1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * Xen leaves the responsibility for maintaining p2m mappings to the
5 * guests themselves, but it must also access and update the p2m array
6 * during suspend/resume when all the pages are reallocated.
7 *
8 * The logical flat p2m table is mapped to a linear kernel memory area.
9 * For accesses by Xen a three-level tree linked via mfns only is set up to
10 * allow the address space to be sparse.
11 *
12 * Xen
13 * |
14 * p2m_top_mfn
15 * / \
16 * p2m_mid_mfn p2m_mid_mfn
17 * / /
18 * p2m p2m p2m ...
19 *
20 * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
21 *
22 * The p2m_top_mfn level is limited to 1 page, so the maximum representable
23 * pseudo-physical address space is:
24 * P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
25 *
26 * P2M_PER_PAGE depends on the architecture, as a mfn is always
27 * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
28 * 512 and 1024 entries respectively.
29 *
30 * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
31 *
32 * However not all entries are filled with MFNs. Specifically for all other
33 * leaf entries, or for the top root, or middle one, for which there is a void
34 * entry, we assume it is "missing". So (for example)
35 * pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
36 * We have a dedicated page p2m_missing with all entries being
37 * INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
38 * list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
39 *
40 * We also have the possibility of setting 1-1 mappings on certain regions, so
41 * that:
42 * pfn_to_mfn(0xc0000)=0xc0000
43 *
44 * The benefit of this is, that we can assume for non-RAM regions (think
45 * PCI BARs, or ACPI spaces), we can create mappings easily because we
46 * get the PFN value to match the MFN.
47 *
48 * For this to work efficiently we have one new page p2m_identity. All entries
49 * in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
50 * recognizes that and MFNs, no other fancy value).
51 *
52 * On lookup we spot that the entry points to p2m_identity and return the
53 * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
54 * If the entry points to an allocated page, we just proceed as before and
55 * return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
56 * appropriate functions (pfn_to_mfn).
57 *
58 * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
59 * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
60 * non-identity pfn. To protect ourselves against we elect to set (and get) the
61 * IDENTITY_FRAME_BIT on all identity mapped PFNs.
62 */
63
64 #include <linux/init.h>
65 #include <linux/export.h>
66 #include <linux/list.h>
67 #include <linux/hash.h>
68 #include <linux/sched.h>
69 #include <linux/seq_file.h>
70 #include <linux/memblock.h>
71 #include <linux/slab.h>
72 #include <linux/vmalloc.h>
73
74 #include <asm/cache.h>
75 #include <asm/setup.h>
76 #include <linux/uaccess.h>
77
78 #include <asm/xen/page.h>
79 #include <asm/xen/hypercall.h>
80 #include <asm/xen/hypervisor.h>
81 #include <xen/balloon.h>
82 #include <xen/grant_table.h>
83
84 #include "xen-ops.h"
85
86 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
87 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
88
89 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
90
91 #define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE)
92
93 unsigned long *xen_p2m_addr __read_mostly;
94 EXPORT_SYMBOL_GPL(xen_p2m_addr);
95 unsigned long xen_p2m_size __read_mostly;
96 EXPORT_SYMBOL_GPL(xen_p2m_size);
97 unsigned long xen_max_p2m_pfn __read_mostly;
98 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
99
100 #ifdef CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
101 #define P2M_LIMIT CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
102 #else
103 #define P2M_LIMIT 0
104 #endif
105
106 static DEFINE_SPINLOCK(p2m_update_lock);
107
108 static unsigned long *p2m_mid_missing_mfn;
109 static unsigned long *p2m_top_mfn;
110 static unsigned long **p2m_top_mfn_p;
111 static unsigned long *p2m_missing;
112 static unsigned long *p2m_identity;
113 static pte_t *p2m_missing_pte;
114 static pte_t *p2m_identity_pte;
115
116 /*
117 * Hint at last populated PFN.
118 *
119 * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
120 * can avoid scanning the whole P2M (which may be sized to account for
121 * hotplugged memory).
