[linux-2.6-block.git] / include / xen / grant_table.h

/******************************************************************************
 * grant_table.h
 *
 * Two sets of functionality:
 * 1. Granting foreign access to our memory reservation.
 * 2. Accessing others' memory reservations via grant references.
 * (i.e., mechanisms for both sender and recipient of grant references)
 *
 * Copyright (c) 2004-2005, K A Fraser
 * Copyright (c) 2005, Christopher Clark
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#ifndef __ASM_GNTTAB_H__
#define __ASM_GNTTAB_H__

#include <asm/page.h>

#include <xen/interface/xen.h>
#include <xen/interface/grant_table.h>

#include <asm/xen/hypervisor.h>

#include <xen/features.h>
#include <xen/page.h>
#include <linux/mm_types.h>
#include <linux/page-flags.h>
#include <linux/kernel.h>

#define GNTTAB_RESERVED_XENSTORE 1

/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
#define NR_GRANT_FRAMES 4

struct gnttab_free_callback {
	struct gnttab_free_callback *next;
	void (*fn)(void *);
	void *arg;
	u16 count;
};

struct gntab_unmap_queue_data;

typedef void (*gnttab_unmap_refs_done)(int result, struct gntab_unmap_queue_data *data);

struct gntab_unmap_queue_data
{
	struct delayed_work	gnttab_work;
	void *data;
	gnttab_unmap_refs_done	done;
	struct gnttab_unmap_grant_ref *unmap_ops;
	struct gnttab_unmap_grant_ref *kunmap_ops;
	struct page **pages;
	unsigned int count;
	unsigned int age;
};

int gnttab_init(void);
int gnttab_suspend(void);
int gnttab_resume(void);

int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
				int readonly);
int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
					int flags, unsigned page_off,
					unsigned length);
int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
				      domid_t trans_domid,
				      grant_ref_t trans_gref);

/*
 * Are sub-page grants available on this version of Xen?  Returns true if they
 * are, and false if they're not.
 */
bool gnttab_subpage_grants_available(void);

/*
 * Are transitive grants available on this version of Xen?  Returns true if they
 * are, and false if they're not.
 */
bool gnttab_trans_grants_available(void);

/*
 * End access through the given grant reference, iff the grant entry is no
 * longer in use.  Return 1 if the grant entry was freed, 0 if it is still in
 * use.
 */
int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly);

/*
 * Eventually end access through the given grant reference, and once that
 * access has been ended, free the given page too.  Access will be ended
 * immediately iff the grant entry is not in use, otherwise it will happen
 * some time later.  page may be 0, in which case no freeing will occur.
 */
void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
			       unsigned long page);

int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn);

unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref);
unsigned long gnttab_end_foreign_transfer(grant_ref_t ref);

int gnttab_query_foreign_access(grant_ref_t ref);

/*
 * operations on reserved batches of grant references
 */
int gnttab_alloc_grant_references(u16 count, grant_ref_t *pprivate_head);

void gnttab_free_grant_reference(grant_ref_t ref);

void gnttab_free_grant_references(grant_ref_t head);

int gnttab_empty_grant_references(const grant_ref_t *pprivate_head);

int gnttab_claim_grant_reference(grant_ref_t *pprivate_head);

void gnttab_release_grant_reference(grant_ref_t *private_head,
				    grant_ref_t release);

void gnttab_request_free_callback(struct gnttab_free_callback *callback,
				  void (*fn)(void *), void *arg, u16 count);
void gnttab_cancel_free_callback(struct gnttab_free_callback *callback);

void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
				     unsigned long frame, int readonly);
int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
					    unsigned long frame, int flags,
					    unsigned page_off,
					    unsigned length);
int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
					  int flags, domid_t trans_domid,
					  grant_ref_t trans_gref);

