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Linux/arch/x86/xen/p2m.c

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  1 /*
  2  * Xen leaves the responsibility for maintaining p2m mappings to the
  3  * guests themselves, but it must also access and update the p2m array
  4  * during suspend/resume when all the pages are reallocated.
  5  *
  6  * The logical flat p2m table is mapped to a linear kernel memory area.
  7  * For accesses by Xen a three-level tree linked via mfns only is set up to
  8  * allow the address space to be sparse.
  9  *
 10  *               Xen
 11  *                |
 12  *          p2m_top_mfn
 13  *              /   \
 14  * p2m_mid_mfn p2m_mid_mfn
 15  *         /           /
 16  *  p2m p2m p2m ...
 17  *
 18  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
 19  *
 20  * The p2m_top_mfn level is limited to 1 page, so the maximum representable
 21  * pseudo-physical address space is:
 22  *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
 23  *
 24  * P2M_PER_PAGE depends on the architecture, as a mfn is always
 25  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
 26  * 512 and 1024 entries respectively.
 27  *
 28  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
 29  *
 30  * However not all entries are filled with MFNs. Specifically for all other
 31  * leaf entries, or for the top  root, or middle one, for which there is a void
 32  * entry, we assume it is  "missing". So (for example)
 33  *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
 34  * We have a dedicated page p2m_missing with all entries being
 35  * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
 36  * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
 37  *
 38  * We also have the possibility of setting 1-1 mappings on certain regions, so
 39  * that:
 40  *  pfn_to_mfn(0xc0000)=0xc0000
 41  *
 42  * The benefit of this is, that we can assume for non-RAM regions (think
 43  * PCI BARs, or ACPI spaces), we can create mappings easily because we
 44  * get the PFN value to match the MFN.
 45  *
 46  * For this to work efficiently we have one new page p2m_identity. All entries
 47  * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
 48  * recognizes that and MFNs, no other fancy value).
 49  *
 50  * On lookup we spot that the entry points to p2m_identity and return the
 51  * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
 52  * If the entry points to an allocated page, we just proceed as before and
 53  * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
 54  * appropriate functions (pfn_to_mfn).
 55  *
 56  * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
 57  * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
 58  * non-identity pfn. To protect ourselves against we elect to set (and get) the
 59  * IDENTITY_FRAME_BIT on all identity mapped PFNs.
 60  */
 61 
 62 #include <linux/init.h>
 63 #include <linux/module.h>
 64 #include <linux/list.h>
 65 #include <linux/hash.h>
 66 #include <linux/sched.h>
 67 #include <linux/seq_file.h>
 68 #include <linux/bootmem.h>
 69 #include <linux/slab.h>
 70 
 71 #include <asm/cache.h>
 72 #include <asm/setup.h>
 73 #include <asm/uaccess.h>
 74 
 75 #include <asm/xen/page.h>
 76 #include <asm/xen/hypercall.h>
 77 #include <asm/xen/hypervisor.h>
 78 #include <xen/balloon.h>
 79 #include <xen/grant_table.h>
 80 
 81 #include "p2m.h"
 82 #include "multicalls.h"
 83 #include "xen-ops.h"
 84 
 85 #define PMDS_PER_MID_PAGE       (P2M_MID_PER_PAGE / PTRS_PER_PTE)
 86 
 87 unsigned long *xen_p2m_addr __read_mostly;
 88 EXPORT_SYMBOL_GPL(xen_p2m_addr);
 89 unsigned long xen_p2m_size __read_mostly;
 90 EXPORT_SYMBOL_GPL(xen_p2m_size);
 91 unsigned long xen_max_p2m_pfn __read_mostly;
 92 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
 93 
 94 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
 95 #define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
 96 #else
 97 #define P2M_LIMIT 0
 98 #endif
 99 
100 static DEFINE_SPINLOCK(p2m_update_lock);
101 
102 static unsigned long *p2m_mid_missing_mfn;
103 static unsigned long *p2m_top_mfn;
104 static unsigned long **p2m_top_mfn_p;
105 static unsigned long *p2m_missing;
106 static unsigned long *p2m_identity;