122 */
123 static unsigned long xen_p2m_last_pfn;
124
125 static inline unsigned p2m_top_index(unsigned long pfn)
126 {
127 BUG_ON(pfn >= MAX_P2M_PFN);
128 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
129 }
130
131 static inline unsigned p2m_mid_index(unsigned long pfn)
132 {
133 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
134 }
135
136 static void p2m_top_mfn_init(unsigned long *top)
137 {
138 unsigned i;
139
140 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
141 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
142 }
143
144 static void p2m_top_mfn_p_init(unsigned long **top)
145 {
146 unsigned i;
147
148 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
149 top[i] = p2m_mid_missing_mfn;
150 }
151
152 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
153 {
154 unsigned i;
155
156 for (i = 0; i < P2M_MID_PER_PAGE; i++)
157 mid[i] = virt_to_mfn(leaf);
158 }
159
160 static void p2m_init(unsigned long *p2m)
161 {
162 unsigned i;
163
164 for (i = 0; i < P2M_PER_PAGE; i++)
165 p2m[i] = INVALID_P2M_ENTRY;
166 }
167
168 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
169 {
170 unsigned i;
171
172 for (i = 0; i < P2M_PER_PAGE; i++)
173 p2m[i] = IDENTITY_FRAME(pfn + i);
174 }
175
176 static void * __ref alloc_p2m_page(void)
177 {
178 if (unlikely(!slab_is_available())) {
179 void *ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
180
181 if (!ptr)
182 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
183 __func__, PAGE_SIZE, PAGE_SIZE);
184
185 return ptr;
186 }
187
188 return (void *)__get_free_page(GFP_KERNEL);
189 }
190
191 static void __ref free_p2m_page(void *p)
192 {
193 if (unlikely(!slab_is_available())) {
194 memblock_free(p, PAGE_SIZE);
195 return;
196 }
197
198 free_page((unsigned long)p);
199 }
200
201 /*
202 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
203 *
204 * This is called both at boot time, and after resuming from suspend:
205 * - At boot time we're called rather early, and must use alloc_bootmem*()
206 * to allocate memory.
207 *
208 * - After resume we're called from within stop_machine, but the mfn
209 * tree should already be completely allocated.
210 */
211 void __ref xen_build_mfn_list_list(void)
212 {
213 unsigned long pfn, mfn;
214 pte_t *ptep;
215 unsigned int level, topidx, mididx;
216 unsigned long *mid_mfn_p;
217
218 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
219 return;
220
221 /* Pre-initialize p2m_top_mfn to be completely missing */
222 if (p2m_top_mfn == NULL) {
223 p2m_mid_missing_mfn = alloc_p2m_page();
224 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
225
226 p2m_top_mfn_p = alloc_p2m_page();
227 p2m_top_mfn_p_init(p2m_top_mfn_p);
228
229 p2m_top_mfn = alloc_p2m_page();
230 p2m_top_mfn_init(p2m_top_mfn);
231 } else {
232 /* Reinitialise, mfn's all change after migration */
233 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
234 }
235
236 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
237 pfn += P2M_PER_PAGE) {
238 topidx = p2m_top_index(pfn);
239 mididx = p2m_mid_index(pfn);
240
241 mid_mfn_p = p2m_top_mfn_p[topidx];
242 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
243 &level);
244 BUG_ON(!ptep || level != PG_LEVEL_4K);
245 mfn = pte_mfn(*ptep);
246 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
247
248 /* Don't bother allocating any mfn mid levels if
249 * they're just missing, just update the stored mfn,
250 * since all could have changed over a migrate.
