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TOMOYO Linux Cross Reference
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 p2m table is logically a flat array, but we implement it as a
  7  * three-level tree to allow the address space to be sparse.
  8  *
  9  *                               Xen
 10  *                                |
 11  *     p2m_top              p2m_top_mfn
 12  *       /  \                   /   \
 13  * p2m_mid p2m_mid      p2m_mid_mfn p2m_mid_mfn
 14  *    / \      / \         /           /
 15  *  p2m p2m p2m p2m p2m p2m p2m ...
 16  *
 17  * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
 18  *
 19  * The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
 20  * maximum representable pseudo-physical address space is:
 21  *  P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
 22  *
 23  * P2M_PER_PAGE depends on the architecture, as a mfn is always
 24  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
 25  * 512 and 1024 entries respectively.
 26  *
 27  * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
 28  *
 29  * However not all entries are filled with MFNs. Specifically for all other
 30  * leaf entries, or for the top  root, or middle one, for which there is a void
 31  * entry, we assume it is  "missing". So (for example)
 32  *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
 33  *
 34  * We also have the possibility of setting 1-1 mappings on certain regions, so
 35  * that:
 36  *  pfn_to_mfn(0xc0000)=0xc0000
 37  *
 38  * The benefit of this is, that we can assume for non-RAM regions (think
 39  * PCI BARs, or ACPI spaces), we can create mappings easily because we
 40  * get the PFN value to match the MFN.
 41  *
 42  * For this to work efficiently we have one new page p2m_identity and
 43  * allocate (via reserved_brk) any other pages we need to cover the sides
 44  * (1GB or 4MB boundary violations). All entries in p2m_identity are set to
 45  * INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
 46  * no other fancy value).
 47  *
 48  * On lookup we spot that the entry points to p2m_identity and return the
 49  * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
 50  * If the entry points to an allocated page, we just proceed as before and
 51  * return the PFN.  If the PFN has IDENTITY_FRAME_BIT set we unmask that in
 52  * appropriate functions (pfn_to_mfn).
 53  *
 54  * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
 55  * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
 56  * non-identity pfn. To protect ourselves against we elect to set (and get) the
 57  * IDENTITY_FRAME_BIT on all identity mapped PFNs.
 58  *
 59  * This simplistic diagram is used to explain the more subtle piece of code.
 60  * There is also a digram of the P2M at the end that can help.
 61  * Imagine your E820 looking as so:
 62  *
 63  *                    1GB                                           2GB    4GB
 64  * /-------------------+---------\/----\         /----------\    /---+-----\
 65  * | System RAM        | Sys RAM ||ACPI|         | reserved |    | Sys RAM |
 66  * \-------------------+---------/\----/         \----------/    \---+-----/
 67  *                               ^- 1029MB                       ^- 2001MB
 68  *
 69  * [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
 70  *  2048MB = 524288 (0x80000)]
 71  *
 72  * And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
 73  * is actually not present (would have to kick the balloon driver to put it in).
 74  *
 75  * When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
 76  * Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
 77  * of the PFN and the end PFN (263424 and 512256 respectively). The first step
 78  * is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
 79  * covers 512^2 of page estate (1GB) and in case the start or end PFN is not
 80  * aligned on 512^2*PAGE_SIZE (1GB) we reserve_brk new middle and leaf pages as
 81  * required to split any existing p2m_mid_missing middle pages.
 82  *
 83  * With the E820 example above, 263424 is not 1GB aligned so we allocate a
 84  * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
 85  * Each entry in the allocate page is "missing" (points to p2m_missing).
 86  *
 87  * Next stage is to determine if we need to do a more granular boundary check
 88  * on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
 89  * We check if the start pfn and end pfn violate that boundary check, and if
 90  * so reserve_brk a (p2m[x][y]) leaf page. This way we have a much finer
 91  * granularity of setting which PFNs are missing and which ones are identity.
 92  * In our example 263424 and 512256 both fail the check so we reserve_brk two
 93  * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
 94  * values) and assign them to p2m[1][2] and p2m[1][488] respectively.
 95  *
 96  * At this point we would at minimum reserve_brk one page, but could be up to
 97  * three. Each call to set_phys_range_identity has at maximum a three page
 98  * cost. If we were to query the P2M at this stage, all those entries from
 99  * start PFN through end PFN (so 1029MB -> 2001MB) would return
100  * INVALID_P2M_ENTRY ("missing").
101  *
102  * The next step is to walk from the start pfn to the end pfn setting
103  * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
104  * If we find that the middle entry is pointing to p2m_missing we can swap it
105  * over to p2m_identity - this way covering 4MB (or 2MB) PFN space (and
106  * similarly swapping p2m_mid_missing for p2m_mid_identity for larger regions).
107  * At this point we do not need to worry about boundary aligment (so no need to
108  * reserve_brk a middle page, figure out which PFNs are "missing" and which
109  * ones are identity), as that has been done earlier.  If we find that the
110  * middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
111  * that page (which covers 512 PFNs) and set the appropriate PFN with
112  * IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
113  * set from p2m[1][2][256->511] and p2m[1][488][0->256] with
114  * IDENTITY_FRAME_BIT set.
115  *
116  * All other regions that are void (or not filled) either point to p2m_missing
117  * (considered missing) or have the default value of INVALID_P2M_ENTRY (also
118  * considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
119  * contain the INVALID_P2M_ENTRY value and are considered "missing."
120  *
121  * Finally, the region beyond the end of of the E820 (4 GB in this example)
122  * is set to be identity (in case there are MMIO regions placed here).