107 static pte_t *p2m_missing_pte;
108 static pte_t *p2m_identity_pte;
109 
110 static inline unsigned p2m_top_index(unsigned long pfn)
111 {
112         BUG_ON(pfn >= MAX_P2M_PFN);
113         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
114 }
115 
116 static inline unsigned p2m_mid_index(unsigned long pfn)
117 {
118         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
119 }
120 
121 static inline unsigned p2m_index(unsigned long pfn)
122 {
123         return pfn % P2M_PER_PAGE;
124 }
125 
126 static void p2m_top_mfn_init(unsigned long *top)
127 {
128         unsigned i;
129 
130         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
131                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
132 }
133 
134 static void p2m_top_mfn_p_init(unsigned long **top)
135 {
136         unsigned i;
137 
138         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
139                 top[i] = p2m_mid_missing_mfn;
140 }
141 
142 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
143 {
144         unsigned i;
145 
146         for (i = 0; i < P2M_MID_PER_PAGE; i++)
147                 mid[i] = virt_to_mfn(leaf);
148 }
149 
150 static void p2m_init(unsigned long *p2m)
151 {
152         unsigned i;
153 
154         for (i = 0; i < P2M_PER_PAGE; i++)
155                 p2m[i] = INVALID_P2M_ENTRY;
156 }
157 
158 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
159 {
160         unsigned i;
161 
162         for (i = 0; i < P2M_PER_PAGE; i++)
163                 p2m[i] = IDENTITY_FRAME(pfn + i);
164 }
165 
166 static void * __ref alloc_p2m_page(void)
167 {
168         if (unlikely(!slab_is_available()))
169                 return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
170 
171         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
172 }
173 
174 static void __ref free_p2m_page(void *p)
175 {
176         if (unlikely(!slab_is_available())) {
177                 free_bootmem((unsigned long)p, PAGE_SIZE);
178                 return;
179         }
180 
181         free_page((unsigned long)p);
182 }
183 
184 /*
185  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
186  *
187  * This is called both at boot time, and after resuming from suspend:
188  * - At boot time we're called rather early, and must use alloc_bootmem*()
189  *   to allocate memory.
190  *
191  * - After resume we're called from within stop_machine, but the mfn
192  *   tree should already be completely allocated.
193  */
194 void __ref xen_build_mfn_list_list(void)
195 {
196         unsigned long pfn, mfn;
197         pte_t *ptep;
198         unsigned int level, topidx, mididx;
199         unsigned long *mid_mfn_p;
200 
201         if (xen_feature(XENFEAT_auto_translated_physmap))
202                 return;
203 
204         /* Pre-initialize p2m_top_mfn to be completely missing */
205         if (p2m_top_mfn == NULL) {
206                 p2m_mid_missing_mfn = alloc_p2m_page();
207                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
208 
209                 p2m_top_mfn_p = alloc_p2m_page();
210                 p2m_top_mfn_p_init(p2m_top_mfn_p);
211 
212                 p2m_top_mfn = alloc_p2m_page();
213                 p2m_top_mfn_init(p2m_top_mfn);
214         } else {
215                 /* Reinitialise, mfn's all change after migration */
216                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
217         }
218 
219         for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
220              pfn += P2M_PER_PAGE) {
221                 topidx = p2m_top_index(pfn);
222                 mididx = p2m_mid_index(pfn);
223 
224                 mid_mfn_p = p2m_top_mfn_p[topidx];
225                 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
226                                       &level);
227                 BUG_ON(!ptep || level != PG_LEVEL_4K);
228                 mfn = pte_mfn(*ptep);
229                 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
230 
231                 /* Don't bother allocating any mfn mid levels if
232                  * they're just missing, just update the stored mfn,
233                  * since all could have changed over a migrate.
