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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 b/c 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
 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 loop on aligned 1GB PFNs from start pfn
 81  * to end pfn.  We reserve_brk top leaf pages if they are missing (means they
 82  * point to p2m_mid_missing).
 83  *
 84  * With the E820 example above, 263424 is not 1GB aligned so we allocate a
 85  * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
 86  * Each entry in the allocate page is "missing" (points to p2m_missing).
 87  *
 88  * Next stage is to determine if we need to do a more granular boundary check
 89  * on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
 90  * We check if the start pfn and end pfn violate that boundary check, and if
 91  * so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
 92  * granularity of setting which PFNs are missing and which ones are identity.
 93  * In our example 263424 and 512256 both fail the check so we reserve_brk two
 94  * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
 95  * values) and assign them to p2m[1][2] and p2m[1][488] respectively.
 96  *
 97  * At this point we would at minimum reserve_brk one page, but could be up to
 98  * three. Each call to set_phys_range_identity has at maximum a three page
 99  * cost. If we were to query the P2M at this stage, all those entries from
100  * start PFN through end PFN (so 1029MB -> 2001MB) would return
101  * INVALID_P2M_ENTRY ("missing").
102  *
103  * The next step is to walk from the start pfn to the end pfn setting
104  * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
105  * If we find that the middle leaf is pointing to p2m_missing we can swap it
106  * over to p2m_identity - this way covering 4MB (or 2MB) PFN space.  At this
107  * 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  * This is what the p2m ends up looking (for the E820 above) with this
122  * fabulous drawing:
123  *
124  *    p2m         /--------------\
125  *  /-----\       | &mfn_list[0],|                           /-----------------\
126  *  |  0  |------>| &mfn_list[1],|    /---------------\      | ~0, ~0, ..      |
127  *  |-----|       |  ..., ~0, ~0 |    | ~0, ~0, [x]---+----->| IDENTITY [@256] |
128  *  |  1  |---\   \--------------/    | [p2m_identity]+\     | IDENTITY [@257] |
129  *  |-----|    \                      | [p2m_identity]+\\    | ....            |
130  *  |  2  |--\  \-------------------->|  ...          | \\   \----------------/
131  *  |-----|   \                       \---------------/  \\
132  *  |  3  |\   \                                          \\  p2m_identity
133  *  |-----| \   \-------------------->/---------------\   /-----------------\
134  *  | ..  +->+                        | [p2m_identity]+-->| ~0, ~0, ~0, ... |
135  *  \-----/ /                         | [p2m_identity]+-->| ..., ~0         |
136  *         / /---------------\        | ....          |   \-----------------/
137  *        /  | IDENTITY[@0]  |      /-+-[x], ~0, ~0.. |
138  *       /   | IDENTITY[@256]|<----/  \---------------/
139  *      /    | ~0, ~0, ....  |
140  *     |     \---------------/
141  *     |
142  *   p2m_mid_missing           p2m_missing
143  * /-----------------\     /------------\
144  * | [p2m_missing]   +---->| ~0, ~0, ~0 |
145  * | [p2m_missing]   +---->| ..., ~0    |
146  * \-----------------/     \------------/
147  *
148  * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
149  */
150 
151 #include <linux/init.h>
152 #include <linux/module.h>
153 #include <linux/list.h>
154 #include <linux/hash.h>
155 #include <linux/sched.h>
156 #include <linux/seq_file.h>
157 
158 #include <asm/cache.h>
159 #include <asm/setup.h>
160 
161 #include <asm/xen/page.h>
162 #include <asm/xen/hypercall.h>
163 #include <asm/xen/hypervisor.h>
164 #include <xen/grant_table.h>
165 
166 #include "multicalls.h"
167 #include "xen-ops.h"
168 
169 static void __init m2p_override_init(void);
170 
171 unsigned long xen_max_p2m_pfn __read_mostly;
172 
173 #define P2M_PER_PAGE            (PAGE_SIZE / sizeof(unsigned long))
174 #define P2M_MID_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long *))
175 #define P2M_TOP_PER_PAGE        (PAGE_SIZE / sizeof(unsigned long **))
176 
177 #define MAX_P2M_PFN             (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
178 
179 /* Placeholders for holes in the address space */
180 static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
181 static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
182 static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
183 
184 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
185 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
186 static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
187 
188 static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
189 
190 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
191 RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
192 
193 /* We might hit two boundary violations at the start and end, at max each
194  * boundary violation will require three middle nodes. */
195 RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
196 
197 /* When we populate back during bootup, the amount of pages can vary. The
198  * max we have is seen is 395979, but that does not mean it can't be more.