123  *
124  * This is what the p2m ends up looking (for the E820 above) with this
125  * fabulous drawing:
126  *
127  *    p2m         /--------------\
128  *  /-----\       | &mfn_list[0],|                           /-----------------\
129  *  |  0  |------>| &mfn_list[1],|    /---------------\      | ~0, ~0, ..      |
130  *  |-----|       |  ..., ~0, ~0 |    | ~0, ~0, [x]---+----->| IDENTITY [@256] |
131  *  |  1  |---\   \--------------/    | [p2m_identity]+\     | IDENTITY [@257] |
132  *  |-----|    \                      | [p2m_identity]+\\    | ....            |
133  *  |  2  |--\  \-------------------->|  ...          | \\   \----------------/
134  *  |-----|   \                       \---------------/  \\
135  *  |  3  |-\  \                                          \\  p2m_identity [1]
136  *  |-----|  \  \-------------------->/---------------\   /-----------------\
137  *  | ..  |\  |                       | [p2m_identity]+-->| ~0, ~0, ~0, ... |
138  *  \-----/ | |                       | [p2m_identity]+-->| ..., ~0         |
139  *          | |                       | ....          |   \-----------------/
140  *          | |                       +-[x], ~0, ~0.. +\
141  *          | |                       \---------------/ \
142  *          | |                                          \-> /---------------\
143  *          | V  p2m_mid_missing       p2m_missing           | IDENTITY[@0]  |
144  *          | /-----------------\     /------------\         | IDENTITY[@256]|
145  *          | | [p2m_missing]   +---->| ~0, ~0, ...|         | ~0, ~0, ....  |
146  *          | | [p2m_missing]   +---->| ..., ~0    |         \---------------/
147  *          | | ...             |     \------------/
148  *          | \-----------------/
149  *          |
150  *          |     p2m_mid_identity
151  *          |   /-----------------\
152  *          \-->| [p2m_identity]  +---->[1]
153  *              | [p2m_identity]  +---->[1]
154  *              | ...             |
155  *              \-----------------/
156  *
157  * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
158  */
159 
160 #include <linux/init.h>
161 #include <linux/module.h>
162 #include <linux/list.h>
163 #include <linux/hash.h>
164 #include <linux/sched.h>
165 #include <linux/seq_file.h>
166 #include <linux/bootmem.h>
167 
168 #include <asm/cache.h>
169 #include <asm/setup.h>
170 
171 #include <asm/xen/page.h>
172 #include <asm/xen/hypercall.h>
173 #include <asm/xen/hypervisor.h>
174 #include <xen/balloon.h>
175 #include <xen/grant_table.h>
176 
177 #include "p2m.h"
178 #include "multicalls.h"
179 #include "xen-ops.h"
180 
181 static void __init m2p_override_init(void);
182 
183 unsigned long xen_max_p2m_pfn __read_mostly;
184 
185 static unsigned long *p2m_mid_missing_mfn;
186 static unsigned long *p2m_top_mfn;
187 static unsigned long **p2m_top_mfn_p;
188 
189 /* Placeholders for holes in the address space */
190 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
191 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
192 
193 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
194 
195 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
196 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_identity, P2M_MID_PER_PAGE);
197 
198 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
199 
200 /* For each I/O range remapped we may lose up to two leaf pages for the boundary
201  * violations and three mid pages to cover up to 3GB. With
202  * early_can_reuse_p2m_middle() most of the leaf pages will be reused by the
203  * remapped region.
204  */
205 RESERVE_BRK(p2m_identity_remap, PAGE_SIZE * 2 * 3 * MAX_REMAP_RANGES);
206 
207 static inline unsigned p2m_top_index(unsigned long pfn)
208 {
209         BUG_ON(pfn >= MAX_P2M_PFN);
210         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
211 }
212 
213 static inline unsigned p2m_mid_index(unsigned long pfn)
214 {
215         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
216 }
217 
218 static inline unsigned p2m_index(unsigned long pfn)
219 {
220         return pfn % P2M_PER_PAGE;
221 }
222 
223 static void p2m_top_init(unsigned long ***top)
224 {
225         unsigned i;
226 
227         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
228                 top[i] = p2m_mid_missing;
229 }
230 
231 static void p2m_top_mfn_init(unsigned long *top)
232 {
233         unsigned i;
234 
235         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
236                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
237 }
238 
239 static void p2m_top_mfn_p_init(unsigned long **top)
240 {
241         unsigned i;
242 
243         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
244                 top[i] = p2m_mid_missing_mfn;
245 }
246 
247 static void p2m_mid_init(unsigned long **mid, unsigned long *leaf)
248 {
249         unsigned i;
250 
251         for (i = 0; i < P2M_MID_PER_PAGE; i++)
252                 mid[i] = leaf;
253 }
254 
255 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
256 {
257         unsigned i;
258 
259         for (i = 0; i < P2M_MID_PER_PAGE; i++)
260                 mid[i] = virt_to_mfn(leaf);
261 }
262 
263 static void p2m_init(unsigned long *p2m)
264 {
265         unsigned i;
266 
267         for (i = 0; i < P2M_MID_PER_PAGE; i++)
268                 p2m[i] = INVALID_P2M_ENTRY;
269 }
270 
271 /*
272  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
273  *
274  * This is called both at boot time, and after resuming from suspend:
275  * - At boot time we're called rather early, and must use alloc_bootmem*()
276  *   to allocate memory.
277  *
278  * - After resume we're called from within stop_machine, but the mfn
279  *   tree should already be completely allocated.