/* Give access to the first 4K of the page */
static inline void gnttab_page_grant_foreign_access_ref_one(
	grant_ref_t ref, domid_t domid,
	struct page *page, int readonly)
{
	gnttab_grant_foreign_access_ref(ref, domid, xen_page_to_gfn(page),
					readonly);
}

void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
				       unsigned long pfn);

static inline void
gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
		  uint32_t flags, grant_ref_t ref, domid_t domid)
{
	if (flags & GNTMAP_contains_pte)
		map->host_addr = addr;
	else if (xen_feature(XENFEAT_auto_translated_physmap))
		map->host_addr = __pa(addr);
	else
		map->host_addr = addr;

	map->flags = flags;
	map->ref = ref;
	map->dom = domid;
}

static inline void
gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
		    uint32_t flags, grant_handle_t handle)
{
	if (flags & GNTMAP_contains_pte)
		unmap->host_addr = addr;
	else if (xen_feature(XENFEAT_auto_translated_physmap))
		unmap->host_addr = __pa(addr);
	else
		unmap->host_addr = addr;

	unmap->handle = handle;
	unmap->dev_bus_addr = 0;
}

int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status);
int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
			   unsigned long max_nr_gframes,
			   void **__shared);
int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
			   unsigned long max_nr_gframes,
			   grant_status_t **__shared);
void arch_gnttab_unmap(void *shared, unsigned long nr_gframes);

struct grant_frames {
	xen_pfn_t *pfn;
	unsigned int count;
	void *vaddr;
};
extern struct grant_frames xen_auto_xlat_grant_frames;
unsigned int gnttab_max_grant_frames(void);
int gnttab_setup_auto_xlat_frames(phys_addr_t addr);
void gnttab_free_auto_xlat_frames(void);

#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))

int gnttab_alloc_pages(int nr_pages, struct page **pages);
void gnttab_free_pages(int nr_pages, struct page **pages);

int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
		    struct gnttab_map_grant_ref *kmap_ops,
		    struct page **pages, unsigned int count);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
		      struct gnttab_unmap_grant_ref *kunmap_ops,
		      struct page **pages, unsigned int count);
void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item);


/* Perform a batch of grant map/copy operations. Retry every batch slot
 * for which the hypervisor returns GNTST_eagain. This is typically due
 * to paged out target frames.
 *
 * Will retry for 1, 2, ... 255 ms, i.e. 256 times during 32 seconds.
 *
 * Return value in each iand every status field of the batch guaranteed
 * to not be GNTST_eagain.
 */
void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count);
void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count);


struct xen_page_foreign {
	domid_t domid;
	grant_ref_t gref;
};

static inline struct xen_page_foreign *xen_page_foreign(struct page *page)
{
	if (!PageForeign(page))
		return NULL;
#if BITS_PER_LONG < 64
	return (struct xen_page_foreign *)page->private;
#else
	BUILD_BUG_ON(sizeof(struct xen_page_foreign) > BITS_PER_LONG);
	return (struct xen_page_foreign *)&page->private;
#endif
}

/* Split Linux page in chunk of the size of the grant and call fn
 *
 * Parameters of fn:
 *	gfn: guest frame number
 *	offset: offset in the grant
 *	len: length of the data in the grant.
 *	data: internal information
 */
typedef void (*xen_grant_fn_t)(unsigned long gfn, unsigned int offset,
			       unsigned int len, void *data);

void gnttab_foreach_grant_in_range(struct page *page,
				   unsigned int offset,
				   unsigned int len,
				   xen_grant_fn_t fn,
				   void *data);

/* Helper to get to call fn only on the first "grant chunk" */
static inline void gnttab_for_one_grant(struct page *page, unsigned int offset,
					unsigned len, xen_grant_fn_t fn,
					void *data)
{
	/* The first request is limited to the size of one grant */
	len = min_t(unsigned int, XEN_PAGE_SIZE - (offset & ~XEN_PAGE_MASK),
		    len);

	gnttab_foreach_grant_in_range(page, offset, len, fn, data);
}

/* Get @nr_grefs grants from an array of page and call fn for each grant */
void gnttab_foreach_grant(struct page **pages,
			  unsigned int nr_grefs,
			  xen_grant_fn_t fn,
			  void *data);

/* Get the number of grant in a specified region
 *
 * start: Offset from the beginning of the first page
 * len: total length of data (can cross multiple page)
 */
static inline unsigned int gnttab_count_grant(unsigned int start,
					      unsigned int len)
{
	return XEN_PFN_UP(xen_offset_in_page(start) + len);
}