234                  */
235                 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
236                         BUG_ON(mididx);
237                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
238                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
239                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
240                         continue;
241                 }
242 
243                 if (mid_mfn_p == p2m_mid_missing_mfn) {
244                         mid_mfn_p = alloc_p2m_page();
245                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
246 
247                         p2m_top_mfn_p[topidx] = mid_mfn_p;
248                 }
249 
250                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
251                 mid_mfn_p[mididx] = mfn;
252         }
253 }
254 
255 void xen_setup_mfn_list_list(void)
256 {
257         if (xen_feature(XENFEAT_auto_translated_physmap))
258                 return;
259 
260         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
261 
262         HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
263                 virt_to_mfn(p2m_top_mfn);
264         HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
265 }
266 
267 /* Set up p2m_top to point to the domain-builder provided p2m pages */
268 void __init xen_build_dynamic_phys_to_machine(void)
269 {
270         unsigned long pfn;
271 
272          if (xen_feature(XENFEAT_auto_translated_physmap))
273                 return;
274 
275         xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
276         xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
277 
278         for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
279                 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
280 
281         xen_max_p2m_pfn = xen_p2m_size;
282 }
283 
284 #define P2M_TYPE_IDENTITY       0
285 #define P2M_TYPE_MISSING        1
286 #define P2M_TYPE_PFN            2
287 #define P2M_TYPE_UNKNOWN        3
288 
289 static int xen_p2m_elem_type(unsigned long pfn)
290 {
291         unsigned long mfn;
292 
293         if (pfn >= xen_p2m_size)
294                 return P2M_TYPE_IDENTITY;
295 
296         mfn = xen_p2m_addr[pfn];
297 
298         if (mfn == INVALID_P2M_ENTRY)
299                 return P2M_TYPE_MISSING;
300 
301         if (mfn & IDENTITY_FRAME_BIT)
302                 return P2M_TYPE_IDENTITY;
303 
304         return P2M_TYPE_PFN;
305 }
306 
307 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
308 {
309         unsigned int i, chunk;
310         unsigned long pfn;
311         unsigned long *mfns;
312         pte_t *ptep;
313         pmd_t *pmdp;
314         int type;
315 
316         p2m_missing = alloc_p2m_page();
317         p2m_init(p2m_missing);
318         p2m_identity = alloc_p2m_page();
319         p2m_init(p2m_identity);
320 
321         p2m_missing_pte = alloc_p2m_page();
322         paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
323         p2m_identity_pte = alloc_p2m_page();
324         paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
325         for (i = 0; i < PTRS_PER_PTE; i++) {
326                 set_pte(p2m_missing_pte + i,
327                         pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
328                 set_pte(p2m_identity_pte + i,
329                         pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
330         }
331 
332         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
333                 /*
334                  * Try to map missing/identity PMDs or p2m-pages if possible.
335                  * We have to respect the structure of the mfn_list_list
336                  * which will be built just afterwards.
337                  * Chunk size to test is one p2m page if we are in the middle
338                  * of a mfn_list_list mid page and the complete mid page area
339                  * if we are at index 0 of the mid page. Please note that a
340                  * mid page might cover more than one PMD, e.g. on 32 bit PAE
341                  * kernels.
342                  */
343                 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
344                         P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
345 
346                 type = xen_p2m_elem_type(pfn);
347                 i = 0;
348                 if (type != P2M_TYPE_PFN)
349                         for (i = 1; i < chunk; i++)
350                                 if (xen_p2m_elem_type(pfn + i) != type)
351                                         break;
352                 if (i < chunk)
353                         /* Reset to minimal chunk size. */
354                         chunk = P2M_PER_PAGE;
355 
356                 if (type == P2M_TYPE_PFN || i < chunk) {
357                         /* Use initial p2m page contents. */
358 #ifdef CONFIG_X86_64
359                         mfns = alloc_p2m_page();
360                         copy_page(mfns, xen_p2m_addr + pfn);
361 #else
362                         mfns = xen_p2m_addr + pfn;
363 #endif
364                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
365                         set_pte(ptep,
366                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
367                         continue;
368                 }
369 
370                 if (chunk == P2M_PER_PAGE) {
371                         /* Map complete missing or identity p2m-page. */
372                         mfns = (type == P2M_TYPE_MISSING) ?
