PDMAllCritSect.cpp@ 98103

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1	/* $Id: PDMAllCritSect.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
2	/** @file
3	* PDM - Write-Only Critical Section, All Contexts.
4	*/
5
6	/*
7	* Copyright (C) 2006-2023 Oracle and/or its affiliates.
8	*
9	* This file is part of VirtualBox base platform packages, as
10	* available from https://www.virtualbox.org.
11	*
12	* This program is free software; you can redistribute it and/or
13	* modify it under the terms of the GNU General Public License
14	* as published by the Free Software Foundation, in version 3 of the
15	* License.
16	*
17	* This program is distributed in the hope that it will be useful, but
18	* WITHOUT ANY WARRANTY; without even the implied warranty of
19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20	* General Public License for more details.
21	*
22	* You should have received a copy of the GNU General Public License
23	* along with this program; if not, see <https://www.gnu.org/licenses>.
24	*
25	* SPDX-License-Identifier: GPL-3.0-only
26	*/
27
28
29	/*********************************************************************************************************************************
30	* Header Files *
31	*********************************************************************************************************************************/
32	#define LOG_GROUP LOG_GROUP_PDM_CRITSECT
33	#include "PDMInternal.h"
34	#include <VBox/vmm/pdmcritsect.h>
35	#include <VBox/vmm/mm.h>
36	#include <VBox/vmm/vmm.h>
37	#include <VBox/vmm/vmcc.h>
38	#include <VBox/err.h>
39	#include <VBox/vmm/hm.h>
40
41	#include <VBox/log.h>
42	#include <iprt/asm.h>
43	#include <iprt/assert.h>
44	#ifdef IN_RING3
45	# include <iprt/lockvalidator.h>
46	#endif
47	#if defined(IN_RING3) \|\| defined(IN_RING0)
48	# include <iprt/semaphore.h>
49	#endif
50	#ifdef IN_RING0
51	# include <iprt/time.h>
52	#endif
53	#if defined(IN_RING3) \|\| defined(IN_RING0)
54	# include <iprt/thread.h>
55	#endif
56
57
58	/*********************************************************************************************************************************
59	* Defined Constants And Macros *
60	*********************************************************************************************************************************/
61	/** The number loops to spin for in ring-3. */
62	#define PDMCRITSECT_SPIN_COUNT_R3 20
63	/** The number loops to spin for in ring-0. */
64	#define PDMCRITSECT_SPIN_COUNT_R0 256
65	/** The number loops to spin for in the raw-mode context. */
66	#define PDMCRITSECT_SPIN_COUNT_RC 256
67
68
69	/** Skips some of the overly paranoid atomic updates.
70	* Makes some assumptions about cache coherence, though not brave enough not to
71	* always end with an atomic update. */
72	#define PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
73
74	/* Undefine the automatic VBOX_STRICT API mappings. */
75	#undef PDMCritSectEnter
76	#undef PDMCritSectTryEnter
77
78
79	/**
80	* Gets the ring-3 native thread handle of the calling thread.
81	*
82	* @returns native thread handle (ring-3).
83	* @param pVM The cross context VM structure.
84	* @param pCritSect The critical section. This is used in R0 and RC.
85	*/
86	DECL_FORCE_INLINE(RTNATIVETHREAD) pdmCritSectGetNativeSelf(PVMCC pVM, PCPDMCRITSECT pCritSect)
87	{
88	#ifdef IN_RING3
89	RT_NOREF(pVM, pCritSect);
90	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
91
92	#elif defined(IN_RING0)
93	AssertMsgReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC, ("%RX32\n", pCritSect->s.Core.u32Magic),
94	NIL_RTNATIVETHREAD);
95	RTNATIVETHREAD hNativeSelf = GVMMR0GetRing3ThreadForSelf(pVM);
96	Assert(hNativeSelf != NIL_RTNATIVETHREAD);
97
98	#else
99	# error "Invalid context"
100	#endif
101	return hNativeSelf;
102	}
103
104
105	#ifdef IN_RING0
106	/**
107	* Marks the critical section as corrupted.
108	*/
109	DECL_NO_INLINE(static, int) pdmCritSectCorrupted(PPDMCRITSECT pCritSect, const char *pszMsg)
110	{
111	ASMAtomicWriteU32(&pCritSect->s.Core.u32Magic, PDMCRITSECT_MAGIC_CORRUPTED);
112	LogRel(("PDMCritSect: %s pCritSect=%p\n", pszMsg, pCritSect));
113	return VERR_PDM_CRITSECT_IPE;
114	}
115	#endif
116
117
118	/**
119	* Tail code called when we've won the battle for the lock.
120	*
121	* @returns VINF_SUCCESS.
122	*
123	* @param pCritSect The critical section.
124	* @param hNativeSelf The native handle of this thread.
125	* @param pSrcPos The source position of the lock operation.
