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 * 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>

/*
 * Technically there's no reliably invalid grant reference or grant handle,
 * so pick the value that is the most unlikely one to be observed valid.
 */
#define INVALID_GRANT_REF          ((grant_ref_t)-1)
#define INVALID_GRANT_HANDLE       ((grant_handle_t)-1)

#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);

/*
 * 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