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 "multicalls.h"
85 #include "xen-ops.h"
86
87 #define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
88 #define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
89
90 #define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
91
92 #define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE)
93
94 unsigned long *xen_p2m_addr __read_mostly;
95 EXPORT_SYMBOL_GPL(xen_p2m_addr);
96 unsigned long xen_p2m_size __read_mostly;
97 EXPORT_SYMBOL_GPL(xen_p2m_size);
98 unsigned long xen_max_p2m_pfn __read_mostly;
99 EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
100
101 #ifdef CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
102 #define P2M_LIMIT CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
103 #else
104 #define P2M_LIMIT 0
105 #endif
106
107 static DEFINE_SPINLOCK(p2m_update_lock);
108
109 static unsigned long *p2m_mid_missing_mfn;
110 static unsigned long *p2m_top_mfn;
111 static unsigned long **p2m_top_mfn_p;
112 static unsigned long *p2m_missing;
113 static unsigned long *p2m_identity;
114 static pte_t *p2m_missing_pte;
115 static pte_t *p2m_identity_pte;
116
117 /*
118 * Hint at last populated PFN.
119 *
120 * Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
121 * can avoid scanning the whole P2M (which may be sized to account for
122 * hotplugged memory).
123 */
124 static unsigned long xen_p2m_last_pfn;
125
p2m_top_index(unsigned long pfn)126 static inline unsigned p2m_top_index(unsigned long pfn)
127 {
128 BUG_ON(pfn >= MAX_P2M_PFN);
129 return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
130 }
131
p2m_mid_index(unsigned long pfn)132 static inline unsigned p2m_mid_index(unsigned long pfn)
133 {
134 return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
135 }
136
p2m_top_mfn_init(unsigned long * top)137 static void p2m_top_mfn_init(unsigned long *top)
138 {
139 unsigned i;
140
141 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
142 top[i] = virt_to_mfn(p2m_mid_missing_mfn);
143 }
144
p2m_top_mfn_p_init(unsigned long ** top)145 static void p2m_top_mfn_p_init(unsigned long **top)
146 {
147 unsigned i;
148
149 for (i = 0; i < P2M_TOP_PER_PAGE; i++)
150 top[i] = p2m_mid_missing_mfn;
151 }
152
p2m_mid_mfn_init(unsigned long * mid,unsigned long * leaf)153 static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
154 {
155 unsigned i;
156
157 for (i = 0; i < P2M_MID_PER_PAGE; i++)
158 mid[i] = virt_to_mfn(leaf);
159 }
160
p2m_init(unsigned long * p2m)161 static void p2m_init(unsigned long *p2m)
162 {
163 unsigned i;
164
165 for (i = 0; i < P2M_PER_PAGE; i++)
166 p2m[i] = INVALID_P2M_ENTRY;
167 }
168
p2m_init_identity(unsigned long * p2m,unsigned long pfn)169 static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
170 {
171 unsigned i;
172
173 for (i = 0; i < P2M_PER_PAGE; i++)
174 p2m[i] = IDENTITY_FRAME(pfn + i);
175 }
176
alloc_p2m_page(void)177 static void * __ref alloc_p2m_page(void)
178 {
179 if (unlikely(!slab_is_available())) {
180 void *ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
181
182 if (!ptr)
183 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
184 __func__, PAGE_SIZE, PAGE_SIZE);
185
186 return ptr;
187 }
188
189 return (void *)__get_free_page(GFP_KERNEL);
190 }
191
free_p2m_page(void * p)192 static void __ref free_p2m_page(void *p)
193 {
194 if (unlikely(!slab_is_available())) {
195 memblock_free(p, PAGE_SIZE);
196 return;
197 }
198
199 free_page((unsigned long)p);
200 }
201
202 /*
203 * Build the parallel p2m_top_mfn and p2m_mid_mfn structures
204 *
205 * This is called both at boot time, and after resuming from suspend:
206 * - At boot time we're called rather early, and must use alloc_bootmem*()
207 * to allocate memory.
208 *
209 * - After resume we're called from within stop_machine, but the mfn
210 * tree should already be completely allocated.
