigned len)141 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
142 unsigned long addr, unsigned len)
143 {
144 void *opfunc = get_call_destination(type);
145 unsigned ret;
146
147 if (opfunc == NULL)
148 /* If there's no function, patch it with a ud2a (BUG) */
149 ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
150 else if (opfunc == _paravirt_nop)
151 ret = 0;
152
153 /* identity functions just return their single argument */
154 else if (opfunc == _paravirt_ident_32)
155 ret = paravirt_patch_ident_32(insnbuf, len);
156 else if (opfunc == _paravirt_ident_64)
157 ret = paravirt_patch_ident_64(insnbuf, len);
158
159 else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
160 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
161 /* If operation requires a jmp, then jmp */
162 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
163 else
164 /* Otherwise call the function; assume target could
165 clobber any caller-save reg */
166 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
167 addr, clobbers, len);
168
169 return ret;
170 }
171
paravirt_patch_insns(void * insnbuf,unsigned len,const char * start,const char * end)172 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
173 const char *start, const char *end)
174 {
175 unsigned insn_len = end - start;
176
177 if (insn_len > len || start == NULL)
178 insn_len = len;
179 else
180 memcpy(insnbuf, start, insn_len);
181
182 return insn_len;
183 }
184
native_flush_tlb(void)185 static void native_flush_tlb(void)
186 {
187 __native_flush_tlb();
188 }
189
190 /*
191 * Global pages have to be flushed a bit differently. Not a real
192 * performance problem because this does not happen often.
193 */
native_flush_tlb_global(void)194 static void native_flush_tlb_global(void)
195 {
196 __native_flush_tlb_global();
197 }
198
native_flush_tlb_one_user(unsigned long addr)199 static void native_flush_tlb_one_user(unsigned long addr)
200 {
201 __native_flush_tlb_one_user(addr);
202 }
203
204 struct static_key paravirt_steal_enabled;
205 struct static_key paravirt_steal_rq_enabled;
206
native_steal_clock(int cpu)207 static u64 native_steal_clock(int cpu)
208 {
209 return 0;
210 }
211
212 /* These are in entry.S */
213 extern void native_iret(void);
214 extern void native_usergs_sysret64(void);
215
216 static struct resource reserve_ioports = {
217 .start = 0,
218 .end = IO_SPACE_LIMIT,
219 .name = "paravirt-ioport",
220 .flags = IORESOURCE_IO | IORESOURCE_BUSY,
221 };
222
223 /*
224 * Reserve the whole legacy IO space to prevent any legacy drivers
225 * from wasting time probing for their hardware. This is a fairly
226 * brute-force approach to disabling all non-virtual drivers.
227 *
228 * Note that this must be called very early to have any effect.
229 */
paravirt_disable_iospace(void)230 int paravirt_disable_iospace(void)
231 {
232 return request_resource(&ioport_resource, &reserve_ioports);
233 }
234
235 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
236
enter_lazy(enum paravirt_lazy_mode mode)237 static inline void enter_lazy(enum paravirt_lazy_mode mode)
238 {
239 BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
240
241 this_cpu_write(paravirt_lazy_mode, mode);
242 }
243
leave_lazy(enum paravirt_lazy_mode mode)244 static void leave_lazy(enum paravirt_lazy_mode mode)
245 {
246 BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
247
248 this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
249 }
250
paravirt_enter_lazy_mmu(void)251 void paravirt_enter_lazy_mmu(void)
252 {
253 enter_lazy(PARAVIRT_LAZY_MMU);
254 }
255
paravirt_leave_lazy_mmu(void)256 void paravirt_leave_lazy_mmu(void)
257 {
258 leave_lazy(PARAVIRT_LAZY_MMU);
259 }
260
paravirt_flush_lazy_mmu(void)261 void paravirt_flush_lazy_mmu(void)
262 {
263 preempt_disable();
264
265 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
266 arch_leave_lazy_mmu_mode();
267 arch_enter_lazy_mmu_mode();
268 }
269
270 preempt_enable();
271 }
272
paravirt_start_context_switch(struct task_struct * prev)273 void paravirt_start_context_switch(struct task_struct *prev)
274 {
275 BUG_ON(preemptible());
276
277 if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
278 arch_leave_lazy_mmu_mode();
279 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
280 }
281 enter_lazy(PARAVIRT_LAZY_CPU);
282 }
283
paravirt_end_context_switch(struct task_struct * next)284 void paravirt_end_context_switch(struct task_struct *next)
285 {
286 BUG_ON(preemptible());
287
288 leave_lazy(PARAVIRT_LAZY_CPU);
289
290 if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
291 arch_enter_lazy_mmu_mode();
292 }
293
paravirt_get_lazy_mode(void)294 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
295 {
296 if (in_interrupt())
297 return PARAVIRT_LAZY_NONE;
298
299 return this_cpu_read(paravirt_lazy_mode);
300 }
301
302 struct pv_info pv_info = {