251 */
252 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
253 BUG_ON(mididx);
254 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
255 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
256 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
257 continue;
258 }
259
260 if (mid_mfn_p == p2m_mid_missing_mfn) {
261 mid_mfn_p = alloc_p2m_page();
262 p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
263
264 p2m_top_mfn_p[topidx] = mid_mfn_p;
265 }
266
267 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
268 mid_mfn_p[mididx] = mfn;
269 }
270 }
271
272 void xen_setup_mfn_list_list(void)
273 {
274 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
275
276 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
277 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
278 else
279 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
280 virt_to_mfn(p2m_top_mfn);
281 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
282 HYPERVISOR_shared_info->arch.p2m_generation = 0;
283 HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
284 HYPERVISOR_shared_info->arch.p2m_cr3 =
285 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
286 }
287
288 /* Set up p2m_top to point to the domain-builder provided p2m pages */
289 void __init xen_build_dynamic_phys_to_machine(void)
290 {
291 unsigned long pfn;
292
293 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
294 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
295
296 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
297 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
298
299 xen_max_p2m_pfn = xen_p2m_size;
300 }
301
302 #define P2M_TYPE_IDENTITY 0
303 #define P2M_TYPE_MISSING 1
304 #define P2M_TYPE_PFN 2
305 #define P2M_TYPE_UNKNOWN 3
306
307 static int xen_p2m_elem_type(unsigned long pfn)
308 {
309 unsigned long mfn;
310
311 if (pfn >= xen_p2m_size)
312 return P2M_TYPE_IDENTITY;
313
314 mfn = xen_p2m_addr[pfn];
315
316 if (mfn == INVALID_P2M_ENTRY)
317 return P2M_TYPE_MISSING;
318
319 if (mfn & IDENTITY_FRAME_BIT)
320 return P2M_TYPE_IDENTITY;
321
322 return P2M_TYPE_PFN;
323 }
324
325 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
326 {
327 unsigned int i, chunk;
328 unsigned long pfn;
329 unsigned long *mfns;
330 pte_t *ptep;
331 pmd_t *pmdp;
332 int type;
333
334 p2m_missing = alloc_p2m_page();
335 p2m_init(p2m_missing);
336 p2m_identity = alloc_p2m_page();
337 p2m_init(p2m_identity);
338
339 p2m_missing_pte = alloc_p2m_page();
340 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
341 p2m_identity_pte = alloc_p2m_page();
342 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
343 for (i = 0; i < PTRS_PER_PTE; i++) {
344 set_pte(p2m_missing_pte + i,
345 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
346 set_pte(p2m_identity_pte + i,
347 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
348 }
349
350 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
351 /*
352 * Try to map missing/identity PMDs or p2m-pages if possible.
353 * We have to respect the structure of the mfn_list_list
354 * which will be built just afterwards.
355 * Chunk size to test is one p2m page if we are in the middle
356 * of a mfn_list_list mid page and the complete mid page area
357 * if we are at index 0 of the mid page. Please note that a
358 * mid page might cover more than one PMD, e.g. on 32 bit PAE
359 * kernels.
360 */
361 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
362 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
363
364 type = xen_p2m_elem_type(pfn);
365 i = 0;
366 if (type != P2M_TYPE_PFN)
367 for (i = 1; i < chunk; i++)
368 if (xen_p2m_elem_type(pfn + i) != type)
369 break;
370 if (i < chunk)
371 /* Reset to minimal chunk size. */
372 chunk = P2M_PER_PAGE;
373
374 if (type == P2M_TYPE_PFN || i < chunk) {
375 /* Use initial p2m page contents. */
376 mfns = alloc_p2m_page();
377 copy_page(mfns, xen_p2m_addr + pfn);
378 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
379 set_pte(ptep,
380 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
381 continue;
382 }
383
384 if (chunk == P2M_PER_PAGE) {
385 /* Map complete missing or identity p2m-page. */
386 mfns = (type == P2M_TYPE_MISSING) ?
387 p2m_missing : p2m_identity;
388 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
389 set_pte(ptep,
390 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
391 continue;
392 }
393
394 /* Complete missing or identity PMD(s) can be mapped. */
395 ptep = (type == P2M_TYPE_MISSING) ?
