hold_page.h revision ae115bc77f6fcde83175c75b4206dc2e50747966
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _SYS_HOLD_PAGE_H
#define _SYS_HOLD_PAGE_H
#pragma ident "%Z%%M% %I% %E% SMI"
#ifdef __cplusplus
extern "C" {
#endif
/*
* swrand generates entropy by mapping different pages in the system. This
* can create problems for some hypervisors, as certain pages may be removed
* from the system at any time. The following interfaces allow swrand to
* check the validity and make sure a page is not given away while it is mapped.
*
* int plat_hold_page(pfn_t pfn, int lock, page_t **pp_ret)
*
* If lock is PLAT_HOLD_NO_LOCK, simply check if the page pfn is valid
* in the system. If the page is valid, PLAT_HOLD_OK will be returned.
* pp_ret is ignored if lock is PLAT_HOLD_NO_LOCK.
*
* If lock is PLAT_HOLD_LOCK, in addition to the above, attempt to lock
* the page exclusively. Again, if the lock is successful, the page
* pointer will be put in pp, and PLAT_HOLD_OK will be returned. pp_ret
* must be passed to a later call to plat_release_page. If the page
* wasn't found, or the lock couldn't be grabbed, the return value will
* be PLAT_HOLD_FAIL.
*
* void plat_release_page(page_t *pp)
*
* Unlock the page pp. Should only be called after a previous,
* successful call to plat_release_page(pfn, PLAT_HOLD_LOCK, &pp);
*/
#define PLAT_HOLD_NO_LOCK 0
#define PLAT_HOLD_LOCK 1
#define PLAT_HOLD_OK 0
#define PLAT_HOLD_FAIL 1
extern void plat_release_page(page_t *);
#ifdef __cplusplus
}
#endif
#endif /* _SYS_HOLD_PAGE_H */