1 /******************************************************************************
2  * grant_table.c
3  *
4  * Granting foreign access to our memory reservation.
5  *
6  * Copyright (c) 2005-2006, Christopher Clark
7  * Copyright (c) 2004-2005, K A Fraser
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License version 2
11  * as published by the Free Software Foundation; or, when distributed
12  * separately from the Linux kernel or incorporated into other
13  * software packages, subject to the following license:
14  *
15  * Permission is hereby granted, free of charge, to any person obtaining a copy
16  * of this source file (the "Software"), to deal in the Software without
17  * restriction, including without limitation the rights to use, copy, modify,
18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19  * and to permit persons to whom the Software is furnished to do so, subject to
20  * the following conditions:
21  *
22  * The above copyright notice and this permission notice shall be included in
23  * all copies or substantial portions of the Software.
24  *
25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31  * IN THE SOFTWARE.
32  */
33 
34 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
35 
36 #include <linux/bitmap.h>
37 #include <linux/memblock.h>
38 #include <linux/sched.h>
39 #include <linux/mm.h>
40 #include <linux/slab.h>
41 #include <linux/vmalloc.h>
42 #include <linux/uaccess.h>
43 #include <linux/io.h>
44 #include <linux/delay.h>
45 #include <linux/hardirq.h>
46 #include <linux/workqueue.h>
47 #include <linux/ratelimit.h>
48 #include <linux/moduleparam.h>
49 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
50 #include <linux/dma-mapping.h>
51 #endif
52 
53 #include <xen/xen.h>
54 #include <xen/interface/xen.h>
55 #include <xen/page.h>
56 #include <xen/grant_table.h>
57 #include <xen/interface/memory.h>
58 #include <xen/hvc-console.h>
59 #include <xen/swiotlb-xen.h>
60 #include <xen/balloon.h>
61 #ifdef CONFIG_X86
62 #include <asm/xen/cpuid.h>
63 #endif
64 #include <xen/mem-reservation.h>
65 #include <asm/xen/hypercall.h>
66 #include <asm/xen/interface.h>
67 
68 #include <asm/sync_bitops.h>
69 
70 #define GNTTAB_LIST_END 0xffffffff
71 
72 static grant_ref_t **gnttab_list;
73 static unsigned int nr_grant_frames;
74 
75 /*
76  * Handling of free grants:
77  *
78  * Free grants are in a simple list anchored in gnttab_free_head. They are
79  * linked by grant ref, the last element contains GNTTAB_LIST_END. The number
80  * of free entries is stored in gnttab_free_count.
81  * Additionally there is a bitmap of free entries anchored in
82  * gnttab_free_bitmap. This is being used for simplifying allocation of
83  * multiple consecutive grants, which is needed e.g. for support of virtio.
84  * gnttab_last_free is used to add free entries of new frames at the end of
85  * the free list.
86  * gnttab_free_tail_ptr specifies the variable which references the start
87  * of consecutive free grants ending with gnttab_last_free. This pointer is
88  * updated in a rather defensive way, in order to avoid performance hits in
89  * hot paths.
90  * All those variables are protected by gnttab_list_lock.
91  */
92 static int gnttab_free_count;
93 static unsigned int gnttab_size;
94 static grant_ref_t gnttab_free_head = GNTTAB_LIST_END;
95 static grant_ref_t gnttab_last_free = GNTTAB_LIST_END;
96 static grant_ref_t *gnttab_free_tail_ptr;
97 static unsigned long *gnttab_free_bitmap;
98 static DEFINE_SPINLOCK(gnttab_list_lock);
99 
100 struct grant_frames xen_auto_xlat_grant_frames;
101 static unsigned int xen_gnttab_version;
102 module_param_named(version, xen_gnttab_version, uint, 0);
103 
104 static union {
105 	struct grant_entry_v1 *v1;
106 	union grant_entry_v2 *v2;
107 	void *addr;
108 } gnttab_shared;
109 
110 /*This is a structure of function pointers for grant table*/
111 struct gnttab_ops {
112 	/*
113 	 * Version of the grant interface.
114 	 */
115 	unsigned int version;
116 	/*
117 	 * Grant refs per grant frame.
118 	 */
119 	unsigned int grefs_per_grant_frame;
120 	/*
121 	 * Mapping a list of frames for storing grant entries. Frames parameter
122 	 * is used to store grant table address when grant table being setup,
123 	 * nr_gframes is the number of frames to map grant table. Returning
124 	 * GNTST_okay means success and negative value means failure.
125 	 */
126 	int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
127 	/*
128 	 * Release a list of frames which are mapped in map_frames for grant
129 	 * entry status.
130 	 */
131 	void (*unmap_frames)(void);
132 	/*
133 	 * Introducing a valid entry into the grant table, granting the frame of
134 	 * this grant entry to domain for accessing. Ref
135 	 * parameter is reference of this introduced grant entry, domid is id of
136 	 * granted domain, frame is the page frame to be granted, and flags is
137 	 * status of the grant entry to be updated.
138 	 */
139 	void (*update_entry)(grant_ref_t ref, domid_t domid,
140 			     unsigned long frame, unsigned flags);
141 	/*
142 	 * Stop granting a grant entry to domain for accessing. Ref parameter is
143 	 * reference of a grant entry whose grant access will be stopped.
144 	 * If the grant entry is currently mapped for reading or writing, just
145 	 * return failure(==0) directly and don't tear down the grant access.
146 	 * Otherwise, stop grant access for this entry and return success(==1).
147 	 */
148 	int (*end_foreign_access_ref)(grant_ref_t ref);
149 	/*
150 	 * Read the frame number related to a given grant reference.
151 	 */
152 	unsigned long (*read_frame)(grant_ref_t ref);
153 };
154 
155 struct unmap_refs_callback_data {
156 	struct completion completion;
157 	int result;
158 };
159 
160 static const struct gnttab_ops *gnttab_interface;
161 
162 /* This reflects status of grant entries, so act as a global value. */
163 static grant_status_t *grstatus;
164 
165 static struct gnttab_free_callback *gnttab_free_callback_list;
166 
167 static int gnttab_expand(unsigned int req_entries);
168 
169 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
170 #define SPP (PAGE_SIZE / sizeof(grant_status_t))
171 
__gnttab_entry(grant_ref_t entry)172 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
173 {
174 	return &gnttab_list[(entry) / RPP][(entry) % RPP];
175 }
176 /* This can be used as an l-value */
177 #define gnttab_entry(entry) (*__gnttab_entry(entry))
178 
get_free_entries(unsigned count)179 static int get_free_entries(unsigned count)
180 {
181 	unsigned long flags;
182 	int ref, rc = 0;
183 	grant_ref_t head;
184 
185 	spin_lock_irqsave(&gnttab_list_lock, flags);
186 
187 	if ((gnttab_free_count < count) &&
188 	    ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
189 		spin_unlock_irqrestore(&gnttab_list_lock, flags);
190 		return rc;
191 	}
192 
193 	ref = head = gnttab_free_head;
194 	gnttab_free_count -= count;
195 	while (count--) {
196 		bitmap_clear(gnttab_free_bitmap, head, 1);
197 		if (gnttab_free_tail_ptr == __gnttab_entry(head))
198 			gnttab_free_tail_ptr = &gnttab_free_head;
199 		if (count)
200 			head = gnttab_entry(head);
201 	}
202 	gnttab_free_head = gnttab_entry(head);
203 	gnttab_entry(head) = GNTTAB_LIST_END;
204 
205 	if (!gnttab_free_count) {
206 		gnttab_last_free = GNTTAB_LIST_END;
207 		gnttab_free_tail_ptr = NULL;
208 	}
209 
210 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
211 
212 	return ref;
213 }
214 
get_seq_entry_count(void)215 static int get_seq_entry_count(void)
216 {
217 	if (gnttab_last_free == GNTTAB_LIST_END || !gnttab_free_tail_ptr ||
218 	    *gnttab_free_tail_ptr == GNTTAB_LIST_END)
219 		return 0;
220 
221 	return gnttab_last_free - *gnttab_free_tail_ptr + 1;
222 }
223 
224 /* Rebuilds the free grant list and tries to find count consecutive entries. */
get_free_seq(unsigned int count)225 static int get_free_seq(unsigned int count)
226 {
227 	int ret = -ENOSPC;
228 	unsigned int from, to;
229 	grant_ref_t *last;
230 
231 	gnttab_free_tail_ptr = &gnttab_free_head;
232 	last = &gnttab_free_head;
233 
234 	for (from = find_first_bit(gnttab_free_bitmap, gnttab_size);
235 	     from < gnttab_size;
236 	     from = find_next_bit(gnttab_free_bitmap, gnttab_size, to + 1)) {
237 		to = find_next_zero_bit(gnttab_free_bitmap, gnttab_size,
238 					from + 1);
239 		if (ret < 0 && to - from >= count) {
240 			ret = from;
241 			bitmap_clear(gnttab_free_bitmap, ret, count);
242 			from += count;
243 			gnttab_free_count -= count;
244 			if (from == to)
245 				continue;
246 		}
247 
248 		/*
249 		 * Recreate the free list in order to have it properly sorted.