#endif /* __ASM_GNTTAB_H__ */
Commit	Line	Data
ad9a8612 JF	1	/******************************************************************************
	2	* grant_table.h
	3	*
	4	* Two sets of functionality:
	5	* 1. Granting foreign access to our memory reservation.
	6	* 2. Accessing others' memory reservations via grant references.
	7	* (i.e., mechanisms for both sender and recipient of grant references)
	8	*
	9	* Copyright (c) 2004-2005, K A Fraser
	10	* Copyright (c) 2005, Christopher Clark
	11	*
	12	* This program is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU General Public License version 2
	14	* as published by the Free Software Foundation; or, when distributed
	15	* separately from the Linux kernel or incorporated into other
	16	* software packages, subject to the following license:
	17	*
	18	* Permission is hereby granted, free of charge, to any person obtaining a copy
	19	* of this source file (the "Software"), to deal in the Software without
	20	* restriction, including without limitation the rights to use, copy, modify,
	21	* merge, publish, distribute, sublicense, and/or sell copies of the Software,
	22	* and to permit persons to whom the Software is furnished to do so, subject to
	23	* the following conditions:
	24	*
	25	* The above copyright notice and this permission notice shall be included in
	26	* all copies or substantial portions of the Software.
	27	*
	28	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	29	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	30	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	31	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	32	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	33	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	34	* IN THE SOFTWARE.
	35	*/
	36
	37	#ifndef __ASM_GNTTAB_H__
	38	#define __ASM_GNTTAB_H__
	39
f0774532 IC	40	#include <asm/page.h>
	41
	42	#include <xen/interface/xen.h>
ad9a8612	43	#include <xen/interface/grant_table.h>
f0774532 IC	44
f0774532 IC	45	#include <asm/xen/hypervisor.h>
ad9a8612	46
f0774532	47	#include <xen/features.h>
008c320a	48	#include <xen/page.h>
8da7633f JH	49	#include <linux/mm_types.h>
8da7633f JH	50	#include <linux/page-flags.h>
008c320a	51	#include <linux/kernel.h>
f0774532	52
d2fb4c51 DDG	53	#define GNTTAB_RESERVED_XENSTORE 1
d2fb4c51 DDG	54
ad9a8612 JF	55	/* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
	56	#define NR_GRANT_FRAMES 4
	57
	58	struct gnttab_free_callback {
	59	struct gnttab_free_callback *next;
	60	void (fn)(void );
	61	void *arg;
	62	u16 count;
	63	};
	64
3f9f1c67 JH	65	struct gntab_unmap_queue_data;
	66
	67	typedef void (gnttab_unmap_refs_done)(int result, struct gntab_unmap_queue_data data);
	68
	69	struct gntab_unmap_queue_data
	70	{
	71	struct delayed_work gnttab_work;
	72	void *data;
	73	gnttab_unmap_refs_done done;
	74	struct gnttab_unmap_grant_ref *unmap_ops;
	75	struct gnttab_unmap_grant_ref *kunmap_ops;
	76	struct page **pages;
	77	unsigned int count;
	78	unsigned int age;
	79	};
	80
183d03cc	81	int gnttab_init(void);
0e91398f JF	82	int gnttab_suspend(void);
	83	int gnttab_resume(void);
	84
ad9a8612 JF	85	int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
ad9a8612 JF	86	int readonly);
b988b8ff JG	87	int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
	88	int flags, unsigned page_off,
	89	unsigned length);
	90	int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
	91	domid_t trans_domid,
	92	grant_ref_t trans_gref);
	93
	94	/*
	95	* Are sub-page grants available on this version of Xen? Returns true if they
	96	* are, and false if they're not.
	97	*/
	98	bool gnttab_subpage_grants_available(void);
	99
	100	/*
	101	* Are transitive grants available on this version of Xen? Returns true if they
	102	* are, and false if they're not.
	103	*/
	104	bool gnttab_trans_grants_available(void);