211 */
xen_build_mfn_list_list(void)212 void __ref xen_build_mfn_list_list(void)
213 {
214 unsigned long pfn, mfn;
215 pte_t *ptep;
216 unsigned int level, topidx, mididx;
217 unsigned long *mid_mfn_p;
218
219 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
220 return;
221
222 /* Pre-initialize p2m_top_mfn to be completely missing */
223 if (p2m_top_mfn == NULL) {
224 p2m_mid_missing_mfn = alloc_p2m_page();
225 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
226
227 p2m_top_mfn_p = alloc_p2m_page();
228 p2m_top_mfn_p_init(p2m_top_mfn_p);
229
230 p2m_top_mfn = alloc_p2m_page();
231 p2m_top_mfn_init(p2m_top_mfn);
232 } else {
233 /* Reinitialise, mfn's all change after migration */
234 p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
235 }
236
237 for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
238 pfn += P2M_PER_PAGE) {
239 topidx = p2m_top_index(pfn);
240 mididx = p2m_mid_index(pfn);
241
242 mid_mfn_p = p2m_top_mfn_p[topidx];
243 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
244 &level);
245 BUG_ON(!ptep || level != PG_LEVEL_4K);
246 mfn = pte_mfn(*ptep);
247 ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
248
249 /* Don't bother allocating any mfn mid levels if
250 * they're just missing, just update the stored mfn,
251 * since all could have changed over a migrate.
252 */
253 if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
254 BUG_ON(mididx);
255 BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
256 p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
257 pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
258 continue;
259 }
260
261 if (mid_mfn_p == p2m_mid_missing_mfn) {
262 mid_mfn_p = alloc_p2m_page();
263 p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
264
265 p2m_top_mfn_p[topidx] = mid_mfn_p;
266 }
267
268 p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
269 mid_mfn_p[mididx] = mfn;
270 }
271 }
272
xen_setup_mfn_list_list(void)273 void xen_setup_mfn_list_list(void)
274 {
275 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
276
277 if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
278 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
279 else
280 HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
281 virt_to_mfn(p2m_top_mfn);
282 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
283 HYPERVISOR_shared_info->arch.p2m_generation = 0;
284 HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
285 HYPERVISOR_shared_info->arch.p2m_cr3 =
286 xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
287 }
288
289 /* Set up p2m_top to point to the domain-builder provided p2m pages */
xen_build_dynamic_phys_to_machine(void)290 void __init xen_build_dynamic_phys_to_machine(void)
291 {
292 unsigned long pfn;
293
294 xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
295 xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
296
297 for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
298 xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
299
300 xen_max_p2m_pfn = xen_p2m_size;
301 }
302
303 #define P2M_TYPE_IDENTITY 0
304 #define P2M_TYPE_MISSING 1
305 #define P2M_TYPE_PFN 2
306 #define P2M_TYPE_UNKNOWN 3
307
xen_p2m_elem_type(unsigned long pfn)308 static int xen_p2m_elem_type(unsigned long pfn)
309 {
310 unsigned long mfn;
311
312 if (pfn >= xen_p2m_size)
313 return P2M_TYPE_IDENTITY;
314
315 mfn = xen_p2m_addr[pfn];
316
317 if (mfn == INVALID_P2M_ENTRY)
318 return P2M_TYPE_MISSING;
319
320 if (mfn & IDENTITY_FRAME_BIT)
321 return P2M_TYPE_IDENTITY;
322
323 return P2M_TYPE_PFN;
324 }
325
xen_rebuild_p2m_list(unsigned long * p2m)326 static void __init xen_rebuild_p2m_list(unsigned long *p2m)
327 {
328 unsigned int i, chunk;
329 unsigned long pfn;
330 unsigned long *mfns;
331 pte_t *ptep;
332 pmd_t *pmdp;
333 int type;
334
335 p2m_missing = alloc_p2m_page();
336 p2m_init(p2m_missing);
337 p2m_identity = alloc_p2m_page();
338 p2m_init(p2m_identity);
339
340 p2m_missing_pte = alloc_p2m_page();
341 paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
342 p2m_identity_pte = alloc_p2m_page();
343 paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
344 for (i = 0; i < PTRS_PER_PTE; i++) {
345 set_pte(p2m_missing_pte + i,
346 pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
347 set_pte(p2m_identity_pte + i,
348 pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
349 }
350
351 for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
352 /*
353 * Try to map missing/identity PMDs or p2m-pages if possible.