250 		 * This is needed to make sure that the free tail has the maximum
251 		 * possible size.
252 		 */
253 		while (from < to) {
254 			*last = from;
255 			last = __gnttab_entry(from);
256 			gnttab_last_free = from;
257 			from++;
258 		}
259 		if (to < gnttab_size)
260 			gnttab_free_tail_ptr = __gnttab_entry(to - 1);
261 	}
262 
263 	*last = GNTTAB_LIST_END;
264 	if (gnttab_last_free != gnttab_size - 1)
265 		gnttab_free_tail_ptr = NULL;
266 
267 	return ret;
268 }
269 
get_free_entries_seq(unsigned int count)270 static int get_free_entries_seq(unsigned int count)
271 {
272 	unsigned long flags;
273 	int ret = 0;
274 
275 	spin_lock_irqsave(&gnttab_list_lock, flags);
276 
277 	if (gnttab_free_count < count) {
278 		ret = gnttab_expand(count - gnttab_free_count);
279 		if (ret < 0)
280 			goto out;
281 	}
282 
283 	if (get_seq_entry_count() < count) {
284 		ret = get_free_seq(count);
285 		if (ret >= 0)
286 			goto out;
287 		ret = gnttab_expand(count - get_seq_entry_count());
288 		if (ret < 0)
289 			goto out;
290 	}
291 
292 	ret = *gnttab_free_tail_ptr;
293 	*gnttab_free_tail_ptr = gnttab_entry(ret + count - 1);
294 	gnttab_free_count -= count;
295 	if (!gnttab_free_count)
296 		gnttab_free_tail_ptr = NULL;
297 	bitmap_clear(gnttab_free_bitmap, ret, count);
298 
299  out:
300 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
301 
302 	return ret;
303 }
304 
do_free_callbacks(void)305 static void do_free_callbacks(void)
306 {
307 	struct gnttab_free_callback *callback, *next;
308 
309 	callback = gnttab_free_callback_list;
310 	gnttab_free_callback_list = NULL;
311 
312 	while (callback != NULL) {
313 		next = callback->next;
314 		if (gnttab_free_count >= callback->count) {
315 			callback->next = NULL;
316 			callback->fn(callback->arg);
317 		} else {
318 			callback->next = gnttab_free_callback_list;
319 			gnttab_free_callback_list = callback;
320 		}
321 		callback = next;
322 	}
323 }
324 
check_free_callbacks(void)325 static inline void check_free_callbacks(void)
326 {
327 	if (unlikely(gnttab_free_callback_list))
328 		do_free_callbacks();
329 }
330 
put_free_entry_locked(grant_ref_t ref)331 static void put_free_entry_locked(grant_ref_t ref)
332 {
333 	if (unlikely(ref < GNTTAB_NR_RESERVED_ENTRIES))
334 		return;
335 
336 	gnttab_entry(ref) = gnttab_free_head;
337 	gnttab_free_head = ref;
338 	if (!gnttab_free_count)
339 		gnttab_last_free = ref;
340 	if (gnttab_free_tail_ptr == &gnttab_free_head)
341 		gnttab_free_tail_ptr = __gnttab_entry(ref);
342 	gnttab_free_count++;
343 	bitmap_set(gnttab_free_bitmap, ref, 1);
344 }
345 
put_free_entry(grant_ref_t ref)346 static void put_free_entry(grant_ref_t ref)
347 {
348 	unsigned long flags;
349 
350 	spin_lock_irqsave(&gnttab_list_lock, flags);
351 	put_free_entry_locked(ref);
352 	check_free_callbacks();
353 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
354 }
355 
gnttab_set_free(unsigned int start,unsigned int n)356 static void gnttab_set_free(unsigned int start, unsigned int n)
357 {
358 	unsigned int i;
359 
360 	for (i = start; i < start + n - 1; i++)
361 		gnttab_entry(i) = i + 1;
362 
363 	gnttab_entry(i) = GNTTAB_LIST_END;
364 	if (!gnttab_free_count) {
365 		gnttab_free_head = start;
366 		gnttab_free_tail_ptr = &gnttab_free_head;
367 	} else {
368 		gnttab_entry(gnttab_last_free) = start;
369 	}
370 	gnttab_free_count += n;
371 	gnttab_last_free = i;
372 
373 	bitmap_set(gnttab_free_bitmap, start, n);
374 }
375 
376 /*
377  * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
378  * Introducing a valid entry into the grant table:
379  *  1. Write ent->domid.
380  *  2. Write ent->frame: Frame to which access is permitted.
381  *  3. Write memory barrier (WMB).
382  *  4. Write ent->flags, inc. valid type.
383  */
gnttab_update_entry_v1(grant_ref_t ref,domid_t domid,unsigned long frame,unsigned flags)384 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
385 				   unsigned long frame, unsigned flags)
386 {
387 	gnttab_shared.v1[ref].domid = domid;
388 	gnttab_shared.v1[ref].frame = frame;
389 	wmb();
390 	gnttab_shared.v1[ref].flags = flags;
391 }
392 
gnttab_update_entry_v2(grant_ref_t ref,domid_t domid,unsigned long frame,unsigned int flags)393 static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
394 				   unsigned long frame, unsigned int flags)
395 {
396 	gnttab_shared.v2[ref].hdr.domid = domid;
397 	gnttab_shared.v2[ref].full_page.frame = frame;
398 	wmb();	/* Hypervisor concurrent accesses. */
399 	gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
400 }
401 
402 /*
403  * Public grant-issuing interface functions
404  */
gnttab_grant_foreign_access_ref(grant_ref_t ref,domid_t domid,unsigned long frame,int readonly)405 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
406 				     unsigned long frame, int readonly)
407 {
408 	gnttab_interface->update_entry(ref, domid, frame,
409 			   GTF_permit_access | (readonly ? GTF_readonly : 0));
410 }
411 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
412 
gnttab_grant_foreign_access(domid_t domid,unsigned long frame,int readonly)413 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
414 				int readonly)
415 {
416 	int ref;
417 
418 	ref = get_free_entries(1);
419 	if (unlikely(ref < 0))
420 		return -ENOSPC;
421 
422 	gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
423 
424 	return ref;
425 }
426 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
427 
gnttab_end_foreign_access_ref_v1(grant_ref_t ref)428 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref)
429 {
430 	u16 flags, nflags;
431 	u16 *pflags;
432 
433 	pflags = &gnttab_shared.v1[ref].flags;
434 	nflags = *pflags;
435 	do {
436 		flags = nflags;
437 		if (flags & (GTF_reading|GTF_writing))
438 			return 0;
439 	} while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
440 
441 	return 1;
442 }
443 
gnttab_end_foreign_access_ref_v2(grant_ref_t ref)444 static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref)
445 {
446 	gnttab_shared.v2[ref].hdr.flags = 0;
447 	mb();	/* Concurrent access by hypervisor. */
448 	if (grstatus[ref] & (GTF_reading|GTF_writing)) {
449 		return 0;
450 	} else {
451 		/*
452 		 * The read of grstatus needs to have acquire semantics.
