MMPagePool.cpp@ 20062

Last change on this file since 20062 was 20011, checked in by vboxsync, 16 years ago
VMM: fix a typo in mmR3PagePoolAlloc() if the memory allocation failed for some reason
Property svn:eol-style set to `native` Property svn:keywords set to `Id`
File size: 18.4 KB

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1	/* $Id: MMPagePool.cpp 20011 2009-05-25 19:31:11Z vboxsync $ */
2	/** @file
3	* MM - Memory Manager - Page Pool.
4	*/
5
6	/*
7	* Copyright (C) 2006-2007 Sun Microsystems, Inc.
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*
17	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
18	* Clara, CA 95054 USA or visit http://www.sun.com if you need
19	* additional information or have any questions.
20	*/
21
22	/*******************************************************************************
23	* Header Files *
24	*******************************************************************************/
25	#define LOG_GROUP LOG_GROUP_MM_POOL
26	#include <VBox/mm.h>
27	#include <VBox/pgm.h>
28	#include <VBox/stam.h>
29	#include "MMInternal.h"
30	#include <VBox/vm.h>
31	#include <VBox/param.h>
32	#include <VBox/err.h>
33	#include <VBox/log.h>
34	#include <iprt/alloc.h>
35	#include <iprt/assert.h>
36	#define USE_INLINE_ASM_BIT_OPS
37	#ifdef USE_INLINE_ASM_BIT_OPS
38	# include <iprt/asm.h>
39	#endif
40	#include <iprt/string.h>
41
42
43
44	/*******************************************************************************
45	* Internal Functions *
46	*******************************************************************************/
47	#ifdef IN_RING3
48	static void * mmR3PagePoolAlloc(PMMPAGEPOOL pPool);
49	static void mmR3PagePoolFree(PMMPAGEPOOL pPool, void *pv);
50	#endif
51
52
53	/**
54	* Initializes the page pool
55	*
56	* @return VBox status.
57	* @param pVM VM handle.
58	* @thread The Emulation Thread.
59	*/
60	int mmR3PagePoolInit(PVM pVM)
61	{
62	AssertMsg(!pVM->mm.s.pPagePoolR3, ("Already initialized!\n"));
63
64	/*
65	* Allocate the pool structures.
66	*/
67	/** @todo @bufref{1865},@bufref{3202}: mapping the page pool page into
68	* ring-0. Need to change the wasy we allocate it... */
69	AssertReleaseReturn(sizeof(pVM->mm.s.pPagePoolR3) + sizeof(pVM->mm.s.pPagePoolLowR3) < PAGE_SIZE, VERR_INTERNAL_ERROR);
70	int rc = SUPPageAllocLockedEx(1, (void **)&pVM->mm.s.pPagePoolR3, NULL);
71	if (RT_FAILURE(rc))
72	return rc;
73	memset(pVM->mm.s.pPagePoolR3, 0, PAGE_SIZE);
74	pVM->mm.s.pPagePoolR3->pVM = pVM;
75	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cPages, STAMTYPE_U32, "/MM/Page/Def/cPages", STAMUNIT_PAGES, "Number of pages in the default pool.");
76	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cFreePages, STAMTYPE_U32, "/MM/Page/Def/cFreePages", STAMUNIT_PAGES, "Number of free pages in the default pool.");
77	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cSubPools, STAMTYPE_U32, "/MM/Page/Def/cSubPools", STAMUNIT_COUNT, "Number of sub pools in the default pool.");
78	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cAllocCalls, STAMTYPE_COUNTER, "/MM/Page/Def/cAllocCalls", STAMUNIT_CALLS, "Number of MMR3PageAlloc() calls for the default pool.");
79	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cFreeCalls, STAMTYPE_COUNTER, "/MM/Page/Def/cFreeCalls", STAMUNIT_CALLS, "Number of MMR3PageFree()+MMR3PageFreeByPhys() calls for the default pool.");
