1 // SPDX-License-Identifier: GPL-2.0 OR MIT
4  * Xen frontend/backend page directory based shared buffer
22 #include <xen/xen-front-pgdir-shbuf.h>
36  * buffer. This structure is common to many Xen para-virtualized
47  * is allocated by the corresponding backend or frontend.
58 	/* Fill page directory according to para-virtual display protocol. */
74  * page directory. Usually this is passed to the backend,
85 	if (!buf->grefs)  in xen_front_pgdir_shbuf_get_dir_start()
88 	return buf->grefs[0];  in xen_front_pgdir_shbuf_get_dir_start()
98  * references onto the backing storage (buf->pages).
105 	if (buf->ops && buf->ops->map)  in xen_front_pgdir_shbuf_map()
106 		return buf->ops->map(buf);  in xen_front_pgdir_shbuf_map()
126 	if (buf->ops && buf->ops->unmap)  in xen_front_pgdir_shbuf_unmap()
127 		return buf->ops->unmap(buf);  in xen_front_pgdir_shbuf_unmap()
141 	if (buf->grefs) {  in xen_front_pgdir_shbuf_free()
144 		for (i = 0; i < buf->num_grefs; i++)  in xen_front_pgdir_shbuf_free()
145 			if (buf->grefs[i] != GRANT_INVALID_REF)  in xen_front_pgdir_shbuf_free()
146 				gnttab_end_foreign_access(buf->grefs[i],  in xen_front_pgdir_shbuf_free()
149 	kfree(buf->grefs);  in xen_front_pgdir_shbuf_free()
150 	kfree(buf->directory);  in xen_front_pgdir_shbuf_free()
158 #define XEN_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
169 	return DIV_ROUND_UP(buf->num_pages, XEN_NUM_GREFS_PER_PAGE);  in get_num_pages_dir()
174  * and its pages when backend allocates the buffer.
181 	buf->num_grefs = get_num_pages_dir(buf);  in backend_calc_num_grefs()
196 	buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;  in guest_calc_num_grefs()
204  * provided by the backend.
214 	if (!buf->pages || !buf->backend_map_handles || !buf->grefs)  in backend_unmap()
217 	unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),  in backend_unmap()
220 		return -ENOMEM;  in backend_unmap()
222 	for (i = 0; i < buf->num_pages; i++) {  in backend_unmap()
225 		addr = xen_page_to_vaddr(buf->pages[i]);  in backend_unmap()
227 				    buf->backend_map_handles[i]);  in backend_unmap()
230 	ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,  in backend_unmap()
231 				buf->num_pages);  in backend_unmap()
233 	for (i = 0; i < buf->num_pages; i++) {  in backend_unmap()
235 			dev_err(&buf->xb_dev->dev,  in backend_unmap()
241 		dev_err(&buf->xb_dev->dev,  in backend_unmap()
245 	kfree(buf->backend_map_handles);  in backend_unmap()
246 	buf->backend_map_handles = NULL;  in backend_unmap()
251  * Map the buffer with grant references provided by the backend.
262 	map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);  in backend_map()
264 		return -ENOMEM;  in backend_map()
266 	buf->backend_map_handles = kcalloc(buf->num_pages,  in backend_map()
267 					   sizeof(*buf->backend_map_handles),  in backend_map()
269 	if (!buf->backend_map_handles) {  in backend_map()
271 		return -ENOMEM;  in backend_map()
275 	 * Read page directory to get grefs from the backend: for external  in backend_map()
276 	 * buffer we only allocate buf->grefs for the page directory,  in backend_map()
277 	 * so buf->num_grefs has number of pages in the page directory itself.  in backend_map()
279 	ptr = buf->directory;  in backend_map()
280 	grefs_left = buf->num_pages;  in backend_map()
282 	for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; cur_dir_page++) {  in backend_map()
293 			addr = xen_page_to_vaddr(buf->pages[cur_page]);  in backend_map()
296 					  page_dir->gref[cur_gref],  in backend_map()
297 					  buf->xb_dev->otherend_id);  in backend_map()
301 		grefs_left -= to_copy;  in backend_map()
304 	ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);  in backend_map()
307 	for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {  in backend_map()
308 		buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;  in backend_map()
310 			dev_err(&buf->xb_dev->dev,  in backend_map()
316 		dev_err(&buf->xb_dev->dev,  in backend_map()
330  * backend in this case.