453 		 *  On x86, reads already have that, and we just need to
454 		 * protect against compiler reorderings.
455 		 * On other architectures we may need a full barrier.
456 		 */
457 #ifdef CONFIG_X86
458 		barrier();
459 #else
460 		mb();
461 #endif
462 	}
463 
464 	return 1;
465 }
466 
_gnttab_end_foreign_access_ref(grant_ref_t ref)467 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref)
468 {
469 	return gnttab_interface->end_foreign_access_ref(ref);
470 }
471 
gnttab_end_foreign_access_ref(grant_ref_t ref)472 int gnttab_end_foreign_access_ref(grant_ref_t ref)
473 {
474 	if (_gnttab_end_foreign_access_ref(ref))
475 		return 1;
476 	pr_warn("WARNING: g.e. %#x still in use!\n", ref);
477 	return 0;
478 }
479 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
480 
gnttab_read_frame_v1(grant_ref_t ref)481 static unsigned long gnttab_read_frame_v1(grant_ref_t ref)
482 {
483 	return gnttab_shared.v1[ref].frame;
484 }
485 
gnttab_read_frame_v2(grant_ref_t ref)486 static unsigned long gnttab_read_frame_v2(grant_ref_t ref)
487 {
488 	return gnttab_shared.v2[ref].full_page.frame;
489 }
490 
491 struct deferred_entry {
492 	struct list_head list;
493 	grant_ref_t ref;
494 	uint16_t warn_delay;
495 	struct page *page;
496 };
497 static LIST_HEAD(deferred_list);
498 static void gnttab_handle_deferred(struct timer_list *);
499 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred);
500 
501 static atomic64_t deferred_count;
502 static atomic64_t leaked_count;
503 static unsigned int free_per_iteration = 10;
504 module_param(free_per_iteration, uint, 0600);
505 
gnttab_handle_deferred(struct timer_list * unused)506 static void gnttab_handle_deferred(struct timer_list *unused)
507 {
508 	unsigned int nr = READ_ONCE(free_per_iteration);
509 	const bool ignore_limit = nr == 0;
510 	struct deferred_entry *first = NULL;
511 	unsigned long flags;
512 	size_t freed = 0;
513 
514 	spin_lock_irqsave(&gnttab_list_lock, flags);
515 	while ((ignore_limit || nr--) && !list_empty(&deferred_list)) {
516 		struct deferred_entry *entry
517 			= list_first_entry(&deferred_list,
518 					   struct deferred_entry, list);
519 
520 		if (entry == first)
521 			break;
522 		list_del(&entry->list);
523 		spin_unlock_irqrestore(&gnttab_list_lock, flags);
524 		if (_gnttab_end_foreign_access_ref(entry->ref)) {
525 			uint64_t ret = atomic64_dec_return(&deferred_count);
526 
527 			put_free_entry(entry->ref);
528 			pr_debug("freeing g.e. %#x (pfn %#lx), %llu remaining\n",
529 				 entry->ref, page_to_pfn(entry->page),
530 				 (unsigned long long)ret);
531 			put_page(entry->page);
532 			freed++;
533 			kfree(entry);
534 			entry = NULL;
535 		} else {
536 			if (!--entry->warn_delay)
537 				pr_info("g.e. %#x still pending\n", entry->ref);
538 			if (!first)
539 				first = entry;
540 		}
541 		spin_lock_irqsave(&gnttab_list_lock, flags);
542 		if (entry)
543 			list_add_tail(&entry->list, &deferred_list);
544 	}
545 	if (list_empty(&deferred_list))
546 		WARN_ON(atomic64_read(&deferred_count));
547 	else if (!timer_pending(&deferred_timer)) {
548 		deferred_timer.expires = jiffies + HZ;
549 		add_timer(&deferred_timer);
550 	}
551 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
552 	pr_debug("Freed %zu references", freed);
553 }
554 
gnttab_add_deferred(grant_ref_t ref,struct page * page)555 static void gnttab_add_deferred(grant_ref_t ref, struct page *page)
556 {
557 	struct deferred_entry *entry;
558 	gfp_t gfp = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
559 	uint64_t leaked, deferred;
560 
561 	entry = kmalloc(sizeof(*entry), gfp);
562 	if (!page) {
563 		unsigned long gfn = gnttab_interface->read_frame(ref);
564 
565 		page = pfn_to_page(gfn_to_pfn(gfn));
566 		get_page(page);
567 	}
568 
569 	if (entry) {
570 		unsigned long flags;
571 
572 		entry->ref = ref;
573 		entry->page = page;
574 		entry->warn_delay = 60;
575 		spin_lock_irqsave(&gnttab_list_lock, flags);
576 		list_add_tail(&entry->list, &deferred_list);
577 		if (!timer_pending(&deferred_timer)) {
578 			deferred_timer.expires = jiffies + HZ;
579 			add_timer(&deferred_timer);
580 		}
581 		spin_unlock_irqrestore(&gnttab_list_lock, flags);
582 		deferred = atomic64_inc_return(&deferred_count);
583 		leaked = atomic64_read(&leaked_count);
584 		pr_debug("deferring g.e. %#x (pfn %#lx) (total deferred %llu, total leaked %llu)\n",
585 			 ref, page ? page_to_pfn(page) : -1, deferred, leaked);
586 	} else {
587 		deferred = atomic64_read(&deferred_count);
588 		leaked = atomic64_inc_return(&leaked_count);
589 		pr_warn("leaking g.e. %#x (pfn %#lx) (total deferred %llu, total leaked %llu)\n",
590 			ref, page ? page_to_pfn(page) : -1, deferred, leaked);
591 	}
592 }
593 
gnttab_try_end_foreign_access(grant_ref_t ref)594 int gnttab_try_end_foreign_access(grant_ref_t ref)
595 {
596 	int ret = _gnttab_end_foreign_access_ref(ref);
597 
598 	if (ret)
599 		put_free_entry(ref);
600 
601 	return ret;
602 }
603 EXPORT_SYMBOL_GPL(gnttab_try_end_foreign_access);
604 
gnttab_end_foreign_access(grant_ref_t ref,struct page * page)605 void gnttab_end_foreign_access(grant_ref_t ref, struct page *page)
606 {
607 	if (gnttab_try_end_foreign_access(ref)) {
608 		if (page)
609 			put_page(page);
610 	} else
611 		gnttab_add_deferred(ref, page);
612 }
613 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
614 
gnttab_free_grant_reference(grant_ref_t ref)615 void gnttab_free_grant_reference(grant_ref_t ref)
616 {
617 	put_free_entry(ref);
618 }
619 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
620 
gnttab_free_grant_references(grant_ref_t head)621 void gnttab_free_grant_references(grant_ref_t head)
622 {
623 	grant_ref_t ref;
624 	unsigned long flags;
625 
626 	spin_lock_irqsave(&gnttab_list_lock, flags);
627 	while (head != GNTTAB_LIST_END) {
628 		ref = gnttab_entry(head);
629 		put_free_entry_locked(head);
630 		head = ref;
631 	}
632 	check_free_callbacks();
633 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
634 }
635 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
636 
gnttab_free_grant_reference_seq(grant_ref_t head,unsigned int count)637 void gnttab_free_grant_reference_seq(grant_ref_t head, unsigned int count)
638 {
639 	unsigned long flags;
640 	unsigned int i;
641 
642 	spin_lock_irqsave(&gnttab_list_lock, flags);
643 	for (i = count; i > 0; i--)
644 		put_free_entry_locked(head + i - 1);
645 	check_free_callbacks();
646 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
647 }
648 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference_seq);
649 
