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109  * out of date, but it will never be set early).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

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