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Linux/arch/x86/xen/mmu_pv.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 
  3 /*
  4  * Xen mmu operations
  5  *
  6  * This file contains the various mmu fetch and update operations.
  7  * The most important job they must perform is the mapping between the
  8  * domain's pfn and the overall machine mfns.
  9  *
 10  * Xen allows guests to directly update the pagetable, in a controlled
 11  * fashion.  In other words, the guest modifies the same pagetable
 12  * that the CPU actually uses, which eliminates the overhead of having
 13  * a separate shadow pagetable.
 14  *
 15  * In order to allow this, it falls on the guest domain to map its
 16  * notion of a "physical" pfn - which is just a domain-local linear
 17  * address - into a real "machine address" which the CPU's MMU can
 18  * use.
 19  *
 20  * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be
 21  * inserted directly into the pagetable.  When creating a new
 22  * pte/pmd/pgd, it converts the passed pfn into an mfn.  Conversely,
 23  * when reading the content back with __(pgd|pmd|pte)_val, it converts
 24  * the mfn back into a pfn.
 25  *
 26  * The other constraint is that all pages which make up a pagetable
 27  * must be mapped read-only in the guest.  This prevents uncontrolled
 28  * guest updates to the pagetable.  Xen strictly enforces this, and
 29  * will disallow any pagetable update which will end up mapping a
 30  * pagetable page RW, and will disallow using any writable page as a
 31  * pagetable.
 32  *
 33  * Naively, when loading %cr3 with the base of a new pagetable, Xen
 34  * would need to validate the whole pagetable before going on.
 35  * Naturally, this is quite slow.  The solution is to "pin" a
 36  * pagetable, which enforces all the constraints on the pagetable even
 37  * when it is not actively in use.  This menas that Xen can be assured
 38  * that it is still valid when you do load it into %cr3, and doesn't
 39  * need to revalidate it.
 40  *
 41  * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
 42  */
 43 #include <linux/sched/mm.h>
 44 #include <linux/highmem.h>
 45 #include <linux/debugfs.h>
 46 #include <linux/bug.h>
 47 #include <linux/vmalloc.h>
 48 #include <linux/export.h>
 49 #include <linux/init.h>
 50 #include <linux/gfp.h>
 51 #include <linux/memblock.h>
 52 #include <linux/seq_file.h>
 53 #include <linux/crash_dump.h>
 54 #ifdef CONFIG_KEXEC_CORE
 55 #include <linux/kexec.h>
 56 #endif
 57 
 58 #include <trace/events/xen.h>
 59 
 60 #include <asm/pgtable.h>
 61 #include <asm/tlbflush.h>
 62 #include <asm/fixmap.h>
 63 #include <asm/mmu_context.h>
 64 #include <asm/setup.h>
 65 #include <asm/paravirt.h>
 66 #include <asm/e820/api.h>
 67 #include <asm/linkage.h>
 68 #include <asm/page.h>
 69 #include <asm/init.h>
 70 #include <asm/memtype.h>
 71 #include <asm/smp.h>
 72 #include <asm/tlb.h>
 73 
 74 #include <asm/xen/hypercall.h>
 75 #include <asm/xen/hypervisor.h>
 76 
 77 #include <xen/xen.h>
 78 #include <xen/page.h>
 79 #include <xen/interface/xen.h>
 80 #include <xen/interface/hvm/hvm_op.h>
 81 #include <xen/interface/version.h>
 82 #include <xen/interface/memory.h>
 83 #include <xen/hvc-console.h>
 84 
 85 #include "multicalls.h"
 86 #include "mmu.h"
 87 #include "debugfs.h"
 88 
 89 #ifdef CONFIG_X86_32
 90 /*
 91  * Identity map, in addition to plain kernel map.  This needs to be
 92  * large enough to allocate page table pages to allocate the rest.
 93  * Each page can map 2MB.
 94  */
 95 #define LEVEL1_IDENT_ENTRIES    (PTRS_PER_PTE * 4)
 96 static RESERVE_BRK_ARRAY(pte_t, level1_ident_pgt, LEVEL1_IDENT_ENTRIES);
 97 #endif
 98 #ifdef CONFIG_X86_64
 99 /* l3 pud for userspace vsyscall mapping */
100 static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss;
101 #endif /* CONFIG_X86_64 */
102 
103 /*
104  * Protects atomic reservation decrease/increase against concurrent increases.
105  * Also protects non-atomic updates of current_pages and balloon lists.
106  */
107 static DEFINE_SPINLOCK(xen_reservation_lock);
108 
109 /*
110  * Note about cr3 (pagetable base) values:
111  *
112  * xen_cr3 contains the current logical cr3 value; it contains the
113  * last set cr3.  This may not be the current effective cr3, because
114  * its update may be being lazily deferred.  However, a vcpu looking
115  * at its own cr3 can use this value knowing that it everything will
116  * be self-consistent.
117  *
118  * xen_current_cr3 contains the actual vcpu cr3; it is set once the
119  * hypercall to set the vcpu cr3 is complete (so it may be a little
120  * out of date, but it will never be set early).  If one vcpu is
121  * looking at another vcpu's cr3 value, it should use this variable.
122  */
123 DEFINE_PER_CPU(unsigned long, xen_cr3);  /* cr3 stored as physaddr */
124 DEFINE_PER_CPU(unsigned long, xen_current_cr3);  /* actual vcpu cr3 */
125 
126 static phys_addr_t xen_pt_base, xen_pt_size __initdata;
127 
128 static DEFINE_STATIC_KEY_FALSE(xen_struct_pages_ready);
129 
130 /*
131  * Just beyond the highest usermode address.  STACK_TOP_MAX has a
132  * redzone above it, so round it up to a PGD boundary.
133  */
134 #define USER_LIMIT      ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK)
135 
136 void make_lowmem_page_readonly(void *vaddr)
137 {
138         pte_t *pte, ptev;
139         unsigned long address = (unsigned long)vaddr;
140         unsigned int level;
141 
142         pte = lookup_address(address, &level);
143         if (pte == NULL)
144                 return;         /* vaddr missing */
145 
146         ptev = pte_wrprotect(*pte);
147 
148         if (HYPERVISOR_update_va_mapping(address, ptev, 0))
149                 BUG();
150 }
151 
152 void make_lowmem_page_readwrite(void *vaddr)
153 {
154         pte_t *pte, ptev;
155         unsigned long address = (unsigned long)vaddr;
156         unsigned int level;
157 
158         pte = lookup_address(address, &level);
159         if (pte == NULL)
160                 return;         /* vaddr missing */
161 
162         ptev = pte_mkwrite(*pte);
163 
164         if (HYPERVISOR_update_va_mapping(address, ptev, 0))
165                 BUG();
166 }
167 
168 
169 /*
170  * During early boot all page table pages are pinned, but we do not have struct
171  * pages, so return true until struct pages are ready.
172  */
173 static bool xen_page_pinned(void *ptr)
174 {
175         if (static_branch_likely(&xen_struct_pages_ready)) {
176                 struct page *page = virt_to_page(ptr);
177 
178                 return PagePinned(page);
179         }
180         return true;
181 }
182 
183 static void xen_extend_mmu_update(const struct mmu_update *update)
184 {
185         struct multicall_space mcs;
186         struct mmu_update *u;
187 
188         mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u));
189 
190         if (mcs.mc != NULL) {
191                 mcs.mc->args[1]++;
192         } else {
193                 mcs = __xen_mc_entry(sizeof(*u));
194                 MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
195         }
196 
197         u = mcs.args;
198         *u = *update;
199 }
200 
201 static void xen_extend_mmuext_op(const struct mmuext_op *op)
202 {
203         struct multicall_space mcs;
204         struct mmuext_op *u;
205 
206         mcs = xen_mc_extend_args(__HYPERVISOR_mmuext_op, sizeof(*u));
207 
208         if (mcs.mc != NULL) {
209                 mcs.mc->args[1]++;
210         } else {
211                 mcs = __xen_mc_entry(sizeof(*u));
212                 MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
213         }
214 
215         u = mcs.args;
216         *u = *op;
217 }
218 
219 static void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
220 {
221         struct mmu_update u;
222 
223         preempt_disable();
224 
225         xen_mc_batch();
226 
227         /* ptr may be ioremapped for 64-bit pagetable setup */
228         u.ptr = arbitrary_virt_to_machine(ptr).maddr;
229         u.val = pmd_val_ma(val);
230         xen_extend_mmu_update(&u);
231 
232         xen_mc_issue(PARAVIRT_LAZY_MMU);
233 
234         preempt_enable();
235 }
236 
237 static void xen_set_pmd(pmd_t *ptr, pmd_t val)
238 {
239         trace_xen_mmu_set_pmd(ptr, val);
240 
241         /* If page is not pinned, we can just update the entry
242            directly */
243         if (!xen_page_pinned(ptr)) {
244                 *ptr = val;
245                 return;
246         }
247 
248         xen_set_pmd_hyper(ptr, val);
249 }
250 
251 /*
252  * Associate a virtual page frame with a given physical page frame
253  * and protection flags for that frame.
254  */
255 void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
256 {
257         set_pte_vaddr(vaddr, mfn_pte(mfn, flags));
258 }
259 
260 static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval)
261 {
262         struct mmu_update u;
263 
264         if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU)
265                 return false;
266 
267         xen_mc_batch();
268 
269         u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
270         u.val = pte_val_ma(pteval);
271         xen_extend_mmu_update(&u);
272 
273         xen_mc_issue(PARAVIRT_LAZY_MMU);
274 
275         return true;
276 }
277 
278 static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
279 {
280         if (!xen_batched_set_pte(ptep, pteval)) {
281                 /*
282                  * Could call native_set_pte() here and trap and
283                  * emulate the PTE write but with 32-bit guests this
284                  * needs two traps (one for each of the two 32-bit
285                  * words in the PTE) so do one hypercall directly
286                  * instead.
287                  */
288                 struct mmu_update u;
289 
290                 u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
291                 u.val = pte_val_ma(pteval);
292                 HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF);
293         }
294 }
295 
296 static void xen_set_pte(pte_t *ptep, pte_t pteval)
297 {
298         trace_xen_mmu_set_pte(ptep, pteval);
299         __xen_set_pte(ptep, pteval);
300 }
301 
302 static void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
303                     pte_t *ptep, pte_t pteval)
304 {
305         trace_xen_mmu_set_pte_at(mm, addr, ptep, pteval);
306         __xen_set_pte(ptep, pteval);
307 }
308 
309 pte_t xen_ptep_modify_prot_start(struct vm_area_struct *vma,
310                                  unsigned long addr, pte_t *ptep)
311 {
312         /* Just return the pte as-is.  We preserve the bits on commit */
313         trace_xen_mmu_ptep_modify_prot_start(vma->vm_mm, addr, ptep, *ptep);
314         return *ptep;
315 }
316 
317 void xen_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
318                                  pte_t *ptep, pte_t pte)
319 {
320         struct mmu_update u;
321 
322         trace_xen_mmu_ptep_modify_prot_commit(vma->vm_mm, addr, ptep, pte);
323         xen_mc_batch();
324 
325         u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
326         u.val = pte_val_ma(pte);
327         xen_extend_mmu_update(&u);
328 
329         xen_mc_issue(PARAVIRT_LAZY_MMU);
330 }
331 
332 /* Assume pteval_t is equivalent to all the other *val_t types. */
333 static pteval_t pte_mfn_to_pfn(pteval_t val)
334 {
335         if (val & _PAGE_PRESENT) {
336                 unsigned long mfn = (val & XEN_PTE_MFN_MASK) >> PAGE_SHIFT;
337                 unsigned long pfn = mfn_to_pfn(mfn);
338 
339                 pteval_t flags = val & PTE_FLAGS_MASK;
340                 if (unlikely(pfn == ~0))
341                         val = flags & ~_PAGE_PRESENT;
342                 else
343                         val = ((pteval_t)pfn << PAGE_SHIFT) | flags;
344         }
345 
346         return val;
347 }
348 
349 static pteval_t pte_pfn_to_mfn(pteval_t val)
350 {
351         if (val & _PAGE_PRESENT) {
352                 unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
353                 pteval_t flags = val & PTE_FLAGS_MASK;
354                 unsigned long mfn;
355 
356                 mfn = __pfn_to_mfn(pfn);
357 
358                 /*
359                  * If there's no mfn for the pfn, then just create an
360                  * empty non-present pte.  Unfortunately this loses
361                  * information about the original pfn, so
362                  * pte_mfn_to_pfn is asymmetric.