126	*/
127	DECL_FORCE_INLINE(int) pdmCritSectEnterFirst(PPDMCRITSECT pCritSect, RTNATIVETHREAD hNativeSelf, PCRTLOCKVALSRCPOS pSrcPos)
128	{
129	Assert(hNativeSelf != NIL_RTNATIVETHREAD);
130	AssertMsg(pCritSect->s.Core.NativeThreadOwner == NIL_RTNATIVETHREAD, ("NativeThreadOwner=%p\n", pCritSect->s.Core.NativeThreadOwner));
131	Assert(!(pCritSect->s.Core.fFlags & PDMCRITSECT_FLAGS_PENDING_UNLOCK));
132
133	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
134	pCritSect->s.Core.cNestings = 1;
135	# else
136	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 1);
137	# endif
138	Assert(pCritSect->s.Core.cNestings == 1);
139	ASMAtomicWriteHandle(&pCritSect->s.Core.NativeThreadOwner, hNativeSelf);
140
141	# ifdef PDMCRITSECT_STRICT
142	RTLockValidatorRecExclSetOwner(pCritSect->s.Core.pValidatorRec, NIL_RTTHREAD, pSrcPos, true);
143	# else
144	NOREF(pSrcPos);
145	# endif
146	if (pSrcPos)
147	Log12Func(("%p: uId=%p ln=%u fn=%s\n", pCritSect, pSrcPos->uId, pSrcPos->uLine, pSrcPos->pszFunction));
148	else
149	Log12Func(("%p\n", pCritSect));
150
151	STAM_PROFILE_ADV_START(&pCritSect->s.StatLocked, l);
152	return VINF_SUCCESS;
153	}
154
155
156	#if defined(IN_RING3) \|\| defined(IN_RING0)
157	/**
158	* Deals with the contended case in ring-3 and ring-0.
159	*
160	* @retval VINF_SUCCESS on success.
161	* @retval VERR_SEM_DESTROYED if destroyed.
162	*
163	* @param pVM The cross context VM structure.
164	* @param pVCpu The cross context virtual CPU structure if ring-0 and on
165	* an EMT, otherwise NULL.
166	* @param pCritSect The critsect.
167	* @param hNativeSelf The native thread handle.
168	* @param pSrcPos The source position of the lock operation.
169	* @param rcBusy The status code to return when we're in RC or R0
170	*/
171	static int pdmR3R0CritSectEnterContended(PVMCC pVM, PVMCPU pVCpu, PPDMCRITSECT pCritSect, RTNATIVETHREAD hNativeSelf,
172	PCRTLOCKVALSRCPOS pSrcPos, int rcBusy)
173	{
174	# ifdef IN_RING0
175	/*
176	* If we've got queued critical section leave operations and rcBusy isn't
177	* VINF_SUCCESS, return to ring-3 immediately to avoid deadlocks.
178	*/
179	if ( !pVCpu
180	\|\| !VMCPU_FF_IS_SET(pVCpu, VMCPU_FF_PDM_CRITSECT)
181	\|\| rcBusy == VINF_SUCCESS )
182	{ /* likely */ }
183	else
184	{
185	/** @todo statistics. */
186	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
187	return rcBusy;
188	}
189	# endif
190
191	/*
192	* Start waiting.
193	*/
194	if (ASMAtomicIncS32(&pCritSect->s.Core.cLockers) == 0)
195	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
196	# ifdef IN_RING3
197	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionR3);
198	# else
199	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
200	# endif
201
202	/*
203	* The wait loop.
204	*
205	* This handles VERR_TIMEOUT and VERR_INTERRUPTED.
206	*/
207	STAM_REL_PROFILE_START(&pCritSect->s.CTX_MID_Z(StatContention,Wait), a);
208	PSUPDRVSESSION const pSession = pVM->pSession;
209	SUPSEMEVENT const hEvent = (SUPSEMEVENT)pCritSect->s.Core.EventSem;
210	# ifdef IN_RING3
211	# ifdef PDMCRITSECT_STRICT
212	RTTHREAD const hThreadSelf = RTThreadSelfAutoAdopt();
213	int rc2 = RTLockValidatorRecExclCheckOrder(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos, RT_INDEFINITE_WAIT);
214	if (RT_FAILURE(rc2))
215	return rc2;
216	# else
217	RTTHREAD const hThreadSelf = RTThreadSelf();
218	# endif
219	# else /* IN_RING0 */
220	uint64_t const tsStart = RTTimeNanoTS();
221	uint64_t const cNsMaxTotalDef = RT_NS_5MIN;
222	uint64_t cNsMaxTotal = cNsMaxTotalDef;
223	uint64_t const cNsMaxRetry = RT_NS_15SEC;
224	uint32_t cMsMaxOne = RT_MS_5SEC;
225	bool fNonInterruptible = false;
226	# endif
227	for (;;)
228	{
229	/*
230	* Do the wait.
231	*
232	* In ring-3 this gets cluttered by lock validation and thread state
233	* maintainence.
234	*
235	* In ring-0 we have to deal with the possibility that the thread has
236	* been signalled and the interruptible wait function returning
237	* immediately. In that case we do normal R0/RC rcBusy handling.
238	*
239	* We always do a timed wait here, so the event handle is revalidated
240	* regularly and we won't end up stuck waiting for a destroyed critsect.
241	*/
242	/** @todo Make SUPSemEventClose wake up all waiters. */
243	# ifdef IN_RING3
244	# ifdef PDMCRITSECT_STRICT
245	int rc9 = RTLockValidatorRecExclCheckBlocking(pCritSect->s.Core.pValidatorRec, hThreadSelf, pSrcPos,
246	!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NO_NESTING),
247	RT_INDEFINITE_WAIT, RTTHREADSTATE_CRITSECT, true);
248	if (RT_FAILURE(rc9))
249	return rc9;
250	# else
251	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_CRITSECT, true);
252	# endif
253	int const rc = SUPSemEventWaitNoResume(pSession, hEvent, RT_MS_5SEC);
254	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_CRITSECT);
255	# else /* IN_RING0 */
256	int const rc = !fNonInterruptible
257	? SUPSemEventWaitNoResume(pSession, hEvent, cMsMaxOne)
258	: SUPSemEventWait(pSession, hEvent, cMsMaxOne);
259	Log11Func(("%p: rc=%Rrc %'RU64 ns (cMsMaxOne=%RU64 hOwner=%p)\n",
260	pCritSect, rc, RTTimeNanoTS() - tsStart, cMsMaxOne, pCritSect->s.Core.NativeThreadOwner));
261	# endif /* IN_RING0 */
262
263	/*
264	* Make sure the critical section hasn't been delete before continuing.