199  * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle
200  * it can re-use Xen provided mfn_list array, so we only need to allocate at
201  * most three P2M top nodes. */
202 RESERVE_BRK(p2m_populated, PAGE_SIZE * 3);
203 
204 static inline unsigned p2m_top_index(unsigned long pfn)
205 {
206         BUG_ON(pfn >= MAX_P2M_PFN);
207         return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
208 }
209 
210 static inline unsigned p2m_mid_index(unsigned long pfn)
211 {
212         return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
213 }
214 
215 static inline unsigned p2m_index(unsigned long pfn)
216 {
217         return pfn % P2M_PER_PAGE;
218 }
219 
220 static void p2m_top_init(unsigned long ***top)
221 {
222         unsigned i;
223 
224         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
225                 top[i] = p2m_mid_missing;
226 }
227 
228 static void p2m_top_mfn_init(unsigned long *top)
229 {
230         unsigned i;
231 
232         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
233                 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
234 }
235 
236 static void p2m_top_mfn_p_init(unsigned long **top)
237 {
238         unsigned i;
239 
240         for (i = 0; i < P2M_TOP_PER_PAGE; i++)
241                 top[i] = p2m_mid_missing_mfn;
242 }
243 
244 static void p2m_mid_init(unsigned long **mid)
245 {
246         unsigned i;
247 
248         for (i = 0; i < P2M_MID_PER_PAGE; i++)
249                 mid[i] = p2m_missing;
250 }
251 
252 static void p2m_mid_mfn_init(unsigned long *mid)
253 {
254         unsigned i;
255 
256         for (i = 0; i < P2M_MID_PER_PAGE; i++)
257                 mid[i] = virt_to_mfn(p2m_missing);
258 }
259 
260 static void p2m_init(unsigned long *p2m)
261 {
262         unsigned i;
263 
264         for (i = 0; i < P2M_MID_PER_PAGE; i++)
265                 p2m[i] = INVALID_P2M_ENTRY;
266 }
267 
268 /*
269  * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
270  *
271  * This is called both at boot time, and after resuming from suspend:
272  * - At boot time we're called very early, and must use extend_brk()
273  *   to allocate memory.
274  *
275  * - After resume we're called from within stop_machine, but the mfn
276  *   tree should alreay be completely allocated.
277  */
278 void __ref xen_build_mfn_list_list(void)
279 {
280         unsigned long pfn;
281 
282         /* Pre-initialize p2m_top_mfn to be completely missing */
283         if (p2m_top_mfn == NULL) {
284                 p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
285                 p2m_mid_mfn_init(p2m_mid_missing_mfn);
286 
287                 p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
288                 p2m_top_mfn_p_init(p2m_top_mfn_p);
289 
290                 p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
291                 p2m_top_mfn_init(p2m_top_mfn);
292         } else {
293                 /* Reinitialise, mfn's all change after migration */
294                 p2m_mid_mfn_init(p2m_mid_missing_mfn);
295         }
296 
297         for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
298                 unsigned topidx = p2m_top_index(pfn);
299                 unsigned mididx = p2m_mid_index(pfn);
300                 unsigned long **mid;
301                 unsigned long *mid_mfn_p;
302 
303                 mid = p2m_top[topidx];
304                 mid_mfn_p = p2m_top_mfn_p[topidx];
305 
306                 /* Don't bother allocating any mfn mid levels if
307                  * they're just missing, just update the stored mfn,
308                  * since all could have changed over a migrate.
309                  */
310                 if (mid == p2m_mid_missing) {
311                         BUG_ON(mididx);
312                         BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
313                         p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
314                         pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
315                         continue;
316                 }
317 
318                 if (mid_mfn_p == p2m_mid_missing_mfn) {
319                         /*
320                          * XXX boot-time only!  We should never find
321                          * missing parts of the mfn tree after
322                          * runtime.  extend_brk() will BUG if we call
323                          * it too late.
324                          */
325                         mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
326                         p2m_mid_mfn_init(mid_mfn_p);
327 
328                         p2m_top_mfn_p[topidx] = mid_mfn_p;
329                 }
330 
331                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
332                 mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
333         }
334 }
335 
336 void xen_setup_mfn_list_list(void)
337 {
338         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
339 
340         HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
341                 virt_to_mfn(p2m_top_mfn);
342         HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
343 }
344 
345 /* Set up p2m_top to point to the domain-builder provided p2m pages */
346 void __init xen_build_dynamic_phys_to_machine(void)
347 {
348         unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
349         unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
350         unsigned long pfn;
351 
352         xen_max_p2m_pfn = max_pfn;
353 
354         p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
355         p2m_init(p2m_missing);
356 
357         p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
358         p2m_mid_init(p2m_mid_missing);
359 
360         p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
361         p2m_top_init(p2m_top);
362 
363         p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
364         p2m_init(p2m_identity);
365 
366         /*
367          * The domain builder gives us a pre-constructed p2m array in
368          * mfn_list for all the pages initially given to us, so we just
369          * need to graft that into our tree structure.