363                  */
364                 if (unlikely(mfn == INVALID_P2M_ENTRY)) {
365                         mfn = 0;
366                         flags = 0;
367                 } else
368                         mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT);
369                 val = ((pteval_t)mfn << PAGE_SHIFT) | flags;
370         }
371 
372         return val;
373 }
374 
375 __visible pteval_t xen_pte_val(pte_t pte)
376 {
377         pteval_t pteval = pte.pte;
378 
379         return pte_mfn_to_pfn(pteval);
380 }
381 PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
382 
383 __visible pgdval_t xen_pgd_val(pgd_t pgd)
384 {
385         return pte_mfn_to_pfn(pgd.pgd);
386 }
387 PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);
388 
389 __visible pte_t xen_make_pte(pteval_t pte)
390 {
391         pte = pte_pfn_to_mfn(pte);
392 
393         return native_make_pte(pte);
394 }
395 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
396 
397 __visible pgd_t xen_make_pgd(pgdval_t pgd)
398 {
399         pgd = pte_pfn_to_mfn(pgd);
400         return native_make_pgd(pgd);
401 }
402 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pgd);
403 
404 __visible pmdval_t xen_pmd_val(pmd_t pmd)
405 {
406         return pte_mfn_to_pfn(pmd.pmd);
407 }
408 PV_CALLEE_SAVE_REGS_THUNK(xen_pmd_val);
409 
410 static void xen_set_pud_hyper(pud_t *ptr, pud_t val)
411 {
412         struct mmu_update u;
413 
414         preempt_disable();
415 
416         xen_mc_batch();
417 
418         /* ptr may be ioremapped for 64-bit pagetable setup */
419         u.ptr = arbitrary_virt_to_machine(ptr).maddr;
420         u.val = pud_val_ma(val);
421         xen_extend_mmu_update(&u);
422 
423         xen_mc_issue(PARAVIRT_LAZY_MMU);
424 
425         preempt_enable();
426 }
427 
428 static void xen_set_pud(pud_t *ptr, pud_t val)
429 {
430         trace_xen_mmu_set_pud(ptr, val);
431 
432         /* If page is not pinned, we can just update the entry
433            directly */
434         if (!xen_page_pinned(ptr)) {
435                 *ptr = val;
436                 return;
437         }
438 
439         xen_set_pud_hyper(ptr, val);
440 }
441 
442 #ifdef CONFIG_X86_PAE
443 static void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
444 {
445         trace_xen_mmu_set_pte_atomic(ptep, pte);
446         __xen_set_pte(ptep, pte);
447 }
448 
449 static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
450 {
451         trace_xen_mmu_pte_clear(mm, addr, ptep);
452         __xen_set_pte(ptep, native_make_pte(0));
453 }
454 
455 static void xen_pmd_clear(pmd_t *pmdp)
456 {
457         trace_xen_mmu_pmd_clear(pmdp);
458         set_pmd(pmdp, __pmd(0));
459 }
460 #endif  /* CONFIG_X86_PAE */
461 
462 __visible pmd_t xen_make_pmd(pmdval_t pmd)
463 {
464         pmd = pte_pfn_to_mfn(pmd);
465         return native_make_pmd(pmd);
466 }
467 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pmd);
468 
469 #ifdef CONFIG_X86_64
470 __visible pudval_t xen_pud_val(pud_t pud)
471 {
472         return pte_mfn_to_pfn(pud.pud);
473 }
474 PV_CALLEE_SAVE_REGS_THUNK(xen_pud_val);
475 
476 __visible pud_t xen_make_pud(pudval_t pud)
477 {
478         pud = pte_pfn_to_mfn(pud);
479 
480         return native_make_pud(pud);
481 }
482 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pud);
483 
484 static pgd_t *xen_get_user_pgd(pgd_t *pgd)
485 {
486         pgd_t *pgd_page = (pgd_t *)(((unsigned long)pgd) & PAGE_MASK);
487         unsigned offset = pgd - pgd_page;
488         pgd_t *user_ptr = NULL;
489 
490         if (offset < pgd_index(USER_LIMIT)) {
491                 struct page *page = virt_to_page(pgd_page);
492                 user_ptr = (pgd_t *)page->private;
493                 if (user_ptr)
494                         user_ptr += offset;
495         }
496 
497         return user_ptr;
498 }
499 
500 static void __xen_set_p4d_hyper(p4d_t *ptr, p4d_t val)
501 {
502         struct mmu_update u;
503 
504         u.ptr = virt_to_machine(ptr).maddr;
505         u.val = p4d_val_ma(val);
506         xen_extend_mmu_update(&u);
507 }
508 
509 /*
510  * Raw hypercall-based set_p4d, intended for in early boot before
511  * there's a page structure.  This implies:
512  *  1. The only existing pagetable is the kernel's
513  *  2. It is always pinned
514  *  3. It has no user pagetable attached to it
515  */
516 static void __init xen_set_p4d_hyper(p4d_t *ptr, p4d_t val)
517 {
518         preempt_disable();
519 
520         xen_mc_batch();
521 
522         __xen_set_p4d_hyper(ptr, val);
523 
524         xen_mc_issue(PARAVIRT_LAZY_MMU);
525 
526         preempt_enable();
527 }
528 
529 static void xen_set_p4d(p4d_t *ptr, p4d_t val)
530 {
531         pgd_t *user_ptr = xen_get_user_pgd((pgd_t *)ptr);
532         pgd_t pgd_val;
533 
534         trace_xen_mmu_set_p4d(ptr, (p4d_t *)user_ptr, val);
535 
536         /* If page is not pinned, we can just update the entry
537            directly */
538         if (!xen_page_pinned(ptr)) {
539                 *ptr = val;
540                 if (user_ptr) {
541                         WARN_ON(xen_page_pinned(user_ptr));
542                         pgd_val.pgd = p4d_val_ma(val);
543                         *user_ptr = pgd_val;
544                 }
545                 return;
546         }
547 
548         /* If it's pinned, then we can at least batch the kernel and
549            user updates together. */
550         xen_mc_batch();
551 
552         __xen_set_p4d_hyper(ptr, val);
553         if (user_ptr)
554                 __xen_set_p4d_hyper((p4d_t *)user_ptr, val);
555 
556         xen_mc_issue(PARAVIRT_LAZY_MMU);
557 }
558 
559 #if CONFIG_PGTABLE_LEVELS >= 5
560 __visible p4dval_t xen_p4d_val(p4d_t p4d)
561 {
562         return pte_mfn_to_pfn(p4d.p4d);
563 }
564 PV_CALLEE_SAVE_REGS_THUNK(xen_p4d_val);
565 
566 __visible p4d_t xen_make_p4d(p4dval_t p4d)
567 {
568         p4d = pte_pfn_to_mfn(p4d);
569 
570         return native_make_p4d(p4d);
571 }
572 PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d);
573 #endif  /* CONFIG_PGTABLE_LEVELS >= 5 */
574 #endif  /* CONFIG_X86_64 */
575 
576 static int xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
577                 int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
578                 bool last, unsigned long limit)
579 {
580         int i, nr, flush = 0;
581 
582         nr = last ? pmd_index(limit) + 1 : PTRS_PER_PMD;
583         for (i = 0; i < nr; i++) {
584                 if (!pmd_none(pmd[i]))
585                         flush |= (*func)(mm, pmd_page(pmd[i]), PT_PTE);
586         }
587         return flush;
588 }
589 
590 static int xen_pud_walk(struct mm_struct *mm, pud_t *pud,
591                 int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
592                 bool last, unsigned long limit)
593 {
594         int i, nr, flush = 0;
595 
596         nr = last ? pud_index(limit) + 1 : PTRS_PER_PUD;
597         for (i = 0; i < nr; i++) {
598                 pmd_t *pmd;
599 
600                 if (pud_none(pud[i]))
601                         continue;
602 
603                 pmd = pmd_offset(&pud[i], 0);
604                 if (PTRS_PER_PMD > 1)
605                         flush |= (*func)(mm, virt_to_page(pmd), PT_PMD);
606                 flush |= xen_pmd_walk(mm, pmd, func,
607                                 last && i == nr - 1, limit);
608         }
609         return flush;
610 }
611 
612 static int xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
613                 int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
614                 bool last, unsigned long limit)
615 {
616         int flush = 0;
617         pud_t *pud;
618 
619 
620         if (p4d_none(*p4d))
621                 return flush;
622 
623         pud = pud_offset(p4d, 0);
624         if (PTRS_PER_PUD > 1)
625                 flush |= (*func)(mm, virt_to_page(pud), PT_PUD);
626         flush |= xen_pud_walk(mm, pud, func, last, limit);
627         return flush;
628 }
629 
630 /*
631  * (Yet another) pagetable walker.  This one is intended for pinning a
632  * pagetable.  This means that it walks a pagetable and calls the
633  * callback function on each page it finds making up the page table,
634  * at every level.  It walks the entire pagetable, but it only bothers
635  * pinning pte pages which are below limit.  In the normal case this
636  * will be STACK_TOP_MAX, but at boot we need to pin up to
637  * FIXADDR_TOP.
638  *
639  * For 32-bit the important bit is that we don't pin beyond there,
640  * because then we start getting into Xen's ptes.
641  *
642  * For 64-bit, we must skip the Xen hole in the middle of the address
643  * space, just after the big x86-64 virtual hole.
644  */
645 static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
646                           int (*func)(struct mm_struct *mm, struct page *,
647                                       enum pt_level),
648                           unsigned long limit)
649 {
650         int i, nr, flush = 0;
651         unsigned hole_low = 0, hole_high = 0;
652 
653         /* The limit is the last byte to be touched */
654         limit--;
655         BUG_ON(limit >= FIXADDR_TOP);
656 
657 #ifdef CONFIG_X86_64
658         /*
659          * 64-bit has a great big hole in the middle of the address
660          * space, which contains the Xen mappings.
661          */
662         hole_low = pgd_index(GUARD_HOLE_BASE_ADDR);
663         hole_high = pgd_index(GUARD_HOLE_END_ADDR);
664 #endif
665 
666         nr = pgd_index(limit) + 1;
667         for (i = 0; i < nr; i++) {
668                 p4d_t *p4d;
669 
670                 if (i >= hole_low && i < hole_high)
671                         continue;
672 
673                 if (pgd_none(pgd[i]))
674                         continue;
675 
676                 p4d = p4d_offset(&pgd[i], 0);
677                 flush |= xen_p4d_walk(mm, p4d, func, i == nr - 1, limit);
678         }
679 
680         /* Do the top level last, so that the callbacks can use it as
681            a cue to do final things like tlb flushes. */
682         flush |= (*func)(mm, virt_to_page(pgd), PT_PGD);
683 
684         return flush;
685 }
686 
687 static int xen_pgd_walk(struct mm_struct *mm,
688                         int (*func)(struct mm_struct *mm, struct page *,
689                                     enum pt_level),
690                         unsigned long limit)
691 {
692         return __xen_pgd_walk(mm, mm->pgd, func, limit);
693 }
694 
695 /* If we're using split pte locks, then take the page's lock and
696    return a pointer to it.  Otherwise return NULL. */
697 static spinlock_t *xen_pte_lock(struct page *page, struct mm_struct *mm)
698 {
699         spinlock_t *ptl = NULL;
700 
701 #if USE_SPLIT_PTE_PTLOCKS
702         ptl = ptlock_ptr(page);
703         spin_lock_nest_lock(ptl, &mm->page_table_lock);
704 #endif
705 
706         return ptl;
707 }
708 
709 static void xen_pte_unlock(void *v)
710 {
711         spinlock_t *ptl = v;
712         spin_unlock(ptl);
713 }
714 
715 static void xen_do_pin(unsigned level, unsigned long pfn)
716 {
717         struct mmuext_op op;
718 
719         op.cmd = level;
720         op.arg1.mfn = pfn_to_mfn(pfn);
721 
722         xen_extend_mmuext_op(&op);
723 }
724 
725 static int xen_pin_page(struct mm_struct *mm, struct page *page,
726                         enum pt_level level)
727 {
728         unsigned pgfl = TestSetPagePinned(page);
729         int flush;
730 
731         if (pgfl)
732                 flush = 0;              /* already pinned */
733         else if (PageHighMem(page))
734                 /* kmaps need flushing if we found an unpinned
735                    highpage */
736                 flush = 1;
737         else {
738                 void *pt = lowmem_page_address(page);
739                 unsigned long pfn = page_to_pfn(page);
740                 struct multicall_space mcs = __xen_mc_entry(0);
741                 spinlock_t *ptl;
742 
743                 flush = 0;
744 
745                 /*
746                  * We need to hold the pagetable lock between the time
747                  * we make the pagetable RO and when we actually pin
748                  * it.  If we don't, then other users may come in and
749                  * attempt to update the pagetable by writing it,
750                  * which will fail because the memory is RO but not
751                  * pinned, so Xen won't do the trap'n'emulate.
752                  *
753                  * If we're using split pte locks, we can't hold the
754                  * entire pagetable's worth of locks during the
755                  * traverse, because we may wrap the preempt count (8
756                  * bits).  The solution is to mark RO and pin each PTE
757                  * page while holding the lock.  This means the number
758                  * of locks we end up holding is never more than a
759                  * batch size (~32 entries, at present).
760                  *
761                  * If we're not using split pte locks, we needn't pin
762                  * the PTE pages independently, because we're
763                  * protected by the overall pagetable lock.