265	*/
266	if (RT_LIKELY(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC))
267	{ /* likely */ }
268	else
269	{
270	LogRel(("PDMCritSectEnter: Destroyed while waiting; pCritSect=%p rc=%Rrc\n", pCritSect, rc));
271	return VERR_SEM_DESTROYED;
272	}
273
274	/*
275	* Most likely we're here because we got signalled.
276	*/
277	if (rc == VINF_SUCCESS)
278	{
279	STAM_REL_PROFILE_STOP(&pCritSect->s.CTX_MID_Z(StatContention,Wait), a);
280	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
281	}
282
283	/*
284	* Timeout and interrupted waits needs careful handling in ring-0
285	* because we're cooperating with ring-3 on this critical section
286	* and thus need to make absolutely sure we won't get stuck here.
287	*
288	* The r0 interrupted case means something is pending (termination,
289	* signal, APC, debugger, whatever), so we must try our best to
290	* return to the caller and to ring-3 so it can be dealt with.
291	*/
292	if (RT_LIKELY(rc == VERR_TIMEOUT \|\| rc == VERR_INTERRUPTED))
293	{
294	# ifdef IN_RING0
295	uint64_t const cNsElapsed = RTTimeNanoTS() - tsStart;
296	int const rcTerm = RTThreadQueryTerminationStatus(NIL_RTTHREAD);
297	AssertMsg(rcTerm == VINF_SUCCESS \|\| rcTerm == VERR_NOT_SUPPORTED \|\| rcTerm == VINF_THREAD_IS_TERMINATING,
298	("rcTerm=%Rrc\n", rcTerm));
299	if (rcTerm == VERR_NOT_SUPPORTED && cNsMaxTotal == cNsMaxTotalDef)
300	cNsMaxTotal = RT_NS_1MIN;
301
302	if (rc == VERR_TIMEOUT)
303	{
304	/* Try return get out of here with a non-VINF_SUCCESS status if
305	the thread is terminating or if the timeout has been exceeded. */
306	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatCritSectVerrTimeout);
307	if ( rcTerm != VINF_THREAD_IS_TERMINATING
308	&& cNsElapsed <= cNsMaxTotal)
309	continue;
310	}
311	else
312	{
313	/* For interrupt cases, we must return if we can. If rcBusy is VINF_SUCCESS,
314	we will try non-interruptible sleep for a while to help resolve the issue
315	w/o guru'ing. */
316	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatCritSectVerrInterrupted);
317	if ( rcTerm != VINF_THREAD_IS_TERMINATING
318	&& rcBusy == VINF_SUCCESS
319	&& pVCpu != NULL
320	&& cNsElapsed <= cNsMaxTotal)
321	{
322	if (!fNonInterruptible)
323	{
324	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatCritSectNonInterruptibleWaits);
325	fNonInterruptible = true;
326	cMsMaxOne = 32;
327	uint64_t cNsLeft = cNsMaxTotal - cNsElapsed;
328	if (cNsLeft > RT_NS_10SEC)
329	cNsMaxTotal = cNsElapsed + RT_NS_10SEC;
330	}
331	continue;
332	}
333	}
334
335	/*
336	* Let try get out of here. We must very carefully undo the
337	* cLockers increment we did using compare-and-exchange so that
338	* we don't race the semaphore signalling in PDMCritSectLeave
339	* and end up with spurious wakeups and two owners at once.
340	*/
341	uint32_t cNoIntWaits = 0;
342	uint32_t cCmpXchgs = 0;
343	int32_t cLockers = ASMAtomicReadS32(&pCritSect->s.Core.cLockers);
344	for (;;)
345	{
346	if (pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC)
347	{
348	if (cLockers > 0 && cCmpXchgs < _64M)
349	{
350	bool fRc = ASMAtomicCmpXchgExS32(&pCritSect->s.Core.cLockers, cLockers - 1, cLockers, &cLockers);
351	if (fRc)
352	{
353	LogFunc(("Aborting wait on %p (rc=%Rrc rcTerm=%Rrc cNsElapsed=%'RU64) -> %Rrc\n", pCritSect,
354	rc, rcTerm, cNsElapsed, rcBusy != VINF_SUCCESS ? rcBusy : rc));
355	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatAbortedCritSectEnters);
356	return rcBusy != VINF_SUCCESS ? rcBusy : rc;
357	}
358	cCmpXchgs++;
359	if ((cCmpXchgs & 0xffff) == 0)
360	Log11Func(("%p: cLockers=%d cCmpXchgs=%u (hOwner=%p)\n",
361	pCritSect, cLockers, cCmpXchgs, pCritSect->s.Core.NativeThreadOwner));
362	ASMNopPause();
363	continue;
364	}
365
366	if (cLockers == 0)
367	{
368	/*
369	* We are racing someone in PDMCritSectLeave.