370          */
371         for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
372                 unsigned topidx = p2m_top_index(pfn);
373                 unsigned mididx = p2m_mid_index(pfn);
374 
375                 if (p2m_top[topidx] == p2m_mid_missing) {
376                         unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
377                         p2m_mid_init(mid);
378 
379                         p2m_top[topidx] = mid;
380                 }
381 
382                 /*
383                  * As long as the mfn_list has enough entries to completely
384                  * fill a p2m page, pointing into the array is ok. But if
385                  * not the entries beyond the last pfn will be undefined.
386                  */
387                 if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
388                         unsigned long p2midx;
389 
390                         p2midx = max_pfn % P2M_PER_PAGE;
391                         for ( ; p2midx < P2M_PER_PAGE; p2midx++)
392                                 mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
393                 }
394                 p2m_top[topidx][mididx] = &mfn_list[pfn];
395         }
396 
397         m2p_override_init();
398 }
399 #ifdef CONFIG_X86_64
400 #include <linux/bootmem.h>
401 unsigned long __init xen_revector_p2m_tree(void)
402 {
403         unsigned long va_start;
404         unsigned long va_end;
405         unsigned long pfn;
406         unsigned long pfn_free = 0;
407         unsigned long *mfn_list = NULL;
408         unsigned long size;
409 
410         va_start = xen_start_info->mfn_list;
411         /*We copy in increments of P2M_PER_PAGE * sizeof(unsigned long),
412          * so make sure it is rounded up to that */
413         size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
414         va_end = va_start + size;
415 
416         /* If we were revectored already, don't do it again. */
417         if (va_start <= __START_KERNEL_map && va_start >= __PAGE_OFFSET)
418                 return 0;
419 
420         mfn_list = alloc_bootmem_align(size, PAGE_SIZE);
421         if (!mfn_list) {
422                 pr_warn("Could not allocate space for a new P2M tree!\n");
423                 return xen_start_info->mfn_list;
424         }
425         /* Fill it out with INVALID_P2M_ENTRY value */
426         memset(mfn_list, 0xFF, size);
427 
428         for (pfn = 0; pfn < ALIGN(MAX_DOMAIN_PAGES, P2M_PER_PAGE); pfn += P2M_PER_PAGE) {
429                 unsigned topidx = p2m_top_index(pfn);
430                 unsigned mididx;
431                 unsigned long *mid_p;
432 
433                 if (!p2m_top[topidx])
434                         continue;
435 
436                 if (p2m_top[topidx] == p2m_mid_missing)
437                         continue;
438 
439                 mididx = p2m_mid_index(pfn);
440                 mid_p = p2m_top[topidx][mididx];
441                 if (!mid_p)
442                         continue;
443                 if ((mid_p == p2m_missing) || (mid_p == p2m_identity))
444                         continue;
445 
446                 if ((unsigned long)mid_p == INVALID_P2M_ENTRY)
447                         continue;
448 
449                 /* The old va. Rebase it on mfn_list */
450                 if (mid_p >= (unsigned long *)va_start && mid_p <= (unsigned long *)va_end) {
451                         unsigned long *new;
452 
453                         if (pfn_free  > (size / sizeof(unsigned long))) {
454                                 WARN(1, "Only allocated for %ld pages, but we want %ld!\n",
455                                      size / sizeof(unsigned long), pfn_free);
456                                 return 0;
457                         }
458                         new = &mfn_list[pfn_free];
459 
460                         copy_page(new, mid_p);
461                         p2m_top[topidx][mididx] = &mfn_list[pfn_free];
462                         p2m_top_mfn_p[topidx][mididx] = virt_to_mfn(&mfn_list[pfn_free]);
463 
464                         pfn_free += P2M_PER_PAGE;
465 
466                 }
467                 /* This should be the leafs allocated for identity from _brk. */
468         }
469         return (unsigned long)mfn_list;
470 
471 }
472 #else
473 unsigned long __init xen_revector_p2m_tree(void)
474 {
475         return 0;
476 }
477 #endif
478 unsigned long get_phys_to_machine(unsigned long pfn)
479 {
480         unsigned topidx, mididx, idx;
481 
482         if (unlikely(pfn >= MAX_P2M_PFN))
483                 return INVALID_P2M_ENTRY;
484 
485         topidx = p2m_top_index(pfn);
486         mididx = p2m_mid_index(pfn);
487         idx = p2m_index(pfn);
488 
489         /*
490          * The INVALID_P2M_ENTRY is filled in both p2m_*identity
491          * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
492          * would be wrong.
