summaryrefslogtreecommitdiffstats
path: root/include/xen/xen-front-pgdir-shbuf.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/xen/xen-front-pgdir-shbuf.h')
-rw-r--r--include/xen/xen-front-pgdir-shbuf.h89
1 files changed, 89 insertions, 0 deletions
diff --git a/include/xen/xen-front-pgdir-shbuf.h b/include/xen/xen-front-pgdir-shbuf.h
new file mode 100644
index 000000000..150ef7ec5
--- /dev/null
+++ b/include/xen/xen-front-pgdir-shbuf.h
@@ -0,0 +1,89 @@
+/* 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_ */