gnttab_alloc_grant_references(u16 count,grant_ref_t * head)650 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
651 {
652 	int h = get_free_entries(count);
653 
654 	if (h < 0)
655 		return -ENOSPC;
656 
657 	*head = h;
658 
659 	return 0;
660 }
661 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
662 
gnttab_alloc_grant_reference_seq(unsigned int count,grant_ref_t * first)663 int gnttab_alloc_grant_reference_seq(unsigned int count, grant_ref_t *first)
664 {
665 	int h;
666 
667 	if (count == 1)
668 		h = get_free_entries(1);
669 	else
670 		h = get_free_entries_seq(count);
671 
672 	if (h < 0)
673 		return -ENOSPC;
674 
675 	*first = h;
676 
677 	return 0;
678 }
679 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_reference_seq);
680 
gnttab_empty_grant_references(const grant_ref_t * private_head)681 int gnttab_empty_grant_references(const grant_ref_t *private_head)
682 {
683 	return (*private_head == GNTTAB_LIST_END);
684 }
685 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
686 
gnttab_claim_grant_reference(grant_ref_t * private_head)687 int gnttab_claim_grant_reference(grant_ref_t *private_head)
688 {
689 	grant_ref_t g = *private_head;
690 	if (unlikely(g == GNTTAB_LIST_END))
691 		return -ENOSPC;
692 	*private_head = gnttab_entry(g);
693 	return g;
694 }
695 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
696 
gnttab_release_grant_reference(grant_ref_t * private_head,grant_ref_t release)697 void gnttab_release_grant_reference(grant_ref_t *private_head,
698 				    grant_ref_t release)
699 {
700 	gnttab_entry(release) = *private_head;
701 	*private_head = release;
702 }
703 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
704 
gnttab_request_free_callback(struct gnttab_free_callback * callback,void (* fn)(void *),void * arg,u16 count)705 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
706 				  void (*fn)(void *), void *arg, u16 count)
707 {
708 	unsigned long flags;
709 	struct gnttab_free_callback *cb;
710 
711 	spin_lock_irqsave(&gnttab_list_lock, flags);
712 
713 	/* Check if the callback is already on the list */
714 	cb = gnttab_free_callback_list;
715 	while (cb) {
716 		if (cb == callback)
717 			goto out;
718 		cb = cb->next;
719 	}
720 
721 	callback->fn = fn;
722 	callback->arg = arg;
723 	callback->count = count;
724 	callback->next = gnttab_free_callback_list;
725 	gnttab_free_callback_list = callback;
726 	check_free_callbacks();
727 out:
728 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
729 }
730 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
731 
gnttab_cancel_free_callback(struct gnttab_free_callback * callback)732 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
733 {
734 	struct gnttab_free_callback **pcb;
735 	unsigned long flags;
736 
737 	spin_lock_irqsave(&gnttab_list_lock, flags);
738 	for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
739 		if (*pcb == callback) {
740 			*pcb = callback->next;
741 			break;
742 		}
743 	}
744 	spin_unlock_irqrestore(&gnttab_list_lock, flags);
745 }
746 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
747 
gnttab_frames(unsigned int frames,unsigned int align)748 static unsigned int gnttab_frames(unsigned int frames, unsigned int align)
749 {
750 	return (frames * gnttab_interface->grefs_per_grant_frame + align - 1) /
751 	       align;
752 }
753 
grow_gnttab_list(unsigned int more_frames)754 static int grow_gnttab_list(unsigned int more_frames)
755 {
756 	unsigned int new_nr_grant_frames, extra_entries, i;
757 	unsigned int nr_glist_frames, new_nr_glist_frames;
758 	unsigned int grefs_per_frame;
759 
760 	grefs_per_frame = gnttab_interface->grefs_per_grant_frame;
761 
762 	new_nr_grant_frames = nr_grant_frames + more_frames;
763 	extra_entries = more_frames * grefs_per_frame;
764 
765 	nr_glist_frames = gnttab_frames(nr_grant_frames, RPP);
766 	new_nr_glist_frames = gnttab_frames(new_nr_grant_frames, RPP);
767 	for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
768 		gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
769 		if (!gnttab_list[i])
770 			goto grow_nomem;
771 	}
772 
773 	gnttab_set_free(gnttab_size, extra_entries);
774 
775 	if (!gnttab_free_tail_ptr)
776 		gnttab_free_tail_ptr = __gnttab_entry(gnttab_size);
777 
778 	nr_grant_frames = new_nr_grant_frames;
779 	gnttab_size += extra_entries;
780 
781 	check_free_callbacks();
782 
783 	return 0;
784 
785 grow_nomem:
786 	while (i-- > nr_glist_frames)
787 		free_page((unsigned long) gnttab_list[i]);
788 	return -ENOMEM;
789 }
790 
__max_nr_grant_frames(void)791 static unsigned int __max_nr_grant_frames(void)
792 {
793 	struct gnttab_query_size query;
794 	int rc;
795 
796 	query.dom = DOMID_SELF;
797 
798 	rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
799 	if ((rc < 0) || (query.status != GNTST_okay))
800 		return 4; /* Legacy max supported number of frames */
801 
802 	return query.max_nr_frames;
803 }
804 
gnttab_max_grant_frames(void)805 unsigned int gnttab_max_grant_frames(void)
806 {
807 	unsigned int xen_max = __max_nr_grant_frames();
808 	static unsigned int boot_max_nr_grant_frames;
809 
810 	/* First time, initialize it properly. */
811 	if (!boot_max_nr_grant_frames)
812 		boot_max_nr_grant_frames = __max_nr_grant_frames();
813 
814 	if (xen_max > boot_max_nr_grant_frames)
815 		return boot_max_nr_grant_frames;
816 	return xen_max;
817 }
818 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
819 
gnttab_setup_auto_xlat_frames(phys_addr_t addr)820 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
821 {
822 	xen_pfn_t *pfn;
823 	unsigned int max_nr_gframes = __max_nr_grant_frames();
824 	unsigned int i;
825 	void *vaddr;
826 
827 	if (xen_auto_xlat_grant_frames.count)
828 		return -EINVAL;
829 
830 	vaddr = memremap(addr, XEN_PAGE_SIZE * max_nr_gframes, MEMREMAP_WB);
831 	if (vaddr == NULL) {
832 		pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
833 			&addr);
834 		return -ENOMEM;
835 	}
836 	pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
837 	if (!pfn) {
838 		memunmap(vaddr);
839 		return -ENOMEM;
840 	}
841 	for (i = 0; i < max_nr_gframes; i++)
842 		pfn[i] = XEN_PFN_DOWN(addr) + i;
843 
844 	xen_auto_xlat_grant_frames.vaddr = vaddr;
845 	xen_auto_xlat_grant_frames.pfn = pfn;
846 	xen_auto_xlat_grant_frames.count = max_nr_gframes;
847 
848 	return 0;
849 }
850 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
851 
gnttab_free_auto_xlat_frames(void)852 void gnttab_free_auto_xlat_frames(void)
853 {
854 	if (!xen_auto_xlat_grant_frames.count)
855 		return;
856 	kfree(xen_auto_xlat_grant_frames.pfn);
857 	memunmap(xen_auto_xlat_grant_frames.vaddr);
858 