764                  */
765                 ptl = NULL;
766                 if (level == PT_PTE)
767                         ptl = xen_pte_lock(page, mm);
768 
769                 MULTI_update_va_mapping(mcs.mc, (unsigned long)pt,
770                                         pfn_pte(pfn, PAGE_KERNEL_RO),
771                                         level == PT_PGD ? UVMF_TLB_FLUSH : 0);
772 
773                 if (ptl) {
774                         xen_do_pin(MMUEXT_PIN_L1_TABLE, pfn);
775 
776                         /* Queue a deferred unlock for when this batch
777                            is completed. */
778                         xen_mc_callback(xen_pte_unlock, ptl);
779                 }
780         }
781 
782         return flush;
783 }
784 
785 /* This is called just after a mm has been created, but it has not
786    been used yet.  We need to make sure that its pagetable is all
787    read-only, and can be pinned. */
788 static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
789 {
790         trace_xen_mmu_pgd_pin(mm, pgd);
791 
792         xen_mc_batch();
793 
794         if (__xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT)) {
795                 /* re-enable interrupts for flushing */
796                 xen_mc_issue(0);
797 
798                 kmap_flush_unused();
799 
800                 xen_mc_batch();
801         }
802 
803 #ifdef CONFIG_X86_64
804         {
805                 pgd_t *user_pgd = xen_get_user_pgd(pgd);
806 
807                 xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
808 
809                 if (user_pgd) {
810                         xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
811                         xen_do_pin(MMUEXT_PIN_L4_TABLE,
812                                    PFN_DOWN(__pa(user_pgd)));
813                 }
814         }
815 #else /* CONFIG_X86_32 */
816 #ifdef CONFIG_X86_PAE
817         /* Need to make sure unshared kernel PMD is pinnable */
818         xen_pin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]),
819                      PT_PMD);
820 #endif
821         xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd)));
822 #endif /* CONFIG_X86_64 */
823         xen_mc_issue(0);
824 }
825 
826 static void xen_pgd_pin(struct mm_struct *mm)
827 {
828         __xen_pgd_pin(mm, mm->pgd);
829 }
830 
831 /*
832  * On save, we need to pin all pagetables to make sure they get their
833  * mfns turned into pfns.  Search the list for any unpinned pgds and pin
834  * them (unpinned pgds are not currently in use, probably because the
835  * process is under construction or destruction).
836  *
837  * Expected to be called in stop_machine() ("equivalent to taking
838  * every spinlock in the system"), so the locking doesn't really
839  * matter all that much.
840  */
841 void xen_mm_pin_all(void)
842 {
843         struct page *page;
844 
845         spin_lock(&pgd_lock);
846 
847         list_for_each_entry(page, &pgd_list, lru) {
848                 if (!PagePinned(page)) {
849                         __xen_pgd_pin(&init_mm, (pgd_t *)page_address(page));
850                         SetPageSavePinned(page);
851                 }
852         }
853 
854         spin_unlock(&pgd_lock);
855 }
856 
857 static int __init xen_mark_pinned(struct mm_struct *mm, struct page *page,
858                                   enum pt_level level)
859 {
860         SetPagePinned(page);
861         return 0;
862 }
863 
864 /*
865  * The init_mm pagetable is really pinned as soon as its created, but
866  * that's before we have page structures to store the bits.  So do all
867  * the book-keeping now once struct pages for allocated pages are
868  * initialized. This happens only after memblock_free_all() is called.
869  */
870 static void __init xen_after_bootmem(void)
871 {
872         static_branch_enable(&xen_struct_pages_ready);
873 #ifdef CONFIG_X86_64
874         SetPagePinned(virt_to_page(level3_user_vsyscall));
875 #endif
876         xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP);
877 }
878 
879 static int xen_unpin_page(struct mm_struct *mm, struct page *page,
880                           enum pt_level level)
881 {
882         unsigned pgfl = TestClearPagePinned(page);
883 
884         if (pgfl && !PageHighMem(page)) {
885                 void *pt = lowmem_page_address(page);
886                 unsigned long pfn = page_to_pfn(page);
887                 spinlock_t *ptl = NULL;
888                 struct multicall_space mcs;
889 
890                 /*
891                  * Do the converse to pin_page.  If we're using split
892                  * pte locks, we must be holding the lock for while
893                  * the pte page is unpinned but still RO to prevent
894                  * concurrent updates from seeing it in this
895                  * partially-pinned state.
896                  */
897                 if (level == PT_PTE) {
898                         ptl = xen_pte_lock(page, mm);
899 
900                         if (ptl)
901                                 xen_do_pin(MMUEXT_UNPIN_TABLE, pfn);
902                 }
903 
904                 mcs = __xen_mc_entry(0);
905 
906                 MULTI_update_va_mapping(mcs.mc, (unsigned long)pt,
907                                         pfn_pte(pfn, PAGE_KERNEL),
908                                         level == PT_PGD ? UVMF_TLB_FLUSH : 0);
909 
910                 if (ptl) {
911                         /* unlock when batch completed */
912                         xen_mc_callback(xen_pte_unlock, ptl);
913                 }
914         }
915 
916         return 0;               /* never need to flush on unpin */
917 }
918 
919 /* Release a pagetables pages back as normal RW */
920 static void __xen_pgd_unpin(struct mm_struct *mm, pgd_t *pgd)
921 {
922         trace_xen_mmu_pgd_unpin(mm, pgd);
923 
924         xen_mc_batch();
925 
926         xen_do_pin(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
927 
928 #ifdef CONFIG_X86_64
929         {
930                 pgd_t *user_pgd = xen_get_user_pgd(pgd);
931 
932                 if (user_pgd) {
933                         xen_do_pin(MMUEXT_UNPIN_TABLE,
934                                    PFN_DOWN(__pa(user_pgd)));
935                         xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);
936                 }
937         }
938 #endif
939 
940 #ifdef CONFIG_X86_PAE
941         /* Need to make sure unshared kernel PMD is unpinned */
942         xen_unpin_page(mm, pgd_page(pgd[pgd_index(TASK_SIZE)]),
943                        PT_PMD);
944 #endif
945 
946         __xen_pgd_walk(mm, pgd, xen_unpin_page, USER_LIMIT);
947 
948         xen_mc_issue(0);
949 }
950 
951 static void xen_pgd_unpin(struct mm_struct *mm)
952 {
953         __xen_pgd_unpin(mm, mm->pgd);
954 }
955 
956 /*
957  * On resume, undo any pinning done at save, so that the rest of the
958  * kernel doesn't see any unexpected pinned pagetables.
959  */
960 void xen_mm_unpin_all(void)
961 {
962         struct page *page;
963 
964         spin_lock(&pgd_lock);
965 
966         list_for_each_entry(page, &pgd_list, lru) {
967                 if (PageSavePinned(page)) {
968                         BUG_ON(!PagePinned(page));
969                         __xen_pgd_unpin(&init_mm, (pgd_t *)page_address(page));
970                         ClearPageSavePinned(page);
971                 }
972         }
973 
974         spin_unlock(&pgd_lock);
975 }
976 
977 static void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next)
978 {
979         spin_lock(&next->page_table_lock);
980         xen_pgd_pin(next);
981         spin_unlock(&next->page_table_lock);
982 }
983 
984 static void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
985 {
986         spin_lock(&mm->page_table_lock);
987         xen_pgd_pin(mm);
988         spin_unlock(&mm->page_table_lock);
989 }
990 
991 static void drop_mm_ref_this_cpu(void *info)
992 {
993         struct mm_struct *mm = info;
994 
995         if (this_cpu_read(cpu_tlbstate.loaded_mm) == mm)
996                 leave_mm(smp_processor_id());
997 
998         /*
999          * If this cpu still has a stale cr3 reference, then make sure
1000          * it has been flushed.
1001          */
1002         if (this_cpu_read(xen_current_cr3) == __pa(mm->pgd))
1003                 xen_mc_flush();
1004 }
1005 
1006 #ifdef CONFIG_SMP
1007 /*
1008  * Another cpu may still have their %cr3 pointing at the pagetable, so
1009  * we need to repoint it somewhere else before we can unpin it.
1010  */
1011 static void xen_drop_mm_ref(struct mm_struct *mm)
1012 {
1013         cpumask_var_t mask;
1014         unsigned cpu;
1015 
1016         drop_mm_ref_this_cpu(mm);
1017 
1018         /* Get the "official" set of cpus referring to our pagetable. */
1019         if (!alloc_cpumask_var(&mask, GFP_ATOMIC)) {
1020                 for_each_online_cpu(cpu) {
1021                         if (per_cpu(xen_current_cr3, cpu) != __pa(mm->pgd))
1022                                 continue;
1023                         smp_call_function_single(cpu, drop_mm_ref_this_cpu, mm, 1);
1024                 }
1025                 return;
1026         }
1027 
1028         /*
1029          * It's possible that a vcpu may have a stale reference to our
1030          * cr3, because its in lazy mode, and it hasn't yet flushed
1031          * its set of pending hypercalls yet.  In this case, we can
1032          * look at its actual current cr3 value, and force it to flush
1033          * if needed.
1034          */
1035         cpumask_clear(mask);
1036         for_each_online_cpu(cpu) {
1037                 if (per_cpu(xen_current_cr3, cpu) == __pa(mm->pgd))
1038                         cpumask_set_cpu(cpu, mask);
1039         }
1040 
1041         smp_call_function_many(mask, drop_mm_ref_this_cpu, mm, 1);
1042         free_cpumask_var(mask);
1043 }
1044 #else
1045 static void xen_drop_mm_ref(struct mm_struct *mm)
1046 {
1047         drop_mm_ref_this_cpu(mm);
1048 }
1049 #endif
1050 
1051 /*
1052  * While a process runs, Xen pins its pagetables, which means that the
1053  * hypervisor forces it to be read-only, and it controls all updates
1054  * to it.  This means that all pagetable updates have to go via the
1055  * hypervisor, which is moderately expensive.
1056  *
1057  * Since we're pulling the pagetable down, we switch to use init_mm,
1058  * unpin old process pagetable and mark it all read-write, which
1059  * allows further operations on it to be simple memory accesses.
1060  *
1061  * The only subtle point is that another CPU may be still using the
1062  * pagetable because of lazy tlb flushing.  This means we need need to
1063  * switch all CPUs off this pagetable before we can unpin it.
1064  */
1065 static void xen_exit_mmap(struct mm_struct *mm)
1066 {
1067         get_cpu();              /* make sure we don't move around */
1068         xen_drop_mm_ref(mm);
1069         put_cpu();
1070 
1071         spin_lock(&mm->page_table_lock);
1072 
1073         /* pgd may not be pinned in the error exit path of execve */
1074         if (xen_page_pinned(mm->pgd))
1075                 xen_pgd_unpin(mm);
1076 
1077         spin_unlock(&mm->page_table_lock);
1078 }
1079 
1080 static void xen_post_allocator_init(void);
1081 
1082 static void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
1083 {
1084         struct mmuext_op op;
1085 
1086         op.cmd = cmd;
1087         op.arg1.mfn = pfn_to_mfn(pfn);
1088         if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
1089                 BUG();
1090 }
1091 
1092 #ifdef CONFIG_X86_64
1093 static void __init xen_cleanhighmap(unsigned long vaddr,
1094                                     unsigned long vaddr_end)
1095 {
1096         unsigned long kernel_end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
1097         pmd_t *pmd = level2_kernel_pgt + pmd_index(vaddr);
1098 
1099         /* NOTE: The loop is more greedy than the cleanup_highmap variant.
1100          * We include the PMD passed in on _both_ boundaries. */
1101         for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PTRS_PER_PMD));
1102                         pmd++, vaddr += PMD_SIZE) {
1103                 if (pmd_none(*pmd))
1104                         continue;
1105                 if (vaddr < (unsigned long) _text || vaddr > kernel_end)
1106                         set_pmd(pmd, __pmd(0));
1107         }
1108         /* In case we did something silly, we should crash in this function
1109          * instead of somewhere later and be confusing. */
1110         xen_mc_flush();
1111 }
1112 
1113 /*
1114  * Make a page range writeable and free it.