280  */
281 void __ref xen_build_mfn_list_list(void)
282 {
283         unsigned long pfn;
284 
285         if (xen_feature(XENFEAT_auto_translated_physmap))
286                 return;
287 
288         /* Pre-initialize p2m_top_mfn to be completely missing */
289         if (p2m_top_mfn == NULL) {
290                 p2m_mid_missing_mfn = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
291                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
292 
293                 p2m_top_mfn_p = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
294                 p2m_top_mfn_p_init(p2m_top_mfn_p);
295 
296                 p2m_top_mfn = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
297                 p2m_top_mfn_init(p2m_top_mfn);
298         } else {
299                 /* Reinitialise, mfn's all change after migration */
300                 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
301         }
302 
303         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
304                 unsigned topidx = p2m_top_index(pfn);
305                 unsigned mididx = p2m_mid_index(pfn);
306                 unsigned long **mid;
307                 unsigned long *mid_mfn_p;
308 
309                 mid = p2m_top[topidx];
310                 mid_mfn_p = p2m_top_mfn_p[topidx];
311 
312                 /* Don't bother allocating any mfn mid levels if
313                  * they're just missing, just update the stored mfn,
314                  * since all could have changed over a migrate.
315                  */
316                 if (mid == p2m_mid_missing) {
317                         BUG_ON(mididx);
318                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
319                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
320                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
321                         continue;
322                 }
323 
324                 if (mid_mfn_p == p2m_mid_missing_mfn) {
325                         /*
326                          * XXX boot-time only!  We should never find
327                          * missing parts of the mfn tree after
328                          * runtime.
329                          */
330                         mid_mfn_p = alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
331                         p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
332 
333                         p2m_top_mfn_p[topidx] = mid_mfn_p;
334                 }
335 
336                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
337                 mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
338         }
339 }
340 
341 void xen_setup_mfn_list_list(void)
342 {
343         if (xen_feature(XENFEAT_auto_translated_physmap))
344                 return;
345 
346         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
347 
348         HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
349                 virt_to_mfn(p2m_top_mfn);
350         HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
351 }
352 
353 /* Set up p2m_top to point to the domain-builder provided p2m pages */
354 void __init xen_build_dynamic_phys_to_machine(void)
355 {
356         unsigned long *mfn_list;
357         unsigned long max_pfn;
358         unsigned long pfn;
359 
360          if (xen_feature(XENFEAT_auto_translated_physmap))
361                 return;
362 
363         mfn_list = (unsigned long *)xen_start_info->mfn_list;
364         max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
365         xen_max_p2m_pfn = max_pfn;
366 
367         p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
368         p2m_init(p2m_missing);
369         p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
370         p2m_init(p2m_identity);
371 
372         p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
373         p2m_mid_init(p2m_mid_missing, p2m_missing);
374         p2m_mid_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
375         p2m_mid_init(p2m_mid_identity, p2m_identity);
376 
377         p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
378         p2m_top_init(p2m_top);
379 
380         /*
381          * The domain builder gives us a pre-constructed p2m array in
382          * mfn_list for all the pages initially given to us, so we just
383          * need to graft that into our tree structure.
384          */
385         for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
386                 unsigned topidx = p2m_top_index(pfn);
387                 unsigned mididx = p2m_mid_index(pfn);
388 
389                 if (p2m_top[topidx] == p2m_mid_missing) {
390                         unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
391                         p2m_mid_init(mid, p2m_missing);
392 
393                         p2m_top[topidx] = mid;
394                 }
395 
396                 /*
397                  * As long as the mfn_list has enough entries to completely
398                  * fill a p2m page, pointing into the array is ok. But if
399                  * not the entries beyond the last pfn will be undefined.
400                  */
401                 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
402                         unsigned long p2midx;
403 
404                         p2midx = max_pfn % P2M_PER_PAGE;
405                         for ( ; p2midx < P2M_PER_PAGE; p2midx++)
406                                 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
407                 }
408                 p2m_top[topidx][mididx] = &mfn_list[pfn];
409         }
410 
411         m2p_override_init();
412 }
413 #ifdef CONFIG_X86_64
414 unsigned long __init xen_revector_p2m_tree(void)
415 {
416         unsigned long va_start;
417         unsigned long va_end;
418         unsigned long pfn;
419         unsigned long pfn_free = 0;
420         unsigned long *mfn_list = NULL;
421         unsigned long size;
422 
423         va_start = xen_start_info->mfn_list;
424         /*We copy in increments of P2M_PER_PAGE * sizeof(unsigned long),
425          * so make sure it is rounded up to that */
426         size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
427         va_end = va_start + size;
428 
429         /* If we were revectored already, don't do it again. */
430         if (va_start <= __START_KERNEL_map && va_start >= __PAGE_OFFSET)
431                 return 0;
432 
433         mfn_list = alloc_bootmem_align(size, PAGE_SIZE);
434         if (!mfn_list) {
435                 pr_warn("Could not allocate space for a new P2M tree!\n");
436                 return xen_start_info->mfn_list;
437         }
438         /* Fill it out with INVALID_P2M_ENTRY value */
439         memset(mfn_list, 0xFF, size);
440 
441         for (pfn = 0; pfn < ALIGN(MAX_DOMAIN_PAGES, P2M_PER_PAGE); pfn += P2M_PER_PAGE) {
442                 unsigned topidx = p2m_top_index(pfn);
443                 unsigned mididx;
444                 unsigned long *mid_p;
445 
446                 if (!p2m_top[topidx])
447                         continue;
448 
449                 if (p2m_top[topidx] == p2m_mid_missing)
450                         continue;
451 
452                 mididx = p2m_mid_index(pfn);
453                 mid_p = p2m_top[topidx][mididx];
454                 if (!mid_p)
455                         continue;
456                 if ((mid_p == p2m_missing) || (mid_p == p2m_identity))
457                         continue;
458 
459                 if ((unsigned long)mid_p == INVALID_P2M_ENTRY)
460                         continue;
461 
462                 /* The old va. Rebase it on mfn_list */
463                 if (mid_p >= (unsigned long *)va_start && mid_p <= (unsigned long *)va_end) {
464                         unsigned long *new;
465 
466                         if (pfn_free  > (size / sizeof(unsigned long))) {
467                                 WARN(1, "Only allocated for %ld pages, but we want %ld!\n",
468                                      size / sizeof(unsigned long), pfn_free);
469                                 return 0;
470                         }
471                         new = &mfn_list[pfn_free];
472 
473                         copy_page(new, mid_p);
474                         p2m_top[topidx][mididx] = &mfn_list[pfn_free];
475 
476                         pfn_free += P2M_PER_PAGE;
477 
478                 }
479                 /* This should be the leafs allocated for identity from _brk. */
480         }
481         return (unsigned long)mfn_list;
482 
483 }
484 #else
485 unsigned long __init xen_revector_p2m_tree(void)
486 {
487         return 0;
488 }
489 #endif
490 unsigned long get_phys_to_machine(unsigned long pfn)
491 {
492         unsigned topidx, mididx, idx;
493 
494         if (unlikely(pfn >= MAX_P2M_PFN))
495                 return IDENTITY_FRAME(pfn);
496 
497         topidx = p2m_top_index(pfn);
498         mididx = p2m_mid_index(pfn);
499         idx = p2m_index(pfn);
500 
501         /*
502          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
503          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
504          * would be wrong.
