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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/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 */
 59 u32 notrace _paravirt_ident_32(u32 x)
 60 {
 61         return x;
 62 }
 63 
 64 u64 notrace _paravirt_ident_64(u64 x)
 65 {
 66         return x;
 67 }
 68 
 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 
 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 
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 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
125 
126 void __init native_pv_lock_init(void)
127 {
128         if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
129                 static_branch_disable(&virt_spin_lock_key);
130 }
131 
132 /*
133  * Neat trick to map patch type back to the call within the
134  * corresponding structure.
135  */
136 static void *get_call_destination(u8 type)
137 {
138         struct paravirt_patch_template tmpl = {
139                 .pv_init_ops = pv_init_ops,
140                 .pv_time_ops = pv_time_ops,
141                 .pv_cpu_ops = pv_cpu_ops,
142                 .pv_irq_ops = pv_irq_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 
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                 ret = 0;
162 
163         /* identity functions just return their single argument */
164         else if (opfunc == _paravirt_ident_32)
165                 ret = paravirt_patch_ident_32(insnbuf, len);
166         else if (opfunc == _paravirt_ident_64)
167                 ret = paravirt_patch_ident_64(insnbuf, len);
168 
169         else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
170                  type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
171                 /* If operation requires a jmp, then jmp */
172                 ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
173         else
174                 /* Otherwise call the function; assume target could
175                    clobber any caller-save reg */
176                 ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
177                                           addr, clobbers, len);
178 
179         return ret;
180 }
181 
182 unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
183                               const char *start, const char *end)
184 {
185         unsigned insn_len = end - start;
186 
187         if (insn_len > len || start == NULL)
188                 insn_len = len;
189         else
190                 memcpy(insnbuf, start, insn_len);
191 
192         return insn_len;
193 }
194 
195 static void native_flush_tlb(void)
196 {
197         __native_flush_tlb();
198 }
199 
200 /*
201  * Global pages have to be flushed a bit differently. Not a real
202  * performance problem because this does not happen often.
203  */
204 static void native_flush_tlb_global(void)
205 {
206         __native_flush_tlb_global();
207 }
208 
209 static void native_flush_tlb_one_user(unsigned long addr)
210 {
211         __native_flush_tlb_one_user(addr);
212 }
213 
214 struct static_key paravirt_steal_enabled;
215 struct static_key paravirt_steal_rq_enabled;
216 
217 static u64 native_steal_clock(int cpu)
218 {
219         return 0;
220 }
221 
222 /* These are in entry.S */
223 extern void native_iret(void);
224 extern void native_usergs_sysret64(void);
225 
226 static struct resource reserve_ioports = {
227         .start = 0,
228         .end = IO_SPACE_LIMIT,
229         .name = "paravirt-ioport",
230         .flags = IORESOURCE_IO | IORESOURCE_BUSY,
231 };
232 
233 /*
234  * Reserve the whole legacy IO space to prevent any legacy drivers
235  * from wasting time probing for their hardware.  This is a fairly
236  * brute-force approach to disabling all non-virtual drivers.
237  *
238  * Note that this must be called very early to have any effect.
239  */
240 int paravirt_disable_iospace(void)
241 {
242         return request_resource(&ioport_resource, &reserve_ioports);
243 }
244 
245 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
246 
247 static inline void enter_lazy(enum paravirt_lazy_mode mode)
248 {
249         BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
250 
251         this_cpu_write(paravirt_lazy_mode, mode);
252 }
253 
254 static void leave_lazy(enum paravirt_lazy_mode mode)
255 {
256         BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
257 
258         this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
259 }
260 
261 void paravirt_enter_lazy_mmu(void)
262 {
263         enter_lazy(PARAVIRT_LAZY_MMU);
264 }
265 
266 void paravirt_leave_lazy_mmu(void)
267 {
268         leave_lazy(PARAVIRT_LAZY_MMU);
269 }
270 
271 void paravirt_flush_lazy_mmu(void)
272 {
273         preempt_disable();
274 
275         if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
276                 arch_leave_lazy_mmu_mode();
277                 arch_enter_lazy_mmu_mode();
278         }
279 
280         preempt_enable();
281 }
282 
283 void paravirt_start_context_switch(struct task_struct *prev)
284 {
285         BUG_ON(preemptible());
286 
287         if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
288                 arch_leave_lazy_mmu_mode();
289                 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
290         }
291         enter_lazy(PARAVIRT_LAZY_CPU);
292 }
293 
294 void paravirt_end_context_switch(struct task_struct *next)
295 {