9438ce9d	105
ad9a8612 JF	106	/*
	107	* End access through the given grant reference, iff the grant entry is no
	108	* longer in use. Return 1 if the grant entry was freed, 0 if it is still in
	109	* use.
	110	*/
	111	int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly);
	112
	113	/*
	114	* Eventually end access through the given grant reference, and once that
	115	* access has been ended, free the given page too. Access will be ended
	116	* immediately iff the grant entry is not in use, otherwise it will happen
	117	* some time later. page may be 0, in which case no freeing will occur.
	118	*/
	119	void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
	120	unsigned long page);
	121
	122	int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn);
	123
	124	unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref);
	125	unsigned long gnttab_end_foreign_transfer(grant_ref_t ref);
	126
	127	int gnttab_query_foreign_access(grant_ref_t ref);
	128
	129	/*
	130	* operations on reserved batches of grant references
	131	*/
	132	int gnttab_alloc_grant_references(u16 count, grant_ref_t *pprivate_head);
	133
	134	void gnttab_free_grant_reference(grant_ref_t ref);
	135
	136	void gnttab_free_grant_references(grant_ref_t head);
	137
	138	int gnttab_empty_grant_references(const grant_ref_t *pprivate_head);
	139
	140	int gnttab_claim_grant_reference(grant_ref_t *pprivate_head);
	141
	142	void gnttab_release_grant_reference(grant_ref_t *private_head,
	143	grant_ref_t release);
	144
	145	void gnttab_request_free_callback(struct gnttab_free_callback *callback,
	146	void (fn)(void ), void *arg, u16 count);
	147	void gnttab_cancel_free_callback(struct gnttab_free_callback *callback);
	148
	149	void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
	150	unsigned long frame, int readonly);
b988b8ff JG	151	int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
	152	unsigned long frame, int flags,
	153	unsigned page_off,
	154	unsigned length);
	155	int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
	156	int flags, domid_t trans_domid,
	157	grant_ref_t trans_gref);
ad9a8612	158
3922f32c JG	159	/* Give access to the first 4K of the page */
	160	static inline void gnttab_page_grant_foreign_access_ref_one(
	161	grant_ref_t ref, domid_t domid,
	162	struct page *page, int readonly)
	163	{
	164	gnttab_grant_foreign_access_ref(ref, domid, xen_page_to_gfn(page),
	165	readonly);
	166	}
	167
ad9a8612 JF	168	void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
	169	unsigned long pfn);
	170
f0774532 IC	171	static inline void
	172	gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr,
	173	uint32_t flags, grant_ref_t ref, domid_t domid)
	174	{
	175	if (flags & GNTMAP_contains_pte)
	176	map->host_addr = addr;
	177	else if (xen_feature(XENFEAT_auto_translated_physmap))
	178	map->host_addr = __pa(addr);
	179	else
	180	map->host_addr = addr;
	181
	182	map->flags = flags;
	183	map->ref = ref;
	184	map->dom = domid;
	185	}
	186
	187	static inline void
	188	gnttab_set_unmap_op(struct gnttab_unmap_grant_ref *unmap, phys_addr_t addr,
	189	uint32_t flags, grant_handle_t handle)
	190	{
	191	if (flags & GNTMAP_contains_pte)
	192	unmap->host_addr = addr;
	193	else if (xen_feature(XENFEAT_auto_translated_physmap))
	194	unmap->host_addr = __pa(addr);
	195	else
	196	unmap->host_addr = addr;
	197
	198	unmap->handle = handle;
	199	unmap->dev_bus_addr = 0;
	200	}
	201
b988b8ff	202	int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status);
ef32f892	203	int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
8d3d2106	204	unsigned long max_nr_gframes,
0f9f5a95	205	void **__shared);
b988b8ff JG	206	int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
	207	unsigned long max_nr_gframes,
	208	grant_status_t **__shared);
85ff6acb	209	void arch_gnttab_unmap(void *shared, unsigned long nr_gframes);
