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