296         BUG_ON(preemptible());
297 
298         leave_lazy(PARAVIRT_LAZY_CPU);
299 
300         if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
301                 arch_enter_lazy_mmu_mode();
302 }
303 
304 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
305 {
306         if (in_interrupt())
307                 return PARAVIRT_LAZY_NONE;
308 
309         return this_cpu_read(paravirt_lazy_mode);
310 }
311 
312 struct pv_info pv_info = {
313         .name = "bare hardware",
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 };
339 
340 __visible struct pv_cpu_ops pv_cpu_ops = {
341         .cpuid = native_cpuid,
342         .get_debugreg = native_get_debugreg,
343         .set_debugreg = native_set_debugreg,
344         .read_cr0 = native_read_cr0,
345         .write_cr0 = native_write_cr0,
346         .write_cr4 = native_write_cr4,
347 #ifdef CONFIG_X86_64
348         .read_cr8 = native_read_cr8,
349         .write_cr8 = native_write_cr8,
350 #endif
351         .wbinvd = native_wbinvd,
352         .read_msr = native_read_msr,
353         .write_msr = native_write_msr,
354         .read_msr_safe = native_read_msr_safe,
355         .write_msr_safe = native_write_msr_safe,
356         .read_pmc = native_read_pmc,
357         .load_tr_desc = native_load_tr_desc,
358         .set_ldt = native_set_ldt,
359         .load_gdt = native_load_gdt,
360         .load_idt = native_load_idt,
361         .store_tr = native_store_tr,
362         .load_tls = native_load_tls,
363 #ifdef CONFIG_X86_64
364         .load_gs_index = native_load_gs_index,
365 #endif
366         .write_ldt_entry = native_write_ldt_entry,
367         .write_gdt_entry = native_write_gdt_entry,
368         .write_idt_entry = native_write_idt_entry,
369 
370         .alloc_ldt = paravirt_nop,
371         .free_ldt = paravirt_nop,
372 
373         .load_sp0 = native_load_sp0,
374 
375 #ifdef CONFIG_X86_64
376         .usergs_sysret64 = native_usergs_sysret64,
377 #endif
378         .iret = native_iret,
379         .swapgs = native_swapgs,
380 
381         .set_iopl_mask = native_set_iopl_mask,
382         .io_delay = native_io_delay,
383 
384         .start_context_switch = paravirt_nop,
385         .end_context_switch = paravirt_nop,
386 };
387 
388 /* At this point, native_get/set_debugreg has real function entries */
389 NOKPROBE_SYMBOL(native_get_debugreg);
390 NOKPROBE_SYMBOL(native_set_debugreg);
391 NOKPROBE_SYMBOL(native_load_idt);
392 
393 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
394 /* 32-bit pagetable entries */
395 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
396 #else
397 /* 64-bit pagetable entries */
398 #define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
399 #endif
400 
401 struct pv_mmu_ops pv_mmu_ops __ro_after_init = {
402 
403         .read_cr2 = native_read_cr2,
404         .write_cr2 = native_write_cr2,
405         .read_cr3 = __native_read_cr3,
406         .write_cr3 = native_write_cr3,
407 
408         .flush_tlb_user = native_flush_tlb,
409         .flush_tlb_kernel = native_flush_tlb_global,
410         .flush_tlb_one_user = native_flush_tlb_one_user,
411         .flush_tlb_others = native_flush_tlb_others,
412 
413         .pgd_alloc = __paravirt_pgd_alloc,
414         .pgd_free = paravirt_nop,
415 
416         .alloc_pte = paravirt_nop,
417         .alloc_pmd = paravirt_nop,
418         .alloc_pud = paravirt_nop,
419         .alloc_p4d = paravirt_nop,
420         .release_pte = paravirt_nop,
421         .release_pmd = paravirt_nop,
422         .release_pud = paravirt_nop,
423         .release_p4d = paravirt_nop,
424 
425         .set_pte = native_set_pte,
426         .set_pte_at = native_set_pte_at,
427         .set_pmd = native_set_pmd,
428 
429         .ptep_modify_prot_start = __ptep_modify_prot_start,
430         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
431 
432 #if CONFIG_PGTABLE_LEVELS >= 3
433 #ifdef CONFIG_X86_PAE
434         .set_pte_atomic = native_set_pte_atomic,
435         .pte_clear = native_pte_clear,
436         .pmd_clear = native_pmd_clear,
437 #endif
438         .set_pud = native_set_pud,
439 
440         .pmd_val = PTE_IDENT,
441         .make_pmd = PTE_IDENT,
442 
443 #if CONFIG_PGTABLE_LEVELS >= 4
444         .pud_val = PTE_IDENT,
445         .make_pud = PTE_IDENT,
446 
447         .set_p4d = native_set_p4d,
448 
449 #if CONFIG_PGTABLE_LEVELS >= 5
450         .p4d_val = PTE_IDENT,
451         .make_p4d = PTE_IDENT,
452 
453         .set_pgd = native_set_pgd,
454 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
455 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
456 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
457 
458         .pte_val = PTE_IDENT,
459         .pgd_val = PTE_IDENT,
460 
461         .make_pte = PTE_IDENT,
462         .make_pgd = PTE_IDENT,
463 
464         .dup_mmap = paravirt_nop,
465         .exit_mmap = paravirt_nop,
466         .activate_mm = paravirt_nop,
467 
468         .lazy_mode = {
469                 .enter = paravirt_nop,
470                 .leave = paravirt_nop,
471                 .flush = paravirt_nop,
472         },
473 
474         .set_fixmap = native_set_fixmap,
475 };
476 
477 EXPORT_SYMBOL_GPL(pv_time_ops);
478 EXPORT_SYMBOL    (pv_cpu_ops);
479 EXPORT_SYMBOL    (pv_mmu_ops);
480 EXPORT_SYMBOL_GPL(pv_info);
481 EXPORT_SYMBOL    (pv_irq_ops);
482 

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