1115  */
1116 static void __init xen_free_ro_pages(unsigned long paddr, unsigned long size)
1117 {
1118         void *vaddr = __va(paddr);
1119         void *vaddr_end = vaddr + size;
1120 
1121         for (; vaddr < vaddr_end; vaddr += PAGE_SIZE)
1122                 make_lowmem_page_readwrite(vaddr);
1123 
1124         memblock_free(paddr, size);
1125 }
1126 
1127 static void __init xen_cleanmfnmap_free_pgtbl(void *pgtbl, bool unpin)
1128 {
1129         unsigned long pa = __pa(pgtbl) & PHYSICAL_PAGE_MASK;
1130 
1131         if (unpin)
1132                 pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(pa));
1133         ClearPagePinned(virt_to_page(__va(pa)));
1134         xen_free_ro_pages(pa, PAGE_SIZE);
1135 }
1136 
1137 static void __init xen_cleanmfnmap_pmd(pmd_t *pmd, bool unpin)
1138 {
1139         unsigned long pa;
1140         pte_t *pte_tbl;
1141         int i;
1142 
1143         if (pmd_large(*pmd)) {
1144                 pa = pmd_val(*pmd) & PHYSICAL_PAGE_MASK;
1145                 xen_free_ro_pages(pa, PMD_SIZE);
1146                 return;
1147         }
1148 
1149         pte_tbl = pte_offset_kernel(pmd, 0);
1150         for (i = 0; i < PTRS_PER_PTE; i++) {
1151                 if (pte_none(pte_tbl[i]))
1152                         continue;
1153                 pa = pte_pfn(pte_tbl[i]) << PAGE_SHIFT;
1154                 xen_free_ro_pages(pa, PAGE_SIZE);
1155         }
1156         set_pmd(pmd, __pmd(0));
1157         xen_cleanmfnmap_free_pgtbl(pte_tbl, unpin);
1158 }
1159 
1160 static void __init xen_cleanmfnmap_pud(pud_t *pud, bool unpin)
1161 {
1162         unsigned long pa;
1163         pmd_t *pmd_tbl;
1164         int i;
1165 
1166         if (pud_large(*pud)) {
1167                 pa = pud_val(*pud) & PHYSICAL_PAGE_MASK;
1168                 xen_free_ro_pages(pa, PUD_SIZE);
1169                 return;
1170         }
1171 
1172         pmd_tbl = pmd_offset(pud, 0);
1173         for (i = 0; i < PTRS_PER_PMD; i++) {
1174                 if (pmd_none(pmd_tbl[i]))
1175                         continue;
1176                 xen_cleanmfnmap_pmd(pmd_tbl + i, unpin);
1177         }
1178         set_pud(pud, __pud(0));
1179         xen_cleanmfnmap_free_pgtbl(pmd_tbl, unpin);
1180 }
1181 
1182 static void __init xen_cleanmfnmap_p4d(p4d_t *p4d, bool unpin)
1183 {
1184         unsigned long pa;
1185         pud_t *pud_tbl;
1186         int i;
1187 
1188         if (p4d_large(*p4d)) {
1189                 pa = p4d_val(*p4d) & PHYSICAL_PAGE_MASK;
1190                 xen_free_ro_pages(pa, P4D_SIZE);
1191                 return;
1192         }
1193 
1194         pud_tbl = pud_offset(p4d, 0);
1195         for (i = 0; i < PTRS_PER_PUD; i++) {
1196                 if (pud_none(pud_tbl[i]))
1197                         continue;
1198                 xen_cleanmfnmap_pud(pud_tbl + i, unpin);
1199         }
1200         set_p4d(p4d, __p4d(0));
1201         xen_cleanmfnmap_free_pgtbl(pud_tbl, unpin);
1202 }
1203 
1204 /*
1205  * Since it is well isolated we can (and since it is perhaps large we should)
1206  * also free the page tables mapping the initial P->M table.
1207  */
1208 static void __init xen_cleanmfnmap(unsigned long vaddr)
1209 {
1210         pgd_t *pgd;
1211         p4d_t *p4d;
1212         bool unpin;
1213 
1214         unpin = (vaddr == 2 * PGDIR_SIZE);
1215         vaddr &= PMD_MASK;
1216         pgd = pgd_offset_k(vaddr);
1217         p4d = p4d_offset(pgd, 0);
1218         if (!p4d_none(*p4d))
1219                 xen_cleanmfnmap_p4d(p4d, unpin);
1220 }
1221 
1222 static void __init xen_pagetable_p2m_free(void)
1223 {
1224         unsigned long size;
1225         unsigned long addr;
1226 
1227         size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
1228 
1229         /* No memory or already called. */
1230         if ((unsigned long)xen_p2m_addr == xen_start_info->mfn_list)
1231                 return;
1232 
1233         /* using __ka address and sticking INVALID_P2M_ENTRY! */
1234         memset((void *)xen_start_info->mfn_list, 0xff, size);
1235 
1236         addr = xen_start_info->mfn_list;
1237         /*
1238          * We could be in __ka space.
1239          * We roundup to the PMD, which means that if anybody at this stage is
1240          * using the __ka address of xen_start_info or
1241          * xen_start_info->shared_info they are in going to crash. Fortunatly
1242          * we have already revectored in xen_setup_kernel_pagetable.
1243          */
1244         size = roundup(size, PMD_SIZE);
1245 
1246         if (addr >= __START_KERNEL_map) {
1247                 xen_cleanhighmap(addr, addr + size);
1248                 size = PAGE_ALIGN(xen_start_info->nr_pages *
1249                                   sizeof(unsigned long));
1250                 memblock_free(__pa(addr), size);
1251         } else {
1252                 xen_cleanmfnmap(addr);
1253         }
1254 }
1255 
1256 static void __init xen_pagetable_cleanhighmap(void)
1257 {
1258         unsigned long size;
1259         unsigned long addr;
1260 
1261         /* At this stage, cleanup_highmap has already cleaned __ka space
1262          * from _brk_limit way up to the max_pfn_mapped (which is the end of
1263          * the ramdisk). We continue on, erasing PMD entries that point to page
1264          * tables - do note that they are accessible at this stage via __va.
1265          * As Xen is aligning the memory end to a 4MB boundary, for good
1266          * measure we also round up to PMD_SIZE * 2 - which means that if
1267          * anybody is using __ka address to the initial boot-stack - and try
1268          * to use it - they are going to crash. The xen_start_info has been
1269          * taken care of already in xen_setup_kernel_pagetable. */
1270         addr = xen_start_info->pt_base;
1271         size = xen_start_info->nr_pt_frames * PAGE_SIZE;
1272 
1273         xen_cleanhighmap(addr, roundup(addr + size, PMD_SIZE * 2));
1274         xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
1275 }
1276 #endif
1277 
1278 static void __init xen_pagetable_p2m_setup(void)
1279 {
1280         xen_vmalloc_p2m_tree();
1281 
1282 #ifdef CONFIG_X86_64
1283         xen_pagetable_p2m_free();
1284 
1285         xen_pagetable_cleanhighmap();
1286 #endif
1287         /* And revector! Bye bye old array */
1288         xen_start_info->mfn_list = (unsigned long)xen_p2m_addr;
1289 }
1290 
1291 static void __init xen_pagetable_init(void)
1292 {
1293         paging_init();
1294         xen_post_allocator_init();
1295 
1296         xen_pagetable_p2m_setup();
1297 
1298         /* Allocate and initialize top and mid mfn levels for p2m structure */
1299         xen_build_mfn_list_list();
1300 
1301         /* Remap memory freed due to conflicts with E820 map */
1302         xen_remap_memory();
1303         xen_setup_mfn_list_list();
1304 }
1305 static void xen_write_cr2(unsigned long cr2)
1306 {
1307         this_cpu_read(xen_vcpu)->arch.cr2 = cr2;
1308 }
1309 
1310 static noinline void xen_flush_tlb(void)
1311 {
1312         struct mmuext_op *op;
1313         struct multicall_space mcs;
1314 
1315         preempt_disable();
1316 
1317         mcs = xen_mc_entry(sizeof(*op));
1318 
1319         op = mcs.args;
1320         op->cmd = MMUEXT_TLB_FLUSH_LOCAL;
1321         MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
1322 
1323         xen_mc_issue(PARAVIRT_LAZY_MMU);
1324 
1325         preempt_enable();
1326 }
1327 
1328 static void xen_flush_tlb_one_user(unsigned long addr)
1329 {
1330         struct mmuext_op *op;
1331         struct multicall_space mcs;
1332 
1333         trace_xen_mmu_flush_tlb_one_user(addr);
1334 
1335         preempt_disable();
1336 
1337         mcs = xen_mc_entry(sizeof(*op));
1338         op = mcs.args;
1339         op->cmd = MMUEXT_INVLPG_LOCAL;
1340         op->arg1.linear_addr = addr & PAGE_MASK;
1341         MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
1342 
1343         xen_mc_issue(PARAVIRT_LAZY_MMU);
1344 
1345         preempt_enable();
1346 }
1347 
1348 static void xen_flush_tlb_others(const struct cpumask *cpus,
1349                                  const struct flush_tlb_info *info)
1350 {
1351         struct {
1352                 struct mmuext_op op;
1353                 DECLARE_BITMAP(mask, NR_CPUS);
1354         } *args;
1355         struct multicall_space mcs;
1356         const size_t mc_entry_size = sizeof(args->op) +
1357                 sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus());
1358 
1359         trace_xen_mmu_flush_tlb_others(cpus, info->mm, info->start, info->end);
1360 
1361         if (cpumask_empty(cpus))
1362                 return;         /* nothing to do */
1363 
1364         mcs = xen_mc_entry(mc_entry_size);
1365         args = mcs.args;
1366         args->op.arg2.vcpumask = to_cpumask(args->mask);
1367 
1368         /* Remove us, and any offline CPUS. */
1369         cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
1370         cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));
1371 
1372         args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
1373         if (info->end != TLB_FLUSH_ALL &&
1374             (info->end - info->start) <= PAGE_SIZE) {
1375                 args->op.cmd = MMUEXT_INVLPG_MULTI;
1376                 args->op.arg1.linear_addr = info->start;
1377         }
1378 
1379         MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF);
1380 
1381         xen_mc_issue(PARAVIRT_LAZY_MMU);
1382 }
1383 
1384 static unsigned long xen_read_cr3(void)
1385 {
1386         return this_cpu_read(xen_cr3);
1387 }
1388 
1389 static void set_current_cr3(void *v)
1390 {
1391         this_cpu_write(xen_current_cr3, (unsigned long)v);
1392 }
1393 
1394 static void __xen_write_cr3(bool kernel, unsigned long cr3)
1395 {
1396         struct mmuext_op op;
1397         unsigned long mfn;
1398 
1399         trace_xen_mmu_write_cr3(kernel, cr3);
1400 
1401         if (cr3)
1402                 mfn = pfn_to_mfn(PFN_DOWN(cr3));
1403         else
1404                 mfn = 0;
1405 
1406         WARN_ON(mfn == 0 && kernel);
1407 
1408         op.cmd = kernel ? MMUEXT_NEW_BASEPTR : MMUEXT_NEW_USER_BASEPTR;
1409         op.arg1.mfn = mfn;
1410 
1411         xen_extend_mmuext_op(&op);
1412 
1413         if (kernel) {
1414                 this_cpu_write(xen_cr3, cr3);
1415 
1416                 /* Update xen_current_cr3 once the batch has actually
1417                    been submitted. */
1418                 xen_mc_callback(set_current_cr3, (void *)cr3);
1419         }
1420 }
1421 static void xen_write_cr3(unsigned long cr3)
1422 {
1423         BUG_ON(preemptible());
1424 
1425         xen_mc_batch();  /* disables interrupts */
1426 
1427         /* Update while interrupts are disabled, so its atomic with
1428            respect to ipis */
1429         this_cpu_write(xen_cr3, cr3);
1430 
1431         __xen_write_cr3(true, cr3);
1432 
1433 #ifdef CONFIG_X86_64
1434         {
1435                 pgd_t *user_pgd = xen_get_user_pgd(__va(cr3));
1436                 if (user_pgd)
1437                         __xen_write_cr3(false, __pa(user_pgd));
1438                 else
1439                         __xen_write_cr3(false, 0);
1440         }
1441 #endif
1442 
1443         xen_mc_issue(PARAVIRT_LAZY_CPU);  /* interrupts restored */
1444 }
1445 
1446 #ifdef CONFIG_X86_64
1447 /*
1448  * At the start of the day - when Xen launches a guest, it has already
1449  * built pagetables for the guest. We diligently look over them
1450  * in xen_setup_kernel_pagetable and graft as appropriate them in the
1451  * init_top_pgt and its friends. Then when we are happy we load
1452  * the new init_top_pgt - and continue on.
1453  *
1454  * The generic code starts (start_kernel) and 'init_mem_mapping' sets
1455  * up the rest of the pagetables. When it has completed it loads the cr3.
1456  * N.B. that baremetal would start at 'start_kernel' (and the early
1457  * #PF handler would create bootstrap pagetables) - so we are running
1458  * with the same assumptions as what to do when write_cr3 is executed
1459  * at this point.
1460  *
1461  * Since there are no user-page tables at all, we have two variants
1462  * of xen_write_cr3 - the early bootup (this one), and the late one
1463  * (xen_write_cr3). The reason we have to do that is that in 64-bit
1464  * the Linux kernel and user-space are both in ring 3 while the
1465  * hypervisor is in ring 0.