505          */
506         if (p2m_top[topidx][mididx] == p2m_identity)
507                 return IDENTITY_FRAME(pfn);
508 
509         return p2m_top[topidx][mididx][idx];
510 }
511 EXPORT_SYMBOL_GPL(get_phys_to_machine);
512 
513 static void *alloc_p2m_page(void)
514 {
515         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
516 }
517 
518 static void free_p2m_page(void *p)
519 {
520         free_page((unsigned long)p);
521 }
522 
523 /*
524  * Fully allocate the p2m structure for a given pfn.  We need to check
525  * that both the top and mid levels are allocated, and make sure the
526  * parallel mfn tree is kept in sync.  We may race with other cpus, so
527  * the new pages are installed with cmpxchg; if we lose the race then
528  * simply free the page we allocated and use the one that's there.
529  */
530 static bool alloc_p2m(unsigned long pfn)
531 {
532         unsigned topidx, mididx;
533         unsigned long ***top_p, **mid;
534         unsigned long *top_mfn_p, *mid_mfn;
535         unsigned long *p2m_orig;
536 
537         topidx = p2m_top_index(pfn);
538         mididx = p2m_mid_index(pfn);
539 
540         top_p = &p2m_top[topidx];
541         mid = ACCESS_ONCE(*top_p);
542 
543         if (mid == p2m_mid_missing) {
544                 /* Mid level is missing, allocate a new one */
545                 mid = alloc_p2m_page();
546                 if (!mid)
547                         return false;
548 
549                 p2m_mid_init(mid, p2m_missing);
550 
551                 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
552                         free_p2m_page(mid);
553         }
554 
555         top_mfn_p = &p2m_top_mfn[topidx];
556         mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
557 
558         BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
559 
560         if (mid_mfn == p2m_mid_missing_mfn) {
561                 /* Separately check the mid mfn level */
562                 unsigned long missing_mfn;
563                 unsigned long mid_mfn_mfn;
564                 unsigned long old_mfn;
565 
566                 mid_mfn = alloc_p2m_page();
567                 if (!mid_mfn)
568                         return false;
569 
570                 p2m_mid_mfn_init(mid_mfn, p2m_missing);
571 
572                 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
573                 mid_mfn_mfn = virt_to_mfn(mid_mfn);
574                 old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
575                 if (old_mfn != missing_mfn) {
576                         free_p2m_page(mid_mfn);
577                         mid_mfn = mfn_to_virt(old_mfn);
578                 } else {
579                         p2m_top_mfn_p[topidx] = mid_mfn;
580                 }
581         }
582 
583         p2m_orig = ACCESS_ONCE(p2m_top[topidx][mididx]);
584         if (p2m_orig == p2m_identity || p2m_orig == p2m_missing) {
585                 /* p2m leaf page is missing */
586                 unsigned long *p2m;
587 
588                 p2m = alloc_p2m_page();
589                 if (!p2m)
590                         return false;
591 
592                 p2m_init(p2m);
593 
594                 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
595                         free_p2m_page(p2m);
596                 else
597                         mid_mfn[mididx] = virt_to_mfn(p2m);
598         }
599 
600         return true;
601 }
602 
603 static bool __init early_alloc_p2m(unsigned long pfn, bool check_boundary)
604 {
605         unsigned topidx, mididx, idx;
606         unsigned long *p2m;
607 
608         topidx = p2m_top_index(pfn);
609         mididx = p2m_mid_index(pfn);
610         idx = p2m_index(pfn);
611 
612         /* Pfff.. No boundary cross-over, lets get out. */
613         if (!idx && check_boundary)
614                 return false;
615 
616         WARN(p2m_top[topidx][mididx] == p2m_identity,
617                 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
618                 topidx, mididx);
619 
620         /*
621          * Could be done by xen_build_dynamic_phys_to_machine..