859 	xen_auto_xlat_grant_frames.pfn = NULL;
860 	xen_auto_xlat_grant_frames.count = 0;
861 	xen_auto_xlat_grant_frames.vaddr = NULL;
862 }
863 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
864 
gnttab_pages_set_private(int nr_pages,struct page ** pages)865 int gnttab_pages_set_private(int nr_pages, struct page **pages)
866 {
867 	int i;
868 
869 	for (i = 0; i < nr_pages; i++) {
870 #if BITS_PER_LONG < 64
871 		struct xen_page_foreign *foreign;
872 
873 		foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
874 		if (!foreign)
875 			return -ENOMEM;
876 
877 		set_page_private(pages[i], (unsigned long)foreign);
878 #endif
879 		SetPagePrivate(pages[i]);
880 	}
881 
882 	return 0;
883 }
884 EXPORT_SYMBOL_GPL(gnttab_pages_set_private);
885 
886 /**
887  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
888  * @nr_pages: number of pages to alloc
889  * @pages: returns the pages
890  */
gnttab_alloc_pages(int nr_pages,struct page ** pages)891 int gnttab_alloc_pages(int nr_pages, struct page **pages)
892 {
893 	int ret;
894 
895 	ret = xen_alloc_unpopulated_pages(nr_pages, pages);
896 	if (ret < 0)
897 		return ret;
898 
899 	ret = gnttab_pages_set_private(nr_pages, pages);
900 	if (ret < 0)
901 		gnttab_free_pages(nr_pages, pages);
902 
903 	return ret;
904 }
905 EXPORT_SYMBOL_GPL(gnttab_alloc_pages);
906 
907 #ifdef CONFIG_XEN_UNPOPULATED_ALLOC
cache_init(struct gnttab_page_cache * cache)908 static inline void cache_init(struct gnttab_page_cache *cache)
909 {
910 	cache->pages = NULL;
911 }
912 
cache_empty(struct gnttab_page_cache * cache)913 static inline bool cache_empty(struct gnttab_page_cache *cache)
914 {
915 	return !cache->pages;
916 }
917 
cache_deq(struct gnttab_page_cache * cache)918 static inline struct page *cache_deq(struct gnttab_page_cache *cache)
919 {
920 	struct page *page;
921 
922 	page = cache->pages;
923 	cache->pages = page->zone_device_data;
924 
925 	return page;
926 }
927 
cache_enq(struct gnttab_page_cache * cache,struct page * page)928 static inline void cache_enq(struct gnttab_page_cache *cache, struct page *page)
929 {
930 	page->zone_device_data = cache->pages;
931 	cache->pages = page;
932 }
933 #else
cache_init(struct gnttab_page_cache * cache)934 static inline void cache_init(struct gnttab_page_cache *cache)
935 {
936 	INIT_LIST_HEAD(&cache->pages);
937 }
938 
cache_empty(struct gnttab_page_cache * cache)939 static inline bool cache_empty(struct gnttab_page_cache *cache)
940 {
941 	return list_empty(&cache->pages);
942 }
943 
cache_deq(struct gnttab_page_cache * cache)944 static inline struct page *cache_deq(struct gnttab_page_cache *cache)
945 {
946 	struct page *page;
947 
948 	page = list_first_entry(&cache->pages, struct page, lru);
949 	list_del(&page->lru);
950 
951 	return page;
952 }
953 
cache_enq(struct gnttab_page_cache * cache,struct page * page)954 static inline void cache_enq(struct gnttab_page_cache *cache, struct page *page)
955 {
956 	list_add(&page->lru, &cache->pages);
957 }
958 #endif
959 
gnttab_page_cache_init(struct gnttab_page_cache * cache)960 void gnttab_page_cache_init(struct gnttab_page_cache *cache)
961 {
962 	spin_lock_init(&cache->lock);
963 	cache_init(cache);
964 	cache->num_pages = 0;
965 }
966 EXPORT_SYMBOL_GPL(gnttab_page_cache_init);
967 
gnttab_page_cache_get(struct gnttab_page_cache * cache,struct page ** page)968 int gnttab_page_cache_get(struct gnttab_page_cache *cache, struct page **page)
969 {
970 	unsigned long flags;
971 
972 	spin_lock_irqsave(&cache->lock, flags);
973 
974 	if (cache_empty(cache)) {
975 		spin_unlock_irqrestore(&cache->lock, flags);
976 		return gnttab_alloc_pages(1, page);
977 	}
978 
979 	page[0] = cache_deq(cache);
980 	cache->num_pages--;
981 
982 	spin_unlock_irqrestore(&cache->lock, flags);
983 
984 	return 0;
985 }
986 EXPORT_SYMBOL_GPL(gnttab_page_cache_get);
987 
gnttab_page_cache_put(struct gnttab_page_cache * cache,struct page ** page,unsigned int num)988 void gnttab_page_cache_put(struct gnttab_page_cache *cache, struct page **page,
989 			   unsigned int num)
990 {
991 	unsigned long flags;
992 	unsigned int i;
993 
994 	spin_lock_irqsave(&cache->lock, flags);
995 
996 	for (i = 0; i < num; i++)
997 		cache_enq(cache, page[i]);
998 	cache->num_pages += num;
999 
1000 	spin_unlock_irqrestore(&cache->lock, flags);
1001 }
1002 EXPORT_SYMBOL_GPL(gnttab_page_cache_put);
1003 
gnttab_page_cache_shrink(struct gnttab_page_cache * cache,unsigned int num)1004 void gnttab_page_cache_shrink(struct gnttab_page_cache *cache, unsigned int num)
1005 {
1006 	struct page *page[10];
1007 	unsigned int i = 0;
1008 	unsigned long flags;
1009 
1010 	spin_lock_irqsave(&cache->lock, flags);
1011 
1012 	while (cache->num_pages > num) {
1013 		page[i] = cache_deq(cache);
1014 		cache->num_pages--;
1015 		if (++i == ARRAY_SIZE(page)) {
1016 			spin_unlock_irqrestore(&cache->lock, flags);
1017 			gnttab_free_pages(i, page);
1018 			i = 0;
1019 			spin_lock_irqsave(&cache->lock, flags);
1020 		}
1021 	}
1022 
1023 	spin_unlock_irqrestore(&cache->lock, flags);
1024 
1025 	if (i != 0)
1026 		gnttab_free_pages(i, page);
1027 }
1028 EXPORT_SYMBOL_GPL(gnttab_page_cache_shrink);
1029 
gnttab_pages_clear_private(int nr_pages,struct page ** pages)1030 void gnttab_pages_clear_private(int nr_pages, struct page **pages)
1031 {
1032 	int i;
1033 
1034 	for (i = 0; i < nr_pages; i++) {
1035 		if (PagePrivate(pages[i])) {
1036 #if BITS_PER_LONG < 64
1037 			kfree((void *)page_private(pages[i]));
1038 #endif
1039 			ClearPagePrivate(pages[i]);
1040 		}
1041 	}
1042 }
1043 EXPORT_SYMBOL_GPL(gnttab_pages_clear_private);
1044 
1045 /**
1046  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
1047  * @nr_pages: number of pages to free
1048  * @pages: the pages
1049  */
gnttab_free_pages(int nr_pages,struct page ** pages)1050 void gnttab_free_pages(int nr_pages, struct page **pages)
1051 {
1052 	gnttab_pages_clear_private(nr_pages, pages);
1053 	xen_free_unpopulated_pages(nr_pages, pages);
1054 }
1055 EXPORT_SYMBOL_GPL(gnttab_free_pages);
1056 
1057 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
1058 /**
1059  * gnttab_dma_alloc_pages - alloc DMAable pages suitable for grant mapping into
1060  * @args: arguments to the function
1061  */
gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args * args)1062 int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args)
1063 {
1064 	unsigned long pfn, start_pfn;
1065 	size_t size;
1066 	int i, ret;
1067 
1068 	if (args->nr_pages < 0 || args->nr_pages > (INT_MAX >> PAGE_SHIFT))
1069 		return -ENOMEM;
1070 
1071 	size = args->nr_pages << PAGE_SHIFT;