1466  */
1467 static void __init xen_write_cr3_init(unsigned long cr3)
1468 {
1469         BUG_ON(preemptible());
1470 
1471         xen_mc_batch();  /* disables interrupts */
1472 
1473         /* Update while interrupts are disabled, so its atomic with
1474            respect to ipis */
1475         this_cpu_write(xen_cr3, cr3);
1476 
1477         __xen_write_cr3(true, cr3);
1478 
1479         xen_mc_issue(PARAVIRT_LAZY_CPU);  /* interrupts restored */
1480 }
1481 #endif
1482 
1483 static int xen_pgd_alloc(struct mm_struct *mm)
1484 {
1485         pgd_t *pgd = mm->pgd;
1486         int ret = 0;
1487 
1488         BUG_ON(PagePinned(virt_to_page(pgd)));
1489 
1490 #ifdef CONFIG_X86_64
1491         {
1492                 struct page *page = virt_to_page(pgd);
1493                 pgd_t *user_pgd;
1494 
1495                 BUG_ON(page->private != 0);
1496 
1497                 ret = -ENOMEM;
1498 
1499                 user_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
1500                 page->private = (unsigned long)user_pgd;
1501 
1502                 if (user_pgd != NULL) {
1503 #ifdef CONFIG_X86_VSYSCALL_EMULATION
1504                         user_pgd[pgd_index(VSYSCALL_ADDR)] =
1505                                 __pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
1506 #endif
1507                         ret = 0;
1508                 }
1509 
1510                 BUG_ON(PagePinned(virt_to_page(xen_get_user_pgd(pgd))));
1511         }
1512 #endif
1513         return ret;
1514 }
1515 
1516 static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
1517 {
1518 #ifdef CONFIG_X86_64
1519         pgd_t *user_pgd = xen_get_user_pgd(pgd);
1520 
1521         if (user_pgd)
1522                 free_page((unsigned long)user_pgd);
1523 #endif
1524 }
1525 
1526 /*
1527  * Init-time set_pte while constructing initial pagetables, which
1528  * doesn't allow RO page table pages to be remapped RW.
1529  *
1530  * If there is no MFN for this PFN then this page is initially
1531  * ballooned out so clear the PTE (as in decrease_reservation() in
1532  * drivers/xen/balloon.c).
1533  *
1534  * Many of these PTE updates are done on unpinned and writable pages
1535  * and doing a hypercall for these is unnecessary and expensive.  At
1536  * this point it is not possible to tell if a page is pinned or not,
1537  * so always write the PTE directly and rely on Xen trapping and
1538  * emulating any updates as necessary.
1539  */
1540 __visible pte_t xen_make_pte_init(pteval_t pte)
1541 {
1542 #ifdef CONFIG_X86_64
1543         unsigned long pfn;
1544 
1545         /*
1546          * Pages belonging to the initial p2m list mapped outside the default
1547          * address range must be mapped read-only. This region contains the
1548          * page tables for mapping the p2m list, too, and page tables MUST be
1549          * mapped read-only.
1550          */
1551         pfn = (pte & PTE_PFN_MASK) >> PAGE_SHIFT;
1552         if (xen_start_info->mfn_list < __START_KERNEL_map &&
1553             pfn >= xen_start_info->first_p2m_pfn &&
1554             pfn < xen_start_info->first_p2m_pfn + xen_start_info->nr_p2m_frames)
1555                 pte &= ~_PAGE_RW;
1556 #endif
1557         pte = pte_pfn_to_mfn(pte);
1558         return native_make_pte(pte);
1559 }
1560 PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_init);
1561 
1562 static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
1563 {
1564 #ifdef CONFIG_X86_32
1565         /* If there's an existing pte, then don't allow _PAGE_RW to be set */
1566         if (pte_mfn(pte) != INVALID_P2M_ENTRY
1567             && pte_val_ma(*ptep) & _PAGE_PRESENT)
1568                 pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
1569                                pte_val_ma(pte));
1570 #endif
1571         __xen_set_pte(ptep, pte);
1572 }
1573 
1574 /* Early in boot, while setting up the initial pagetable, assume
1575    everything is pinned. */
1576 static void __init xen_alloc_pte_init(struct mm_struct *mm, unsigned long pfn)
1577 {
1578 #ifdef CONFIG_FLATMEM
1579         BUG_ON(mem_map);        /* should only be used early */
1580 #endif
1581         make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
1582         pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
1583 }
1584 
1585 /* Used for pmd and pud */
1586 static void __init xen_alloc_pmd_init(struct mm_struct *mm, unsigned long pfn)
1587 {
1588 #ifdef CONFIG_FLATMEM
1589         BUG_ON(mem_map);        /* should only be used early */
1590 #endif
1591         make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
1592 }
1593 
1594 /* Early release_pte assumes that all pts are pinned, since there's
1595    only init_mm and anything attached to that is pinned. */
1596 static void __init xen_release_pte_init(unsigned long pfn)
1597 {
1598         pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
1599         make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
1600 }
1601 
1602 static void __init xen_release_pmd_init(unsigned long pfn)
1603 {
1604         make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
1605 }
1606 
1607 static inline void __pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
1608 {
1609         struct multicall_space mcs;
1610         struct mmuext_op *op;
1611 
1612         mcs = __xen_mc_entry(sizeof(*op));
1613         op = mcs.args;
1614         op->cmd = cmd;
1615         op->arg1.mfn = pfn_to_mfn(pfn);
1616 
1617         MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
1618 }
1619 
1620 static inline void __set_pfn_prot(unsigned long pfn, pgprot_t prot)
1621 {
1622         struct multicall_space mcs;
1623         unsigned long addr = (unsigned long)__va(pfn << PAGE_SHIFT);
1624 
1625         mcs = __xen_mc_entry(0);
1626         MULTI_update_va_mapping(mcs.mc, (unsigned long)addr,
1627                                 pfn_pte(pfn, prot), 0);
1628 }
1629 
1630 /* This needs to make sure the new pte page is pinned iff its being
1631    attached to a pinned pagetable. */
1632 static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn,
1633                                     unsigned level)
1634 {
1635         bool pinned = xen_page_pinned(mm->pgd);
1636 
1637         trace_xen_mmu_alloc_ptpage(mm, pfn, level, pinned);
1638 
1639         if (pinned) {
1640                 struct page *page = pfn_to_page(pfn);
1641 
1642                 if (static_branch_likely(&xen_struct_pages_ready))
1643                         SetPagePinned(page);
1644 
1645                 if (!PageHighMem(page)) {
1646                         xen_mc_batch();
1647 
1648                         __set_pfn_prot(pfn, PAGE_KERNEL_RO);
1649 
1650                         if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
1651                                 __pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
1652 
1653                         xen_mc_issue(PARAVIRT_LAZY_MMU);
1654                 } else {
1655                         /* make sure there are no stray mappings of
1656                            this page */
1657                         kmap_flush_unused();
1658                 }
1659         }
1660 }
1661 
1662 static void xen_alloc_pte(struct mm_struct *mm, unsigned long pfn)
1663 {
1664         xen_alloc_ptpage(mm, pfn, PT_PTE);
1665 }
1666 
1667 static void xen_alloc_pmd(struct mm_struct *mm, unsigned long pfn)
1668 {
1669         xen_alloc_ptpage(mm, pfn, PT_PMD);
1670 }
1671 
1672 /* This should never happen until we're OK to use struct page */
1673 static inline void xen_release_ptpage(unsigned long pfn, unsigned level)
1674 {
1675         struct page *page = pfn_to_page(pfn);
1676         bool pinned = PagePinned(page);
1677 
1678         trace_xen_mmu_release_ptpage(pfn, level, pinned);
1679 
1680         if (pinned) {
1681                 if (!PageHighMem(page)) {
1682                         xen_mc_batch();
1683 
1684                         if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
1685                                 __pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
1686 
1687                         __set_pfn_prot(pfn, PAGE_KERNEL);
1688 
1689                         xen_mc_issue(PARAVIRT_LAZY_MMU);
1690                 }
1691                 ClearPagePinned(page);
1692         }
1693 }
1694 
1695 static void xen_release_pte(unsigned long pfn)
1696 {
1697         xen_release_ptpage(pfn, PT_PTE);
1698 }
1699 
1700 static void xen_release_pmd(unsigned long pfn)
1701 {
1702         xen_release_ptpage(pfn, PT_PMD);
1703 }
1704 
1705 #ifdef CONFIG_X86_64
1706 static void xen_alloc_pud(struct mm_struct *mm, unsigned long pfn)
1707 {
1708         xen_alloc_ptpage(mm, pfn, PT_PUD);
1709 }
1710 
1711 static void xen_release_pud(unsigned long pfn)
1712 {
1713         xen_release_ptpage(pfn, PT_PUD);
1714 }
1715 #endif
1716 
1717 void __init xen_reserve_top(void)
1718 {
1719 #ifdef CONFIG_X86_32
1720         unsigned long top = HYPERVISOR_VIRT_START;
1721         struct xen_platform_parameters pp;
1722 
1723         if (HYPERVISOR_xen_version(XENVER_platform_parameters, &pp) == 0)
1724                 top = pp.virt_start;
1725 
1726         reserve_top_address(-top);
1727 #endif  /* CONFIG_X86_32 */
1728 }
1729 
1730 /*
1731  * Like __va(), but returns address in the kernel mapping (which is
1732  * all we have until the physical memory mapping has been set up.
1733  */
1734 static void * __init __ka(phys_addr_t paddr)
1735 {
1736 #ifdef CONFIG_X86_64
1737         return (void *)(paddr + __START_KERNEL_map);
1738 #else
1739         return __va(paddr);
1740 #endif
1741 }
1742 
1743 /* Convert a machine address to physical address */
1744 static unsigned long __init m2p(phys_addr_t maddr)
1745 {
1746         phys_addr_t paddr;
1747 
1748         maddr &= XEN_PTE_MFN_MASK;
1749         paddr = mfn_to_pfn(maddr >> PAGE_SHIFT) << PAGE_SHIFT;
1750 
1751         return paddr;
1752 }
1753 
1754 /* Convert a machine address to kernel virtual */
1755 static void * __init m2v(phys_addr_t maddr)
1756 {
1757         return __ka(m2p(maddr));
1758 }
1759 
1760 /* Set the page permissions on an identity-mapped pages */
1761 static void __init set_page_prot_flags(void *addr, pgprot_t prot,
1762                                        unsigned long flags)
1763 {
1764         unsigned long pfn = __pa(addr) >> PAGE_SHIFT;
1765         pte_t pte = pfn_pte(pfn, prot);
1766 
1767         if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, flags))
1768                 BUG();
1769 }
1770 static void __init set_page_prot(void *addr, pgprot_t prot)
1771 {
1772         return set_page_prot_flags(addr, prot, UVMF_NONE);
1773 }
1774 #ifdef CONFIG_X86_32
1775 static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
1776 {
1777         unsigned pmdidx, pteidx;
1778         unsigned ident_pte;
1779         unsigned long pfn;
1780 
1781         level1_ident_pgt = extend_brk(sizeof(pte_t) * LEVEL1_IDENT_ENTRIES,
1782                                       PAGE_SIZE);
1783 
1784         ident_pte = 0;
1785         pfn = 0;
1786         for (pmdidx = 0; pmdidx < PTRS_PER_PMD && pfn < max_pfn; pmdidx++) {
1787                 pte_t *pte_page;
1788 
1789                 /* Reuse or allocate a page of ptes */
1790                 if (pmd_present(pmd[pmdidx]))
1791                         pte_page = m2v(pmd[pmdidx].pmd);
1792                 else {
1793                         /* Check for free pte pages */
1794                         if (ident_pte == LEVEL1_IDENT_ENTRIES)
1795                                 break;
1796 
1797                         pte_page = &level1_ident_pgt[ident_pte];
1798                         ident_pte += PTRS_PER_PTE;
1799 
1800                         pmd[pmdidx] = __pmd(__pa(pte_page) | _PAGE_TABLE);
1801                 }
1802 
1803                 /* Install mappings */
1804                 for (pteidx = 0; pteidx < PTRS_PER_PTE; pteidx++, pfn++) {
1805                         pte_t pte;
1806 
1807                         if (pfn > max_pfn_mapped)
1808                                 max_pfn_mapped = pfn;
1809 
1810                         if (!pte_none(pte_page[pteidx]))
1811                                 continue;
1812 
1813                         pte = pfn_pte(pfn, PAGE_KERNEL_EXEC);
1814                         pte_page[pteidx] = pte;
1815                 }
1816         }
1817 
1818         for (pteidx = 0; pteidx < ident_pte; pteidx += PTRS_PER_PTE)
1819                 set_page_prot(&level1_ident_pgt[pteidx], PAGE_KERNEL_RO);
1820 
1821         set_page_prot(pmd, PAGE_KERNEL_RO);
1822 }
1823 #endif
1824 void __init xen_setup_machphys_mapping(void)
1825 {
1826         struct xen_machphys_mapping mapping;
1827 
1828         if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
1829                 machine_to_phys_mapping = (unsigned long *)mapping.v_start;
1830                 machine_to_phys_nr = mapping.max_mfn + 1;
1831         } else {
1832                 machine_to_phys_nr = MACH2PHYS_NR_ENTRIES;
1833         }
1834 #ifdef CONFIG_X86_32
1835         WARN_ON((machine_to_phys_mapping + (machine_to_phys_nr - 1))
1836                 < machine_to_phys_mapping);
1837 #endif
1838 }
1839 
1840 #ifdef CONFIG_X86_64
1841 static void __init convert_pfn_mfn(void *v)
1842 {
1843         pte_t *pte = v;
1844         int i;
1845 
1846         /* All levels are converted the same way, so just treat them
1847            as ptes. */
1848         for (i = 0; i < PTRS_PER_PTE; i++)
1849                 pte[i] = xen_make_pte(pte[i].pte);
1850 }
1851 static void __init check_pt_base(unsigned long *pt_base, unsigned long *pt_end,
1852                                  unsigned long addr)
1853 {
1854         if (*pt_base == PFN_DOWN(__pa(addr))) {
1855                 set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG);
1856                 clear_page((void *)addr);
1857                 (*pt_base)++;
1858         }
1859         if (*pt_end == PFN_DOWN(__pa(addr))) {
1860                 set_page_prot_flags((void *)addr, PAGE_KERNEL, UVMF_INVLPG);
1861                 clear_page((void *)addr);
1862                 (*pt_end)--;
1863         }
1864 }
1865 /*
1866  * Set up the initial kernel pagetable.