370	*
371	* For the VERR_TIMEOUT case we'll just retry taking it the normal
372	* way for a while. For VERR_INTERRUPTED we're in for more fun as
373	* the previous owner might not have signalled the semaphore yet,
374	* so we'll do a short non-interruptible wait instead and then guru.
375	*/
376	if ( rc == VERR_TIMEOUT
377	&& RTTimeNanoTS() - tsStart <= cNsMaxTotal + cNsMaxRetry)
378	break;
379
380	if ( rc == VERR_INTERRUPTED
381	&& ( cNoIntWaits == 0
382	\|\| RTTimeNanoTS() - (tsStart + cNsElapsed) < RT_NS_100MS))
383	{
384	int const rc2 = SUPSemEventWait(pSession, hEvent, 1 /ms/);
385	if (rc2 == VINF_SUCCESS)
386	{
387	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatCritSectEntersWhileAborting);
388	STAM_REL_PROFILE_STOP(&pCritSect->s.CTX_MID_Z(StatContention,Wait), a);
389	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
390	}
391	cNoIntWaits++;
392	cLockers = ASMAtomicReadS32(&pCritSect->s.Core.cLockers);
393	continue;
394	}
395	}
396	else
397	LogFunc(("Critical section %p has a broken cLockers count. Aborting.\n", pCritSect));
398
399	/* Sabotage the critical section and return error to caller. */
400	ASMAtomicWriteU32(&pCritSect->s.Core.u32Magic, PDMCRITSECT_MAGIC_FAILED_ABORT);
401	LogRel(("PDMCritSectEnter: Failed to abort wait on pCritSect=%p (rc=%Rrc rcTerm=%Rrc)\n",
402	pCritSect, rc, rcTerm));
403	return VERR_PDM_CRITSECT_ABORT_FAILED;
404	}
405	LogRel(("PDMCritSectEnter: Destroyed while aborting wait; pCritSect=%p/%#x rc=%Rrc rcTerm=%Rrc\n",
406	pCritSect, pCritSect->s.Core.u32Magic, rc, rcTerm));
407	return VERR_SEM_DESTROYED;
408	}
409
410	/* We get here if we timed out. Just retry now that it
411	appears someone left already. */
412	Assert(rc == VERR_TIMEOUT);
413	cMsMaxOne = 10 /ms/;
414
415	# else /* IN_RING3 */
416	RT_NOREF(pVM, pVCpu, rcBusy);
417	# endif /* IN_RING3 */
418	}
419	/*
420	* Any other return code is fatal.
421	*/
422	else
423	{
424	AssertMsgFailed(("rc=%Rrc\n", rc));
425	return RT_FAILURE_NP(rc) ? rc : -rc;
426	}
427	}
428	/* won't get here */
429	}
430	#endif /* IN_RING3 \|\| IN_RING0 */
431
432
433	/**
434	* Common worker for the debug and normal APIs.
435	*
436	* @returns VINF_SUCCESS if entered successfully.
437	* @returns rcBusy when encountering a busy critical section in RC/R0.
438	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
439	* during the operation.
440	*
441	* @param pVM The cross context VM structure.
442	* @param pCritSect The PDM critical section to enter.
443	* @param rcBusy The status code to return when we're in RC or R0
444	* @param pSrcPos The source position of the lock operation.
445	*/
446	DECL_FORCE_INLINE(int) pdmCritSectEnter(PVMCC pVM, PPDMCRITSECT pCritSect, int rcBusy, PCRTLOCKVALSRCPOS pSrcPos)
447	{
448	Assert(pCritSect->s.Core.cNestings < 8); /* useful to catch incorrect locking */
449	Assert(pCritSect->s.Core.cNestings >= 0);
450	#if defined(VBOX_STRICT) && defined(IN_RING0)
451	/* Hope we're not messing with critical sections while in the no-block
452	zone, that would complicate things a lot. */
453	PVMCPUCC pVCpuAssert = VMMGetCpu(pVM);
454	Assert(pVCpuAssert && VMMRZCallRing3IsEnabled(pVCpuAssert));
455	#endif
456
457	/*
458	* If the critical section has already been destroyed, then inform the caller.
459	*/
460	AssertMsgReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC,
461	("%p %RX32\n", pCritSect, pCritSect->s.Core.u32Magic),
462	VERR_SEM_DESTROYED);
463
464	/*
465	* See if we're lucky.
466	*/
467	/* NOP ... */
468	if (!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP))
469	{ /* We're more likely to end up here with real critsects than a NOP one. */ }
470	else
471	return VINF_SUCCESS;
472
473	RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pVM, pCritSect);
474	AssertReturn(hNativeSelf != NIL_RTNATIVETHREAD, VERR_VM_THREAD_NOT_EMT);
475	/* ... not owned ... */
476	if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
477	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
478
479	/* ... or nested. */
480	if (pCritSect->s.Core.NativeThreadOwner == hNativeSelf)
481	{
482	Assert(pCritSect->s.Core.cNestings >= 1);
483	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
484	pCritSect->s.Core.cNestings += 1;
485	# else
486	ASMAtomicIncS32(&pCritSect->s.Core.cNestings);
487	# endif
488	ASMAtomicIncS32(&pCritSect->s.Core.cLockers);
489	Log12Func(("%p: cNestings=%d cLockers=%d\n", pCritSect, pCritSect->s.Core.cNestings, pCritSect->s.Core.cLockers));
490	return VINF_SUCCESS;
491	}
492
493	/*
494	* Spin for a bit without incrementing the counter.