80	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cToPhysCalls, STAMTYPE_COUNTER, "/MM/Page/Def/cToPhysCalls", STAMUNIT_CALLS, "Number of MMR3Page2Phys() calls for this pool.");
81	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cToVirtCalls, STAMTYPE_COUNTER, "/MM/Page/Def/cToVirtCalls", STAMUNIT_CALLS, "Number of MMR3PagePhys2Page()+MMR3PageFreeByPhys() calls for the default pool.");
82	STAM_REG(pVM, &pVM->mm.s.pPagePoolR3->cErrors, STAMTYPE_COUNTER, "/MM/Page/Def/cErrors", STAMUNIT_ERRORS,"Number of errors for the default pool.");
83
84	pVM->mm.s.pPagePoolLowR3 = pVM->mm.s.pPagePoolR3 + 1;
85	pVM->mm.s.pPagePoolLowR3->pVM = pVM;
86	pVM->mm.s.pPagePoolLowR3->fLow = true;
87	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cPages, STAMTYPE_U32, "/MM/Page/Low/cPages", STAMUNIT_PAGES, "Number of pages in the <4GB pool.");
88	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cFreePages, STAMTYPE_U32, "/MM/Page/Low/cFreePages", STAMUNIT_PAGES, "Number of free pages in the <4GB pool.");
89	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cSubPools, STAMTYPE_U32, "/MM/Page/Low/cSubPools", STAMUNIT_COUNT, "Number of sub pools in the <4GB pool.");
90	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cAllocCalls, STAMTYPE_COUNTER, "/MM/Page/Low/cAllocCalls", STAMUNIT_CALLS, "Number of MMR3PageAllocLow() calls for the <4GB pool.");
91	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cFreeCalls, STAMTYPE_COUNTER, "/MM/Page/Low/cFreeCalls", STAMUNIT_CALLS, "Number of MMR3PageFreeLow()+MMR3PageFreeByPhys() calls for the <4GB pool.");
92	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cToPhysCalls,STAMTYPE_COUNTER, "/MM/Page/Low/cToPhysCalls", STAMUNIT_CALLS, "Number of MMR3Page2Phys() calls for the <4GB pool.");
93	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cToVirtCalls,STAMTYPE_COUNTER, "/MM/Page/Low/cToVirtCalls", STAMUNIT_CALLS, "Number of MMR3PagePhys2Page()+MMR3PageFreeByPhys() calls for the <4GB pool.");
94	STAM_REG(pVM, &pVM->mm.s.pPagePoolLowR3->cErrors, STAMTYPE_COUNTER, "/MM/Page/Low/cErrors", STAMUNIT_ERRORS,"Number of errors for the <4GB pool.");
95
96	#ifndef VBOX_WITH_2X_4GB_ADDR_SPACE
97	pVM->mm.s.pPagePoolR0 = (uintptr_t)pVM->mm.s.pPagePoolR3;
98	pVM->mm.s.pPagePoolLowR0 = (uintptr_t)pVM->mm.s.pPagePoolLowR3;
99	#endif
100
101	/** @todo init a mutex? */
102	return VINF_SUCCESS;
103	}
104
105
106	/**
107	* Release all locks and free the allocated memory.
108	*
109	* @param pVM VM handle.
110	* @thread The Emulation Thread.
111	*/
112	void mmR3PagePoolTerm(PVM pVM)
113	{
114	if (pVM->mm.s.pPagePoolR3)
115	{
116	/*
117	* Unlock all memory held by subpools and free the memory.
118	* (The MM Heap will free the memory used for internal stuff.)
119	*/
120	Assert(!pVM->mm.s.pPagePoolR3->fLow);
121	PMMPAGESUBPOOL pSubPool = pVM->mm.s.pPagePoolR3->pHead;
122	while (pSubPool)
123	{
124	int rc = SUPR3PageFreeEx(pSubPool->pvPages, pSubPool->cPages);
125	AssertMsgRC(rc, ("SUPPageFree(%p) failed with rc=%Rrc\n", pSubPool->pvPages, rc));
126	pSubPool->pvPages = NULL;
127
128	/* next */
129	pSubPool = pSubPool->pNext;
130	}
131	pVM->mm.s.pPagePoolR3 = NULL;
132	#ifndef VBOX_WITH_2X_4GB_ADDR_SPACE
133	pVM->mm.s.pPagePoolR0 = NIL_RTR0PTR;
134	#endif
135	}
136
137	if (pVM->mm.s.pPagePoolLowR3)
138	{
139	/*
140	* Free the memory.