354 * We have to respect the structure of the mfn_list_list
355 * which will be built just afterwards.
356 * Chunk size to test is one p2m page if we are in the middle
357 * of a mfn_list_list mid page and the complete mid page area
358 * if we are at index 0 of the mid page. Please note that a
359 * mid page might cover more than one PMD, e.g. on 32 bit PAE
360 * kernels.
361 */
362 chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
363 P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
364
365 type = xen_p2m_elem_type(pfn);
366 i = 0;
367 if (type != P2M_TYPE_PFN)
368 for (i = 1; i < chunk; i++)
369 if (xen_p2m_elem_type(pfn + i) != type)
370 break;
371 if (i < chunk)
372 /* Reset to minimal chunk size. */
373 chunk = P2M_PER_PAGE;
374
375 if (type == P2M_TYPE_PFN || i < chunk) {
376 /* Use initial p2m page contents. */
377 mfns = alloc_p2m_page();
378 copy_page(mfns, xen_p2m_addr + pfn);
379 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
380 set_pte(ptep,
381 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
382 continue;
383 }
384
385 if (chunk == P2M_PER_PAGE) {
386 /* Map complete missing or identity p2m-page. */
387 mfns = (type == P2M_TYPE_MISSING) ?
388 p2m_missing : p2m_identity;
389 ptep = populate_extra_pte((unsigned long)(p2m + pfn));
390 set_pte(ptep,
391 pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
392 continue;
393 }
394
395 /* Complete missing or identity PMD(s) can be mapped. */
396 ptep = (type == P2M_TYPE_MISSING) ?
397 p2m_missing_pte : p2m_identity_pte;
398 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
399 pmdp = populate_extra_pmd(
400 (unsigned long)(p2m + pfn) + i * PMD_SIZE);
401 set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
402 }
403 }
404 }
405
xen_vmalloc_p2m_tree(void)406 void __init xen_vmalloc_p2m_tree(void)
407 {
408 static struct vm_struct vm;
409 unsigned long p2m_limit;
410
411 xen_p2m_last_pfn = xen_max_p2m_pfn;
412
413 p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
414 vm.flags = VM_ALLOC;
415 vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
416 PMD_SIZE * PMDS_PER_MID_PAGE);
417 vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
418 pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
419
420 xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
421
422 xen_rebuild_p2m_list(vm.addr);
423
424 xen_p2m_addr = vm.addr;
425 xen_p2m_size = xen_max_p2m_pfn;
426
427 xen_inv_extra_mem();
428 }
429
get_phys_to_machine(unsigned long pfn)430 unsigned long get_phys_to_machine(unsigned long pfn)
431 {
432 pte_t *ptep;
433 unsigned int level;
434
435 if (unlikely(pfn >= xen_p2m_size)) {
436 if (pfn < xen_max_p2m_pfn)
437 return xen_chk_extra_mem(pfn);
438
439 return IDENTITY_FRAME(pfn);
440 }
441
442 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
443 BUG_ON(!ptep || level != PG_LEVEL_4K);
444
445 /*
446 * The INVALID_P2M_ENTRY is filled in both p2m_*identity
447 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
448 * would be wrong.
449 */
450 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
451 return IDENTITY_FRAME(pfn);
452
453 return xen_p2m_addr[pfn];
454 }
455 EXPORT_SYMBOL_GPL(get_phys_to_machine);
456
457 /*
458 * Allocate new pmd(s). It is checked whether the old pmd is still in place.
459 * If not, nothing is changed. This is okay as the only reason for allocating
460 * a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
461 * pmd.