495	*/
496	/** @todo Move this to cfgm variables since it doesn't make sense to spin on UNI
497	* cpu systems. */
498	int32_t cSpinsLeft = CTX_SUFF(PDMCRITSECT_SPIN_COUNT_);
499	while (cSpinsLeft-- > 0)
500	{
501	if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
502	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
503	ASMNopPause();
504	/** @todo Should use monitor/mwait on e.g. &cLockers here, possibly with a
505	cli'ed pendingpreemption check up front using sti w/ instruction fusing
506	for avoiding races. Hmm ... This is assuming the other party is actually
507	executing code on another CPU ... which we could keep track of if we
508	wanted. */
509	}
510
511	#ifdef IN_RING3
512	/*
513	* Take the slow path.
514	*/
515	NOREF(rcBusy);
516	return pdmR3R0CritSectEnterContended(pVM, NULL, pCritSect, hNativeSelf, pSrcPos, rcBusy);
517
518	#elif defined(IN_RING0)
519	# if 1 /* new code */
520	/*
521	* In ring-0 context we have to take the special VT-x/AMD-V HM context into
522	* account when waiting on contended locks.
523	*
524	* While we usually (it can be VINF_SUCCESS) have the option of returning
525	* rcBusy and force the caller to go back to ring-3 and to re-start the work
526	* there, it's almost always more efficient to try wait for the lock here.
527	* The rcBusy will be used if we encounter an VERR_INTERRUPTED situation
528	* though.
529	*/
530	PVMCPUCC pVCpu = VMMGetCpu(pVM);
531	if (pVCpu)
532	{
533	VMMR0EMTBLOCKCTX Ctx;
534	int rc = VMMR0EmtPrepareToBlock(pVCpu, rcBusy, __FUNCTION__, pCritSect, &Ctx);
535	if (rc == VINF_SUCCESS)
536	{
537	Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
538
539	rc = pdmR3R0CritSectEnterContended(pVM, pVCpu, pCritSect, hNativeSelf, pSrcPos, rcBusy);
540
541	VMMR0EmtResumeAfterBlocking(pVCpu, &Ctx);
542	}
543	else
544	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLockBusy);
545	return rc;
546	}
547
548	/* Non-EMT. */
549	Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
550	return pdmR3R0CritSectEnterContended(pVM, NULL, pCritSect, hNativeSelf, pSrcPos, rcBusy);
551
552	# else /* old code: */
553	/*
554	* We preemption hasn't been disabled, we can block here in ring-0.
555	*/
556	if ( RTThreadPreemptIsEnabled(NIL_RTTHREAD)
557	&& ASMIntAreEnabled())
558	return pdmR3R0CritSectEnterContended(pVM, VMMGetCpu(pVM), pCritSect, hNativeSelf, pSrcPos, rcBusy);
559
560	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLock);
561
562	/*
563	* Call ring-3 to acquire the critical section?
564	*/
565	if (rcBusy == VINF_SUCCESS)
566	{
567	PVMCPUCC pVCpu = VMMGetCpu(pVM);
568	AssertReturn(pVCpu, VERR_PDM_CRITSECT_IPE);
569	return VMMRZCallRing3(pVM, pVCpu, VMMCALLRING3_PDM_CRIT_SECT_ENTER, MMHyperCCToR3(pVM, pCritSect));
570	}
571
572	/*
573	* Return busy.
574	*/
575	LogFlow(("PDMCritSectEnter: locked => R3 (%Rrc)\n", rcBusy));
576	return rcBusy;
577	# endif /* old code */
578	#else
579	# error "Unsupported context"
580	#endif
581	}
582
583
584	/**
585	* Enters a PDM critical section.
586	*
587	* @returns VINF_SUCCESS if entered successfully.
588	* @returns rcBusy when encountering a busy critical section in RC/R0.
589	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
590	* during the operation.
591	*
592	* @param pVM The cross context VM structure.
593	* @param pCritSect The PDM critical section to enter.
594	* @param rcBusy The status code to return when we're in RC or R0
595	* and the section is busy. Pass VINF_SUCCESS to
596	* acquired the critical section thru a ring-3
597	* call if necessary.
598	*
599	* @note Even callers setting @a rcBusy to VINF_SUCCESS must either handle
600	* possible failures in ring-0 or apply
601	* PDM_CRITSECT_RELEASE_ASSERT_RC(),
602	* PDM_CRITSECT_RELEASE_ASSERT_RC_DEV(),
603	* PDM_CRITSECT_RELEASE_ASSERT_RC_DRV() or
604	* PDM_CRITSECT_RELEASE_ASSERT_RC_USB() to the return value of this
605	* function.
606	*/
607	VMMDECL(DECL_CHECK_RETURN_NOT_R3(int)) PDMCritSectEnter(PVMCC pVM, PPDMCRITSECT pCritSect, int rcBusy)
608	{
609	#ifndef PDMCRITSECT_STRICT
610	return pdmCritSectEnter(pVM, pCritSect, rcBusy, NULL);
611	#else
612	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
613	return pdmCritSectEnter(pVM, pCritSect, rcBusy, &SrcPos);
614	#endif
615	}
616
617
618	/**
619	* Enters a PDM critical section, with location information for debugging.
620	*
621	* @returns VINF_SUCCESS if entered successfully.
622	* @returns rcBusy when encountering a busy critical section in RC/R0.
623	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
624	* during the operation.
625	*
626	* @param pVM The cross context VM structure.
627	* @param pCritSect The PDM critical section to enter.
628	* @param rcBusy The status code to return when we're in RC or R0
629	* and the section is busy. Pass VINF_SUCCESS to
630	* acquired the critical section thru a ring-3
631	* call if necessary.