493          */
494         if (p2m_top[topidx][mididx] == p2m_identity)
495                 return IDENTITY_FRAME(pfn);
496 
497         return p2m_top[topidx][mididx][idx];
498 }
499 EXPORT_SYMBOL_GPL(get_phys_to_machine);
500 
501 static void *alloc_p2m_page(void)
502 {
503         return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
504 }
505 
506 static void free_p2m_page(void *p)
507 {
508         free_page((unsigned long)p);
509 }
510 
511 /*
512  * Fully allocate the p2m structure for a given pfn.  We need to check
513  * that both the top and mid levels are allocated, and make sure the
514  * parallel mfn tree is kept in sync.  We may race with other cpus, so
515  * the new pages are installed with cmpxchg; if we lose the race then
516  * simply free the page we allocated and use the one that's there.
517  */
518 static bool alloc_p2m(unsigned long pfn)
519 {
520         unsigned topidx, mididx;
521         unsigned long ***top_p, **mid;
522         unsigned long *top_mfn_p, *mid_mfn;
523 
524         topidx = p2m_top_index(pfn);
525         mididx = p2m_mid_index(pfn);
526 
527         top_p = &p2m_top[topidx];
528         mid = *top_p;
529 
530         if (mid == p2m_mid_missing) {
531                 /* Mid level is missing, allocate a new one */
532                 mid = alloc_p2m_page();
533                 if (!mid)
534                         return false;
535 
536                 p2m_mid_init(mid);
537 
538                 if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
539                         free_p2m_page(mid);
540         }
541 
542         top_mfn_p = &p2m_top_mfn[topidx];
543         mid_mfn = p2m_top_mfn_p[topidx];
544 
545         BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
546 
547         if (mid_mfn == p2m_mid_missing_mfn) {
548                 /* Separately check the mid mfn level */
549                 unsigned long missing_mfn;
550                 unsigned long mid_mfn_mfn;
551 
552                 mid_mfn = alloc_p2m_page();
553                 if (!mid_mfn)
554                         return false;
555 
556                 p2m_mid_mfn_init(mid_mfn);
557 
558                 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
559                 mid_mfn_mfn = virt_to_mfn(mid_mfn);
560                 if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
561                         free_p2m_page(mid_mfn);
562                 else
563                         p2m_top_mfn_p[topidx] = mid_mfn;
564         }
565 
566         if (p2m_top[topidx][mididx] == p2m_identity ||
567             p2m_top[topidx][mididx] == p2m_missing) {
568                 /* p2m leaf page is missing */
569                 unsigned long *p2m;
570                 unsigned long *p2m_orig = p2m_top[topidx][mididx];
571 
572                 p2m = alloc_p2m_page();
573                 if (!p2m)
574                         return false;
575 
576                 p2m_init(p2m);
577 
578                 if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
579                         free_p2m_page(p2m);
580                 else
581                         mid_mfn[mididx] = virt_to_mfn(p2m);
582         }
583 
584         return true;
585 }
586 
587 static bool __init early_alloc_p2m_middle(unsigned long pfn, bool check_boundary)
588 {
589         unsigned topidx, mididx, idx;
590         unsigned long *p2m;
591         unsigned long *mid_mfn_p;
592 
593         topidx = p2m_top_index(pfn);
594         mididx = p2m_mid_index(pfn);
595         idx = p2m_index(pfn);
596 
597         /* Pfff.. No boundary cross-over, lets get out. */
598         if (!idx && check_boundary)
599                 return false;
600 
601         WARN(p2m_top[topidx][mididx] == p2m_identity,
602                 "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
603                 topidx, mididx);
604 
605         /*
606          * Could be done by xen_build_dynamic_phys_to_machine..
607          */
608         if (p2m_top[topidx][mididx] != p2m_missing)
609                 return false;
610 
611         /* Boundary cross-over for the edges: */
612         p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
613 
614         p2m_init(p2m);
615 
616         p2m_top[topidx][mididx] = p2m;
617 
618         /* For save/restore we need to MFN of the P2M saved */
619 
620         mid_mfn_p = p2m_top_mfn_p[topidx];
621         WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing),
622                 "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n",
623                 topidx, mididx);
624         mid_mfn_p[mididx] = virt_to_mfn(p2m);
625 
626         return true;
627 }
628 
629 static bool __init early_alloc_p2m(unsigned long pfn)
630 {
631         unsigned topidx = p2m_top_index(pfn);
632         unsigned long *mid_mfn_p;
633         unsigned long **mid;
634 
635         mid = p2m_top[topidx];
636         mid_mfn_p = p2m_top_mfn_p[topidx];
637         if (mid == p2m_mid_missing) {
638                 mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
639 
640                 p2m_mid_init(mid);
641 
642                 p2m_top[topidx] = mid;
643 
644                 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
645         }
646         /* And the save/restore P2M tables.. */
647         if (mid_mfn_p == p2m_mid_missing_mfn) {
648                 mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
649                 p2m_mid_mfn_init(mid_mfn_p);
650 
651                 p2m_top_mfn_p[topidx] = mid_mfn_p;
652                 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
653                 /* Note: we don't set mid_mfn_p[midix] here,
654                  * look in early_alloc_p2m_middle */
655         }
656         return true;
657 }
658 
659 /*
660  * Skim over the P2M tree looking at pages that are either filled with
661  * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and
662  * replace the P2M leaf with a p2m_missing or p2m_identity.
