name : xen-front-pgdir-shbuf.h /* 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_ */