462 */
alloc_p2m_pmd(unsigned long addr,pte_t * pte_pg)463 static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
464 {
465 pte_t *ptechk;
466 pte_t *pte_newpg[PMDS_PER_MID_PAGE];
467 pmd_t *pmdp;
468 unsigned int level;
469 unsigned long flags;
470 unsigned long vaddr;
471 int i;
472
473 /* Do all allocations first to bail out in error case. */
474 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
475 pte_newpg[i] = alloc_p2m_page();
476 if (!pte_newpg[i]) {
477 for (i--; i >= 0; i--)
478 free_p2m_page(pte_newpg[i]);
479
480 return NULL;
481 }
482 }
483
484 vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
485
486 for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
487 copy_page(pte_newpg[i], pte_pg);
488 paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
489
490 pmdp = lookup_pmd_address(vaddr);
491 BUG_ON(!pmdp);
492
493 spin_lock_irqsave(&p2m_update_lock, flags);
494
495 ptechk = lookup_address(vaddr, &level);
496 if (ptechk == pte_pg) {
497 HYPERVISOR_shared_info->arch.p2m_generation++;
498 wmb(); /* Tools are synchronizing via p2m_generation. */
499 set_pmd(pmdp,
500 __pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
501 wmb(); /* Tools are synchronizing via p2m_generation. */
502 HYPERVISOR_shared_info->arch.p2m_generation++;
503 pte_newpg[i] = NULL;
504 }
505
506 spin_unlock_irqrestore(&p2m_update_lock, flags);
507
508 if (pte_newpg[i]) {
509 paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
510 free_p2m_page(pte_newpg[i]);
511 }
512
513 vaddr += PMD_SIZE;
514 }
515
516 return lookup_address(addr, &level);
517 }
518
519 /*
520 * Fully allocate the p2m structure for a given pfn. We need to check
521 * that both the top and mid levels are allocated, and make sure the
522 * parallel mfn tree is kept in sync. We may race with other cpus, so
523 * the new pages are installed with cmpxchg; if we lose the race then
524 * simply free the page we allocated and use the one that's there.
525 */
xen_alloc_p2m_entry(unsigned long pfn)526 int xen_alloc_p2m_entry(unsigned long pfn)
527 {
528 unsigned topidx;
529 unsigned long *top_mfn_p, *mid_mfn;
530 pte_t *ptep, *pte_pg;
531 unsigned int level;
532 unsigned long flags;
533 unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
534 unsigned long p2m_pfn;
535
536 ptep = lookup_address(addr, &level);
537 BUG_ON(!ptep || level != PG_LEVEL_4K);
538 pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
539
540 if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
541 /* PMD level is missing, allocate a new one */
542 ptep = alloc_p2m_pmd(addr, pte_pg);
543 if (!ptep)
544 return -ENOMEM;
545 }
546
547 if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
548 topidx = p2m_top_index(pfn);
549 top_mfn_p = &p2m_top_mfn[topidx];
550 mid_mfn = READ_ONCE(p2m_top_mfn_p[topidx]);
551
552 BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
553
554 if (mid_mfn == p2m_mid_missing_mfn) {
555 /* Separately check the mid mfn level */
556 unsigned long missing_mfn;
557 unsigned long mid_mfn_mfn;
558 unsigned long old_mfn;
559
560 mid_mfn = alloc_p2m_page();
561 if (!mid_mfn)
562 return -ENOMEM;
563
564 p2m_mid_mfn_init(mid_mfn, p2m_missing);
565
566 missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
567 mid_mfn_mfn = virt_to_mfn(mid_mfn);
568 old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
569 if (old_mfn != missing_mfn) {
570 free_p2m_page(mid_mfn);
571 mid_mfn = mfn_to_virt(old_mfn);
572 } else {
573 p2m_top_mfn_p[topidx] = mid_mfn;
574 }
575 }
576 } else {
577 mid_mfn = NULL;
578 }
579
580 p2m_pfn = pte_pfn(READ_ONCE(*ptep));
581 if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
582 p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
583 /* p2m leaf page is missing */
584 unsigned long *p2m;
585
586 p2m = alloc_p2m_page();
587 if (!p2m)
588 return -ENOMEM;
589
590 if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
591 p2m_init(p2m);
592 else
593 p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
