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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 (tgt_clobbers & ~site_clobbers)
101 		return len;	/* target would clobber too much for this site */
102 	if (len < 5)
103 		return len;	/* call too long for patch site */
104 
105 	b->opcode = 0xe8; /* call */
106 	b->delta = delta;
107 	BUILD_BUG_ON(sizeof(*b) != 5);
108 
109 	return 5;
110 }
111 
paravirt_patch_jmp(void * insnbuf,const void * target,unsigned long addr,unsigned len)112 unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
113 			    unsigned long addr, unsigned len)
114 {
115 	struct branch *b = insnbuf;
116 	unsigned long delta = (unsigned long)target - (addr+5);
117 
118 	if (len < 5)
119 		return len;	/* call too long for patch site */
120 
121 	b->opcode = 0xe9;	/* jmp */
122 	b->delta = delta;
123 
124 	return 5;
125 }
126 
127 /* Neat trick to map patch type back to the call within the
128  * corresponding structure. */
get_call_destination(u8 type)129 static void *get_call_destination(u8 type)
130 {
131 	struct paravirt_patch_template tmpl = {
132 		.pv_init_ops = pv_init_ops,
133 		.pv_time_ops = pv_time_ops,
134 		.pv_cpu_ops = pv_cpu_ops,
135 		.pv_irq_ops = pv_irq_ops,
136 		.pv_apic_ops = pv_apic_ops,
137 		.pv_mmu_ops = pv_mmu_ops,
138 #ifdef CONFIG_PARAVIRT_SPINLOCKS
139 		.pv_lock_ops = pv_lock_ops,
140 #endif
141 	};
142 	return *((void **)&tmpl + type);
143 }
144 
paravirt_patch_default(u8 type,u16 clobbers,void * insnbuf,unsigned long addr,unsigned len)145 unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
146 				unsigned long addr, unsigned len)
147 {
148 	void *opfunc = get_call_destination(type);
149 	unsigned ret;
150 
151 	if (opfunc == NULL)
152 		/* If there's no function, patch it with a ud2a (BUG) */
153 		ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
154 	else if (opfunc == _paravirt_nop)
155 		/* If the operation is a nop, then nop the callsite */
156 		ret = paravirt_patch_nop();
157 
158 	/* identity functions just return their single argument */
159 	else if (opfunc == _paravirt_ident_32)
160 		ret = paravirt_patch_ident_32(insnbuf, len);
161 	else if (opfunc == _paravirt_ident_64)
162 		ret = paravirt_patch_ident_64(insnbuf, len);
163 
164 	else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
165 		 type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||
166 		 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||
167 		 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
168 		/* If operation requires a jmp, then jmp */
169 		ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
170 	else
171 		/* Otherwise call the function; assume target could
172 		   clobber any caller-save reg */
173 		ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
174 					  addr, clobbers, len);
175 
176 	return ret;
177 }
178 
paravirt_patch_insns(void * insnbuf,unsigned len,const char * start,const char * end)179 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
180 			      const char *start, const char *end)
181 {
182 	unsigned insn_len = end - start;
183 
184 	if (insn_len > len || start == NULL)
185 		insn_len = len;
186 	else
187 		memcpy(insnbuf, start, insn_len);
188 
189 	return insn_len;
190 }
191 
native_flush_tlb(void)192 static void native_flush_tlb(void)
193 {
194 	__native_flush_tlb();
195 }
196 
197 /*
198  * Global pages have to be flushed a bit differently. Not a real
199  * performance problem because this does not happen often.
200  */
native_flush_tlb_global(void)201 static void native_flush_tlb_global(void)
202 {
203 	__native_flush_tlb_global();
204 }
205 
native_flush_tlb_single(unsigned long addr)206 static void native_flush_tlb_single(unsigned long addr)
207 {
208 	__native_flush_tlb_single(addr);
209 }
210 
211 struct static_key paravirt_steal_enabled;
212 struct static_key paravirt_steal_rq_enabled;
213 
native_steal_clock(int cpu)214 static u64 native_steal_clock(int cpu)
215 {
216 	return 0;
217 }
218 
219 /* These are in entry.S */
220 extern void native_iret(void);
221 extern void native_irq_enable_sysexit(void);
222 extern void native_usergs_sysret32(void);
223 extern void native_usergs_sysret64(void);
224 
225 static struct resource reserve_ioports = {
226 	.start = 0,
227 	.end = IO_SPACE_LIMIT,
228 	.name = "paravirt-ioport",
229 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
230 };
231 
232 /*
233  * Reserve the whole legacy IO space to prevent any legacy drivers
234  * from wasting time probing for their hardware.  This is a fairly
235  * brute-force approach to disabling all non-virtual drivers.
236  *
237  * Note that this must be called very early to have any effect.