1072 	if (args->coherent)
1073 		args->vaddr = dma_alloc_coherent(args->dev, size,
1074 						 &args->dev_bus_addr,
1075 						 GFP_KERNEL | __GFP_NOWARN);
1076 	else
1077 		args->vaddr = dma_alloc_wc(args->dev, size,
1078 					   &args->dev_bus_addr,
1079 					   GFP_KERNEL | __GFP_NOWARN);
1080 	if (!args->vaddr) {
1081 		pr_debug("Failed to allocate DMA buffer of size %zu\n", size);
1082 		return -ENOMEM;
1083 	}
1084 
1085 	start_pfn = __phys_to_pfn(args->dev_bus_addr);
1086 	for (pfn = start_pfn, i = 0; pfn < start_pfn + args->nr_pages;
1087 			pfn++, i++) {
1088 		struct page *page = pfn_to_page(pfn);
1089 
1090 		args->pages[i] = page;
1091 		args->frames[i] = xen_page_to_gfn(page);
1092 		xenmem_reservation_scrub_page(page);
1093 	}
1094 
1095 	xenmem_reservation_va_mapping_reset(args->nr_pages, args->pages);
1096 
1097 	ret = xenmem_reservation_decrease(args->nr_pages, args->frames);
1098 	if (ret != args->nr_pages) {
1099 		pr_debug("Failed to decrease reservation for DMA buffer\n");
1100 		ret = -EFAULT;
1101 		goto fail;
1102 	}
1103 
1104 	ret = gnttab_pages_set_private(args->nr_pages, args->pages);
1105 	if (ret < 0)
1106 		goto fail;
1107 
1108 	return 0;
1109 
1110 fail:
1111 	gnttab_dma_free_pages(args);
1112 	return ret;
1113 }
1114 EXPORT_SYMBOL_GPL(gnttab_dma_alloc_pages);
1115 
1116 /**
1117  * gnttab_dma_free_pages - free DMAable pages
1118  * @args: arguments to the function
1119  */
gnttab_dma_free_pages(struct gnttab_dma_alloc_args * args)1120 int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args)
1121 {
1122 	size_t size;
1123 	int i, ret;
1124 
1125 	gnttab_pages_clear_private(args->nr_pages, args->pages);
1126 
1127 	for (i = 0; i < args->nr_pages; i++)
1128 		args->frames[i] = page_to_xen_pfn(args->pages[i]);
1129 
1130 	ret = xenmem_reservation_increase(args->nr_pages, args->frames);
1131 	if (ret != args->nr_pages) {
1132 		pr_debug("Failed to increase reservation for DMA buffer\n");
1133 		ret = -EFAULT;
1134 	} else {
1135 		ret = 0;
1136 	}
1137 
1138 	xenmem_reservation_va_mapping_update(args->nr_pages, args->pages,
1139 					     args->frames);
1140 
1141 	size = args->nr_pages << PAGE_SHIFT;
1142 	if (args->coherent)
1143 		dma_free_coherent(args->dev, size,
1144 				  args->vaddr, args->dev_bus_addr);
1145 	else
1146 		dma_free_wc(args->dev, size,
1147 			    args->vaddr, args->dev_bus_addr);
1148 	return ret;
1149 }
1150 EXPORT_SYMBOL_GPL(gnttab_dma_free_pages);
1151 #endif
1152 
1153 /* Handling of paged out grant targets (GNTST_eagain) */
1154 #define MAX_DELAY 256
1155 static inline void
gnttab_retry_eagain_gop(unsigned int cmd,void * gop,int16_t * status,const char * func)1156 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
1157 						const char *func)
1158 {
1159 	unsigned delay = 1;
1160 
1161 	do {
1162 		BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
1163 		if (*status == GNTST_eagain)
1164 			msleep(delay++);
1165 	} while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
1166 
1167 	if (delay >= MAX_DELAY) {
1168 		pr_err("%s: %s eagain grant\n", func, current->comm);
1169 		*status = GNTST_bad_page;
1170 	}
1171 }
1172 
gnttab_batch_map(struct gnttab_map_grant_ref * batch,unsigned count)1173 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
1174 {
1175 	struct gnttab_map_grant_ref *op;
1176 
1177 	if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
1178 		BUG();
1179 	for (op = batch; op < batch + count; op++)
1180 		if (op->status == GNTST_eagain)
1181 			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
1182 						&op->status, __func__);
1183 }
1184 EXPORT_SYMBOL_GPL(gnttab_batch_map);
1185 
gnttab_batch_copy(struct gnttab_copy * batch,unsigned count)1186 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
1187 {
1188 	struct gnttab_copy *op;
1189 
1190 	if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
1191 		BUG();
1192 	for (op = batch; op < batch + count; op++)
1193 		if (op->status == GNTST_eagain)
1194 			gnttab_retry_eagain_gop(GNTTABOP_copy, op,
1195 						&op->status, __func__);
1196 }
1197 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
1198 
gnttab_foreach_grant_in_range(struct page * page,unsigned int offset,unsigned int len,xen_grant_fn_t fn,void * data)1199 void gnttab_foreach_grant_in_range(struct page *page,
1200 				   unsigned int offset,
1201 				   unsigned int len,
1202 				   xen_grant_fn_t fn,
1203 				   void *data)
1204 {
1205 	unsigned int goffset;
1206 	unsigned int glen;
1207 	unsigned long xen_pfn;
1208 
1209 	len = min_t(unsigned int, PAGE_SIZE - offset, len);
1210 	goffset = xen_offset_in_page(offset);
1211 
1212 	xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
1213 
1214 	while (len) {
1215 		glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
1216 		fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
1217 
1218 		goffset = 0;
1219 		xen_pfn++;
1220 		len -= glen;
1221 	}
1222 }
1223 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
1224 
gnttab_foreach_grant(struct page ** pages,unsigned int nr_grefs,xen_grant_fn_t fn,void * data)1225 void gnttab_foreach_grant(struct page **pages,
1226 			  unsigned int nr_grefs,
1227 			  xen_grant_fn_t fn,
1228 			  void *data)
1229 {
1230 	unsigned int goffset = 0;
1231 	unsigned long xen_pfn = 0;
1232 	unsigned int i;
1233 
1234 	for (i = 0; i < nr_grefs; i++) {
1235 		if ((i % XEN_PFN_PER_PAGE) == 0) {
1236 			xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
1237 			goffset = 0;
1238 		}
1239 
1240 		fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
1241 
1242 		goffset += XEN_PAGE_SIZE;
1243 		xen_pfn++;
1244 	}
1245 }
1246 
gnttab_map_refs(struct gnttab_map_grant_ref * map_ops,struct gnttab_map_grant_ref * kmap_ops,struct page ** pages,unsigned int count)1247 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
1248 		    struct gnttab_map_grant_ref *kmap_ops,
1249 		    struct page **pages, unsigned int count)
1250 {
1251 	int i, ret;
1252 
1253 	ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
1254 	if (ret)
1255 		return ret;
1256 
1257 	for (i = 0; i < count; i++) {
1258 		switch (map_ops[i].status) {
1259 		case GNTST_okay:
1260 		{
1261 			struct xen_page_foreign *foreign;
1262 
1263 			SetPageForeign(pages[i]);
1264 			foreign = xen_page_foreign(pages[i]);
1265 			foreign->domid = map_ops[i].dom;
1266 			foreign->gref = map_ops[i].ref;
1267 			break;
1268 		}
1269 
1270 		case GNTST_no_device_space:
1271 			pr_warn_ratelimited("maptrack limit reached, can't map all guest pages\n");
1272 			break;
1273 
1274 		case GNTST_eagain:
1275 			/* Retry eagain maps */