663  * Stick the old page in the new P2M tree location.
664  */
665 bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn)
666 {
667         unsigned topidx;
668         unsigned mididx;
669         unsigned ident_pfns;
670         unsigned inv_pfns;
671         unsigned long *p2m;
672         unsigned long *mid_mfn_p;
673         unsigned idx;
674         unsigned long pfn;
675 
676         /* We only look when this entails a P2M middle layer */
677         if (p2m_index(set_pfn))
678                 return false;
679 
680         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) {
681                 topidx = p2m_top_index(pfn);
682 
683                 if (!p2m_top[topidx])
684                         continue;
685 
686                 if (p2m_top[topidx] == p2m_mid_missing)
687                         continue;
688 
689                 mididx = p2m_mid_index(pfn);
690                 p2m = p2m_top[topidx][mididx];
691                 if (!p2m)
692                         continue;
693 
694                 if ((p2m == p2m_missing) || (p2m == p2m_identity))
695                         continue;
696 
697                 if ((unsigned long)p2m == INVALID_P2M_ENTRY)
698                         continue;
699 
700                 ident_pfns = 0;
701                 inv_pfns = 0;
702                 for (idx = 0; idx < P2M_PER_PAGE; idx++) {
703                         /* IDENTITY_PFNs are 1:1 */
704                         if (p2m[idx] == IDENTITY_FRAME(pfn + idx))
705                                 ident_pfns++;
706                         else if (p2m[idx] == INVALID_P2M_ENTRY)
707                                 inv_pfns++;
708                         else
709                                 break;
710                 }
711                 if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE))
712                         goto found;
713         }
714         return false;
715 found:
716         /* Found one, replace old with p2m_identity or p2m_missing */
717         p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing);
718         /* And the other for save/restore.. */
719         mid_mfn_p = p2m_top_mfn_p[topidx];
720         /* NOTE: Even if it is a p2m_identity it should still be point to
721          * a page filled with INVALID_P2M_ENTRY entries. */
722         mid_mfn_p[mididx] = virt_to_mfn(p2m_missing);
723 
724         /* Reset where we want to stick the old page in. */
725         topidx = p2m_top_index(set_pfn);
726         mididx = p2m_mid_index(set_pfn);
727 
728         /* This shouldn't happen */
729         if (WARN_ON(p2m_top[topidx] == p2m_mid_missing))
730                 early_alloc_p2m(set_pfn);
731 
732         if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing))
733                 return false;
734 
735         p2m_init(p2m);
736         p2m_top[topidx][mididx] = p2m;
737         mid_mfn_p = p2m_top_mfn_p[topidx];
738         mid_mfn_p[mididx] = virt_to_mfn(p2m);
739 
740         return true;
741 }
742 bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn)
743 {
744         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
745                 if (!early_alloc_p2m(pfn))
746                         return false;
747 
748                 if (early_can_reuse_p2m_middle(pfn, mfn))
749                         return __set_phys_to_machine(pfn, mfn);
750 
751                 if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/))
752                         return false;
753 
754                 if (!__set_phys_to_machine(pfn, mfn))
755                         return false;
756         }
757 
758         return true;
759 }
760 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
761                                       unsigned long pfn_e)
762 {
763         unsigned long pfn;
764 
765         if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
766                 return 0;
767 
768         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
769                 return pfn_e - pfn_s;
770 
771         if (pfn_s > pfn_e)
772                 return 0;
773 
774         for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
775                 pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
776                 pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
777         {
778                 WARN_ON(!early_alloc_p2m(pfn));
779         }
780 
781         early_alloc_p2m_middle(pfn_s, true);
782         early_alloc_p2m_middle(pfn_e, true);
783 
784         for (pfn = pfn_s; pfn < pfn_e; pfn++)
785                 if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
786                         break;
787 
788         if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
789                 "Identity mapping failed. We are %ld short of 1-1 mappings!\n",
790                 (pfn_e - pfn_s) - (pfn - pfn_s)))
791                 printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
792 
793         return pfn - pfn_s;
794 }
795 
796 /* Try to install p2m mapping; fail if intermediate bits missing */
797 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
798 {
799         unsigned topidx, mididx, idx;
800 
801         if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
802                 BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
803                 return true;
804         }
805         if (unlikely(pfn >= MAX_P2M_PFN)) {
806                 BUG_ON(mfn != INVALID_P2M_ENTRY);
807                 return true;
808         }
809 
810         topidx = p2m_top_index(pfn);
811         mididx = p2m_mid_index(pfn);
812         idx = p2m_index(pfn);
813 
814         /* For sparse holes were the p2m leaf has real PFN along with
815          * PCI holes, stick in the PFN as the MFN value.