594
595 spin_lock_irqsave(&p2m_update_lock, flags);
596
597 if (pte_pfn(*ptep) == p2m_pfn) {
598 HYPERVISOR_shared_info->arch.p2m_generation++;
599 wmb(); /* Tools are synchronizing via p2m_generation. */
600 set_pte(ptep,
601 pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
602 wmb(); /* Tools are synchronizing via p2m_generation. */
603 HYPERVISOR_shared_info->arch.p2m_generation++;
604 if (mid_mfn)
605 mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
606 p2m = NULL;
607 }
608
609 spin_unlock_irqrestore(&p2m_update_lock, flags);
610
611 if (p2m)
612 free_p2m_page(p2m);
613 }
614
615 /* Expanded the p2m? */
616 if (pfn >= xen_p2m_last_pfn) {
617 xen_p2m_last_pfn = ALIGN(pfn + 1, P2M_PER_PAGE);
618 HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
619 }
620
621 return 0;
622 }
623 EXPORT_SYMBOL(xen_alloc_p2m_entry);
624
set_phys_range_identity(unsigned long pfn_s,unsigned long pfn_e)625 unsigned long __init set_phys_range_identity(unsigned long pfn_s,
626 unsigned long pfn_e)
627 {
628 unsigned long pfn;
629
630 if (unlikely(pfn_s >= xen_p2m_size))
631 return 0;
632
633 if (pfn_s > pfn_e)
634 return 0;
635
636 if (pfn_e > xen_p2m_size)
637 pfn_e = xen_p2m_size;
638
639 for (pfn = pfn_s; pfn < pfn_e; pfn++)
640 xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
641
642 return pfn - pfn_s;
643 }
644
__set_phys_to_machine(unsigned long pfn,unsigned long mfn)645 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
646 {
647 pte_t *ptep;
648 unsigned int level;
649
650 /* Only invalid entries allowed above the highest p2m covered frame. */
651 if (unlikely(pfn >= xen_p2m_size))
652 return mfn == INVALID_P2M_ENTRY;
653
654 /*
655 * The interface requires atomic updates on p2m elements.
656 * xen_safe_write_ulong() is using an atomic store via asm().
657 */
658 if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
659 return true;
660
661 ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
662 BUG_ON(!ptep || level != PG_LEVEL_4K);
663
664 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
665 return mfn == INVALID_P2M_ENTRY;
666
667 if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
668 return mfn == IDENTITY_FRAME(pfn);
669
670 return false;
671 }
672
set_phys_to_machine(unsigned long pfn,unsigned long mfn)673 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
674 {
675 if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
676 int ret;
677
678 ret = xen_alloc_p2m_entry(pfn);
679 if (ret < 0)
680 return false;
681
682 return __set_phys_to_machine(pfn, mfn);
683 }
684
685 return true;
686 }
687
set_foreign_p2m_mapping(struct gnttab_map_grant_ref * map_ops,struct gnttab_map_grant_ref * kmap_ops,struct page ** pages,unsigned int count)688 int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
689 struct gnttab_map_grant_ref *kmap_ops,
690 struct page **pages, unsigned int count)
691 {
692 int i, ret = 0;
693 pte_t *pte;
694
695 if (xen_feature(XENFEAT_auto_translated_physmap))
696 return 0;
697
698 if (kmap_ops) {
699 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
700 kmap_ops, count);
701 if (ret)
702 goto out;
703 }
704
705 for (i = 0; i < count; i++) {
706 unsigned long mfn, pfn;
707 struct gnttab_unmap_grant_ref unmap[2];
708 int rc;
709
710 /* Do not add to override if the map failed. */
711 if (map_ops[i].status != GNTST_okay ||
712 (kmap_ops && kmap_ops[i].status != GNTST_okay))
713 continue;
714
715 if (map_ops[i].flags & GNTMAP_contains_pte) {
716 pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
717 (map_ops[i].host_addr & ~PAGE_MASK));
718 mfn = pte_mfn(*pte);
719 } else {
720 mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
721 }
722 pfn = page_to_pfn(pages[i]);
723
724 WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
725
726 if (likely(set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
727 continue;
728
729 /*
730 * Signal an error for this slot. This in turn requires
731 * immediate unmapping.