632	* @param uId Some kind of locking location ID. Typically a
633	* return address up the stack. Optional (0).
634	* @param SRC_POS The source position where to lock is being
635	* acquired from. Optional.
636	*/
637	VMMDECL(DECL_CHECK_RETURN_NOT_R3(int))
638	PDMCritSectEnterDebug(PVMCC pVM, PPDMCRITSECT pCritSect, int rcBusy, RTHCUINTPTR uId, RT_SRC_POS_DECL)
639	{
640	#ifdef PDMCRITSECT_STRICT
641	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
642	return pdmCritSectEnter(pVM, pCritSect, rcBusy, &SrcPos);
643	#else
644	NOREF(uId); RT_SRC_POS_NOREF();
645	return pdmCritSectEnter(pVM, pCritSect, rcBusy, NULL);
646	#endif
647	}
648
649
650	/**
651	* Common worker for the debug and normal APIs.
652	*
653	* @retval VINF_SUCCESS on success.
654	* @retval VERR_SEM_BUSY if the critsect was owned.
655	* @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.)
656	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
657	* during the operation.
658	*
659	* @param pVM The cross context VM structure.
660	* @param pCritSect The critical section.
661	* @param pSrcPos The source position of the lock operation.
662	*/
663	static int pdmCritSectTryEnter(PVMCC pVM, PPDMCRITSECT pCritSect, PCRTLOCKVALSRCPOS pSrcPos)
664	{
665	/*
666	* If the critical section has already been destroyed, then inform the caller.
667	*/
668	AssertMsgReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC,
669	("%p %RX32\n", pCritSect, pCritSect->s.Core.u32Magic),
670	VERR_SEM_DESTROYED);
671
672	/*
673	* See if we're lucky.
674	*/
675	/* NOP ... */
676	if (!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP))
677	{ /* We're more likely to end up here with real critsects than a NOP one. */ }
678	else
679	return VINF_SUCCESS;
680
681	RTNATIVETHREAD hNativeSelf = pdmCritSectGetNativeSelf(pVM, pCritSect);
682	AssertReturn(hNativeSelf != NIL_RTNATIVETHREAD, VERR_VM_THREAD_NOT_EMT);
683	/* ... not owned ... */
684	if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, 0, -1))
685	return pdmCritSectEnterFirst(pCritSect, hNativeSelf, pSrcPos);
686
687	/* ... or nested. */
688	if (pCritSect->s.Core.NativeThreadOwner == hNativeSelf)
689	{
690	Assert(pCritSect->s.Core.cNestings >= 1);
691	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
692	pCritSect->s.Core.cNestings += 1;
693	# else
694	ASMAtomicIncS32(&pCritSect->s.Core.cNestings);
695	# endif
696	ASMAtomicIncS32(&pCritSect->s.Core.cLockers);
697	Log12Func(("%p: cNestings=%d cLockers=%d\n", pCritSect, pCritSect->s.Core.cNestings, pCritSect->s.Core.cLockers));
698	return VINF_SUCCESS;
699	}
700
701	/* no spinning */
702
703	/*
704	* Return busy.
705	*/
706	#ifdef IN_RING3
707	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionR3);
708	#else
709	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZLockBusy);
710	#endif
711	LogFlow(("PDMCritSectTryEnter: locked\n"));
712	return VERR_SEM_BUSY;
713	}
714
715
716	/**
717	* Try enter a critical section.
718	*
719	* @retval VINF_SUCCESS on success.
720	* @retval VERR_SEM_BUSY if the critsect was owned.
721	* @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.)
722	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
723	* during the operation.
724	*
725	* @param pVM The cross context VM structure.
726	* @param pCritSect The critical section.
727	*/
728	VMMDECL(DECL_CHECK_RETURN(int)) PDMCritSectTryEnter(PVMCC pVM, PPDMCRITSECT pCritSect)
729	{
730	#ifndef PDMCRITSECT_STRICT
731	return pdmCritSectTryEnter(pVM, pCritSect, NULL);
732	#else
733	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
734	return pdmCritSectTryEnter(pVM, pCritSect, &SrcPos);
735	#endif
736	}
737
738
739	/**
740	* Try enter a critical section, with location information for debugging.
741	*
742	* @retval VINF_SUCCESS on success.
743	* @retval VERR_SEM_BUSY if the critsect was owned.
744	* @retval VERR_SEM_NESTED if nested enter on a no nesting section. (Asserted.)
745	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
746	* during the operation.
747	*
748	* @param pVM The cross context VM structure.
749	* @param pCritSect The critical section.
750	* @param uId Some kind of locking location ID. Typically a
751	* return address up the stack. Optional (0).
752	* @param SRC_POS The source position where to lock is being
753	* acquired from. Optional.
754	*/
755	VMMDECL(DECL_CHECK_RETURN(int))
756	PDMCritSectTryEnterDebug(PVMCC pVM, PPDMCRITSECT pCritSect, RTHCUINTPTR uId, RT_SRC_POS_DECL)
757	{
758	#ifdef PDMCRITSECT_STRICT
759	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
760	return pdmCritSectTryEnter(pVM, pCritSect, &SrcPos);
761	#else
762	NOREF(uId); RT_SRC_POS_NOREF();
763	return pdmCritSectTryEnter(pVM, pCritSect, NULL);
764	#endif
765	}
766
767
768	#ifdef IN_RING3
769	/**
770	* Enters a PDM critical section.