238  */
paravirt_disable_iospace(void)239 int paravirt_disable_iospace(void)
240 {
241 	return request_resource(&ioport_resource, &reserve_ioports);
242 }
243 
244 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
245 
enter_lazy(enum paravirt_lazy_mode mode)246 static inline void enter_lazy(enum paravirt_lazy_mode mode)
247 {
248 	BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
249 
250 	this_cpu_write(paravirt_lazy_mode, mode);
251 }
252 
leave_lazy(enum paravirt_lazy_mode mode)253 static void leave_lazy(enum paravirt_lazy_mode mode)
254 {
255 	BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
256 
257 	this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
258 }
259 
paravirt_enter_lazy_mmu(void)260 void paravirt_enter_lazy_mmu(void)
261 {
262 	enter_lazy(PARAVIRT_LAZY_MMU);
263 }
264 
paravirt_leave_lazy_mmu(void)265 void paravirt_leave_lazy_mmu(void)
266 {
267 	leave_lazy(PARAVIRT_LAZY_MMU);
268 }
269 
paravirt_flush_lazy_mmu(void)270 void paravirt_flush_lazy_mmu(void)
271 {
272 	preempt_disable();
273 
274 	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
275 		arch_leave_lazy_mmu_mode();
276 		arch_enter_lazy_mmu_mode();
277 	}
278 
279 	preempt_enable();
280 }
281 
paravirt_start_context_switch(struct task_struct * prev)282 void paravirt_start_context_switch(struct task_struct *prev)
283 {
284 	BUG_ON(preemptible());
285 
286 	if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
287 		arch_leave_lazy_mmu_mode();
288 		set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
289 	}
290 	enter_lazy(PARAVIRT_LAZY_CPU);
291 }
292 
paravirt_end_context_switch(struct task_struct * next)293 void paravirt_end_context_switch(struct task_struct *next)
294 {
295 	BUG_ON(preemptible());
296 
297 	leave_lazy(PARAVIRT_LAZY_CPU);
298 
299 	if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
300 		arch_enter_lazy_mmu_mode();
301 }
302 
paravirt_get_lazy_mode(void)303 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
304 {
305 	if (in_interrupt())
306 		return PARAVIRT_LAZY_NONE;
307 
308 	return this_cpu_read(paravirt_lazy_mode);
309 }
310 
311 struct pv_info pv_info = {
312 	.name = "bare hardware",
313 	.paravirt_enabled = 0,
314 	.kernel_rpl = 0,
315 	.shared_kernel_pmd = 1,	/* Only used when CONFIG_X86_PAE is set */
316 
317 #ifdef CONFIG_X86_64
318 	.extra_user_64bit_cs = __USER_CS,
319 #endif
320 };
321 
322 struct pv_init_ops pv_init_ops = {
323 	.patch = native_patch,
324 };
325 
326 struct pv_time_ops pv_time_ops = {
327 	.sched_clock = native_sched_clock,
328 	.steal_clock = native_steal_clock,
329 };
330 
331 __visible struct pv_irq_ops pv_irq_ops = {
332 	.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
333 	.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
334 	.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
335 	.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
336 	.safe_halt = native_safe_halt,
337 	.halt = native_halt,
338 #ifdef CONFIG_X86_64
339 	.adjust_exception_frame = paravirt_nop,
340 #endif
341 };
342 
343 __visible struct pv_cpu_ops pv_cpu_ops = {
344 	.cpuid = native_cpuid,
345 	.get_debugreg = native_get_debugreg,
346 	.set_debugreg = native_set_debugreg,
347 	.clts = native_clts,
348 	.read_cr0 = native_read_cr0,
349 	.write_cr0 = native_write_cr0,
350 	.read_cr4 = native_read_cr4,
351 	.read_cr4_safe = native_read_cr4_safe,
352 	.write_cr4 = native_write_cr4,
353 #ifdef CONFIG_X86_64
354 	.read_cr8 = native_read_cr8,
355 	.write_cr8 = native_write_cr8,
356 #endif
357 	.wbinvd = native_wbinvd,
358 	.read_msr = native_read_msr_safe,
359 	.write_msr = native_write_msr_safe,
360 	.read_tsc = native_read_tsc,
361 	.read_pmc = native_read_pmc,
362 	.read_tscp = native_read_tscp,
363 	.load_tr_desc = native_load_tr_desc,
364 	.set_ldt = native_set_ldt,
