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>
27  * buffer. This structure is common to many Xen para-virtualized
45 	 * e.g. if grefs are required for page directory only or the buffer
50 	/* Fill page directory according to para-virtual display protocol. */
66  * page directory. Usually this is passed to the backend,
70  * \param buf shared buffer which page directory is of interest.
72  * page directory.
77 	if (!buf->grefs)  in xen_front_pgdir_shbuf_get_dir_start()
80 	return buf->grefs[0];  in xen_front_pgdir_shbuf_get_dir_start()
90  * references onto the backing storage (buf->pages).
97 	if (buf->ops && buf->ops->map)  in xen_front_pgdir_shbuf_map()
98 		return buf->ops->map(buf);  in xen_front_pgdir_shbuf_map()
118 	if (buf->ops && buf->ops->unmap)  in xen_front_pgdir_shbuf_unmap()
119 		return buf->ops->unmap(buf);  in xen_front_pgdir_shbuf_unmap()
133 	if (buf->grefs) {  in xen_front_pgdir_shbuf_free()
136 		for (i = 0; i < buf->num_grefs; i++)  in xen_front_pgdir_shbuf_free()
137 			if (buf->grefs[i] != INVALID_GRANT_REF)  in xen_front_pgdir_shbuf_free()
138 				gnttab_end_foreign_access(buf->grefs[i], NULL);  in xen_front_pgdir_shbuf_free()
140 	kfree(buf->grefs);  in xen_front_pgdir_shbuf_free()
141 	kfree(buf->directory);  in xen_front_pgdir_shbuf_free()
149 #define XEN_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
154  * Get the number of pages the page directory consumes itself.
160 	return DIV_ROUND_UP(buf->num_pages, XEN_NUM_GREFS_PER_PAGE);  in get_num_pages_dir()
171 	/* Only for pages the page directory consumes itself. */  in backend_calc_num_grefs()
172 	buf->num_grefs = get_num_pages_dir(buf);  in backend_calc_num_grefs()
184 	 * Number of pages the page directory consumes itself  in guest_calc_num_grefs()
187 	buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;  in guest_calc_num_grefs()
205 	if (!buf->pages || !buf->backend_map_handles || !buf->grefs)  in backend_unmap()
208 	unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),  in backend_unmap()
211 		return -ENOMEM;  in backend_unmap()
213 	for (i = 0; i < buf->num_pages; i++) {  in backend_unmap()
216 		addr = xen_page_to_vaddr(buf->pages[i]);  in backend_unmap()
218 				    buf->backend_map_handles[i]);  in backend_unmap()
221 	ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,  in backend_unmap()
222 				buf->num_pages);  in backend_unmap()
224 	for (i = 0; i < buf->num_pages; i++) {  in backend_unmap()
226 			dev_err(&buf->xb_dev->dev,  in backend_unmap()
232 		dev_err(&buf->xb_dev->dev,  in backend_unmap()
236 	kfree(buf->backend_map_handles);  in backend_unmap()
237 	buf->backend_map_handles = NULL;  in backend_unmap()
253 	map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);  in backend_map()
255 		return -ENOMEM;  in backend_map()
257 	buf->backend_map_handles = kcalloc(buf->num_pages,  in backend_map()
258 					   sizeof(*buf->backend_map_handles),  in backend_map()
260 	if (!buf->backend_map_handles) {  in backend_map()
262 		return -ENOMEM;  in backend_map()
266 	 * Read page directory to get grefs from the backend: for external  in backend_map()
267 	 * buffer we only allocate buf->grefs for the page directory,  in backend_map()
268 	 * so buf->num_grefs has number of pages in the page directory itself.  in backend_map()
270 	ptr = buf->directory;  in backend_map()
271 	grefs_left = buf->num_pages;  in backend_map()
273 	for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; cur_dir_page++) {  in backend_map()
284 			addr = xen_page_to_vaddr(buf->pages[cur_page]);  in backend_map()
287 					  page_dir->gref[cur_gref],  in backend_map()
288 					  buf->xb_dev->otherend_id);  in backend_map()
292 		grefs_left -= to_copy;  in backend_map()
295 	ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);  in backend_map()
298 	for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {  in backend_map()
300 			buf->backend_map_handles[cur_page] =  in backend_map()
303 			buf->backend_map_handles[cur_page] =  in backend_map()
306 				ret = -ENXIO;  in backend_map()
307 			dev_err(&buf->xb_dev->dev,  in backend_map()
314 		dev_err(&buf->xb_dev->dev,  in backend_map()
324  * Fill page directory with grant references to the pages of the
325  * page directory itself.