396 p2m_missing_pte : p2m_identity_pte;
397 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
398 pmdp = populate_extra_pmd(
399 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
400 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
401 }
402 }
403 }
404
405 void __init xen_vmalloc_p2m_tree(void)
406 {
407 static struct vm_struct vm;
408 unsigned long p2m_limit;
409
410 xen_p2m_last_pfn = xen_max_p2m_pfn;
411
412 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
413 vm.flags = VM_ALLOC;
414 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
415 PMD_SIZE * PMDS_PER_MID_PAGE);
416 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
417 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
418
419 xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
420
421 xen_rebuild_p2m_list(vm.addr);
422
423 xen_p2m_addr = vm.addr;
424 xen_p2m_size = xen_max_p2m_pfn;
425
426 xen_inv_extra_mem();
427 }
428
429 unsigned long get_phys_to_machine(unsigned long pfn)
430 {
431 pte_t *ptep;
432 unsigned int level;
433
434 if (unlikely(pfn >= xen_p2m_size)) {
435 if (pfn < xen_max_p2m_pfn)
436 return xen_chk_extra_mem(pfn);
437
438 return IDENTITY_FRAME(pfn);
439 }
440
441 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
442 BUG_ON(!ptep || level != PG_LEVEL_4K);
443
444 /*
445 * The INVALID_P2M_ENTRY is filled in both p2m_*identity
446 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
447 * would be wrong.
448 */
449 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
450 return IDENTITY_FRAME(pfn);
451
452 return xen_p2m_addr[pfn];
453 }
454 EXPORT_SYMBOL_GPL(get_phys_to_machine);
455
456 /*
457 * Allocate new pmd(s). It is checked whether the old pmd is still in place.
458 * If not, nothing is changed. This is okay as the only reason for allocating
459 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
460 * pmd.
461 */
462 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
463 {
464 pte_t *ptechk;
465 pte_t *pte_newpg[PMDS_PER_MID_PAGE];
466 pmd_t *pmdp;
467 unsigned int level;
468 unsigned long flags;
469 unsigned long vaddr;
470 int i;
471
472 /* Do all allocations first to bail out in error case. */
473 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
474 pte_newpg[i] = alloc_p2m_page();
475 if (!pte_newpg[i]) {
476 for (i--; i >= 0; i--)
477 free_p2m_page(pte_newpg[i]);
478
479 return NULL;
480 }
481 }
482
483 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
484
485 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
486 copy_page(pte_newpg[i], pte_pg);
487 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
488
489 pmdp = lookup_pmd_address(vaddr);
490 BUG_ON(!pmdp);
491
492 spin_lock_irqsave(&p2m_update_lock, flags);
493
494 ptechk = lookup_address(vaddr, &level);
495 if (ptechk == pte_pg) {
496 HYPERVISOR_shared_info->arch.p2m_generation++;
497 wmb(); /* Tools are synchronizing via p2m_generation. */
498 set_pmd(pmdp,
499 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
500 wmb(); /* Tools are synchronizing via p2m_generation. */
501 HYPERVISOR_shared_info->arch.p2m_generation++;
502 pte_newpg[i] = NULL;
503 }
504
505 spin_unlock_irqrestore(&p2m_update_lock, flags);
506
507 if (pte_newpg[i]) {
508 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
509 free_p2m_page(pte_newpg[i]);
510 }
511
512 vaddr += PMD_SIZE;
513 }
514
515 return lookup_address(addr, &level);
516 }
517
518 /*
519 * Fully allocate the p2m structure for a given pfn. We need to check
520 * that both the top and mid levels are allocated, and make sure the
521 * parallel mfn tree is kept in sync. We may race with other cpus, so
522 * the new pages are installed with cmpxchg; if we lose the race then
523 * simply free the page we allocated and use the one that's there.