141	*/
142	Assert(pVM->mm.s.pPagePoolLowR3->fLow);
143	PMMPAGESUBPOOL pSubPool = pVM->mm.s.pPagePoolLowR3->pHead;
144	while (pSubPool)
145	{
146	int rc = SUPLowFree(pSubPool->pvPages, pSubPool->cPages);
147	AssertMsgRC(rc, ("SUPPageFree(%p) failed with rc=%d\n", pSubPool->pvPages, rc));
148	pSubPool->pvPages = NULL;
149
150	/* next */
151	pSubPool = pSubPool->pNext;
152	}
153	pVM->mm.s.pPagePoolLowR3 = NULL;
154	#ifndef VBOX_WITH_2X_4GB_ADDR_SPACE
155	pVM->mm.s.pPagePoolLowR0 = NIL_RTR0PTR;
156	#endif
157	}
158	}
159
160
161	/**
162	* Allocates a page from the page pool.
163	*
164	* @returns Pointer to allocated page(s).
165	* @returns NULL on failure.
166	* @param pPool Pointer to the page pool.
167	* @thread The Emulation Thread.
168	*/
169	DECLINLINE(void *) mmR3PagePoolAlloc(PMMPAGEPOOL pPool)
170	{
171	VM_ASSERT_EMT(pPool->pVM);
172	STAM_COUNTER_INC(&pPool->cAllocCalls);
173
174	/*
175	* Walk free list.
176	*/
177	if (pPool->pHeadFree)
178	{
179	PMMPAGESUBPOOL pSub = pPool->pHeadFree;
180	/* decrement free count and unlink if no more free entries. */
181	if (!--pSub->cPagesFree)
182	pPool->pHeadFree = pSub->pNextFree;
183	#ifdef VBOX_WITH_STATISTICS
184	pPool->cFreePages--;
185	#endif
186
187	/* find free spot in bitmap. */
188	#ifdef USE_INLINE_ASM_BIT_OPS
189	const int iPage = ASMBitFirstClear(pSub->auBitmap, pSub->cPages);
190	if (iPage >= 0)
191	{
192	Assert(!ASMBitTest(pSub->auBitmap, iPage));
193	ASMBitSet(pSub->auBitmap, iPage);
194	return (uint8_t )pSub->pvPages + PAGE_SIZE iPage;
195	}
196	#else
197	unsigned *pu = &pSub->auBitmap[0];
198	unsigned puEnd = &pSub->auBitmap[pSub->cPages / (sizeof(pSub->auBitmap) 8)];
199	while (pu < puEnd)
200	{
201	unsigned u;
202	if ((u = *pu) != ~0U)
203	{
204	unsigned iBit = 0;
205	unsigned uMask = 1;
206	while (iBit < sizeof(pSub->auBitmap[0]) * 8)
207	{
208	if (!(u & uMask))
209	{
210	*pu \|= uMask;
211	return (uint8_t *)pSub->pvPages
212	+ PAGE_SIZE * (iBit + ((uint8_t )pu - (uint8_t )&pSub->auBitmap[0]) * 8);
213	}
214	iBit++;
215	uMask <<= 1;
216	}
217	STAM_COUNTER_INC(&pPool->cErrors);
218	AssertMsgFailed(("how odd, expected to find a free bit in %#x, but didn't\n", u));
219	}
220	/* next */
221	pu++;
222	}
223	#endif
224	STAM_COUNTER_INC(&pPool->cErrors);
225	#ifdef VBOX_WITH_STATISTICS
226	pPool->cFreePages++;
227	#endif
228	AssertMsgFailed(("how strange, expected to find a free bit in %p, but didn't (%d pages supposed to be free!)\n", pSub, pSub->cPagesFree + 1));
229	}
230
231	/*
232	* Allocate new subpool.