1867  *
1868  * We can construct this by grafting the Xen provided pagetable into
1869  * head_64.S's preconstructed pagetables.  We copy the Xen L2's into
1870  * level2_ident_pgt, and level2_kernel_pgt.  This means that only the
1871  * kernel has a physical mapping to start with - but that's enough to
1872  * get __va working.  We need to fill in the rest of the physical
1873  * mapping once some sort of allocator has been set up.
1874  */
1875 void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
1876 {
1877         pud_t *l3;
1878         pmd_t *l2;
1879         unsigned long addr[3];
1880         unsigned long pt_base, pt_end;
1881         unsigned i;
1882 
1883         /* max_pfn_mapped is the last pfn mapped in the initial memory
1884          * mappings. Considering that on Xen after the kernel mappings we
1885          * have the mappings of some pages that don't exist in pfn space, we
1886          * set max_pfn_mapped to the last real pfn mapped. */
1887         if (xen_start_info->mfn_list < __START_KERNEL_map)
1888                 max_pfn_mapped = xen_start_info->first_p2m_pfn;
1889         else
1890                 max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->mfn_list));
1891 
1892         pt_base = PFN_DOWN(__pa(xen_start_info->pt_base));
1893         pt_end = pt_base + xen_start_info->nr_pt_frames;
1894 
1895         /* Zap identity mapping */
1896         init_top_pgt[0] = __pgd(0);
1897 
1898         /* Pre-constructed entries are in pfn, so convert to mfn */
1899         /* L4[273] -> level3_ident_pgt  */
1900         /* L4[511] -> level3_kernel_pgt */
1901         convert_pfn_mfn(init_top_pgt);
1902 
1903         /* L3_i[0] -> level2_ident_pgt */
1904         convert_pfn_mfn(level3_ident_pgt);
1905         /* L3_k[510] -> level2_kernel_pgt */
1906         /* L3_k[511] -> level2_fixmap_pgt */
1907         convert_pfn_mfn(level3_kernel_pgt);
1908 
1909         /* L3_k[511][508-FIXMAP_PMD_NUM ... 507] -> level1_fixmap_pgt */
1910         convert_pfn_mfn(level2_fixmap_pgt);
1911 
1912         /* We get [511][511] and have Xen's version of level2_kernel_pgt */
1913         l3 = m2v(pgd[pgd_index(__START_KERNEL_map)].pgd);
1914         l2 = m2v(l3[pud_index(__START_KERNEL_map)].pud);
1915 
1916         addr[0] = (unsigned long)pgd;
1917         addr[1] = (unsigned long)l3;
1918         addr[2] = (unsigned long)l2;
1919         /* Graft it onto L4[273][0]. Note that we creating an aliasing problem:
1920          * Both L4[273][0] and L4[511][510] have entries that point to the same
1921          * L2 (PMD) tables. Meaning that if you modify it in __va space
1922          * it will be also modified in the __ka space! (But if you just
1923          * modify the PMD table to point to other PTE's or none, then you
1924          * are OK - which is what cleanup_highmap does) */
1925         copy_page(level2_ident_pgt, l2);
1926         /* Graft it onto L4[511][510] */
1927         copy_page(level2_kernel_pgt, l2);
1928 
1929         /*
1930          * Zap execute permission from the ident map. Due to the sharing of
1931          * L1 entries we need to do this in the L2.
1932          */
1933         if (__supported_pte_mask & _PAGE_NX) {
1934                 for (i = 0; i < PTRS_PER_PMD; ++i) {
1935                         if (pmd_none(level2_ident_pgt[i]))
1936                                 continue;
1937                         level2_ident_pgt[i] = pmd_set_flags(level2_ident_pgt[i], _PAGE_NX);
1938                 }
1939         }
1940 
1941         /* Copy the initial P->M table mappings if necessary. */
1942         i = pgd_index(xen_start_info->mfn_list);
1943         if (i && i < pgd_index(__START_KERNEL_map))
1944                 init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i];
1945 
1946         /* Make pagetable pieces RO */
1947         set_page_prot(init_top_pgt, PAGE_KERNEL_RO);
1948         set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO);
1949         set_page_prot(level3_kernel_pgt, PAGE_KERNEL_RO);
1950         set_page_prot(level3_user_vsyscall, PAGE_KERNEL_RO);
1951         set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO);
1952         set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO);
1953         set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO);
1954 
1955         for (i = 0; i < FIXMAP_PMD_NUM; i++) {
1956                 set_page_prot(level1_fixmap_pgt + i * PTRS_PER_PTE,
1957                               PAGE_KERNEL_RO);
1958         }
1959 
1960         /* Pin down new L4 */
1961         pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
1962                           PFN_DOWN(__pa_symbol(init_top_pgt)));
1963 
1964         /* Unpin Xen-provided one */
1965         pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
1966 
1967         /*
1968          * At this stage there can be no user pgd, and no page structure to
1969          * attach it to, so make sure we just set kernel pgd.
1970          */
1971         xen_mc_batch();
1972         __xen_write_cr3(true, __pa(init_top_pgt));
1973         xen_mc_issue(PARAVIRT_LAZY_CPU);
1974 
1975         /* We can't that easily rip out L3 and L2, as the Xen pagetables are
1976          * set out this way: [L4], [L1], [L2], [L3], [L1], [L1] ...  for
1977          * the initial domain. For guests using the toolstack, they are in:
1978          * [L4], [L3], [L2], [L1], [L1], order .. So for dom0 we can only
1979          * rip out the [L4] (pgd), but for guests we shave off three pages.
1980          */
1981         for (i = 0; i < ARRAY_SIZE(addr); i++)
1982                 check_pt_base(&pt_base, &pt_end, addr[i]);
1983 
1984         /* Our (by three pages) smaller Xen pagetable that we are using */
1985         xen_pt_base = PFN_PHYS(pt_base);
1986         xen_pt_size = (pt_end - pt_base) * PAGE_SIZE;
1987         memblock_reserve(xen_pt_base, xen_pt_size);
1988 
1989         /* Revector the xen_start_info */
1990         xen_start_info = (struct start_info *)__va(__pa(xen_start_info));
1991 }
1992 
1993 /*
1994  * Read a value from a physical address.
1995  */
1996 static unsigned long __init xen_read_phys_ulong(phys_addr_t addr)
1997 {
1998         unsigned long *vaddr;
1999         unsigned long val;
2000 
2001         vaddr = early_memremap_ro(addr, sizeof(val));
2002         val = *vaddr;
2003         early_memunmap(vaddr, sizeof(val));
2004         return val;
2005 }
2006 
2007 /*
2008  * Translate a virtual address to a physical one without relying on mapped
2009  * page tables. Don't rely on big pages being aligned in (guest) physical
2010  * space!
2011  */
2012 static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr)
2013 {
2014         phys_addr_t pa;
2015         pgd_t pgd;
2016         pud_t pud;
2017         pmd_t pmd;
2018         pte_t pte;
2019 
2020         pa = read_cr3_pa();
2021         pgd = native_make_pgd(xen_read_phys_ulong(pa + pgd_index(vaddr) *
2022                                                        sizeof(pgd)));
2023         if (!pgd_present(pgd))
2024                 return 0;
2025 
2026         pa = pgd_val(pgd) & PTE_PFN_MASK;
2027         pud = native_make_pud(xen_read_phys_ulong(pa + pud_index(vaddr) *
2028                                                        sizeof(pud)));
2029         if (!pud_present(pud))
2030                 return 0;
2031         pa = pud_val(pud) & PTE_PFN_MASK;
2032         if (pud_large(pud))
2033                 return pa + (vaddr & ~PUD_MASK);
2034 
2035         pmd = native_make_pmd(xen_read_phys_ulong(pa + pmd_index(vaddr) *
2036                                                        sizeof(pmd)));
2037         if (!pmd_present(pmd))
2038                 return 0;
2039         pa = pmd_val(pmd) & PTE_PFN_MASK;
2040         if (pmd_large(pmd))
2041                 return pa + (vaddr & ~PMD_MASK);
2042 
2043         pte = native_make_pte(xen_read_phys_ulong(pa + pte_index(vaddr) *
2044                                                        sizeof(pte)));
2045         if (!pte_present(pte))
2046                 return 0;
2047         pa = pte_pfn(pte) << PAGE_SHIFT;
2048 
2049         return pa | (vaddr & ~PAGE_MASK);
2050 }
2051 
2052 /*
2053  * Find a new area for the hypervisor supplied p2m list and relocate the p2m to
2054  * this area.
2055  */
2056 void __init xen_relocate_p2m(void)
2057 {
2058         phys_addr_t size, new_area, pt_phys, pmd_phys, pud_phys;
2059         unsigned long p2m_pfn, p2m_pfn_end, n_frames, pfn, pfn_end;
2060         int n_pte, n_pt, n_pmd, n_pud, idx_pte, idx_pt, idx_pmd, idx_pud;
2061         pte_t *pt;
2062         pmd_t *pmd;
2063         pud_t *pud;
2064         pgd_t *pgd;
2065         unsigned long *new_p2m;
2066 
2067         size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
2068         n_pte = roundup(size, PAGE_SIZE) >> PAGE_SHIFT;
2069         n_pt = roundup(size, PMD_SIZE) >> PMD_SHIFT;
2070         n_pmd = roundup(size, PUD_SIZE) >> PUD_SHIFT;
2071         n_pud = roundup(size, P4D_SIZE) >> P4D_SHIFT;
2072         n_frames = n_pte + n_pt + n_pmd + n_pud;
2073 
2074         new_area = xen_find_free_area(PFN_PHYS(n_frames));
2075         if (!new_area) {
2076                 xen_raw_console_write("Can't find new memory area for p2m needed due to E820 map conflict\n");
2077                 BUG();
2078         }
2079 
2080         /*
2081          * Setup the page tables for addressing the new p2m list.
2082          * We have asked the hypervisor to map the p2m list at the user address
2083          * PUD_SIZE. It may have done so, or it may have used a kernel space
2084          * address depending on the Xen version.
2085          * To avoid any possible virtual address collision, just use
2086          * 2 * PUD_SIZE for the new area.
2087          */
2088         pud_phys = new_area;
2089         pmd_phys = pud_phys + PFN_PHYS(n_pud);
2090         pt_phys = pmd_phys + PFN_PHYS(n_pmd);
2091         p2m_pfn = PFN_DOWN(pt_phys) + n_pt;
2092 
2093         pgd = __va(read_cr3_pa());
2094         new_p2m = (unsigned long *)(2 * PGDIR_SIZE);
2095         for (idx_pud = 0; idx_pud < n_pud; idx_pud++) {
2096                 pud = early_memremap(pud_phys, PAGE_SIZE);
2097                 clear_page(pud);
2098                 for (idx_pmd = 0; idx_pmd < min(n_pmd, PTRS_PER_PUD);
2099                                 idx_pmd++) {
2100                         pmd = early_memremap(pmd_phys, PAGE_SIZE);
2101                         clear_page(pmd);
2102                         for (idx_pt = 0; idx_pt < min(n_pt, PTRS_PER_PMD);
2103                                         idx_pt++) {
2104                                 pt = early_memremap(pt_phys, PAGE_SIZE);
2105                                 clear_page(pt);
2106                                 for (idx_pte = 0;
2107                                      idx_pte < min(n_pte, PTRS_PER_PTE);
2108                                      idx_pte++) {
2109                                         pt[idx_pte] = pfn_pte(p2m_pfn,
2110                                                               PAGE_KERNEL);
2111                                         p2m_pfn++;
2112                                 }
2113                                 n_pte -= PTRS_PER_PTE;
2114                                 early_memunmap(pt, PAGE_SIZE);
2115                                 make_lowmem_page_readonly(__va(pt_phys));
2116                                 pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE,
2117                                                 PFN_DOWN(pt_phys));
2118                                 pmd[idx_pt] = __pmd(_PAGE_TABLE | pt_phys);
2119                                 pt_phys += PAGE_SIZE;
2120                         }
2121                         n_pt -= PTRS_PER_PMD;
2122                         early_memunmap(pmd, PAGE_SIZE);
2123                         make_lowmem_page_readonly(__va(pmd_phys));
2124                         pin_pagetable_pfn(MMUEXT_PIN_L2_TABLE,
2125                                         PFN_DOWN(pmd_phys));
2126                         pud[idx_pmd] = __pud(_PAGE_TABLE | pmd_phys);
2127                         pmd_phys += PAGE_SIZE;
2128                 }
2129                 n_pmd -= PTRS_PER_PUD;
2130                 early_memunmap(pud, PAGE_SIZE);
2131                 make_lowmem_page_readonly(__va(pud_phys));
2132                 pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(pud_phys));
2133                 set_pgd(pgd + 2 + idx_pud, __pgd(_PAGE_TABLE | pud_phys));
2134                 pud_phys += PAGE_SIZE;
2135         }
2136 
2137         /* Now copy the old p2m info to the new area. */
2138         memcpy(new_p2m, xen_p2m_addr, size);
2139         xen_p2m_addr = new_p2m;
2140 
2141         /* Release the old p2m list and set new list info. */
2142         p2m_pfn = PFN_DOWN(xen_early_virt_to_phys(xen_start_info->mfn_list));
2143         BUG_ON(!p2m_pfn);
2144         p2m_pfn_end = p2m_pfn + PFN_DOWN(size);
2145 
2146         if (xen_start_info->mfn_list < __START_KERNEL_map) {
2147                 pfn = xen_start_info->first_p2m_pfn;
2148                 pfn_end = xen_start_info->first_p2m_pfn +
2149                           xen_start_info->nr_p2m_frames;
2150                 set_pgd(pgd + 1, __pgd(0));
2151         } else {
2152                 pfn = p2m_pfn;
2153                 pfn_end = p2m_pfn_end;
2154         }
2155 
2156         memblock_free(PFN_PHYS(pfn), PAGE_SIZE * (pfn_end - pfn));
2157         while (pfn < pfn_end) {
2158                 if (pfn == p2m_pfn) {
2159                         pfn = p2m_pfn_end;
2160                         continue;
2161                 }
2162                 make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
2163                 pfn++;
2164         }
2165 
2166         xen_start_info->mfn_list = (unsigned long)xen_p2m_addr;
2167         xen_start_info->first_p2m_pfn =  PFN_DOWN(new_area);
2168         xen_start_info->nr_p2m_frames = n_frames;
2169 }
2170 
2171 #else   /* !CONFIG_X86_64 */
2172 static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);
2173 static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD);
2174 RESERVE_BRK(fixup_kernel_pmd, PAGE_SIZE);
2175 RESERVE_BRK(fixup_kernel_pte, PAGE_SIZE);
2176 
2177 static void __init xen_write_cr3_init(unsigned long cr3)
2178 {
2179         unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir));
2180 
2181         BUG_ON(read_cr3_pa() != __pa(initial_page_table));
2182         BUG_ON(cr3 != __pa(swapper_pg_dir));
2183 
2184         /*
2185          * We are switching to swapper_pg_dir for the first time (from
2186          * initial_page_table) and therefore need to mark that page
2187          * read-only and then pin it.
