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/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/*
* Xen frontend/backend page directory based shared buffer
* helper module.
*
* Copyright (C) 2018 EPAM Systems Inc.
*
* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
*/
#ifndef __XEN_FRONT_PGDIR_SHBUF_H_
#define __XEN_FRONT_PGDIR_SHBUF_H_
#include <linux/kernel.h>
#include <xen/grant_table.h>
struct xen_front_pgdir_shbuf_ops;
struct xen_front_pgdir_shbuf {
/*
* Number of references granted for the backend use:
*
* - for frontend allocated/imported buffers this holds the number
* of grant references for the page directory and the pages
* of the buffer
*
* - for the buffer provided by the backend this only holds the number
* of grant references for the page directory itself as grant
* references for the buffer will be provided by the backend.
*/
int num_grefs;
grant_ref_t *grefs;
/* Page directory backing storage. */
u8 *directory;
/*
* Number of pages for the shared buffer itself (excluding the page
* directory).
*/
int num_pages;
/*
* Backing storage of the shared buffer: these are the pages being
* shared.
*/
struct page **pages;
struct xenbus_device *xb_dev;
/* These are the ops used internally depending on be_alloc mode. */
const struct xen_front_pgdir_shbuf_ops *ops;
/* Xen map handles for the buffer allocated by the backend. */
grant_handle_t *backend_map_handles;
};
struct xen_front_pgdir_shbuf_cfg {
struct xenbus_device *xb_dev;
/* Number of pages of the buffer backing storage. */
int num_pages;
/* Pages of the buffer to be shared. */
struct page **pages;
/*
* This is allocated outside because there are use-cases when
* the buffer structure is allocated as a part of a bigger one.
*/
struct xen_front_pgdir_shbuf *pgdir;
/*
* Mode of grant reference sharing: if set then backend will share
* grant references to the buffer with the frontend.
*/
int be_alloc;
};
int xen_front_pgdir_shbuf_alloc(struct xen_front_pgdir_shbuf_cfg *cfg);
grant_ref_t
xen_front_pgdir_shbuf_get_dir_start(struct xen_front_pgdir_shbuf *buf);
int xen_front_pgdir_shbuf_map(struct xen_front_pgdir_shbuf *buf);
int xen_front_pgdir_shbuf_unmap(struct xen_front_pgdir_shbuf *buf);
void xen_front_pgdir_shbuf_free(struct xen_front_pgdir_shbuf *buf);
#endif /* __XEN_FRONT_PGDIR_SHBUF_H_ */
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