233	*/
234	unsigned cPages = !pPool->fLow ? 128 : 32;
235	PMMPAGESUBPOOL pSub;
236	int rc = MMHyperAlloc(pPool->pVM,
237	RT_OFFSETOF(MMPAGESUBPOOL, auBitmap[cPages / (sizeof(pSub->auBitmap[0] * 8))])
238	+ (sizeof(SUPPAGE) + sizeof(MMPPLOOKUPHCPHYS)) * cPages
239	+ sizeof(MMPPLOOKUPHCPTR),
240	0,
241	MM_TAG_MM_PAGE,
242	(void **)&pSub);
243	if (RT_FAILURE(rc))
244	return NULL;
245
246	PSUPPAGE paPhysPages = (PSUPPAGE)&pSub->auBitmap[cPages / (sizeof(pSub->auBitmap[0]) * 8)];
247	Assert((uintptr_t)paPhysPages >= (uintptr_t)&pSub->auBitmap[1]);
248	if (!pPool->fLow)
249	{
250	rc = SUPR3PageAllocEx(cPages,
251	0 /* fFlags */,
252	&pSub->pvPages,
253	NULL,
254	paPhysPages);
255	if (RT_FAILURE(rc))
256	rc = VMSetError(pPool->pVM, rc, RT_SRC_POS,
257	N_("Failed to lock host %zd bytes of memory (out of memory)"), (size_t)cPages << PAGE_SHIFT);
258	}
259	else
260	rc = SUPLowAlloc(cPages, &pSub->pvPages, NULL, paPhysPages);
261	if (RT_SUCCESS(rc))
262	{
263	/*
264	* Setup the sub structure and allocate the requested page.
265	*/
266	pSub->cPages = cPages;
267	pSub->cPagesFree= cPages - 1;
268	pSub->paPhysPages = paPhysPages;
269	memset(pSub->auBitmap, 0, cPages / 8);
270	/* allocate first page. */
271	pSub->auBitmap[0] \|= 1;
272	/* link into free chain. */
273	pSub->pNextFree = pPool->pHeadFree;
274	pPool->pHeadFree= pSub;
275	/* link into main chain. */
276	pSub->pNext = pPool->pHead;
277	pPool->pHead = pSub;
278	/* update pool statistics. */
279	pPool->cSubPools++;
280	pPool->cPages += cPages;
281	#ifdef VBOX_WITH_STATISTICS
282	pPool->cFreePages += cPages - 1;
283	#endif
284
285	/*
286	* Initialize the physical pages with backpointer to subpool.
287	*/
288	unsigned i = cPages;
289	while (i-- > 0)
290	{
291	AssertMsg(paPhysPages[i].Phys && !(paPhysPages[i].Phys & PAGE_OFFSET_MASK),
292	("i=%d Phys=%d\n", i, paPhysPages[i].Phys));
293	paPhysPages[i].uReserved = (RTHCUINTPTR)pSub;
294	}
295
296	/*
297	* Initialize the physical lookup record with backpointers to the physical pages.
298	*/
299	PMMPPLOOKUPHCPHYS paLookupPhys = (PMMPPLOOKUPHCPHYS)&paPhysPages[cPages];
300	i = cPages;
301	while (i-- > 0)
302	{
303	paLookupPhys[i].pPhysPage = &paPhysPages[i];
304	paLookupPhys[i].Core.Key = paPhysPages[i].Phys;
305	RTAvlHCPhysInsert(&pPool->pLookupPhys, &paLookupPhys[i].Core);
306	}
307
308	/*
309	* And the one record for virtual memory lookup.
310	*/
311	PMMPPLOOKUPHCPTR pLookupVirt = (PMMPPLOOKUPHCPTR)&paLookupPhys[cPages];
312	pLookupVirt->pSubPool = pSub;
313	pLookupVirt->Core.Key = pSub->pvPages;
314	RTAvlPVInsert(&pPool->pLookupVirt, &pLookupVirt->Core);
315
316	/* return allocated page (first). */
317	return pSub->pvPages;
318	}
319
320	MMHyperFree(pPool->pVM, pSub);
321	STAM_COUNTER_INC(&pPool->cErrors);
322	if (pPool->fLow)
323	VMSetError(pPool->pVM, rc, RT_SRC_POS,
324	N_("Failed to expand page pool for memory below 4GB. Current size: %d pages"),
325	pPool->cPages);
326	AssertMsgFailed(("Failed to expand pool%s. rc=%Rrc poolsize=%d\n",
327	pPool->fLow ? " (<4GB)" : "", rc, pPool->cPages));
328	return NULL;
329	}
330
331
332	/**
333	* Frees a page from the page pool.