771	*
772	* @returns VINF_SUCCESS if entered successfully.
773	* @returns rcBusy when encountering a busy critical section in GC/R0.
774	* @retval VERR_SEM_DESTROYED if the critical section is delete before or
775	* during the operation.
776	*
777	* @param pVM The cross context VM structure.
778	* @param pCritSect The PDM critical section to enter.
779	* @param fCallRing3 Whether this is a VMMRZCallRing3()request.
780	*/
781	VMMR3DECL(int) PDMR3CritSectEnterEx(PVM pVM, PPDMCRITSECT pCritSect, bool fCallRing3)
782	{
783	int rc = PDMCritSectEnter(pVM, pCritSect, VERR_IGNORED);
784	if ( rc == VINF_SUCCESS
785	&& fCallRing3
786	&& pCritSect->s.Core.pValidatorRec
787	&& pCritSect->s.Core.pValidatorRec->hThread != NIL_RTTHREAD)
788	RTLockValidatorRecExclReleaseOwnerUnchecked(pCritSect->s.Core.pValidatorRec);
789	return rc;
790	}
791	#endif /* IN_RING3 */
792
793
794	/**
795	* Leaves a critical section entered with PDMCritSectEnter().
796	*
797	* @returns Indication whether we really exited the critical section.
798	* @retval VINF_SUCCESS if we really exited.
799	* @retval VINF_SEM_NESTED if we only reduced the nesting count.
800	* @retval VERR_NOT_OWNER if you somehow ignore release assertions.
801	*
802	* @param pVM The cross context VM structure.
803	* @param pCritSect The PDM critical section to leave.
804	*
805	* @remarks Can be called from no-ring-3-call context in ring-0 (TM/VirtualSync)
806	* where we'll queue leaving operation for ring-3 processing.
807	*/
808	VMMDECL(int) PDMCritSectLeave(PVMCC pVM, PPDMCRITSECT pCritSect)
809	{
810	AssertMsg(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC, ("%p %RX32\n", pCritSect, pCritSect->s.Core.u32Magic));
811	Assert(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC);
812
813	/*
814	* Check for NOP sections before asserting ownership.
815	*/
816	if (!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP))
817	{ /* We're more likely to end up here with real critsects than a NOP one. */ }
818	else
819	return VINF_SUCCESS;
820
821	/*
822	* Always check that the caller is the owner (screw performance).
823	*/
824	RTNATIVETHREAD const hNativeSelf = pdmCritSectGetNativeSelf(pVM, pCritSect);
825	VMM_ASSERT_RELEASE_MSG_RETURN(pVM, pCritSect->s.Core.NativeThreadOwner == hNativeSelf && hNativeSelf != NIL_RTNATIVETHREAD,
826	("%p %s: %p != %p; cLockers=%d cNestings=%d\n", pCritSect, R3STRING(pCritSect->s.pszName),
827	pCritSect->s.Core.NativeThreadOwner, hNativeSelf,
828	pCritSect->s.Core.cLockers, pCritSect->s.Core.cNestings),
829	VERR_NOT_OWNER);
830
831	/*
832	* Nested leave.
833	*/
834	int32_t const cNestings = pCritSect->s.Core.cNestings;
835	Assert(cNestings >= 1);
836	if (cNestings > 1)
837	{
838	#ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
839	pCritSect->s.Core.cNestings = cNestings - 1;
840	#else
841	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, cNestings - 1);
842	#endif
843	int32_t const cLockers = ASMAtomicDecS32(&pCritSect->s.Core.cLockers);
844	Assert(cLockers >= 0); RT_NOREF(cLockers);
845	Log12Func(("%p: cNestings=%d cLockers=%d\n", pCritSect, cNestings - 1, cLockers));
846	return VINF_SEM_NESTED;
847	}
848
849	Log12Func(("%p: cNestings=%d cLockers=%d hOwner=%p - leave for real\n",
850	pCritSect, cNestings, pCritSect->s.Core.cLockers, pCritSect->s.Core.NativeThreadOwner));
851
852	#ifdef IN_RING3
853	/*
854	* Ring-3: Leave for real.
855	*/
856	SUPSEMEVENT const hEventToSignal = pCritSect->s.hEventToSignal;
857	pCritSect->s.hEventToSignal = NIL_SUPSEMEVENT;
858
859	# if defined(PDMCRITSECT_STRICT)
860	if (pCritSect->s.Core.pValidatorRec->hThread != NIL_RTTHREAD)
861	RTLockValidatorRecExclReleaseOwnerUnchecked(pCritSect->s.Core.pValidatorRec);
862	# endif
863	Assert(!pCritSect->s.Core.pValidatorRec \|\| pCritSect->s.Core.pValidatorRec->hThread == NIL_RTTHREAD);
864
865	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
866	//pCritSect->s.Core.cNestings = 0; /* not really needed */
867	pCritSect->s.Core.NativeThreadOwner = NIL_RTNATIVETHREAD;
868	# else
869	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 0);
870	ASMAtomicWriteHandle(&pCritSect->s.Core.NativeThreadOwner, NIL_RTNATIVETHREAD);
871	# endif
872	ASMAtomicAndU32(&pCritSect->s.Core.fFlags, ~PDMCRITSECT_FLAGS_PENDING_UNLOCK);
873
874	/* Stop profiling and decrement lockers. */
875	STAM_PROFILE_ADV_STOP(&pCritSect->s.StatLocked, l);
876	ASMCompilerBarrier();
877	int32_t const cLockers = ASMAtomicDecS32(&pCritSect->s.Core.cLockers);
878	if (cLockers < 0)
879	AssertMsg(cLockers == -1, ("cLockers=%d\n", cLockers));
880	else
881	{
882	/* Someone is waiting, wake up one of them. */
883	Assert(cLockers < _8K);
884	Log8(("PDMCritSectLeave: Waking up %p (cLockers=%u)\n", pCritSect, cLockers));
885	SUPSEMEVENT hEvent = (SUPSEMEVENT)pCritSect->s.Core.EventSem;
886	int rc = SUPSemEventSignal(pVM->pSession, hEvent);
887	AssertRC(rc);
888	}
889
890	/* Signal exit event. */
891	if (RT_LIKELY(hEventToSignal == NIL_SUPSEMEVENT))
892	{ /* likely */ }
893	else
894	{
895	Log8(("PDMCritSectLeave: Signalling %#p (%p)\n", hEventToSignal, pCritSect));
896	int rc = SUPSemEventSignal(pVM->pSession, hEventToSignal);
897	AssertRC(rc);
898	}
899
900	return VINF_SUCCESS;
901
902
903	#elif defined(IN_RING0)
904	/*
905	* Ring-0: Try leave for real, depends on host and context.