524 */
525 int xen_alloc_p2m_entry(unsigned long pfn)
526 {
527 unsigned topidx;
528 unsigned long *top_mfn_p, *mid_mfn;
529 pte_t *ptep, *pte_pg;
530 unsigned int level;
531 unsigned long flags;
532 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
533 unsigned long p2m_pfn;
534
535 ptep = lookup_address(addr, &level);
536 BUG_ON(!ptep || level != PG_LEVEL_4K);
537 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
538
539 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
540 /* PMD level is missing, allocate a new one */
541 ptep = alloc_p2m_pmd(addr, pte_pg);
542 if (!ptep)
543 return -ENOMEM;
544 }
545
546 if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
547 topidx = p2m_top_index(pfn);
548 top_mfn_p = &p2m_top_mfn[topidx];
549 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]);
550
551 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
552
553 if (mid_mfn == p2m_mid_missing_mfn) {
554 /* Separately check the mid mfn level */
555 unsigned long missing_mfn;
556 unsigned long mid_mfn_mfn;
557
558 mid_mfn = alloc_p2m_page();
559 if (!mid_mfn)
560 return -ENOMEM;
561
562 p2m_mid_mfn_init(mid_mfn, p2m_missing);
563
564 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
565 mid_mfn_mfn = virt_to_mfn(mid_mfn);
566 /* try_cmpxchg() updates missing_mfn on failure. */
567 if (try_cmpxchg(top_mfn_p, &missing_mfn, mid_mfn_mfn)) {
568 p2m_top_mfn_p[topidx] = mid_mfn;
569 } else {
570 free_p2m_page(mid_mfn);
571 mid_mfn = mfn_to_virt(missing_mfn);
572 }
573 }
574 } else {
575 mid_mfn = NULL;
576 }
577
578 p2m_pfn = pte_pfn(READ_ONCE(*ptep));
579 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
580 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
581 /* p2m leaf page is missing */
582 unsigned long *p2m;
583
584 p2m = alloc_p2m_page();
585 if (!p2m)
586 return -ENOMEM;
587
588 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
589 p2m_init(p2m);
590 else
591 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
592
593 spin_lock_irqsave(&p2m_update_lock, flags);
594
595 if (pte_pfn(*ptep) == p2m_pfn) {
596 HYPERVISOR_shared_info->arch.p2m_generation++;
597 wmb(); /* Tools are synchronizing via p2m_generation. */
598 set_pte(ptep,
599 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
600 wmb(); /* Tools are synchronizing via p2m_generation. */
601 HYPERVISOR_shared_info->arch.p2m_generation++;
602 if (mid_mfn)
603 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
604 p2m = NULL;
605 }
606
607 spin_unlock_irqrestore(&p2m_update_lock, flags);
608
609 if (p2m)
610 free_p2m_page(p2m);
611 }
612
613 /* Expanded the p2m? */
614 if (pfn >= xen_p2m_last_pfn) {
615 xen_p2m_last_pfn = ALIGN(pfn + 1, P2M_PER_PAGE);
616 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
617 }
618
619 return 0;
620 }
621 EXPORT_SYMBOL(xen_alloc_p2m_entry);
622
623 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
624 unsigned long pfn_e)
625 {
626 unsigned long pfn;
627
628 if (unlikely(pfn_s >= xen_p2m_size))
629 return 0;
630
631 if (pfn_s > pfn_e)
632 return 0;
633
634 if (pfn_e > xen_p2m_size)
635 pfn_e = xen_p2m_size;
636
637 for (pfn = pfn_s; pfn < pfn_e; pfn++)
638 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
639
640 return pfn - pfn_s;
641 }
642
643 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
644 {
645 pte_t *ptep;
646 unsigned int level;
647
648 /* Only invalid entries allowed above the highest p2m covered frame. */
649 if (unlikely(pfn >= xen_p2m_size))
650 return mfn == INVALID_P2M_ENTRY;
651
652 /*
653 * The interface requires atomic updates on p2m elements.
654 * xen_safe_write_ulong() is using an atomic store via asm().
655 */
656 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
657 return true;
658
659 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
660 BUG_ON(!ptep || level != PG_LEVEL_4K);
661
662 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
663 return mfn == INVALID_P2M_ENTRY;
664
665 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
666 return mfn == IDENTITY_FRAME(pfn);
667
668 return false;
669 }
670
671 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
672 {
673 if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
674 int ret;
675
676 ret = xen_alloc_p2m_entry(pfn);
677 if (ret < 0)
678 return false;
679
680 return __set_phys_to_machine(pfn, mfn);
681 }
682
683 return true;
684 }
685
686 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
687 struct gnttab_map_grant_ref *kmap_ops,
688 struct page **pages, unsigned int count)
689 {
690 int i, ret = 0;
691 pte_t *pte;
692
693 if (xen_feature(XENFEAT_auto_translated_physmap))
694 return 0;
695
696 if (kmap_ops) {
697 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
698 kmap_ops, count);
699 if (ret)
700 goto out;
701 }
702
703 for (i = 0; i < count; i++) {
704 unsigned long mfn, pfn;
705 struct gnttab_unmap_grant_ref unmap[2];
706 int rc;
707
708 /* Do not add to override if the map failed. */
709 if (map_ops[i].status != GNTST_okay ||
710 (kmap_ops && kmap_ops[i].status != GNTST_okay))
711 continue;
712
713 if (map_ops[i].flags & GNTMAP_contains_pte) {
714 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
715 (map_ops[i].host_addr & ~PAGE_MASK));
716 mfn = pte_mfn(*pte);
717 } else {
718 mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
719 }
720 pfn = page_to_pfn(pages[i]);
721
722 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
723
724 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
725 continue;
726
727 /*
728 * Signal an error for this slot. This in turn requires
729 * immediate unmapping.