365 	.load_gdt = native_load_gdt,
366 	.load_idt = native_load_idt,
367 	.store_idt = native_store_idt,
368 	.store_tr = native_store_tr,
369 	.load_tls = native_load_tls,
370 #ifdef CONFIG_X86_64
371 	.load_gs_index = native_load_gs_index,
372 #endif
373 	.write_ldt_entry = native_write_ldt_entry,
374 	.write_gdt_entry = native_write_gdt_entry,
375 	.write_idt_entry = native_write_idt_entry,
376 
377 	.alloc_ldt = paravirt_nop,
378 	.free_ldt = paravirt_nop,
379 
380 	.load_sp0 = native_load_sp0,
381 
382 #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
383 	.irq_enable_sysexit = native_irq_enable_sysexit,
384 #endif
385 #ifdef CONFIG_X86_64
386 #ifdef CONFIG_IA32_EMULATION
387 	.usergs_sysret32 = native_usergs_sysret32,
388 #endif
389 	.usergs_sysret64 = native_usergs_sysret64,
390 #endif
391 	.iret = native_iret,
392 	.swapgs = native_swapgs,
393 
394 	.set_iopl_mask = native_set_iopl_mask,
395 	.io_delay = native_io_delay,
396 
397 	.start_context_switch = paravirt_nop,
398 	.end_context_switch = paravirt_nop,
399 };
400 
401 /* At this point, native_get/set_debugreg has real function entries */
402 NOKPROBE_SYMBOL(native_get_debugreg);
403 NOKPROBE_SYMBOL(native_set_debugreg);
404 NOKPROBE_SYMBOL(native_load_idt);
405 
406 struct pv_apic_ops pv_apic_ops = {
407 #ifdef CONFIG_X86_LOCAL_APIC
408 	.startup_ipi_hook = paravirt_nop,
409 #endif
410 };
411 
412 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
413 /* 32-bit pagetable entries */
414 #define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_32)
415 #else
416 /* 64-bit pagetable entries */
417 #define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_64)
418 #endif
419 
420 struct pv_mmu_ops pv_mmu_ops = {
421 
422 	.read_cr2 = native_read_cr2,
423 	.write_cr2 = native_write_cr2,
424 	.read_cr3 = native_read_cr3,
425 	.write_cr3 = native_write_cr3,
426 
427 	.flush_tlb_user = native_flush_tlb,
428 	.flush_tlb_kernel = native_flush_tlb_global,
429 	.flush_tlb_single = native_flush_tlb_single,
430 	.flush_tlb_others = native_flush_tlb_others,
431 
432 	.pgd_alloc = __paravirt_pgd_alloc,
433 	.pgd_free = paravirt_nop,
434 
435 	.alloc_pte = paravirt_nop,
436 	.alloc_pmd = paravirt_nop,
437 	.alloc_pud = paravirt_nop,
438 	.release_pte = paravirt_nop,
439 	.release_pmd = paravirt_nop,
440 	.release_pud = paravirt_nop,
441 
442 	.set_pte = native_set_pte,
443 	.set_pte_at = native_set_pte_at,
444 	.set_pmd = native_set_pmd,
445 	.set_pmd_at = native_set_pmd_at,
446 	.pte_update = paravirt_nop,
447 	.pte_update_defer = paravirt_nop,
448 	.pmd_update = paravirt_nop,
449 	.pmd_update_defer = paravirt_nop,
450 
451 	.ptep_modify_prot_start = __ptep_modify_prot_start,
452 	.ptep_modify_prot_commit = __ptep_modify_prot_commit,
453 
454 #if PAGETABLE_LEVELS >= 3
455 #ifdef CONFIG_X86_PAE
456 	.set_pte_atomic = native_set_pte_atomic,
457 	.pte_clear = native_pte_clear,
458 	.pmd_clear = native_pmd_clear,
459 #endif
460 	.set_pud = native_set_pud,
461 
462 	.pmd_val = PTE_IDENT,
463 	.make_pmd = PTE_IDENT,
464 
465 #if PAGETABLE_LEVELS == 4
466 	.pud_val = PTE_IDENT,
467 	.make_pud = PTE_IDENT,
468 
469 	.set_pgd = native_set_pgd,
470 #endif
471 #endif /* PAGETABLE_LEVELS >= 3 */
472 
473 	.pte_val = PTE_IDENT,
474 	.pgd_val = PTE_IDENT,
475 
476 	.make_pte = PTE_IDENT,
477 	.make_pgd = PTE_IDENT,
478 
479 	.dup_mmap = paravirt_nop,
480 	.exit_mmap = paravirt_nop,
481 	.activate_mm = paravirt_nop,
482 
483 	.lazy_mode = {
484 		.enter = paravirt_nop,
485 		.leave = paravirt_nop,
486 		.flush = paravirt_nop,
487 	},
488 
489 	.set_fixmap = native_set_fixmap,
490 };
491 
492 EXPORT_SYMBOL_GPL(pv_time_ops);
493 EXPORT_SYMBOL    (pv_cpu_ops);
494 EXPORT_SYMBOL    (pv_mmu_ops);
495 EXPORT_SYMBOL_GPL(pv_apic_ops);
496 EXPORT_SYMBOL_GPL(pv_info);
497 EXPORT_SYMBOL    (pv_irq_ops);
498