1276 			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref,
1277 						map_ops + i,
1278 						&map_ops[i].status, __func__);
1279 			/* Test status in next loop iteration. */
1280 			i--;
1281 			break;
1282 
1283 		default:
1284 			break;
1285 		}
1286 	}
1287 
1288 	return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
1289 }
1290 EXPORT_SYMBOL_GPL(gnttab_map_refs);
1291 
gnttab_unmap_refs(struct gnttab_unmap_grant_ref * unmap_ops,struct gnttab_unmap_grant_ref * kunmap_ops,struct page ** pages,unsigned int count)1292 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
1293 		      struct gnttab_unmap_grant_ref *kunmap_ops,
1294 		      struct page **pages, unsigned int count)
1295 {
1296 	unsigned int i;
1297 	int ret;
1298 
1299 	ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
1300 	if (ret)
1301 		return ret;
1302 
1303 	for (i = 0; i < count; i++)
1304 		ClearPageForeign(pages[i]);
1305 
1306 	return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
1307 }
1308 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
1309 
1310 #define GNTTAB_UNMAP_REFS_DELAY 5
1311 
1312 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
1313 
gnttab_unmap_work(struct work_struct * work)1314 static void gnttab_unmap_work(struct work_struct *work)
1315 {
1316 	struct gntab_unmap_queue_data
1317 		*unmap_data = container_of(work,
1318 					   struct gntab_unmap_queue_data,
1319 					   gnttab_work.work);
1320 	if (unmap_data->age != UINT_MAX)
1321 		unmap_data->age++;
1322 	__gnttab_unmap_refs_async(unmap_data);
1323 }
1324 
__gnttab_unmap_refs_async(struct gntab_unmap_queue_data * item)1325 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
1326 {
1327 	int ret;
1328 	int pc;
1329 
1330 	for (pc = 0; pc < item->count; pc++) {
1331 		if (page_count(item->pages[pc]) > 1) {
1332 			unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
1333 			schedule_delayed_work(&item->gnttab_work,
1334 					      msecs_to_jiffies(delay));
1335 			return;
1336 		}
1337 	}
1338 
1339 	ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
1340 				item->pages, item->count);
1341 	item->done(ret, item);
1342 }
1343 
gnttab_unmap_refs_async(struct gntab_unmap_queue_data * item)1344 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
1345 {
1346 	INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
1347 	item->age = 0;
1348 
1349 	__gnttab_unmap_refs_async(item);
1350 }
1351 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
1352 
unmap_refs_callback(int result,struct gntab_unmap_queue_data * data)1353 static void unmap_refs_callback(int result,
1354 		struct gntab_unmap_queue_data *data)
1355 {
1356 	struct unmap_refs_callback_data *d = data->data;
1357 
1358 	d->result = result;
1359 	complete(&d->completion);
1360 }
1361 
gnttab_unmap_refs_sync(struct gntab_unmap_queue_data * item)1362 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
1363 {
1364 	struct unmap_refs_callback_data data;
1365 
1366 	init_completion(&data.completion);
1367 	item->data = &data;
1368 	item->done = &unmap_refs_callback;
1369 	gnttab_unmap_refs_async(item);
1370 	wait_for_completion(&data.completion);
1371 
1372 	return data.result;
1373 }
1374 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
1375 
nr_status_frames(unsigned int nr_grant_frames)1376 static unsigned int nr_status_frames(unsigned int nr_grant_frames)
1377 {
1378 	return gnttab_frames(nr_grant_frames, SPP);
1379 }
1380 
gnttab_map_frames_v1(xen_pfn_t * frames,unsigned int nr_gframes)1381 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
1382 {
1383 	int rc;
1384 
1385 	rc = arch_gnttab_map_shared(frames, nr_gframes,
1386 				    gnttab_max_grant_frames(),
1387 				    &gnttab_shared.addr);
1388 	BUG_ON(rc);
1389 
1390 	return 0;
1391 }
1392 
gnttab_unmap_frames_v1(void)1393 static void gnttab_unmap_frames_v1(void)
1394 {
1395 	arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1396 }
1397 
gnttab_map_frames_v2(xen_pfn_t * frames,unsigned int nr_gframes)1398 static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes)
1399 {
1400 	uint64_t *sframes;
1401 	unsigned int nr_sframes;
1402 	struct gnttab_get_status_frames getframes;
1403 	int rc;
1404 
1405 	nr_sframes = nr_status_frames(nr_gframes);
1406 
1407 	/* No need for kzalloc as it is initialized in following hypercall
1408 	 * GNTTABOP_get_status_frames.
1409 	 */
1410 	sframes = kmalloc_array(nr_sframes, sizeof(uint64_t), GFP_ATOMIC);
1411 	if (!sframes)
1412 		return -ENOMEM;
1413 
1414 	getframes.dom        = DOMID_SELF;
1415 	getframes.nr_frames  = nr_sframes;
1416 	set_xen_guest_handle(getframes.frame_list, sframes);
1417 
1418 	rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
1419 				       &getframes, 1);
1420 	if (rc == -ENOSYS) {
1421 		kfree(sframes);
1422 		return -ENOSYS;
1423 	}
1424 
1425 	BUG_ON(rc || getframes.status);
1426 
1427 	rc = arch_gnttab_map_status(sframes, nr_sframes,
1428 				    nr_status_frames(gnttab_max_grant_frames()),
1429 				    &grstatus);
1430 	BUG_ON(rc);
1431 	kfree(sframes);
1432 
1433 	rc = arch_gnttab_map_shared(frames, nr_gframes,
1434 				    gnttab_max_grant_frames(),
1435 				    &gnttab_shared.addr);
1436 	BUG_ON(rc);
1437 
1438 	return 0;
1439 }
1440 
gnttab_unmap_frames_v2(void)1441 static void gnttab_unmap_frames_v2(void)
1442 {
1443 	arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1444 	arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
1445 }
1446 
gnttab_map(unsigned int start_idx,unsigned int end_idx)1447 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
1448 {
1449 	struct gnttab_setup_table setup;
1450 	xen_pfn_t *frames;
1451 	unsigned int nr_gframes = end_idx + 1;
1452 	int rc;
1453 
1454 	if (xen_feature(XENFEAT_auto_translated_physmap)) {
1455 		struct xen_add_to_physmap xatp;
1456 		unsigned int i = end_idx;
1457 		rc = 0;
1458 		BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
1459 		/*
1460 		 * Loop backwards, so that the first hypercall has the largest
1461 		 * index, ensuring that the table will grow only once.
1462 		 */
1463 		do {
1464 			xatp.domid = DOMID_SELF;
1465 			xatp.idx = i;
1466 			xatp.space = XENMAPSPACE_grant_table;
1467 			xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
1468 			rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
1469 			if (rc != 0) {
1470 				pr_warn("grant table add_to_physmap failed, err=%d\n",
1471 					rc);
1472 				break;
1473 			}
1474 		} while (i-- > start_idx);
1475 
1476 		return rc;
1477 	}
1478 
1479 	/* No need for kzalloc as it is initialized in following hypercall
1480 	 * GNTTABOP_setup_table.