2188          *
2189          * Xen disallows sharing of kernel PMDs for PAE
2190          * guests. Therefore we must copy the kernel PMD from
2191          * initial_page_table into a new kernel PMD to be used in
2192          * swapper_pg_dir.
2193          */
2194         swapper_kernel_pmd =
2195                 extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
2196         copy_page(swapper_kernel_pmd, initial_kernel_pmd);
2197         swapper_pg_dir[KERNEL_PGD_BOUNDARY] =
2198                 __pgd(__pa(swapper_kernel_pmd) | _PAGE_PRESENT);
2199         set_page_prot(swapper_kernel_pmd, PAGE_KERNEL_RO);
2200 
2201         set_page_prot(swapper_pg_dir, PAGE_KERNEL_RO);
2202         xen_write_cr3(cr3);
2203         pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, pfn);
2204 
2205         pin_pagetable_pfn(MMUEXT_UNPIN_TABLE,
2206                           PFN_DOWN(__pa(initial_page_table)));
2207         set_page_prot(initial_page_table, PAGE_KERNEL);
2208         set_page_prot(initial_kernel_pmd, PAGE_KERNEL);
2209 
2210         pv_ops.mmu.write_cr3 = &xen_write_cr3;
2211 }
2212 
2213 /*
2214  * For 32 bit domains xen_start_info->pt_base is the pgd address which might be
2215  * not the first page table in the page table pool.
2216  * Iterate through the initial page tables to find the real page table base.
2217  */
2218 static phys_addr_t __init xen_find_pt_base(pmd_t *pmd)
2219 {
2220         phys_addr_t pt_base, paddr;
2221         unsigned pmdidx;
2222 
2223         pt_base = min(__pa(xen_start_info->pt_base), __pa(pmd));
2224 
2225         for (pmdidx = 0; pmdidx < PTRS_PER_PMD; pmdidx++)
2226                 if (pmd_present(pmd[pmdidx]) && !pmd_large(pmd[pmdidx])) {
2227                         paddr = m2p(pmd[pmdidx].pmd);
2228                         pt_base = min(pt_base, paddr);
2229                 }
2230 
2231         return pt_base;
2232 }
2233 
2234 void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
2235 {
2236         pmd_t *kernel_pmd;
2237 
2238         kernel_pmd = m2v(pgd[KERNEL_PGD_BOUNDARY].pgd);
2239 
2240         xen_pt_base = xen_find_pt_base(kernel_pmd);
2241         xen_pt_size = xen_start_info->nr_pt_frames * PAGE_SIZE;
2242 
2243         initial_kernel_pmd =
2244                 extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
2245 
2246         max_pfn_mapped = PFN_DOWN(xen_pt_base + xen_pt_size + 512 * 1024);
2247 
2248         copy_page(initial_kernel_pmd, kernel_pmd);
2249 
2250         xen_map_identity_early(initial_kernel_pmd, max_pfn);
2251 
2252         copy_page(initial_page_table, pgd);
2253         initial_page_table[KERNEL_PGD_BOUNDARY] =
2254                 __pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT);
2255 
2256         set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
2257         set_page_prot(initial_page_table, PAGE_KERNEL_RO);
2258         set_page_prot(empty_zero_page, PAGE_KERNEL_RO);
2259 
2260         pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
2261 
2262         pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
2263                           PFN_DOWN(__pa(initial_page_table)));
2264         xen_write_cr3(__pa(initial_page_table));
2265 
2266         memblock_reserve(xen_pt_base, xen_pt_size);
2267 }
2268 #endif  /* CONFIG_X86_64 */
2269 
2270 void __init xen_reserve_special_pages(void)
2271 {
2272         phys_addr_t paddr;
2273 
2274         memblock_reserve(__pa(xen_start_info), PAGE_SIZE);
2275         if (xen_start_info->store_mfn) {
2276                 paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->store_mfn));
2277                 memblock_reserve(paddr, PAGE_SIZE);
2278         }
2279         if (!xen_initial_domain()) {
2280                 paddr = PFN_PHYS(mfn_to_pfn(xen_start_info->console.domU.mfn));
2281                 memblock_reserve(paddr, PAGE_SIZE);
2282         }
2283 }
2284 
2285 void __init xen_pt_check_e820(void)
2286 {
2287         if (xen_is_e820_reserved(xen_pt_base, xen_pt_size)) {
2288                 xen_raw_console_write("Xen hypervisor allocated page table memory conflicts with E820 map\n");
2289                 BUG();
2290         }
2291 }
2292 
2293 static unsigned char dummy_mapping[PAGE_SIZE] __page_aligned_bss;
2294 
2295 static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
2296 {
2297         pte_t pte;
2298 
2299         phys >>= PAGE_SHIFT;
2300 
2301         switch (idx) {
2302         case FIX_BTMAP_END ... FIX_BTMAP_BEGIN:
2303 #ifdef CONFIG_X86_32
2304         case FIX_WP_TEST:
2305 # ifdef CONFIG_HIGHMEM
2306         case FIX_KMAP_BEGIN ... FIX_KMAP_END:
2307 # endif
2308 #elif defined(CONFIG_X86_VSYSCALL_EMULATION)
2309         case VSYSCALL_PAGE:
2310 #endif
2311                 /* All local page mappings */
2312                 pte = pfn_pte(phys, prot);
2313                 break;
2314 
2315 #ifdef CONFIG_X86_LOCAL_APIC
2316         case FIX_APIC_BASE:     /* maps dummy local APIC */
2317                 pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL);
2318                 break;
2319 #endif
2320 
2321 #ifdef CONFIG_X86_IO_APIC
2322         case FIX_IO_APIC_BASE_0 ... FIX_IO_APIC_BASE_END:
2323                 /*
2324                  * We just don't map the IO APIC - all access is via
2325                  * hypercalls.  Keep the address in the pte for reference.
2326                  */
2327                 pte = pfn_pte(PFN_DOWN(__pa(dummy_mapping)), PAGE_KERNEL);
2328                 break;
2329 #endif
2330 
2331         case FIX_PARAVIRT_BOOTMAP:
2332                 /* This is an MFN, but it isn't an IO mapping from the
2333                    IO domain */
2334                 pte = mfn_pte(phys, prot);
2335                 break;
2336 
2337         default:
2338                 /* By default, set_fixmap is used for hardware mappings */
2339                 pte = mfn_pte(phys, prot);
2340                 break;
2341         }
2342 
2343         __native_set_fixmap(idx, pte);
2344 
2345 #ifdef CONFIG_X86_VSYSCALL_EMULATION
2346         /* Replicate changes to map the vsyscall page into the user
2347            pagetable vsyscall mapping. */
2348         if (idx == VSYSCALL_PAGE) {
2349                 unsigned long vaddr = __fix_to_virt(idx);
2350                 set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte);
2351         }
2352 #endif
2353 }
2354 
2355 static void __init xen_post_allocator_init(void)
2356 {
2357         pv_ops.mmu.set_pte = xen_set_pte;
2358         pv_ops.mmu.set_pmd = xen_set_pmd;
2359         pv_ops.mmu.set_pud = xen_set_pud;
2360 #ifdef CONFIG_X86_64
2361         pv_ops.mmu.set_p4d = xen_set_p4d;
2362 #endif
2363 
2364         /* This will work as long as patching hasn't happened yet
2365            (which it hasn't) */
2366         pv_ops.mmu.alloc_pte = xen_alloc_pte;
2367         pv_ops.mmu.alloc_pmd = xen_alloc_pmd;
2368         pv_ops.mmu.release_pte = xen_release_pte;
2369         pv_ops.mmu.release_pmd = xen_release_pmd;
2370 #ifdef CONFIG_X86_64
2371         pv_ops.mmu.alloc_pud = xen_alloc_pud;
2372         pv_ops.mmu.release_pud = xen_release_pud;
2373 #endif
2374         pv_ops.mmu.make_pte = PV_CALLEE_SAVE(xen_make_pte);
2375 
2376 #ifdef CONFIG_X86_64
2377         pv_ops.mmu.write_cr3 = &xen_write_cr3;
2378 #endif
2379 }
2380 
2381 static void xen_leave_lazy_mmu(void)
2382 {
2383         preempt_disable();
2384         xen_mc_flush();
2385         paravirt_leave_lazy_mmu();
2386         preempt_enable();
2387 }
2388 
2389 static const struct pv_mmu_ops xen_mmu_ops __initconst = {
2390         .read_cr2 = __PV_IS_CALLEE_SAVE(xen_read_cr2),
2391         .write_cr2 = xen_write_cr2,
2392 
2393         .read_cr3 = xen_read_cr3,
2394         .write_cr3 = xen_write_cr3_init,
2395 
2396         .flush_tlb_user = xen_flush_tlb,
2397         .flush_tlb_kernel = xen_flush_tlb,
2398         .flush_tlb_one_user = xen_flush_tlb_one_user,
2399         .flush_tlb_others = xen_flush_tlb_others,
2400         .tlb_remove_table = tlb_remove_table,
2401 
2402         .pgd_alloc = xen_pgd_alloc,
2403         .pgd_free = xen_pgd_free,
2404 
2405         .alloc_pte = xen_alloc_pte_init,
2406         .release_pte = xen_release_pte_init,
2407         .alloc_pmd = xen_alloc_pmd_init,
2408         .release_pmd = xen_release_pmd_init,
2409 
2410         .set_pte = xen_set_pte_init,
2411         .set_pte_at = xen_set_pte_at,
2412         .set_pmd = xen_set_pmd_hyper,
2413 
2414         .ptep_modify_prot_start = __ptep_modify_prot_start,
2415         .ptep_modify_prot_commit = __ptep_modify_prot_commit,
2416 
2417         .pte_val = PV_CALLEE_SAVE(xen_pte_val),
2418         .pgd_val = PV_CALLEE_SAVE(xen_pgd_val),
2419 
2420         .make_pte = PV_CALLEE_SAVE(xen_make_pte_init),
2421         .make_pgd = PV_CALLEE_SAVE(xen_make_pgd),
2422 
2423 #ifdef CONFIG_X86_PAE
2424         .set_pte_atomic = xen_set_pte_atomic,
2425         .pte_clear = xen_pte_clear,
2426         .pmd_clear = xen_pmd_clear,
2427 #endif  /* CONFIG_X86_PAE */
2428         .set_pud = xen_set_pud_hyper,
2429 
2430         .make_pmd = PV_CALLEE_SAVE(xen_make_pmd),
2431         .pmd_val = PV_CALLEE_SAVE(xen_pmd_val),
2432 
2433 #ifdef CONFIG_X86_64
2434         .pud_val = PV_CALLEE_SAVE(xen_pud_val),
2435         .make_pud = PV_CALLEE_SAVE(xen_make_pud),
2436         .set_p4d = xen_set_p4d_hyper,
2437 
2438         .alloc_pud = xen_alloc_pmd_init,
2439         .release_pud = xen_release_pmd_init,
2440 
2441 #if CONFIG_PGTABLE_LEVELS >= 5
2442         .p4d_val = PV_CALLEE_SAVE(xen_p4d_val),
2443         .make_p4d = PV_CALLEE_SAVE(xen_make_p4d),
2444 #endif
2445 #endif  /* CONFIG_X86_64 */
2446 
2447         .activate_mm = xen_activate_mm,
2448         .dup_mmap = xen_dup_mmap,
2449         .exit_mmap = xen_exit_mmap,
2450 
2451         .lazy_mode = {
2452                 .enter = paravirt_enter_lazy_mmu,
2453                 .leave = xen_leave_lazy_mmu,
2454                 .flush = paravirt_flush_lazy_mmu,
2455         },
2456 
2457         .set_fixmap = xen_set_fixmap,
2458 };
2459 
2460 void __init xen_init_mmu_ops(void)
2461 {
2462         x86_init.paging.pagetable_init = xen_pagetable_init;
2463         x86_init.hyper.init_after_bootmem = xen_after_bootmem;
2464 
2465         pv_ops.mmu = xen_mmu_ops;
2466 
2467         memset(dummy_mapping, 0xff, PAGE_SIZE);
2468 }
2469 
2470 /* Protected by xen_reservation_lock. */
2471 #define MAX_CONTIG_ORDER 9 /* 2MB */
2472 static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
2473 
2474 #define VOID_PTE (mfn_pte(0, __pgprot(0)))
2475 static void xen_zap_pfn_range(unsigned long vaddr, unsigned int order,
2476                                 unsigned long *in_frames,
2477                                 unsigned long *out_frames)
2478 {
2479         int i;
2480         struct multicall_space mcs;
2481 
2482         xen_mc_batch();
2483         for (i = 0; i < (1UL<<order); i++, vaddr += PAGE_SIZE) {
2484                 mcs = __xen_mc_entry(0);
2485 
2486                 if (in_frames)
2487                         in_frames[i] = virt_to_mfn(vaddr);
2488 
2489                 MULTI_update_va_mapping(mcs.mc, vaddr, VOID_PTE, 0);
2490                 __set_phys_to_machine(virt_to_pfn(vaddr), INVALID_P2M_ENTRY);
2491 
2492                 if (out_frames)
2493                         out_frames[i] = virt_to_pfn(vaddr);
2494         }
2495         xen_mc_issue(0);
2496 }
2497 
2498 /*
2499  * Update the pfn-to-mfn mappings for a virtual address range, either to
2500  * point to an array of mfns, or contiguously from a single starting
2501  * mfn.