730 */
731 map_ops[i].status = GNTST_general_error;
732 unmap[0].host_addr = map_ops[i].host_addr;
733 unmap[0].handle = map_ops[i].handle;
734 map_ops[i].handle = INVALID_GRANT_HANDLE;
735 if (map_ops[i].flags & GNTMAP_device_map)
736 unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
737 else
738 unmap[0].dev_bus_addr = 0;
739
740 if (kmap_ops) {
741 kmap_ops[i].status = GNTST_general_error;
742 unmap[1].host_addr = kmap_ops[i].host_addr;
743 unmap[1].handle = kmap_ops[i].handle;
744 kmap_ops[i].handle = INVALID_GRANT_HANDLE;
745 if (kmap_ops[i].flags & GNTMAP_device_map)
746 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
747 else
748 unmap[1].dev_bus_addr = 0;
749 }
750
751 /*
752 * Pre-populate both status fields, to be recognizable in
753 * the log message below.
754 */
755 unmap[0].status = 1;
756 unmap[1].status = 1;
757
758 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
759 unmap, 1 + !!kmap_ops);
760 if (rc || unmap[0].status != GNTST_okay ||
761 unmap[1].status != GNTST_okay)
762 pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n",
763 rc, unmap[0].status, unmap[1].status);
764 }
765
766 out:
767 return ret;
768 }
769
770 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
771 struct gnttab_unmap_grant_ref *kunmap_ops,
772 struct page **pages, unsigned int count)
773 {
774 int i, ret = 0;
775
776 if (xen_feature(XENFEAT_auto_translated_physmap))
777 return 0;
778
779 for (i = 0; i < count; i++) {
780 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
781 unsigned long pfn = page_to_pfn(pages[i]);
782
783 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT))
784 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
785 else
786 ret = -EINVAL;
787 }
788 if (kunmap_ops)
789 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
790 kunmap_ops, count) ?: ret;
791
792 return ret;
793 }
794
795 #ifdef CONFIG_XEN_DEBUG_FS
796 #include <linux/debugfs.h>
797 static int p2m_dump_show(struct seq_file *m, void *v)
798 {
799 static const char * const type_name[] = {
800 [P2M_TYPE_IDENTITY] = "identity",
801 [P2M_TYPE_MISSING] = "missing",
802 [P2M_TYPE_PFN] = "pfn",
803 [P2M_TYPE_UNKNOWN] = "abnormal"};
804 unsigned long pfn, first_pfn;
805 int type, prev_type;
806
807 prev_type = xen_p2m_elem_type(0);
808 first_pfn = 0;
809
810 for (pfn = 0; pfn < xen_p2m_size; pfn++) {
811 type = xen_p2m_elem_type(pfn);
812 if (type != prev_type) {
813 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
814 type_name[prev_type]);
815 prev_type = type;
816 first_pfn = pfn;
817 }
818 }
819 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
820 type_name[prev_type]);
821 return 0;
822 }
823
824 DEFINE_SHOW_ATTRIBUTE(p2m_dump);
825
826 static struct dentry *d_mmu_debug;
827
828 static int __init xen_p2m_debugfs(void)
829 {
830 struct dentry *d_xen = xen_init_debugfs();
831
832 d_mmu_debug = debugfs_create_dir("mmu", d_xen);
833
834 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
835 return 0;
836 }
837 fs_initcall(xen_p2m_debugfs);
838 #endif /* CONFIG_XEN_DEBUG_FS */
839
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