arch/x86/kernel/platform/i86pc/os/hold_page.c

   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 /*
  23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #include <sys/hold_page.h>
  28
  29
  30 int
  31 plat_hold_page(pfn_t pfn, int lock, page_t **pp_ret)
  32 {
  33         page_t *pp = page_numtopp_nolock(pfn);
  34
  35         if (pp == NULL)
  36                 return (PLAT_HOLD_FAIL);
  37
  38         /*
  39          * Pages are locked SE_SHARED because some hypervisors
  40          * like xVM ESX reclaim Guest OS memory by locking
  41          * it SE_EXCL so we want to leave these pages alone.
  42          */
  43         if (lock == PLAT_HOLD_LOCK) {
  44                 ASSERT(pp_ret != NULL);
  45                 if (page_trylock(pp, SE_SHARED) == 0)
  46                         return (PLAT_HOLD_FAIL);
  47         }
  48
  49         if (lock == PLAT_HOLD_LOCK)
  50                 *pp_ret = pp;
  51
  52         return (PLAT_HOLD_OK);
  53 }
  54
  55 void
  56 plat_release_page(page_t *pp)
  57 {
  58         ASSERT((pp != NULL) && PAGE_LOCKED(pp));
  59         page_unlock(pp);
  60 }