816          */
817         if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
818                 if (p2m_top[topidx][mididx] == p2m_identity)
819                         return true;
820 
821                 /* Swap over from MISSING to IDENTITY if needed. */
822                 if (p2m_top[topidx][mididx] == p2m_missing) {
823                         WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
824                                 p2m_identity) != p2m_missing);
825                         return true;
826                 }
827         }
828 
829         if (p2m_top[topidx][mididx] == p2m_missing)
830                 return mfn == INVALID_P2M_ENTRY;
831 
832         p2m_top[topidx][mididx][idx] = mfn;
833 
834         return true;
835 }
836 
837 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
838 {
839         if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
840                 if (!alloc_p2m(pfn))
841                         return false;
842 
843                 if (!__set_phys_to_machine(pfn, mfn))
844                         return false;
845         }
846 
847         return true;
848 }
849 
850 #define M2P_OVERRIDE_HASH_SHIFT 10
851 #define M2P_OVERRIDE_HASH       (1 << M2P_OVERRIDE_HASH_SHIFT)
852 
853 static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
854 static DEFINE_SPINLOCK(m2p_override_lock);
855 
856 static void __init m2p_override_init(void)
857 {
858         unsigned i;
859 
860         m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
861                                    sizeof(unsigned long));
862 
863         for (i = 0; i < M2P_OVERRIDE_HASH; i++)
864                 INIT_LIST_HEAD(&m2p_overrides[i]);
865 }
866 
867 static unsigned long mfn_hash(unsigned long mfn)
868 {
869         return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
870 }
871 
872 /* Add an MFN override for a particular page */
873 int m2p_add_override(unsigned long mfn, struct page *page,
874                 struct gnttab_map_grant_ref *kmap_op)
875 {
876         unsigned long flags;
877         unsigned long pfn;
878         unsigned long uninitialized_var(address);
879         unsigned level;
880         pte_t *ptep = NULL;
881         int ret = 0;
882 
883         pfn = page_to_pfn(page);
884         if (!PageHighMem(page)) {
885                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
886                 ptep = lookup_address(address, &level);
887                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
888                                         "m2p_add_override: pfn %lx not mapped", pfn))
889                         return -EINVAL;
890         }
891         WARN_ON(PagePrivate(page));
892         SetPagePrivate(page);
893         set_page_private(page, mfn);
894         page->index = pfn_to_mfn(pfn);
895 
896         if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
897                 return -ENOMEM;
898 
899         if (kmap_op != NULL) {
900                 if (!PageHighMem(page)) {
901                         struct multicall_space mcs =
902                                 xen_mc_entry(sizeof(*kmap_op));
903 
904                         MULTI_grant_table_op(mcs.mc,
905                                         GNTTABOP_map_grant_ref, kmap_op, 1);
906 
907                         xen_mc_issue(PARAVIRT_LAZY_MMU);
908                 }
909         }
910         spin_lock_irqsave(&m2p_override_lock, flags);
911         list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
912         spin_unlock_irqrestore(&m2p_override_lock, flags);
913 
914         /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
915          * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
916          * pfn so that the following mfn_to_pfn(mfn) calls will return the
917          * pfn from the m2p_override (the backend pfn) instead.
918          * We need to do this because the pages shared by the frontend
919          * (xen-blkfront) can be already locked (lock_page, called by
920          * do_read_cache_page); when the userspace backend tries to use them
921          * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
922          * do_blockdev_direct_IO is going to try to lock the same pages
923          * again resulting in a deadlock.