622          */
623         if (p2m_top[topidx][mididx] != p2m_missing)
624                 return false;
625 
626         /* Boundary cross-over for the edges: */
627         p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
628 
629         p2m_init(p2m);
630 
631         p2m_top[topidx][mididx] = p2m;
632 
633         return true;
634 }
635 
636 static bool __init early_alloc_p2m_middle(unsigned long pfn)
637 {
638         unsigned topidx = p2m_top_index(pfn);
639         unsigned long **mid;
640 
641         mid = p2m_top[topidx];
642         if (mid == p2m_mid_missing) {
643                 mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
644 
645                 p2m_mid_init(mid, p2m_missing);
646 
647                 p2m_top[topidx] = mid;
648         }
649         return true;
650 }
651 
652 /*
653  * Skim over the P2M tree looking at pages that are either filled with
654  * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
655  * replace the P2M leaf with a p2m_missing or p2m_identity.
656  * Stick the old page in the new P2M tree location.
657  */
658 static bool __init early_can_reuse_p2m_middle(unsigned long set_pfn)
659 {
660         unsigned topidx;
661         unsigned mididx;
662         unsigned ident_pfns;
663         unsigned inv_pfns;
664         unsigned long *p2m;
665         unsigned idx;
666         unsigned long pfn;
667 
668         /* We only look when this entails a P2M middle layer */
669         if (p2m_index(set_pfn))
670                 return false;
671 
672         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
673                 topidx = p2m_top_index(pfn);
674 
675                 if (!p2m_top[topidx])
676                         continue;
677 
678                 if (p2m_top[topidx] == p2m_mid_missing)
679                         continue;
680 
681                 mididx = p2m_mid_index(pfn);
682                 p2m = p2m_top[topidx][mididx];
683                 if (!p2m)
684                         continue;
685 
686                 if ((p2m == p2m_missing) || (p2m == p2m_identity))
687                         continue;
688 
689                 if ((unsigned long)p2m == INVALID_P2M_ENTRY)
690                         continue;
691 
692                 ident_pfns = 0;
693                 inv_pfns = 0;
694                 for (idx = 0; idx < P2M_PER_PAGE; idx++) {
695                         /* IDENTITY_PFNs are 1:1 */
696                         if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
697                                 ident_pfns++;
698                         else if (p2m[idx] == INVALID_P2M_ENTRY)
699                                 inv_pfns++;
700                         else
701                                 break;
702                 }
703                 if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
704                         goto found;
705         }
706         return false;
707 found:
708         /* Found one, replace old with p2m_identity or p2m_missing */
709         p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
710 
711         /* Reset where we want to stick the old page in. */
712         topidx = p2m_top_index(set_pfn);
713         mididx = p2m_mid_index(set_pfn);
714 
715         /* This shouldn't happen */
716         if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
717                 early_alloc_p2m_middle(set_pfn);
718 
719         if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
720                 return false;
721 
722         p2m_init(p2m);
723         p2m_top[topidx][mididx] = p2m;
724 
725         return true;
726 }
727 bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
728 {
729         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
730                 if (!early_alloc_p2m_middle(pfn))
731                         return false;
732 
733                 if (early_can_reuse_p2m_middle(pfn))
734                         return __set_phys_to_machine(pfn, mfn);
735 
736                 if (!early_alloc_p2m(pfn, false /* boundary crossover OK!*/))
737                         return false;
738 
739                 if (!__set_phys_to_machine(pfn, mfn))
740                         return false;
741         }
742 
743         return true;
744 }
745 
746 static void __init early_split_p2m(unsigned long pfn)
747 {
748         unsigned long mididx, idx;
749 
750         mididx = p2m_mid_index(pfn);
751         idx = p2m_index(pfn);
752 
753         /*
754          * Allocate new middle and leaf pages if this pfn lies in the
755          * middle of one.
756          */
757         if (mididx || idx)
758                 early_alloc_p2m_middle(pfn);
759         if (idx)
760                 early_alloc_p2m(pfn, false);
761 }
762 
763 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
764                                       unsigned long pfn_e)
765 {
766         unsigned long pfn;
767 
768         if (unlikely(pfn_s >= MAX_P2M_PFN))
769                 return 0;
770 
771         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
772                 return pfn_e - pfn_s;
773 
774         if (pfn_s > pfn_e)
775                 return 0;
776 
777         if (pfn_e > MAX_P2M_PFN)
778                 pfn_e = MAX_P2M_PFN;
779 
780         early_split_p2m(pfn_s);
781         early_split_p2m(pfn_e);
782 
783         for (pfn = pfn_s; pfn < pfn_e;) {
784                 unsigned topidx = p2m_top_index(pfn);
785                 unsigned mididx = p2m_mid_index(pfn);
786 
787                 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
788                         break;
789                 pfn++;
790 
791                 /*
792                  * If the PFN was set to a middle or leaf identity
793                  * page the remainder must also be identity, so skip
794                  * ahead to the next middle or leaf entry.
795                  */
796                 if (p2m_top[topidx] == p2m_mid_identity)
797                         pfn = ALIGN(pfn, P2M_MID_PER_PAGE * P2M_PER_PAGE);
798                 else if (p2m_top[topidx][mididx] == p2m_identity)
799                         pfn = ALIGN(pfn, P2M_PER_PAGE);
800         }
801 
802         WARN((pfn - pfn_s) != (pfn_e - pfn_s),
803                 "Identity mapping failed. We are %ld short of 1-1 mappings!\n",
804                 (pfn_e - pfn_s) - (pfn - pfn_s));
805 
806         return pfn - pfn_s;
807 }
808 
809 /* Try to install p2m mapping; fail if intermediate bits missing */
810 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
811 {
812         unsigned topidx, mididx, idx;
813 
814         /* don't track P2M changes in autotranslate guests */
815         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
816                 return true;
817 
818         if (unlikely(pfn >= MAX_P2M_PFN)) {
819                 BUG_ON(mfn != INVALID_P2M_ENTRY);
820                 return true;
821         }
822 
823         topidx = p2m_top_index(pfn);
824         mididx = p2m_mid_index(pfn);
825         idx = p2m_index(pfn);
826 
827         /* For sparse holes were the p2m leaf has real PFN along with
828          * PCI holes, stick in the PFN as the MFN value.