373                                 p2m_missing : p2m_identity;
374                         ptep = populate_extra_pte((unsigned long)(p2m + pfn));
375                         set_pte(ptep,
376                                 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
377                         continue;
378                 }
379 
380                 /* Complete missing or identity PMD(s) can be mapped. */
381                 ptep = (type == P2M_TYPE_MISSING) ?
382                         p2m_missing_pte : p2m_identity_pte;
383                 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
384                         pmdp = populate_extra_pmd(
385                                 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
386                         set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
387                 }
388         }
389 }
390 
391 void __init xen_vmalloc_p2m_tree(void)
392 {
393         static struct vm_struct vm;
394         unsigned long p2m_limit;
395 
396         p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
397         vm.flags = VM_ALLOC;
398         vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
399                         PMD_SIZE * PMDS_PER_MID_PAGE);
400         vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
401         pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
402 
403         xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
404 
405         xen_rebuild_p2m_list(vm.addr);
406 
407         xen_p2m_addr = vm.addr;
408         xen_p2m_size = xen_max_p2m_pfn;
409 
410         xen_inv_extra_mem();
411 }
412 
413 unsigned long get_phys_to_machine(unsigned long pfn)
414 {
415         pte_t *ptep;
416         unsigned int level;
417 
418         if (unlikely(pfn >= xen_p2m_size)) {
419                 if (pfn < xen_max_p2m_pfn)
420                         return xen_chk_extra_mem(pfn);
421 
422                 return IDENTITY_FRAME(pfn);
423         }
424 
425         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
426         BUG_ON(!ptep || level != PG_LEVEL_4K);
427 
428         /*
429          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
430          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
431          * would be wrong.
432          */
433         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
434                 return IDENTITY_FRAME(pfn);
435 
436         return xen_p2m_addr[pfn];
437 }
438 EXPORT_SYMBOL_GPL(get_phys_to_machine);
439 
440 /*
441  * Allocate new pmd(s). It is checked whether the old pmd is still in place.
442  * If not, nothing is changed. This is okay as the only reason for allocating
443  * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
444  * pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
445  */
446 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
447 {
448         pte_t *ptechk;
449         pte_t *pte_newpg[PMDS_PER_MID_PAGE];
450         pmd_t *pmdp;
451         unsigned int level;
452         unsigned long flags;
453         unsigned long vaddr;
454         int i;
455 
456         /* Do all allocations first to bail out in error case. */
457         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
458                 pte_newpg[i] = alloc_p2m_page();
459                 if (!pte_newpg[i]) {
460                         for (i--; i >= 0; i--)
461                                 free_p2m_page(pte_newpg[i]);
462 
463                         return NULL;
464                 }
465         }
466 
467         vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
468 
469         for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
470                 copy_page(pte_newpg[i], pte_pg);
471                 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
472 
473                 pmdp = lookup_pmd_address(vaddr);
474                 BUG_ON(!pmdp);
475 
476                 spin_lock_irqsave(&p2m_update_lock, flags);
477 
478                 ptechk = lookup_address(vaddr, &level);
479                 if (ptechk == pte_pg) {
480                         set_pmd(pmdp,
481                                 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
482                         pte_newpg[i] = NULL;
483                 }
484 
485                 spin_unlock_irqrestore(&p2m_update_lock, flags);
486 
487                 if (pte_newpg[i]) {
488                         paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
489                         free_p2m_page(pte_newpg[i]);
490                 }
491 
492                 vaddr += PMD_SIZE;
493         }
494 
495         return lookup_address(addr, &level);
496 }
497 
498 /*
499  * Fully allocate the p2m structure for a given pfn.  We need to check
500  * that both the top and mid levels are allocated, and make sure the
501  * parallel mfn tree is kept in sync.  We may race with other cpus, so
502  * the new pages are installed with cmpxchg; if we lose the race then
503  * simply free the page we allocated and use the one that's there.