334	*
335	* @param pPool Pointer to the page pool.
336	* @param pv Pointer to the page to free.
337	* I.e. pointer returned by mmR3PagePoolAlloc().
338	* @thread The Emulation Thread.
339	*/
340	DECLINLINE(void) mmR3PagePoolFree(PMMPAGEPOOL pPool, void *pv)
341	{
342	VM_ASSERT_EMT(pPool->pVM);
343	STAM_COUNTER_INC(&pPool->cFreeCalls);
344
345	/*
346	* Lookup the virtual address.
347	*/
348	PMMPPLOOKUPHCPTR pLookup = (PMMPPLOOKUPHCPTR)RTAvlPVGetBestFit(&pPool->pLookupVirt, pv, false);
349	if ( !pLookup
350	\|\| (uint8_t )pv >= (uint8_t )pLookup->pSubPool->pvPages + (pLookup->pSubPool->cPages << PAGE_SHIFT)
351	)
352	{
353	STAM_COUNTER_INC(&pPool->cErrors);
354	AssertMsgFailed(("invalid pointer %p\n", pv));
355	return;
356	}
357
358	/*
359	* Free the page.
360	*/
361	PMMPAGESUBPOOL pSubPool = pLookup->pSubPool;
362	/* clear bitmap bit */
363	const unsigned iPage = ((uint8_t )pv - (uint8_t )pSubPool->pvPages) >> PAGE_SHIFT;
364	#ifdef USE_INLINE_ASM_BIT_OPS
365	Assert(ASMBitTest(pSubPool->auBitmap, iPage));
366	ASMBitClear(pSubPool->auBitmap, iPage);
367	#else
368	unsigned iBit = iPage % (sizeof(pSubPool->auBitmap[0]) * 8);
369	unsigned iIndex = iPage / (sizeof(pSubPool->auBitmap[0]) * 8);
370	pSubPool->auBitmap[iIndex] &= ~(1 << iBit);
371	#endif
372	/* update stats. */
373	pSubPool->cPagesFree++;
374	#ifdef VBOX_WITH_STATISTICS
375	pPool->cFreePages++;
376	#endif
377	if (pSubPool->cPagesFree == 1)
378	{
379	pSubPool->pNextFree = pPool->pHeadFree;
380	pPool->pHeadFree = pSubPool;
381	}
382	}
383
384
385	/**
386	* Allocates a page from the page pool.
387	*
388	* This function may returns pages which has physical addresses any
389	* where. If you require a page to be within the first 4GB of physical
390	* memory, use MMR3PageAllocLow().
391	*
392	* @returns Pointer to the allocated page page.
393	* @returns NULL on failure.
394	* @param pVM VM handle.
395	* @thread The Emulation Thread.
396	*/
397	VMMR3DECL(void *) MMR3PageAlloc(PVM pVM)
398	{
399	return mmR3PagePoolAlloc(pVM->mm.s.pPagePoolR3);
400	}
401
402
403	/**
404	* Allocates a page from the page pool and return its physical address.
405	*
406	* This function may returns pages which has physical addresses any
407	* where. If you require a page to be within the first 4GB of physical
408	* memory, use MMR3PageAllocLow().
409	*
410	* @returns Pointer to the allocated page page.
411	* @returns NIL_RTHCPHYS on failure.
412	* @param pVM VM handle.
413	* @thread The Emulation Thread.
414	*/
415	VMMR3DECL(RTHCPHYS) MMR3PageAllocPhys(PVM pVM)
416	{
417	/** @todo optimize this, it's the most common case now. */
418	void *pv = mmR3PagePoolAlloc(pVM->mm.s.pPagePoolR3);
419	if (pv)
420	return mmPagePoolPtr2Phys(pVM->mm.s.pPagePoolR3, pv);
421	return NIL_RTHCPHYS;
422	}
423
424
425	/**
426	* Frees a page allocated from the page pool by MMR3PageAlloc() or
427	* MMR3PageAllocPhys().
428	*
429	* @param pVM VM handle.