829          *
830          * set_phys_range_identity() will have allocated new middle
831          * and leaf pages as required so an existing p2m_mid_missing
832          * or p2m_missing mean that whole range will be identity so
833          * these can be switched to p2m_mid_identity or p2m_identity.
834          */
835         if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
836                 if (p2m_top[topidx] == p2m_mid_identity)
837                         return true;
838 
839                 if (p2m_top[topidx] == p2m_mid_missing) {
840                         WARN_ON(cmpxchg(&p2m_top[topidx], p2m_mid_missing,
841                                         p2m_mid_identity) != p2m_mid_missing);
842                         return true;
843                 }
844 
845                 if (p2m_top[topidx][mididx] == p2m_identity)
846                         return true;
847 
848                 /* Swap over from MISSING to IDENTITY if needed. */
849                 if (p2m_top[topidx][mididx] == p2m_missing) {
850                         WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
851                                 p2m_identity) != p2m_missing);
852                         return true;
853                 }
854         }
855 
856         if (p2m_top[topidx][mididx] == p2m_missing)
857                 return mfn == INVALID_P2M_ENTRY;
858 
859         p2m_top[topidx][mididx][idx] = mfn;
860 
861         return true;
862 }
863 
864 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
865 {
866         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
867                 if (!alloc_p2m(pfn))
868                         return false;
869 
870                 if (!__set_phys_to_machine(pfn, mfn))
871                         return false;
872         }
873 
874         return true;
875 }
876 
877 #define M2P_OVERRIDE_HASH_SHIFT 10
878 #define M2P_OVERRIDE_HASH       (1 << M2P_OVERRIDE_HASH_SHIFT)
879 
880 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
881 static DEFINE_SPINLOCK(m2p_override_lock);
882 
883 static void __init m2p_override_init(void)
884 {
885         unsigned i;
886 
887         m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
888                                    sizeof(unsigned long));
889 
890         for (i = 0; i < M2P_OVERRIDE_HASH; i++)
891                 INIT_LIST_HEAD(&m2p_overrides[i]);
892 }
893 
894 static unsigned long mfn_hash(unsigned long mfn)
895 {
896         return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
897 }
898 
899 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
900                             struct gnttab_map_grant_ref *kmap_ops,
901                             struct page **pages, unsigned int count)
902 {
903         int i, ret = 0;
904         bool lazy = false;
905         pte_t *pte;
906 
907         if (xen_feature(XENFEAT_auto_translated_physmap))
908                 return 0;
909 
910         if (kmap_ops &&
911             !in_interrupt() &&
912             paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
913                 arch_enter_lazy_mmu_mode();
914                 lazy = true;
915         }
916 
917         for (i = 0; i < count; i++) {
918                 unsigned long mfn, pfn;
919 
920                 /* Do not add to override if the map failed. */
921                 if (map_ops[i].status)
922                         continue;
923 
924                 if (map_ops[i].flags & GNTMAP_contains_pte) {
925                         pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
926                                 (map_ops[i].host_addr & ~PAGE_MASK));
927                         mfn = pte_mfn(*pte);
928                 } else {
929                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
930                 }
931                 pfn = page_to_pfn(pages[i]);
932 
933                 WARN_ON(PagePrivate(pages[i]));
934                 SetPagePrivate(pages[i]);
935                 set_page_private(pages[i], mfn);
936                 pages[i]->index = pfn_to_mfn(pfn);
937 
938                 if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
939                         ret = -ENOMEM;
940                         goto out;
941                 }
942 
943                 if (kmap_ops) {
944                         ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
945                         if (ret)
946                                 goto out;
947                 }
948         }
949 
950 out:
951         if (lazy)
952                 arch_leave_lazy_mmu_mode();
953 
954         return ret;
955 }
956 EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
957 
958 /* Add an MFN override for a particular page */
959 int m2p_add_override(unsigned long mfn, struct page *page,
960                 struct gnttab_map_grant_ref *kmap_op)
961 {
962         unsigned long flags;
963         unsigned long pfn;
964         unsigned long uninitialized_var(address);
965         unsigned level;
966         pte_t *ptep = NULL;
967 
968         pfn = page_to_pfn(page);
969         if (!PageHighMem(page)) {
970                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
971                 ptep = lookup_address(address, &level);
972                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
973                                         "m2p_add_override: pfn %lx not mapped", pfn))
974                         return -EINVAL;
975         }
976 
977         if (kmap_op != NULL) {
978                 if (!PageHighMem(page)) {
979                         struct multicall_space mcs =
980                                 xen_mc_entry(sizeof(*kmap_op));
981 
982                         MULTI_grant_table_op(mcs.mc,
983                                         GNTTABOP_map_grant_ref, kmap_op, 1);
984 
985                         xen_mc_issue(PARAVIRT_LAZY_MMU);
986                 }
987         }
988         spin_lock_irqsave(&m2p_override_lock, flags);
989         list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
990         spin_unlock_irqrestore(&m2p_override_lock, flags);
991 
992         /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
993          * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
994          * pfn so that the following mfn_to_pfn(mfn) calls will return the
995          * pfn from the m2p_override (the backend pfn) instead.
996          * We need to do this because the pages shared by the frontend
997          * (xen-blkfront) can be already locked (lock_page, called by
998          * do_read_cache_page); when the userspace backend tries to use them
999          * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
1000          * do_blockdev_direct_IO is going to try to lock the same pages
1001          * again resulting in a deadlock.