924          * As a side effect get_user_pages_fast might not be safe on the
925          * frontend pages while they are being shared with the backend,
926          * because mfn_to_pfn (that ends up being called by GUPF) will
927          * return the backend pfn rather than the frontend pfn. */
928         ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
929         if (ret == 0 && get_phys_to_machine(pfn) == mfn)
930                 set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
931 
932         return 0;
933 }
934 EXPORT_SYMBOL_GPL(m2p_add_override);
935 int m2p_remove_override(struct page *page,
936                 struct gnttab_map_grant_ref *kmap_op)
937 {
938         unsigned long flags;
939         unsigned long mfn;
940         unsigned long pfn;
941         unsigned long uninitialized_var(address);
942         unsigned level;
943         pte_t *ptep = NULL;
944         int ret = 0;
945 
946         pfn = page_to_pfn(page);
947         mfn = get_phys_to_machine(pfn);
948         if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
949                 return -EINVAL;
950 
951         if (!PageHighMem(page)) {
952                 address = (unsigned long)__va(pfn << PAGE_SHIFT);
953                 ptep = lookup_address(address, &level);
954 
955                 if (WARN(ptep == NULL || level != PG_LEVEL_4K,
956                                         "m2p_remove_override: pfn %lx not mapped", pfn))
957                         return -EINVAL;
958         }
959 
960         spin_lock_irqsave(&m2p_override_lock, flags);
961         list_del(&page->lru);
962         spin_unlock_irqrestore(&m2p_override_lock, flags);
963         WARN_ON(!PagePrivate(page));
964         ClearPagePrivate(page);
965 
966         set_phys_to_machine(pfn, page->index);
967         if (kmap_op != NULL) {
968                 if (!PageHighMem(page)) {
969                         struct multicall_space mcs;
970                         struct gnttab_unmap_grant_ref *unmap_op;
971 
972                         /*
973                          * It might be that we queued all the m2p grant table
974                          * hypercalls in a multicall, then m2p_remove_override
975                          * get called before the multicall has actually been
976                          * issued. In this case handle is going to -1 because
977                          * it hasn't been modified yet.
978                          */
979                         if (kmap_op->handle == -1)
980                                 xen_mc_flush();
981                         /*
982                          * Now if kmap_op->handle is negative it means that the
983                          * hypercall actually returned an error.
984                          */
985                         if (kmap_op->handle == GNTST_general_error) {
986                                 printk(KERN_WARNING "m2p_remove_override: "
987                                                 "pfn %lx mfn %lx, failed to modify kernel mappings",
988                                                 pfn, mfn);
989                                 return -1;
990                         }
991 
992                         mcs = xen_mc_entry(
993                                         sizeof(struct gnttab_unmap_grant_ref));
994                         unmap_op = mcs.args;
995                         unmap_op->host_addr = kmap_op->host_addr;
996                         unmap_op->handle = kmap_op->handle;
997                         unmap_op->dev_bus_addr = 0;
998 
999                         MULTI_grant_table_op(mcs.mc,
1000                                         GNTTABOP_unmap_grant_ref, unmap_op, 1);
1001 
1002                         xen_mc_issue(PARAVIRT_LAZY_MMU);
1003 
1004                         set_pte_at(&init_mm, address, ptep,
1005                                         pfn_pte(pfn, PAGE_KERNEL));
1006                         __flush_tlb_single(address);
1007                         kmap_op->host_addr = 0;
1008                 }
1009         }
1010 
1011         /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
1012          * somewhere in this domain, even before being added to the
1013          * m2p_override (see comment above in m2p_add_override).
1014          * If there are no other entries in the m2p_override corresponding
1015          * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
1016          * the original pfn (the one shared by the frontend): the backend
1017          * cannot do any IO on this page anymore because it has been
1018          * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
1019          * the original pfn causes mfn_to_pfn(mfn) to return the frontend
1020          * pfn again. */
1021         mfn &= ~FOREIGN_FRAME_BIT;
1022         ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
1023         if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
1024                         m2p_find_override(mfn) == NULL)
1025                 set_phys_to_machine(pfn, mfn);
1026 
1027         return 0;
1028 }
1029 EXPORT_SYMBOL_GPL(m2p_remove_override);
1030 
1031 struct page *m2p_find_override(unsigned long mfn)
1032 {
1033         unsigned long flags;
1034         struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
1035         struct page *p, *ret;
1036 
1037         ret = NULL;
1038 