340 	ptr = buf->directory;  in backend_fill_page_dir()
344 	for (i = 0; i < num_pages_dir - 1; i++) {  in backend_fill_page_dir()
347 		page_dir->gref_dir_next_page = buf->grefs[i + 1];  in backend_fill_page_dir()
352 	page_dir->gref_dir_next_page = GRANT_INVALID_REF;  in backend_fill_page_dir()
357  * page directory and the buffer we share with the backend.
366 	ptr = buf->directory;  in guest_fill_page_dir()
374 	grefs_left = buf->num_pages;  in guest_fill_page_dir()
381 			page_dir->gref_dir_next_page = GRANT_INVALID_REF;  in guest_fill_page_dir()
384 			page_dir->gref_dir_next_page = buf->grefs[i + 1];  in guest_fill_page_dir()
386 		memcpy(&page_dir->gref, &buf->grefs[cur_gref],  in guest_fill_page_dir()
389 		grefs_left -= to_copy;  in guest_fill_page_dir()
397  * These will be shared with the backend, so it can
409 	otherend_id = buf->xb_dev->otherend_id;  in guest_grant_refs_for_buffer()
410 	for (i = 0; i < buf->num_pages; i++) {  in guest_grant_refs_for_buffer()
416 						xen_page_to_gfn(buf->pages[i]),  in guest_grant_refs_for_buffer()
418 		buf->grefs[gref_idx++] = cur_ref;  in guest_grant_refs_for_buffer()
438 	ret = gnttab_alloc_grant_references(buf->num_grefs, &priv_gref_head);  in grant_references()
440 		dev_err(&buf->xb_dev->dev,  in grant_references()
445 	otherend_id = buf->xb_dev->otherend_id;  in grant_references()
455 		frame = xen_page_to_gfn(virt_to_page(buf->directory +  in grant_references()
458 		buf->grefs[j++] = cur_ref;  in grant_references()
461 	if (buf->ops->grant_refs_for_buffer) {  in grant_references()
462 		ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j);  in grant_references()
479 	buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL);  in alloc_storage()
480 	if (!buf->grefs)  in alloc_storage()
481 		return -ENOMEM;  in alloc_storage()
483 	buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL);  in alloc_storage()
484 	if (!buf->directory)  in alloc_storage()
485 		return -ENOMEM;  in alloc_storage()
491  * For backend allocated buffers we don't need grant_refs_for_buffer
492  * as those grant references are allocated at backend side.
519 	struct xen_front_pgdir_shbuf *buf = cfg->pgdir;  in xen_front_pgdir_shbuf_alloc()
522 	if (cfg->be_alloc)  in xen_front_pgdir_shbuf_alloc()
523 		buf->ops = &backend_ops;  in xen_front_pgdir_shbuf_alloc()
525 		buf->ops = &local_ops;  in xen_front_pgdir_shbuf_alloc()
526 	buf->xb_dev = cfg->xb_dev;  in xen_front_pgdir_shbuf_alloc()
527 	buf->num_pages = cfg->num_pages;  in xen_front_pgdir_shbuf_alloc()
528 	buf->pages = cfg->pages;  in xen_front_pgdir_shbuf_alloc()
530 	buf->ops->calc_num_grefs(buf);  in xen_front_pgdir_shbuf_alloc()
540 	buf->ops->fill_page_dir(buf);  in xen_front_pgdir_shbuf_alloc()
550 MODULE_DESCRIPTION("Xen frontend/backend page directory based "