8d3d2106	210
efaf30a3 KRW	211	struct grant_frames {
	212	xen_pfn_t *pfn;
	213	unsigned int count;
	214	void *vaddr;
	215	};
	216	extern struct grant_frames xen_auto_xlat_grant_frames;
183d03cc	217	unsigned int gnttab_max_grant_frames(void);
47c54205	218	int gnttab_setup_auto_xlat_frames(phys_addr_t addr);
efaf30a3	219	void gnttab_free_auto_xlat_frames(void);
183d03cc	220
ad9a8612 JF	221	#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))
ad9a8612 JF	222
ff4b156f DV	223	int gnttab_alloc_pages(int nr_pages, struct page **pages);
	224	void gnttab_free_pages(int nr_pages, struct page **pages);
	225
289b777e	226	int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
e85fc980	227	struct gnttab_map_grant_ref *kmap_ops,
289b777e SS	228	struct page **pages, unsigned int count);
289b777e SS	229	int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
853d0289	230	struct gnttab_unmap_grant_ref *kunmap_ops,
2fc136ee	231	struct page **pages, unsigned int count);
3f9f1c67	232	void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
b44166cd	233	int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item);
3f9f1c67	234
289b777e	235
c571898f ALC	236	/* Perform a batch of grant map/copy operations. Retry every batch slot
	237	* for which the hypervisor returns GNTST_eagain. This is typically due
	238	* to paged out target frames.
	239	*
	240	* Will retry for 1, 2, ... 255 ms, i.e. 256 times during 32 seconds.
	241	*
	242	* Return value in each iand every status field of the batch guaranteed
	243	* to not be GNTST_eagain.
	244	*/
	245	void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count);
	246	void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count);
	247
8da7633f JH	248
	249	struct xen_page_foreign {
	250	domid_t domid;
	251	grant_ref_t gref;
	252	};
	253
	254	static inline struct xen_page_foreign xen_page_foreign(struct page page)
	255	{
	256	if (!PageForeign(page))
	257	return NULL;
	258	#if BITS_PER_LONG < 64
	259	return (struct xen_page_foreign *)page->private;
	260	#else
	261	BUILD_BUG_ON(sizeof(struct xen_page_foreign) > BITS_PER_LONG);
	262	return (struct xen_page_foreign *)&page->private;
	263	#endif
	264	}
	265
008c320a JG	266	/* Split Linux page in chunk of the size of the grant and call fn
	267	*
	268	* Parameters of fn:
	269	* gfn: guest frame number
	270	* offset: offset in the grant
	271	* len: length of the data in the grant.
	272	* data: internal information
	273	*/
	274	typedef void (*xen_grant_fn_t)(unsigned long gfn, unsigned int offset,
	275	unsigned int len, void *data);
	276
	277	void gnttab_foreach_grant_in_range(struct page *page,
	278	unsigned int offset,
	279	unsigned int len,
	280	xen_grant_fn_t fn,
	281	void *data);
	282
	283	/* Helper to get to call fn only on the first "grant chunk" */
	284	static inline void gnttab_for_one_grant(struct page *page, unsigned int offset,
	285	unsigned len, xen_grant_fn_t fn,
	286	void *data)
	287	{
	288	/* The first request is limited to the size of one grant */
	289	len = min_t(unsigned int, XEN_PAGE_SIZE - (offset & ~XEN_PAGE_MASK),
	290	len);
	291
	292	gnttab_foreach_grant_in_range(page, offset, len, fn, data);
	293	}
	294
f73314b2 JG	295	/* Get @nr_grefs grants from an array of page and call fn for each grant */
	296	void gnttab_foreach_grant(struct page **pages,
	297	unsigned int nr_grefs,
	298	xen_grant_fn_t fn,
	299	void *data);
	300
008c320a JG	301	/* Get the number of grant in a specified region
	302	*
	303	* start: Offset from the beginning of the first page
	304	* len: total length of data (can cross multiple page)
	305	*/
	306	static inline unsigned int gnttab_count_grant(unsigned int start,
	307	unsigned int len)
	308	{
	309	return XEN_PFN_UP(xen_offset_in_page(start) + len);
	310	}
	311
ad9a8612	312	#endif /* __ASM_GNTTAB_H__ */