1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #ifndef _SYS_HOLD_PAGE_H 27 #define _SYS_HOLD_PAGE_H 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 #include <sys/types.h> 34 #include <vm/page.h> 35 36 /* 37 * swrand generates entropy by mapping different pages in the system. This 38 * can create problems for some hypervisors, as certain pages may be removed 39 * from the system at any time. The following interfaces allow swrand to 40 * check the validity and make sure a page is not given away while it is mapped. 41 * 42 * int plat_hold_page(pfn_t pfn, int lock, page_t **pp_ret) 43 * 44 * If lock is PLAT_HOLD_NO_LOCK, simply check if the page pfn is valid 45 * in the system. If the page is valid, PLAT_HOLD_OK will be returned. 46 * pp_ret is ignored if lock is PLAT_HOLD_NO_LOCK. 47 * 48 * If lock is PLAT_HOLD_LOCK, in addition to the above, attempt to lock 49 * the page exclusively. Again, if the lock is successful, the page 50 * pointer will be put in pp_ret, and PLAT_HOLD_OK will be returned. 51 * pp_ret must be passed to a later call to plat_release_page. If the 52 * page wasn't found, or the lock couldn't be grabbed, the return value 53 * will be PLAT_HOLD_FAIL. 54 * 55 * void plat_release_page(page_t *pp) 56 * 57 * Unlock the page pp. Should only be called after a previous, 58 * successful call to plat_hold_page(pfn, PLAT_HOLD_LOCK, &pp); 59 */ 60 61 #define PLAT_HOLD_NO_LOCK 0 62 #define PLAT_HOLD_LOCK 1 63 64 #define PLAT_HOLD_OK 0 65 #define PLAT_HOLD_FAIL 1 66 67 extern int plat_hold_page(pfn_t, int, page_t **); 68 extern void plat_release_page(page_t *); 69 70 #ifdef __cplusplus 71 } 72 #endif 73 74 #endif /* _SYS_HOLD_PAGE_H */ 75