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Linux/arch/x86/kernel/paravirt.c

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

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