732 */
733 map_ops[i].status = GNTST_general_error;
734 unmap[0].host_addr = map_ops[i].host_addr,
735 unmap[0].handle = map_ops[i].handle;
736 map_ops[i].handle = INVALID_GRANT_HANDLE;
737 if (map_ops[i].flags & GNTMAP_device_map)
738 unmap[0].dev_bus_addr = map_ops[i].dev_bus_addr;
739 else
740 unmap[0].dev_bus_addr = 0;
741
742 if (kmap_ops) {
743 kmap_ops[i].status = GNTST_general_error;
744 unmap[1].host_addr = kmap_ops[i].host_addr,
745 unmap[1].handle = kmap_ops[i].handle;
746 kmap_ops[i].handle = INVALID_GRANT_HANDLE;
747 if (kmap_ops[i].flags & GNTMAP_device_map)
748 unmap[1].dev_bus_addr = kmap_ops[i].dev_bus_addr;
749 else
750 unmap[1].dev_bus_addr = 0;
751 }
752
753 /*
754 * Pre-populate both status fields, to be recognizable in
755 * the log message below.
756 */
757 unmap[0].status = 1;
758 unmap[1].status = 1;
759
760 rc = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
761 unmap, 1 + !!kmap_ops);
762 if (rc || unmap[0].status != GNTST_okay ||
763 unmap[1].status != GNTST_okay)
764 pr_err_once("gnttab unmap failed: rc=%d st0=%d st1=%d\n",
765 rc, unmap[0].status, unmap[1].status);
766 }
767
768 out:
769 return ret;
770 }
771
clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref * unmap_ops,struct gnttab_unmap_grant_ref * kunmap_ops,struct page ** pages,unsigned int count)772 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
773 struct gnttab_unmap_grant_ref *kunmap_ops,
774 struct page **pages, unsigned int count)
775 {
776 int i, ret = 0;
777
778 if (xen_feature(XENFEAT_auto_translated_physmap))
779 return 0;
780
781 for (i = 0; i < count; i++) {
782 unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
783 unsigned long pfn = page_to_pfn(pages[i]);
784
785 if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT))
786 set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
787 else
788 ret = -EINVAL;
789 }
790 if (kunmap_ops)
791 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
792 kunmap_ops, count) ?: ret;
793
794 return ret;
795 }
796
797 #ifdef CONFIG_XEN_DEBUG_FS
798 #include <linux/debugfs.h>
799 #include "debugfs.h"
p2m_dump_show(struct seq_file * m,void * v)800 static int p2m_dump_show(struct seq_file *m, void *v)
801 {
802 static const char * const type_name[] = {
803 [P2M_TYPE_IDENTITY] = "identity",
804 [P2M_TYPE_MISSING] = "missing",
805 [P2M_TYPE_PFN] = "pfn",
806 [P2M_TYPE_UNKNOWN] = "abnormal"};
807 unsigned long pfn, first_pfn;
808 int type, prev_type;
809
810 prev_type = xen_p2m_elem_type(0);
811 first_pfn = 0;
812
813 for (pfn = 0; pfn < xen_p2m_size; pfn++) {
814 type = xen_p2m_elem_type(pfn);
815 if (type != prev_type) {
816 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
817 type_name[prev_type]);
818 prev_type = type;
819 first_pfn = pfn;
820 }
821 }
822 seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
823 type_name[prev_type]);
824 return 0;
825 }
826
827 DEFINE_SHOW_ATTRIBUTE(p2m_dump);
828
829 static struct dentry *d_mmu_debug;
830
xen_p2m_debugfs(void)831 static int __init xen_p2m_debugfs(void)
832 {
833 struct dentry *d_xen = xen_init_debugfs();
834
835 d_mmu_debug = debugfs_create_dir("mmu", d_xen);
836
837 debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
838 return 0;
839 }
840 fs_initcall(xen_p2m_debugfs);
841 #endif /* CONFIG_XEN_DEBUG_FS */
842