2502  */
2503 static void xen_remap_exchanged_ptes(unsigned long vaddr, int order,
2504                                      unsigned long *mfns,
2505                                      unsigned long first_mfn)
2506 {
2507         unsigned i, limit;
2508         unsigned long mfn;
2509 
2510         xen_mc_batch();
2511 
2512         limit = 1u << order;
2513         for (i = 0; i < limit; i++, vaddr += PAGE_SIZE) {
2514                 struct multicall_space mcs;
2515                 unsigned flags;
2516 
2517                 mcs = __xen_mc_entry(0);
2518                 if (mfns)
2519                         mfn = mfns[i];
2520                 else
2521                         mfn = first_mfn + i;
2522 
2523                 if (i < (limit - 1))
2524                         flags = 0;
2525                 else {
2526                         if (order == 0)
2527                                 flags = UVMF_INVLPG | UVMF_ALL;
2528                         else
2529                                 flags = UVMF_TLB_FLUSH | UVMF_ALL;
2530                 }
2531 
2532                 MULTI_update_va_mapping(mcs.mc, vaddr,
2533                                 mfn_pte(mfn, PAGE_KERNEL), flags);
2534 
2535                 set_phys_to_machine(virt_to_pfn(vaddr), mfn);
2536         }
2537 
2538         xen_mc_issue(0);
2539 }
2540 
2541 /*
2542  * Perform the hypercall to exchange a region of our pfns to point to
2543  * memory with the required contiguous alignment.  Takes the pfns as
2544  * input, and populates mfns as output.
2545  *
2546  * Returns a success code indicating whether the hypervisor was able to
2547  * satisfy the request or not.
2548  */
2549 static int xen_exchange_memory(unsigned long extents_in, unsigned int order_in,
2550                                unsigned long *pfns_in,
2551                                unsigned long extents_out,
2552                                unsigned int order_out,
2553                                unsigned long *mfns_out,
2554                                unsigned int address_bits)
2555 {
2556         long rc;
2557         int success;
2558 
2559         struct xen_memory_exchange exchange = {
2560                 .in = {
2561                         .nr_extents   = extents_in,
2562                         .extent_order = order_in,
2563                         .extent_start = pfns_in,
2564                         .domid        = DOMID_SELF
2565                 },
2566                 .out = {
2567                         .nr_extents   = extents_out,
2568                         .extent_order = order_out,
2569                         .extent_start = mfns_out,
2570                         .address_bits = address_bits,
2571                         .domid        = DOMID_SELF
2572                 }
2573         };
2574 
2575         BUG_ON(extents_in << order_in != extents_out << order_out);
2576 
2577         rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
2578         success = (exchange.nr_exchanged == extents_in);
2579 
2580         BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
2581         BUG_ON(success && (rc != 0));
2582 
2583         return success;
2584 }
2585 
2586 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
2587                                  unsigned int address_bits,
2588                                  dma_addr_t *dma_handle)
2589 {
2590         unsigned long *in_frames = discontig_frames, out_frame;
2591         unsigned long  flags;
2592         int            success;
2593         unsigned long vstart = (unsigned long)phys_to_virt(pstart);
2594 
2595         /*
2596          * Currently an auto-translated guest will not perform I/O, nor will
2597          * it require PAE page directories below 4GB. Therefore any calls to
2598          * this function are redundant and can be ignored.
2599          */
2600 
2601         if (unlikely(order > MAX_CONTIG_ORDER))
2602                 return -ENOMEM;
2603 
2604         memset((void *) vstart, 0, PAGE_SIZE << order);
2605 
2606         spin_lock_irqsave(&xen_reservation_lock, flags);
2607 
2608         /* 1. Zap current PTEs, remembering MFNs. */
2609         xen_zap_pfn_range(vstart, order, in_frames, NULL);
2610 
2611         /* 2. Get a new contiguous memory extent. */
2612         out_frame = virt_to_pfn(vstart);
2613         success = xen_exchange_memory(1UL << order, 0, in_frames,
2614                                       1, order, &out_frame,
2615                                       address_bits);
2616 
2617         /* 3. Map the new extent in place of old pages. */
2618         if (success)
2619                 xen_remap_exchanged_ptes(vstart, order, NULL, out_frame);
2620         else
2621                 xen_remap_exchanged_ptes(vstart, order, in_frames, 0);
2622 
2623         spin_unlock_irqrestore(&xen_reservation_lock, flags);
2624 
2625         *dma_handle = virt_to_machine(vstart).maddr;
2626         return success ? 0 : -ENOMEM;
2627 }
2628 
2629 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
2630 {
2631         unsigned long *out_frames = discontig_frames, in_frame;
2632         unsigned long  flags;
2633         int success;
2634         unsigned long vstart;
2635 
2636         if (unlikely(order > MAX_CONTIG_ORDER))
2637                 return;
2638 
2639         vstart = (unsigned long)phys_to_virt(pstart);
2640         memset((void *) vstart, 0, PAGE_SIZE << order);
2641 
2642         spin_lock_irqsave(&xen_reservation_lock, flags);
2643 
2644         /* 1. Find start MFN of contiguous extent. */
2645         in_frame = virt_to_mfn(vstart);
2646 
2647         /* 2. Zap current PTEs. */
2648         xen_zap_pfn_range(vstart, order, NULL, out_frames);
2649 
2650         /* 3. Do the exchange for non-contiguous MFNs. */
2651         success = xen_exchange_memory(1, order, &in_frame, 1UL << order,
2652                                         0, out_frames, 0);
2653 
2654         /* 4. Map new pages in place of old pages. */
2655         if (success)
2656                 xen_remap_exchanged_ptes(vstart, order, out_frames, 0);
2657         else
2658                 xen_remap_exchanged_ptes(vstart, order, NULL, in_frame);
2659 
2660         spin_unlock_irqrestore(&xen_reservation_lock, flags);
2661 }
2662 
2663 static noinline void xen_flush_tlb_all(void)
2664 {
2665         struct mmuext_op *op;
2666         struct multicall_space mcs;
2667 
2668         preempt_disable();
2669 
2670         mcs = xen_mc_entry(sizeof(*op));
2671 
2672         op = mcs.args;
2673         op->cmd = MMUEXT_TLB_FLUSH_ALL;
2674         MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
2675 
2676         xen_mc_issue(PARAVIRT_LAZY_MMU);
2677 
2678         preempt_enable();
2679 }
2680 
2681 #define REMAP_BATCH_SIZE 16
2682 
2683 struct remap_data {
2684         xen_pfn_t *pfn;
2685         bool contiguous;
2686         bool no_translate;
2687         pgprot_t prot;
2688         struct mmu_update *mmu_update;
2689 };
2690 
2691 static int remap_area_pfn_pte_fn(pte_t *ptep, unsigned long addr, void *data)
2692 {
2693         struct remap_data *rmd = data;
2694         pte_t pte = pte_mkspecial(mfn_pte(*rmd->pfn, rmd->prot));
2695 
2696         /*
2697          * If we have a contiguous range, just update the pfn itself,
2698          * else update pointer to be "next pfn".
2699          */
2700         if (rmd->contiguous)
2701                 (*rmd->pfn)++;
2702         else
2703                 rmd->pfn++;
2704 
2705         rmd->mmu_update->ptr = virt_to_machine(ptep).maddr;
2706         rmd->mmu_update->ptr |= rmd->no_translate ?
2707                 MMU_PT_UPDATE_NO_TRANSLATE :
2708                 MMU_NORMAL_PT_UPDATE;
2709         rmd->mmu_update->val = pte_val_ma(pte);
2710         rmd->mmu_update++;
2711 
2712         return 0;
2713 }
2714 
2715 int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr,
2716                   xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot,
2717                   unsigned int domid, bool no_translate, struct page **pages)
2718 {
2719         int err = 0;
2720         struct remap_data rmd;
2721         struct mmu_update mmu_update[REMAP_BATCH_SIZE];
2722         unsigned long range;
2723         int mapped = 0;
2724 
2725         BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
2726 
2727         rmd.pfn = pfn;
2728         rmd.prot = prot;
2729         /*
2730          * We use the err_ptr to indicate if there we are doing a contiguous
2731          * mapping or a discontigious mapping.
2732          */
2733         rmd.contiguous = !err_ptr;
2734         rmd.no_translate = no_translate;
2735 
2736         while (nr) {
2737                 int index = 0;
2738                 int done = 0;
2739                 int batch = min(REMAP_BATCH_SIZE, nr);
2740                 int batch_left = batch;
2741 
2742                 range = (unsigned long)batch << PAGE_SHIFT;
2743 
2744                 rmd.mmu_update = mmu_update;
2745                 err = apply_to_page_range(vma->vm_mm, addr, range,
2746                                           remap_area_pfn_pte_fn, &rmd);
2747                 if (err)
2748                         goto out;
2749 
2750                 /*
2751                  * We record the error for each page that gives an error, but
2752                  * continue mapping until the whole set is done
2753                  */
2754                 do {
2755                         int i;
2756 
2757                         err = HYPERVISOR_mmu_update(&mmu_update[index],
2758                                                     batch_left, &done, domid);
2759 
2760                         /*
2761                          * @err_ptr may be the same buffer as @gfn, so
2762                          * only clear it after each chunk of @gfn is
2763                          * used.
2764                          */
2765                         if (err_ptr) {
2766                                 for (i = index; i < index + done; i++)
2767                                         err_ptr[i] = 0;
2768                         }
2769                         if (err < 0) {
2770                                 if (!err_ptr)
2771                                         goto out;
2772                                 err_ptr[i] = err;
2773                                 done++; /* Skip failed frame. */
2774                         } else
2775                                 mapped += done;
2776                         batch_left -= done;
2777                         index += done;
2778                 } while (batch_left);
2779 
2780                 nr -= batch;
2781                 addr += range;
2782                 if (err_ptr)
2783                         err_ptr += batch;
2784                 cond_resched();
2785         }
2786 out:
2787 
2788         xen_flush_tlb_all();
2789 
2790         return err < 0 ? err : mapped;
2791 }
2792 EXPORT_SYMBOL_GPL(xen_remap_pfn);
2793 
2794 #ifdef CONFIG_KEXEC_CORE
2795 phys_addr_t paddr_vmcoreinfo_note(void)
2796 {
2797         if (xen_pv_domain())
2798                 return virt_to_machine(vmcoreinfo_note).maddr;
2799         else
2800                 return __pa(vmcoreinfo_note);
2801 }
2802 #endif /* CONFIG_KEXEC_CORE */
2803 

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