1002          * As a side effect get_user_pages_fast might not be safe on the
1003          * frontend pages while they are being shared with the backend,
1004          * because mfn_to_pfn (that ends up being called by GUPF) will
1005          * return the backend pfn rather than the frontend pfn. */
1006         pfn = mfn_to_pfn_no_overrides(mfn);
1007         if (get_phys_to_machine(pfn) == mfn)
1008                 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
1009 
1010         return 0;
1011 }
1012 EXPORT_SYMBOL_GPL(m2p_add_override);
1013 
1014 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
1015                               struct gnttab_map_grant_ref *kmap_ops,
1016                               struct page **pages, unsigned int count)
1017 {
1018         int i, ret = 0;
1019         bool lazy = false;
1020 
1021         if (xen_feature(XENFEAT_auto_translated_physmap))
1022                 return 0;
1023 
1024         if (kmap_ops &&
1025             !in_interrupt() &&
1026             paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
1027                 arch_enter_lazy_mmu_mode();
1028                 lazy = true;
1029         }
1030 
1031         for (i = 0; i < count; i++) {
1032                 unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i]));
1033                 unsigned long pfn = page_to_pfn(pages[i]);
1034 
1035                 if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
1036                         ret = -EINVAL;
1037                         goto out;
1038                 }
1039 
1040                 set_page_private(pages[i], INVALID_P2M_ENTRY);
1041                 WARN_ON(!PagePrivate(pages[i]));
1042                 ClearPagePrivate(pages[i]);
1043                 set_phys_to_machine(pfn, pages[i]->index);
1044 
1045                 if (kmap_ops)
1046                         ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);
1047                 if (ret)
1048                         goto out;
1049         }
1050 
1051 out:
1052         if (lazy)
1053                 arch_leave_lazy_mmu_mode();
1054         return ret;
1055 }
1056 EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
1057 
1058 int m2p_remove_override(struct page *page,
1059                         struct gnttab_map_grant_ref *kmap_op,
1060                         unsigned long mfn)
1061 {
1062         unsigned long flags;
1063         unsigned long pfn;
1064         unsigned long uninitialized_var(address);
1065         unsigned level;
1066         pte_t *ptep = NULL;
1067 
1068         pfn = page_to_pfn(page);
1069 
1070         if (!PageHighMem(page)) {
1071                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
1072                 ptep = lookup_address(address, &level);
1073 
1074                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
1075                                         "m2p_remove_override: pfn %lx not mapped", pfn))
1076                         return -EINVAL;
1077         }
1078 
1079         spin_lock_irqsave(&m2p_override_lock, flags);
1080         list_del(&page->lru);
1081         spin_unlock_irqrestore(&m2p_override_lock, flags);
1082 
1083         if (kmap_op != NULL) {
1084                 if (!PageHighMem(page)) {
1085                         struct multicall_space mcs;
1086                         struct gnttab_unmap_and_replace *unmap_op;
1087                         struct page *scratch_page = get_balloon_scratch_page();
1088                         unsigned long scratch_page_address = (unsigned long)
1089                                 __va(page_to_pfn(scratch_page) << PAGE_SHIFT);
1090 
1091                         /*
1092                          * It might be that we queued all the m2p grant table
1093                          * hypercalls in a multicall, then m2p_remove_override
1094                          * get called before the multicall has actually been
1095                          * issued. In this case handle is going to -1 because
1096                          * it hasn't been modified yet.
1097                          */
1098                         if (kmap_op->handle == -1)
1099                                 xen_mc_flush();
1100                         /*
1101                          * Now if kmap_op->handle is negative it means that the
1102                          * hypercall actually returned an error.
1103                          */
1104                         if (kmap_op->handle == GNTST_general_error) {
1105                                 printk(KERN_WARNING "m2p_remove_override: "
1106                                                 "pfn %lx mfn %lx, failed to modify kernel mappings",
1107                                                 pfn, mfn);
1108                                 put_balloon_scratch_page();
1109                                 return -1;
1110                         }
1111 
1112                         xen_mc_batch();
1113 
1114                         mcs = __xen_mc_entry(
1115                                         sizeof(struct gnttab_unmap_and_replace));
1116                         unmap_op = mcs.args;
1117                         unmap_op->host_addr = kmap_op->host_addr;
1118                         unmap_op->new_addr = scratch_page_address;
1119                         unmap_op->handle = kmap_op->handle;
1120 
1121                         MULTI_grant_table_op(mcs.mc,
1122                                         GNTTABOP_unmap_and_replace, unmap_op, 1);
1123 
1124                         mcs = __xen_mc_entry(0);
1125                         MULTI_update_va_mapping(mcs.mc, scratch_page_address,
1126                                         pfn_pte(page_to_pfn(scratch_page),
1127                                         PAGE_KERNEL_RO), 0);
1128 
1129                         xen_mc_issue(PARAVIRT_LAZY_MMU);
1130 
1131                         kmap_op->host_addr = 0;
1132                         put_balloon_scratch_page();
1133                 }
1134         }
1135 
1136         /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
1137          * somewhere in this domain, even before being added to the
1138          * m2p_override (see comment above in m2p_add_override).