303 .name = "bare hardware",
304 .kernel_rpl = 0,
305 .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
306
307 #ifdef CONFIG_X86_64
308 .extra_user_64bit_cs = __USER_CS,
309 #endif
310 };
311
312 struct pv_init_ops pv_init_ops = {
313 .patch = native_patch,
314 };
315
316 struct pv_time_ops pv_time_ops = {
317 .sched_clock = native_sched_clock,
318 .steal_clock = native_steal_clock,
319 };
320
321 __visible struct pv_irq_ops pv_irq_ops = {
322 .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
323 .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
324 .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
325 .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
326 .safe_halt = native_safe_halt,
327 .halt = native_halt,
328 };
329
330 __visible struct pv_cpu_ops pv_cpu_ops = {
331 .cpuid = native_cpuid,
332 .get_debugreg = native_get_debugreg,
333 .set_debugreg = native_set_debugreg,
334 .read_cr0 = native_read_cr0,
335 .write_cr0 = native_write_cr0,
336 .write_cr4 = native_write_cr4,
337 #ifdef CONFIG_X86_64
338 .read_cr8 = native_read_cr8,
339 .write_cr8 = native_write_cr8,
340 #endif
341 .wbinvd = native_wbinvd,
342 .read_msr = native_read_msr,
343 .write_msr = native_write_msr,
344 .read_msr_safe = native_read_msr_safe,
345 .write_msr_safe = native_write_msr_safe,
346 .read_pmc = native_read_pmc,
347 .load_tr_desc = native_load_tr_desc,
348 .set_ldt = native_set_ldt,
349 .load_gdt = native_load_gdt,
350 .load_idt = native_load_idt,
351 .store_tr = native_store_tr,
352 .load_tls = native_load_tls,
353 #ifdef CONFIG_X86_64
354 .load_gs_index = native_load_gs_index,
355 #endif
356 .write_ldt_entry = native_write_ldt_entry,
357 .write_gdt_entry = native_write_gdt_entry,
358 .write_idt_entry = native_write_idt_entry,
359
360 .alloc_ldt = paravirt_nop,
361 .free_ldt = paravirt_nop,
362
363 .load_sp0 = native_load_sp0,
364
365 #ifdef CONFIG_X86_64
366 .usergs_sysret64 = native_usergs_sysret64,
367 #endif
368 .iret = native_iret,
369 .swapgs = native_swapgs,
370
371 .set_iopl_mask = native_set_iopl_mask,
372 .io_delay = native_io_delay,
373
374 .start_context_switch = paravirt_nop,
375 .end_context_switch = paravirt_nop,
376 };
377
378 /* At this point, native_get/set_debugreg has real function entries */
379 NOKPROBE_SYMBOL(native_get_debugreg);
380 NOKPROBE_SYMBOL(native_set_debugreg);
381 NOKPROBE_SYMBOL(native_load_idt);
382
383 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
384 /* 32-bit pagetable entries */
385 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
386 #else
387 /* 64-bit pagetable entries */
388 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
389 #endif
390
391 struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
392
393 .read_cr2 = native_read_cr2,
394 .write_cr2 = native_write_cr2,
395 .read_cr3 = __native_read_cr3,
396 .write_cr3 = native_write_cr3,
397
398 .flush_tlb_user = native_flush_tlb,
399 .flush_tlb_kernel = native_flush_tlb_global,
400 .flush_tlb_one_user = native_flush_tlb_one_user,
401 .flush_tlb_others = native_flush_tlb_others,
402
403 .pgd_alloc = __paravirt_pgd_alloc,
404 .pgd_free = paravirt_nop,
405
406 .alloc_pte = paravirt_nop,
407 .alloc_pmd = paravirt_nop,
408 .alloc_pud = paravirt_nop,
409 .alloc_p4d = paravirt_nop,
410 .release_pte = paravirt_nop,
411 .release_pmd = paravirt_nop,
412 .release_pud = paravirt_nop,
413 .release_p4d = paravirt_nop,
414
415 .set_pte = native_set_pte,
416 .set_pte_at = native_set_pte_at,
417 .set_pmd = native_set_pmd,
418
419 .ptep_modify_prot_start = __ptep_modify_prot_start,
420 .ptep_modify_prot_commit = __ptep_modify_prot_commit,
421
422 #if CONFIG_PGTABLE_LEVELS >= 3
423 #ifdef CONFIG_X86_PAE
424 .set_pte_atomic = native_set_pte_atomic,
425 .pte_clear = native_pte_clear,
426 .pmd_clear = native_pmd_clear,
427 #endif
428 .set_pud = native_set_pud,
429
430 .pmd_val = PTE_IDENT,
431 .make_pmd = PTE_IDENT,
432
433 #if CONFIG_PGTABLE_LEVELS >= 4
434 .pud_val = PTE_IDENT,
435 .make_pud = PTE_IDENT,
436
437 .set_p4d = native_set_p4d,
438
439 #if CONFIG_PGTABLE_LEVELS >= 5
440 .p4d_val = PTE_IDENT,
441 .make_p4d = PTE_IDENT,
442
443 .set_pgd = native_set_pgd,
444 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
445 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
446 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
447
448 .pte_val = PTE_IDENT,
449 .pgd_val = PTE_IDENT,
450
451 .make_pte = PTE_IDENT,
452 .make_pgd = PTE_IDENT,
453
454 .dup_mmap = paravirt_nop,
455 .exit_mmap = paravirt_nop,
456 .activate_mm = paravirt_nop,
457
458 .lazy_mode = {
459 .enter = paravirt_nop,
460 .leave = paravirt_nop,
461 .flush = paravirt_nop,
462 },
463
464 .set_fixmap = native_set_fixmap,
465 };
466
467 EXPORT_SYMBOL_GPL(pv_time_ops);
468 EXPORT_SYMBOL (pv_cpu_ops);
469 EXPORT_SYMBOL (pv_mmu_ops);
470 EXPORT_SYMBOL_GPL(pv_info);
471 EXPORT_SYMBOL (pv_irq_ops);
472