1481 	 */
1482 	frames = kmalloc_array(nr_gframes, sizeof(unsigned long), GFP_ATOMIC);
1483 	if (!frames)
1484 		return -ENOMEM;
1485 
1486 	setup.dom        = DOMID_SELF;
1487 	setup.nr_frames  = nr_gframes;
1488 	set_xen_guest_handle(setup.frame_list, frames);
1489 
1490 	rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1491 	if (rc == -ENOSYS) {
1492 		kfree(frames);
1493 		return -ENOSYS;
1494 	}
1495 
1496 	BUG_ON(rc || setup.status);
1497 
1498 	rc = gnttab_interface->map_frames(frames, nr_gframes);
1499 
1500 	kfree(frames);
1501 
1502 	return rc;
1503 }
1504 
1505 static const struct gnttab_ops gnttab_v1_ops = {
1506 	.version			= 1,
1507 	.grefs_per_grant_frame		= XEN_PAGE_SIZE /
1508 					  sizeof(struct grant_entry_v1),
1509 	.map_frames			= gnttab_map_frames_v1,
1510 	.unmap_frames			= gnttab_unmap_frames_v1,
1511 	.update_entry			= gnttab_update_entry_v1,
1512 	.end_foreign_access_ref		= gnttab_end_foreign_access_ref_v1,
1513 	.read_frame			= gnttab_read_frame_v1,
1514 };
1515 
1516 static const struct gnttab_ops gnttab_v2_ops = {
1517 	.version			= 2,
1518 	.grefs_per_grant_frame		= XEN_PAGE_SIZE /
1519 					  sizeof(union grant_entry_v2),
1520 	.map_frames			= gnttab_map_frames_v2,
1521 	.unmap_frames			= gnttab_unmap_frames_v2,
1522 	.update_entry			= gnttab_update_entry_v2,
1523 	.end_foreign_access_ref		= gnttab_end_foreign_access_ref_v2,
1524 	.read_frame			= gnttab_read_frame_v2,
1525 };
1526 
gnttab_need_v2(void)1527 static bool gnttab_need_v2(void)
1528 {
1529 #ifdef CONFIG_X86
1530 	uint32_t base, width;
1531 
1532 	if (xen_pv_domain()) {
1533 		base = xen_cpuid_base();
1534 		if (cpuid_eax(base) < 5)
1535 			return false;	/* Information not available, use V1. */
1536 		width = cpuid_ebx(base + 5) &
1537 			XEN_CPUID_MACHINE_ADDRESS_WIDTH_MASK;
1538 		return width > 32 + PAGE_SHIFT;
1539 	}
1540 #endif
1541 	return !!(max_possible_pfn >> 32);
1542 }
1543 
gnttab_request_version(void)1544 static void gnttab_request_version(void)
1545 {
1546 	long rc;
1547 	struct gnttab_set_version gsv;
1548 
1549 	if (gnttab_need_v2())
1550 		gsv.version = 2;
1551 	else
1552 		gsv.version = 1;
1553 
1554 	/* Boot parameter overrides automatic selection. */
1555 	if (xen_gnttab_version >= 1 && xen_gnttab_version <= 2)
1556 		gsv.version = xen_gnttab_version;
1557 
1558 	rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
1559 	if (rc == 0 && gsv.version == 2)
1560 		gnttab_interface = &gnttab_v2_ops;
1561 	else
1562 		gnttab_interface = &gnttab_v1_ops;
1563 	pr_info("Grant tables using version %d layout\n",
1564 		gnttab_interface->version);
1565 }
1566 
gnttab_setup(void)1567 static int gnttab_setup(void)
1568 {
1569 	unsigned int max_nr_gframes;
1570 
1571 	max_nr_gframes = gnttab_max_grant_frames();
1572 	if (max_nr_gframes < nr_grant_frames)
1573 		return -ENOSYS;
1574 
1575 	if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1576 		gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1577 		if (gnttab_shared.addr == NULL) {
1578 			pr_warn("gnttab share frames is not mapped!\n");
1579 			return -ENOMEM;
1580 		}
1581 	}
1582 	return gnttab_map(0, nr_grant_frames - 1);
1583 }
1584 
gnttab_resume(void)1585 int gnttab_resume(void)
1586 {
1587 	gnttab_request_version();
1588 	return gnttab_setup();
1589 }
1590 
gnttab_suspend(void)1591 int gnttab_suspend(void)
1592 {
1593 	if (!xen_feature(XENFEAT_auto_translated_physmap))
1594 		gnttab_interface->unmap_frames();
1595 	return 0;
1596 }
1597 
gnttab_expand(unsigned int req_entries)1598 static int gnttab_expand(unsigned int req_entries)
1599 {
1600 	int rc;
1601 	unsigned int cur, extra;
1602 
1603 	cur = nr_grant_frames;
1604 	extra = ((req_entries + gnttab_interface->grefs_per_grant_frame - 1) /
1605 		 gnttab_interface->grefs_per_grant_frame);
1606 	if (cur + extra > gnttab_max_grant_frames()) {
1607 		pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
1608 				    " cur=%u extra=%u limit=%u"
1609 				    " gnttab_free_count=%u req_entries=%u\n",
1610 				    cur, extra, gnttab_max_grant_frames(),
1611 				    gnttab_free_count, req_entries);
1612 		return -ENOSPC;
1613 	}
1614 
1615 	rc = gnttab_map(cur, cur + extra - 1);
1616 	if (rc == 0)
1617 		rc = grow_gnttab_list(extra);
1618 
1619 	return rc;
1620 }
1621 
gnttab_init(void)1622 int gnttab_init(void)
1623 {
1624 	int i;
1625 	unsigned long max_nr_grant_frames, max_nr_grefs;
1626 	unsigned int max_nr_glist_frames, nr_glist_frames;
1627 	int ret;
1628 
1629 	gnttab_request_version();
1630 	max_nr_grant_frames = gnttab_max_grant_frames();
1631 	max_nr_grefs = max_nr_grant_frames *
1632 			gnttab_interface->grefs_per_grant_frame;
1633 	nr_grant_frames = 1;
1634 
1635 	/* Determine the maximum number of frames required for the
1636 	 * grant reference free list on the current hypervisor.
1637 	 */
1638 	max_nr_glist_frames = max_nr_grefs / RPP;
1639 
1640 	gnttab_list = kmalloc_array(max_nr_glist_frames,
1641 				    sizeof(grant_ref_t *),
1642 				    GFP_KERNEL);
1643 	if (gnttab_list == NULL)
1644 		return -ENOMEM;
1645 
1646 	nr_glist_frames = gnttab_frames(nr_grant_frames, RPP);
1647 	for (i = 0; i < nr_glist_frames; i++) {
1648 		gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1649 		if (gnttab_list[i] == NULL) {
1650 			ret = -ENOMEM;
1651 			goto ini_nomem;
1652 		}
1653 	}
1654 
1655 	gnttab_free_bitmap = bitmap_zalloc(max_nr_grefs, GFP_KERNEL);
1656 	if (!gnttab_free_bitmap) {
1657 		ret = -ENOMEM;
1658 		goto ini_nomem;
1659 	}
1660 
1661 	ret = arch_gnttab_init(max_nr_grant_frames,
1662 			       nr_status_frames(max_nr_grant_frames));
1663 	if (ret < 0)
1664 		goto ini_nomem;
1665 
1666 	if (gnttab_setup() < 0) {
1667 		ret = -ENODEV;
1668 		goto ini_nomem;
1669 	}
1670 
1671 	gnttab_size = nr_grant_frames * gnttab_interface->grefs_per_grant_frame;
1672 
1673 	gnttab_set_free(GNTTAB_NR_RESERVED_ENTRIES,
1674 			gnttab_size - GNTTAB_NR_RESERVED_ENTRIES);
1675 
1676 	printk("Grant table initialized\n");
1677 	return 0;
1678 
1679  ini_nomem:
1680 	for (i--; i >= 0; i--)
1681 		free_page((unsigned long)gnttab_list[i]);
1682 	kfree(gnttab_list);
1683 	bitmap_free(gnttab_free_bitmap);
1684 	return ret;
1685 }
1686 EXPORT_SYMBOL_GPL(gnttab_init);
1687 
__gnttab_init(void)1688 static int __gnttab_init(void)
1689 {
1690 	if (!xen_domain())
1691 		return -ENODEV;
1692 
1693 	/* Delay grant-table initialization in the PV on HVM case */
1694 	if (xen_hvm_domain() && !xen_pvh_domain())
1695 		return 0;
1696 
1697 	return gnttab_init();
1698 }
1699 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1700  * beforehand to initialize xen_auto_xlat_grant_frames. */
1701 core_initcall_sync(__gnttab_init);
1702