1139          * If there are no other entries in the m2p_override corresponding
1140          * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
1141          * the original pfn (the one shared by the frontend): the backend
1142          * cannot do any IO on this page anymore because it has been
1143          * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
1144          * the original pfn causes mfn_to_pfn(mfn) to return the frontend
1145          * pfn again. */
1146         mfn &= ~FOREIGN_FRAME_BIT;
1147         pfn = mfn_to_pfn_no_overrides(mfn);
1148         if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
1149                         m2p_find_override(mfn) == NULL)
1150                 set_phys_to_machine(pfn, mfn);
1151 
1152         return 0;
1153 }
1154 EXPORT_SYMBOL_GPL(m2p_remove_override);
1155 
1156 struct page *m2p_find_override(unsigned long mfn)
1157 {
1158         unsigned long flags;
1159         struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
1160         struct page *p, *ret;
1161 
1162         ret = NULL;
1163 
1164         spin_lock_irqsave(&m2p_override_lock, flags);
1165 
1166         list_for_each_entry(p, bucket, lru) {
1167                 if (page_private(p) == mfn) {
1168                         ret = p;
1169                         break;
1170                 }
1171         }
1172 
1173         spin_unlock_irqrestore(&m2p_override_lock, flags);
1174 
1175         return ret;
1176 }
1177 
1178 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
1179 {
1180         struct page *p = m2p_find_override(mfn);
1181         unsigned long ret = pfn;
1182 
1183         if (p)
1184                 ret = page_to_pfn(p);
1185 
1186         return ret;
1187 }
1188 EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
1189 
1190 #ifdef CONFIG_XEN_DEBUG_FS
1191 #include <linux/debugfs.h>
1192 #include "debugfs.h"
1193 static int p2m_dump_show(struct seq_file *m, void *v)
1194 {
1195         static const char * const level_name[] = { "top", "middle",
1196                                                 "entry", "abnormal", "error"};
1197 #define TYPE_IDENTITY 0
1198 #define TYPE_MISSING 1
1199 #define TYPE_PFN 2
1200 #define TYPE_UNKNOWN 3
1201         static const char * const type_name[] = {
1202                                 [TYPE_IDENTITY] = "identity",
1203                                 [TYPE_MISSING] = "missing",
1204                                 [TYPE_PFN] = "pfn",
1205                                 [TYPE_UNKNOWN] = "abnormal"};
1206         unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
1207         unsigned int uninitialized_var(prev_level);
1208         unsigned int uninitialized_var(prev_type);
1209 
1210         if (!p2m_top)
1211                 return 0;
1212 
1213         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
1214                 unsigned topidx = p2m_top_index(pfn);
1215                 unsigned mididx = p2m_mid_index(pfn);
1216                 unsigned idx = p2m_index(pfn);
1217                 unsigned lvl, type;
1218 
1219                 lvl = 4;
1220                 type = TYPE_UNKNOWN;
1221                 if (p2m_top[topidx] == p2m_mid_missing) {
1222                         lvl = 0; type = TYPE_MISSING;
1223                 } else if (p2m_top[topidx] == NULL) {
1224                         lvl = 0; type = TYPE_UNKNOWN;
1225                 } else if (p2m_top[topidx][mididx] == NULL) {
1226                         lvl = 1; type = TYPE_UNKNOWN;
1227                 } else if (p2m_top[topidx][mididx] == p2m_identity) {
1228                         lvl = 1; type = TYPE_IDENTITY;
1229                 } else if (p2m_top[topidx][mididx] == p2m_missing) {
1230                         lvl = 1; type = TYPE_MISSING;
1231                 } else if (p2m_top[topidx][mididx][idx] == 0) {
1232                         lvl = 2; type = TYPE_UNKNOWN;
1233                 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
1234                         lvl = 2; type = TYPE_IDENTITY;
1235                 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
1236                         lvl = 2; type = TYPE_MISSING;
1237                 } else if (p2m_top[topidx][mididx][idx] == pfn) {
1238                         lvl = 2; type = TYPE_PFN;
1239                 } else if (p2m_top[topidx][mididx][idx] != pfn) {
1240                         lvl = 2; type = TYPE_PFN;
1241                 }
1242                 if (pfn == 0) {
1243                         prev_level = lvl;
1244                         prev_type = type;
1245                 }
1246                 if (pfn == MAX_DOMAIN_PAGES-1) {
1247                         lvl = 3;
1248                         type = TYPE_UNKNOWN;
1249                 }
1250                 if (prev_type != type) {
1251                         seq_printf(m, " [0x%lx->0x%lx] %s\n",
1252                                 prev_pfn_type, pfn, type_name[prev_type]);
1253                         prev_pfn_type = pfn;
1254                         prev_type = type;
1255                 }
1256                 if (prev_level != lvl) {
1257                         seq_printf(m, " [0x%lx->0x%lx] level %s\n",
1258                                 prev_pfn_level, pfn, level_name[prev_level]);
1259                         prev_pfn_level = pfn;
1260                         prev_level = lvl;
1261                 }
1262         }
1263         return 0;
1264 #undef TYPE_IDENTITY
1265 #undef TYPE_MISSING
1266 #undef TYPE_PFN
1267 #undef TYPE_UNKNOWN
1268 }
1269 
1270 static int p2m_dump_open(struct inode *inode, struct file *filp)
1271 {
1272         return single_open(filp, p2m_dump_show, NULL);
1273 }
1274 
1275 static const struct file_operations p2m_dump_fops = {
1276         .open           = p2m_dump_open,
1277         .read           = seq_read,
1278         .llseek         = seq_lseek,
1279         .release        = single_release,
1280 };
1281 
1282 static struct dentry *d_mmu_debug;
1283 
1284 static int __init xen_p2m_debugfs(void)
1285 {
1286         struct dentry *d_xen = xen_init_debugfs();
1287 
1288         if (d_xen == NULL)
1289                 return -ENOMEM;
1290 
1291         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
1292 
1293         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
1294         return 0;
1295 }
1296 fs_initcall(xen_p2m_debugfs);
1297 #endif /* CONFIG_XEN_DEBUG_FS */
1298 

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