338 	ptr = buf->directory;  in backend_fill_page_dir()
341 	/* Fill only grefs for the page directory itself. */  in backend_fill_page_dir()
342 	for (i = 0; i < num_pages_dir - 1; i++) {  in backend_fill_page_dir()
345 		page_dir->gref_dir_next_page = buf->grefs[i + 1];  in backend_fill_page_dir()
350 	page_dir->gref_dir_next_page = XEN_GREF_LIST_END;  in backend_fill_page_dir()
354  * Fill page directory with grant references to the pages of the
355  * page directory and the buffer we share with the backend.
364 	ptr = buf->directory;  in guest_fill_page_dir()
369 	 * granted for the page directory itself.  in guest_fill_page_dir()
372 	grefs_left = buf->num_pages;  in guest_fill_page_dir()
379 			page_dir->gref_dir_next_page = XEN_GREF_LIST_END;  in guest_fill_page_dir()
382 			page_dir->gref_dir_next_page = buf->grefs[i + 1];  in guest_fill_page_dir()
384 		memcpy(&page_dir->gref, &buf->grefs[cur_gref],  in guest_fill_page_dir()
387 		grefs_left -= to_copy;  in guest_fill_page_dir()
407 	otherend_id = buf->xb_dev->otherend_id;  in guest_grant_refs_for_buffer()
408 	for (i = 0; i < buf->num_pages; i++) {  in guest_grant_refs_for_buffer()
414 						xen_page_to_gfn(buf->pages[i]),  in guest_grant_refs_for_buffer()
416 		buf->grefs[gref_idx++] = cur_ref;  in guest_grant_refs_for_buffer()
424  * Grant references to the page directory pages and, if
436 	ret = gnttab_alloc_grant_references(buf->num_grefs, &priv_gref_head);  in grant_references()
438 		dev_err(&buf->xb_dev->dev,  in grant_references()
443 	otherend_id = buf->xb_dev->otherend_id;  in grant_references()
453 		frame = xen_page_to_gfn(virt_to_page(buf->directory +  in grant_references()
456 		buf->grefs[j++] = cur_ref;  in grant_references()
459 	if (buf->ops->grant_refs_for_buffer) {  in grant_references()
460 		ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j);  in grant_references()
477 	buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL);  in alloc_storage()
478 	if (!buf->grefs)  in alloc_storage()
479 		return -ENOMEM;  in alloc_storage()
481 	buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL);  in alloc_storage()
482 	if (!buf->directory)  in alloc_storage()
483 		return -ENOMEM;  in alloc_storage()
517 	struct xen_front_pgdir_shbuf *buf = cfg->pgdir;  in xen_front_pgdir_shbuf_alloc()
520 	if (cfg->be_alloc)  in xen_front_pgdir_shbuf_alloc()
521 		buf->ops = &backend_ops;  in xen_front_pgdir_shbuf_alloc()
523 		buf->ops = &local_ops;  in xen_front_pgdir_shbuf_alloc()
524 	buf->xb_dev = cfg->xb_dev;  in xen_front_pgdir_shbuf_alloc()
525 	buf->num_pages = cfg->num_pages;  in xen_front_pgdir_shbuf_alloc()
526 	buf->pages = cfg->pages;  in xen_front_pgdir_shbuf_alloc()
528 	buf->ops->calc_num_grefs(buf);  in xen_front_pgdir_shbuf_alloc()
538 	buf->ops->fill_page_dir(buf);  in xen_front_pgdir_shbuf_alloc()
548 MODULE_DESCRIPTION("Xen frontend/backend page directory based "