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#if defined(__xpv)
30#include <sys/hypervisor.h>
31#endif
32
33int
34plat_hold_page(pfn_t pfn, int lock, page_t **pp_ret)
35{
36	page_t *pp = page_numtopp_nolock(pfn);
37
38	if (pp == NULL)
39		return (PLAT_HOLD_FAIL);
40
41#if !defined(__xpv)
42	/*
43	 * Pages are locked SE_SHARED because some hypervisors
44	 * like xVM ESX reclaim Guest OS memory by locking
45	 * it SE_EXCL so we want to leave these pages alone.
46	 */
47	if (lock == PLAT_HOLD_LOCK) {
48		ASSERT(pp_ret != NULL);
49		if (page_trylock(pp, SE_SHARED) == 0)
50			return (PLAT_HOLD_FAIL);
51	}
52#else	/* __xpv */
53	if (lock == PLAT_HOLD_LOCK) {
54		ASSERT(pp_ret != NULL);
55		if (page_trylock(pp, SE_EXCL) == 0)
56			return (PLAT_HOLD_FAIL);
57	}
58
59	if (mfn_list[pfn] == MFN_INVALID) {
60		/* We failed - release the lock if we grabbed it earlier */
61		if (lock == PLAT_HOLD_LOCK) {
62			page_unlock(pp);
63		}
64		return (PLAT_HOLD_FAIL);
65	}
66#endif	/* __xpv */
67
68	if (lock == PLAT_HOLD_LOCK)
69		*pp_ret = pp;
70
71	return (PLAT_HOLD_OK);
72}
73
74void
75plat_release_page(page_t *pp)
76{
77	ASSERT((pp != NULL) && PAGE_LOCKED(pp));
78	page_unlock(pp);
79}
80