1039         spin_lock_irqsave(&m2p_override_lock, flags);
1040 
1041         list_for_each_entry(p, bucket, lru) {
1042                 if (page_private(p) == mfn) {
1043                         ret = p;
1044                         break;
1045                 }
1046         }
1047 
1048         spin_unlock_irqrestore(&m2p_override_lock, flags);
1049 
1050         return ret;
1051 }
1052 
1053 unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
1054 {
1055         struct page *p = m2p_find_override(mfn);
1056         unsigned long ret = pfn;
1057 
1058         if (p)
1059                 ret = page_to_pfn(p);
1060 
1061         return ret;
1062 }
1063 EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
1064 
1065 #ifdef CONFIG_XEN_DEBUG_FS
1066 #include <linux/debugfs.h>
1067 #include "debugfs.h"
1068 static int p2m_dump_show(struct seq_file *m, void *v)
1069 {
1070         static const char * const level_name[] = { "top", "middle",
1071                                                 "entry", "abnormal", "error"};
1072 #define TYPE_IDENTITY 0
1073 #define TYPE_MISSING 1
1074 #define TYPE_PFN 2
1075 #define TYPE_UNKNOWN 3
1076         static const char * const type_name[] = {
1077                                 [TYPE_IDENTITY] = "identity",
1078                                 [TYPE_MISSING] = "missing",
1079                                 [TYPE_PFN] = "pfn",
1080                                 [TYPE_UNKNOWN] = "abnormal"};
1081         unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
1082         unsigned int uninitialized_var(prev_level);
1083         unsigned int uninitialized_var(prev_type);
1084 
1085         if (!p2m_top)
1086                 return 0;
1087 
1088         for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
1089                 unsigned topidx = p2m_top_index(pfn);
1090                 unsigned mididx = p2m_mid_index(pfn);
1091                 unsigned idx = p2m_index(pfn);
1092                 unsigned lvl, type;
1093 
1094                 lvl = 4;
1095                 type = TYPE_UNKNOWN;
1096                 if (p2m_top[topidx] == p2m_mid_missing) {
1097                         lvl = 0; type = TYPE_MISSING;
1098                 } else if (p2m_top[topidx] == NULL) {
1099                         lvl = 0; type = TYPE_UNKNOWN;
1100                 } else if (p2m_top[topidx][mididx] == NULL) {
1101                         lvl = 1; type = TYPE_UNKNOWN;
1102                 } else if (p2m_top[topidx][mididx] == p2m_identity) {
1103                         lvl = 1; type = TYPE_IDENTITY;
1104                 } else if (p2m_top[topidx][mididx] == p2m_missing) {
1105                         lvl = 1; type = TYPE_MISSING;
1106                 } else if (p2m_top[topidx][mididx][idx] == 0) {
1107                         lvl = 2; type = TYPE_UNKNOWN;
1108                 } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
1109                         lvl = 2; type = TYPE_IDENTITY;
1110                 } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
1111                         lvl = 2; type = TYPE_MISSING;
1112                 } else if (p2m_top[topidx][mididx][idx] == pfn) {
1113                         lvl = 2; type = TYPE_PFN;
1114                 } else if (p2m_top[topidx][mididx][idx] != pfn) {
1115                         lvl = 2; type = TYPE_PFN;
1116                 }
1117                 if (pfn == 0) {
1118                         prev_level = lvl;
1119                         prev_type = type;
1120                 }
1121                 if (pfn == MAX_DOMAIN_PAGES-1) {
1122                         lvl = 3;
1123                         type = TYPE_UNKNOWN;
1124                 }
1125                 if (prev_type != type) {
1126                         seq_printf(m, " [0x%lx->0x%lx] %s\n",
1127                                 prev_pfn_type, pfn, type_name[prev_type]);
1128                         prev_pfn_type = pfn;
1129                         prev_type = type;
1130                 }
1131                 if (prev_level != lvl) {
1132                         seq_printf(m, " [0x%lx->0x%lx] level %s\n",
1133                                 prev_pfn_level, pfn, level_name[prev_level]);
1134                         prev_pfn_level = pfn;
1135                         prev_level = lvl;
1136                 }
1137         }
1138         return 0;
1139 #undef TYPE_IDENTITY
1140 #undef TYPE_MISSING
1141 #undef TYPE_PFN
1142 #undef TYPE_UNKNOWN
1143 }
1144 
1145 static int p2m_dump_open(struct inode *inode, struct file *filp)
1146 {
1147         return single_open(filp, p2m_dump_show, NULL);
1148 }
1149 
1150 static const struct file_operations p2m_dump_fops = {
1151         .open           = p2m_dump_open,
1152         .read           = seq_read,
1153         .llseek         = seq_lseek,
1154         .release        = single_release,
1155 };
1156 
1157 static struct dentry *d_mmu_debug;
1158 
1159 static int __init xen_p2m_debugfs(void)
1160 {
1161         struct dentry *d_xen = xen_init_debugfs();
1162 
1163         if (d_xen == NULL)
1164                 return -ENOMEM;
1165 
1166         d_mmu_debug = debugfs_create_dir("mmu", d_xen);
1167 
1168         debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
1169         return 0;
1170 }
1171 fs_initcall(xen_p2m_debugfs);
1172 #endif /* CONFIG_XEN_DEBUG_FS */
1173 

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