430	* @param pvPage Pointer to the page.
431	* @thread The Emulation Thread.
432	*/
433	VMMR3DECL(void) MMR3PageFree(PVM pVM, void *pvPage)
434	{
435	mmR3PagePoolFree(pVM->mm.s.pPagePoolR3, pvPage);
436	}
437
438
439	/**
440	* Allocates a page from the low page pool.
441	*
442	* @returns Pointer to the allocated page.
443	* @returns NULL on failure.
444	* @param pVM VM handle.
445	* @thread The Emulation Thread.
446	*/
447	VMMR3DECL(void *) MMR3PageAllocLow(PVM pVM)
448	{
449	return mmR3PagePoolAlloc(pVM->mm.s.pPagePoolLowR3);
450	}
451
452
453	/**
454	* Frees a page allocated from the page pool by MMR3PageAllocLow().
455	*
456	* @param pVM VM handle.
457	* @param pvPage Pointer to the page.
458	* @thread The Emulation Thread.
459	*/
460	VMMR3DECL(void) MMR3PageFreeLow(PVM pVM, void *pvPage)
461	{
462	mmR3PagePoolFree(pVM->mm.s.pPagePoolLowR3, pvPage);
463	}
464
465
466	/**
467	* Free a page allocated from the page pool by physical address.
468	* This works for pages allocated by MMR3PageAlloc(), MMR3PageAllocPhys()
469	* and MMR3PageAllocLow().
470	*
471	* @param pVM VM handle.
472	* @param HCPhysPage The physical address of the page to be freed.
473	* @thread The Emulation Thread.
474	*/
475	VMMR3DECL(void) MMR3PageFreeByPhys(PVM pVM, RTHCPHYS HCPhysPage)
476	{
477	void *pvPage = mmPagePoolPhys2Ptr(pVM->mm.s.pPagePoolR3, HCPhysPage);
478	if (!pvPage)
479	pvPage = mmPagePoolPhys2Ptr(pVM->mm.s.pPagePoolLowR3, HCPhysPage);
480	if (pvPage)
481	mmR3PagePoolFree(pVM->mm.s.pPagePoolR3, pvPage);
482	else
483	AssertMsgFailed(("Invalid address HCPhysPT=%#x\n", HCPhysPage));
484	}
485
486
487	/**
488	* Gets the HC pointer to the dummy page.
489	*
490	* The dummy page is used as a place holder to prevent potential bugs
491	* from doing really bad things to the system.
492	*
493	* @returns Pointer to the dummy page.
494	* @param pVM VM handle.
495	* @thread The Emulation Thread.
496	*/
497	VMMR3DECL(void *) MMR3PageDummyHCPtr(PVM pVM)
498	{
499	VM_ASSERT_EMT(pVM);
500	if (!pVM->mm.s.pvDummyPage)
501	{
502	pVM->mm.s.pvDummyPage = mmR3PagePoolAlloc(pVM->mm.s.pPagePoolR3);
503	AssertRelease(pVM->mm.s.pvDummyPage);
504	pVM->mm.s.HCPhysDummyPage = mmPagePoolPtr2Phys(pVM->mm.s.pPagePoolR3, pVM->mm.s.pvDummyPage);
505	AssertRelease(!(pVM->mm.s.HCPhysDummyPage & ~X86_PTE_PAE_PG_MASK));
506	}
507	return pVM->mm.s.pvDummyPage;
508	}
509
510
511	/**
512	* Gets the HC Phys to the dummy page.
513	*
514	* The dummy page is used as a place holder to prevent potential bugs
515	* from doing really bad things to the system.
516	*
517	* @returns Pointer to the dummy page.
518	* @param pVM VM handle.
519	* @thread The Emulation Thread.
520	*/
521	VMMR3DECL(RTHCPHYS) MMR3PageDummyHCPhys(PVM pVM)
522	{
523	VM_ASSERT_EMT(pVM);
524	if (!pVM->mm.s.pvDummyPage)
525	MMR3PageDummyHCPtr(pVM);
526	return pVM->mm.s.HCPhysDummyPage;
527	}
528

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source: vbox/trunk/src/VBox/VMM/MMPagePool.cpp@ 20062

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