504  */
505 static bool alloc_p2m(unsigned long pfn)
506 {
507         unsigned topidx, mididx;
508         unsigned long *top_mfn_p, *mid_mfn;
509         pte_t *ptep, *pte_pg;
510         unsigned int level;
511         unsigned long flags;
512         unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
513         unsigned long p2m_pfn;
514 
515         topidx = p2m_top_index(pfn);
516         mididx = p2m_mid_index(pfn);
517 
518         ptep = lookup_address(addr, &level);
519         BUG_ON(!ptep || level != PG_LEVEL_4K);
520         pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
521 
522         if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
523                 /* PMD level is missing, allocate a new one */
524                 ptep = alloc_p2m_pmd(addr, pte_pg);
525                 if (!ptep)
526                         return false;
527         }
528 
529         if (p2m_top_mfn) {
530                 top_mfn_p = &p2m_top_mfn[topidx];
531                 mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
532 
533                 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
534 
535                 if (mid_mfn == p2m_mid_missing_mfn) {
536                         /* Separately check the mid mfn level */
537                         unsigned long missing_mfn;
538                         unsigned long mid_mfn_mfn;
539                         unsigned long old_mfn;
540 
541                         mid_mfn = alloc_p2m_page();
542                         if (!mid_mfn)
543                                 return false;
544 
545                         p2m_mid_mfn_init(mid_mfn, p2m_missing);
546 
547                         missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
548                         mid_mfn_mfn = virt_to_mfn(mid_mfn);
549                         old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
550                         if (old_mfn != missing_mfn) {
551                                 free_p2m_page(mid_mfn);
552                                 mid_mfn = mfn_to_virt(old_mfn);
553                         } else {
554                                 p2m_top_mfn_p[topidx] = mid_mfn;
555                         }
556                 }
557         } else {
558                 mid_mfn = NULL;
559         }
560 
561         p2m_pfn = pte_pfn(READ_ONCE(*ptep));
562         if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
563             p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
564                 /* p2m leaf page is missing */
565                 unsigned long *p2m;
566 
567                 p2m = alloc_p2m_page();
568                 if (!p2m)
569                         return false;
570 
571                 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
572                         p2m_init(p2m);
573                 else
574                         p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
575 
576                 spin_lock_irqsave(&p2m_update_lock, flags);
577 
578                 if (pte_pfn(*ptep) == p2m_pfn) {
579                         set_pte(ptep,
580                                 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
581                         if (mid_mfn)
582                                 mid_mfn[mididx] = virt_to_mfn(p2m);
583                         p2m = NULL;
584                 }
585 
586                 spin_unlock_irqrestore(&p2m_update_lock, flags);
587 
588                 if (p2m)
589                         free_p2m_page(p2m);
590         }
591 
592         return true;
593 }
594 
595 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
596                                       unsigned long pfn_e)
597 {
598         unsigned long pfn;
599 
600         if (unlikely(pfn_s >= xen_p2m_size))
601                 return 0;
602 
603         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
604                 return pfn_e - pfn_s;
605 
606         if (pfn_s > pfn_e)
607                 return 0;
608 
609         if (pfn_e > xen_p2m_size)
610                 pfn_e = xen_p2m_size;
611 
612         for (pfn = pfn_s; pfn < pfn_e; pfn++)
613                 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
614 
615         return pfn - pfn_s;
616 }
617 
618 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
619 {
620         pte_t *ptep;
621         unsigned int level;
622 
623         /* don't track P2M changes in autotranslate guests */
624         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
625                 return true;
626 
627         if (unlikely(pfn >= xen_p2m_size)) {
628                 BUG_ON(mfn != INVALID_P2M_ENTRY);
629                 return true;
630         }
631 
632         if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
633                 return true;
634 
635         ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
636         BUG_ON(!ptep || level != PG_LEVEL_4K);
637 
638         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
639                 return mfn == INVALID_P2M_ENTRY;
640 
641         if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
642                 return mfn == IDENTITY_FRAME(pfn);
643 
644         return false;
645 }
646 
647 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
648 {
649         if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
650                 if (!alloc_p2m(pfn))
651                         return false;
652 
653                 return __set_phys_to_machine(pfn, mfn);
654         }
655 
656         return true;
657 }
658 
659 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
660                             struct gnttab_map_grant_ref *kmap_ops,
661                             struct page **pages, unsigned int count)
662 {
663         int i, ret = 0;
664         pte_t *pte;
665 
666         if (xen_feature(XENFEAT_auto_translated_physmap))
667                 return 0;
668 
669         if (kmap_ops) {
670                 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
671                                                 kmap_ops, count);
672                 if (ret)
673                         goto out;
674         }
675 
676         for (i = 0; i < count; i++) {
677                 unsigned long mfn, pfn;
678 
679                 /* Do not add to override if the map failed. */
680                 if (map_ops[i].status)
681                         continue;
682 
683                 if (map_ops[i].flags & GNTMAP_contains_pte) {
684                         pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
685                                 (map_ops[i].host_addr & ~PAGE_MASK));
686                         mfn = pte_mfn(*pte);
687                 } else {
688                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
689                 }
690                 pfn = page_to_pfn(pages[i]);
691 
692                 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
693 
694                 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
695                         ret = -ENOMEM;
696                         goto out;
697                 }
698         }
699 
700 out:
701         return ret;
702 }
703 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
704 
705 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
706                               struct gnttab_unmap_grant_ref *kunmap_ops,
707                               struct page **pages, unsigned int count)
708 {
709         int i, ret = 0;
710 
711         if (xen_feature(XENFEAT_auto_translated_physmap))
712                 return 0;
713 
714         for (i = 0; i < count; i++) {
715                 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
716                 unsigned long pfn = page_to_pfn(pages[i]);
717 
718                 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
719                         ret = -EINVAL;
720                         goto out;
721                 }
722 
723                 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
724         }
725         if (kunmap_ops)
726                 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
727                                                 kunmap_ops, count);
728 out:
729         return ret;
730 }
731 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
732 
733 #ifdef CONFIG_XEN_DEBUG_FS
734 #include <linux/debugfs.h>
735 #include "debugfs.h"
736 static int p2m_dump_show(struct seq_file *m, void *v)
737 {
738         static const char * const type_name[] = {
739                                 [P2M_TYPE_IDENTITY] = "identity",
740                                 [P2M_TYPE_MISSING] = "missing",
741                                 [P2M_TYPE_PFN] = "pfn",
742                                 [P2M_TYPE_UNKNOWN] = "abnormal"};
743         unsigned long pfn, first_pfn;
744         int type, prev_type;
745 
746         prev_type = xen_p2m_elem_type(0);
747         first_pfn = 0;
748 
749         for (pfn = 0; pfn < xen_p2m_size; pfn++) {
750                 type = xen_p2m_elem_type(pfn);
751                 if (type != prev_type) {
752                         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
753                                    type_name[prev_type]);
754                         prev_type = type;
755                         first_pfn = pfn;
756                 }
757         }
758         seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
759                    type_name[prev_type]);
760         return 0;
761 }
762 
763 static int p2m_dump_open(struct inode *inode, struct file *filp)
764 {
765         return single_open(filp, p2m_dump_show, NULL);
766 }
767 
768 static const struct file_operations p2m_dump_fops = {
769         .open           = p2m_dump_open,
770         .read           = seq_read,
771         .llseek         = seq_lseek,
772         .release        = single_release,
773 };
774 
775 static struct dentry *d_mmu_debug;
776 
777 static int __init xen_p2m_debugfs(void)
778 {
779         struct dentry *d_xen = xen_init_debugfs();
780 
781         if (d_xen == NULL)
782                 return -ENOMEM;
783 
784         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
785 
786         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
787         return 0;
788 }
789 fs_initcall(xen_p2m_debugfs);
790 #endif /* CONFIG_XEN_DEBUG_FS */
791 

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