906	*/
907	SUPSEMEVENT const hEventToSignal = pCritSect->s.hEventToSignal;
908	pCritSect->s.hEventToSignal = NIL_SUPSEMEVENT;
909	PVMCPUCC pVCpu = VMMGetCpu(pVM);
910	bool fQueueOnTrouble = false; /* Set this to true to test queueing. */
911	if ( pVCpu == NULL /* non-EMT access, if we implement it must be able to block */
912	\|\| VMMRZCallRing3IsEnabled(pVCpu)
913	\|\| RTSemEventIsSignalSafe()
914	\|\| ( VMMR0ThreadCtxHookIsEnabled(pVCpu) /* Doesn't matter if Signal() blocks if we have hooks, ... */
915	&& RTThreadPreemptIsEnabled(NIL_RTTHREAD) /* ... and preemption is still enabled, */
916	&& ASMIntAreEnabled()) /* ... and interrupts hasn't yet been disabled. Special pre-GC HM env. */
917	\|\| (fQueueOnTrouble = ( hEventToSignal == NIL_SUPSEMEVENT
918	&& ASMAtomicUoReadS32(&pCritSect->s.Core.cLockers) == 0)) )
919	{
920	pCritSect->s.hEventToSignal = NIL_SUPSEMEVENT;
921
922	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
923	//pCritSect->s.Core.cNestings = 0; /* not really needed */
924	pCritSect->s.Core.NativeThreadOwner = NIL_RTNATIVETHREAD;
925	# else
926	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 0);
927	ASMAtomicWriteHandle(&pCritSect->s.Core.NativeThreadOwner, NIL_RTNATIVETHREAD);
928	# endif
929	ASMAtomicAndU32(&pCritSect->s.Core.fFlags, ~PDMCRITSECT_FLAGS_PENDING_UNLOCK);
930
931	/*
932	* Stop profiling and decrement lockers.
933	*/
934	STAM_PROFILE_ADV_STOP(&pCritSect->s.StatLocked, l);
935	ASMCompilerBarrier();
936
937	bool fQueueIt = false;
938	int32_t cLockers;
939	if (!fQueueOnTrouble)
940	cLockers = ASMAtomicDecS32(&pCritSect->s.Core.cLockers);
941	else
942	{
943	cLockers = -1;
944	if (!ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, -1, 0))
945	fQueueIt = true;
946	}
947	if (!fQueueIt)
948	{
949	VMMR0EMTBLOCKCTX Ctx;
950	bool fLeaveCtx = false;
951	if (cLockers < 0)
952	AssertMsg(cLockers == -1, ("cLockers=%d\n", cLockers));
953	else
954	{
955	/* Someone is waiting, wake up one of them. */
956	Assert(cLockers < _8K);
957	SUPSEMEVENT hEvent = (SUPSEMEVENT)pCritSect->s.Core.EventSem;
958	if (!RTSemEventIsSignalSafe() && (pVCpu = VMMGetCpu(pVM)) != NULL)
959	{
960	int rc = VMMR0EmtPrepareToBlock(pVCpu, VINF_SUCCESS, __FUNCTION__, pCritSect, &Ctx);
961	VMM_ASSERT_RELEASE_MSG_RETURN(pVM, RT_SUCCESS(rc), ("rc=%Rrc\n", rc), rc);
962	fLeaveCtx = true;
963	}
964	int rc = SUPSemEventSignal(pVM->pSession, hEvent);
965	AssertRC(rc);
966	}
967
968	/*
969	* Signal exit event.
970	*/
971	if (RT_LIKELY(hEventToSignal == NIL_SUPSEMEVENT))
972	{ /* likely */ }
973	else
974	{
975	if (!fLeaveCtx && pVCpu != NULL && !RTSemEventIsSignalSafe() && (pVCpu = VMMGetCpu(pVM)) != NULL)
976	{
977	int rc = VMMR0EmtPrepareToBlock(pVCpu, VINF_SUCCESS, __FUNCTION__, pCritSect, &Ctx);
978	VMM_ASSERT_RELEASE_MSG_RETURN(pVM, RT_SUCCESS(rc), ("rc=%Rrc\n", rc), rc);
979	fLeaveCtx = true;
980	}
981	Log8(("Signalling %#p\n", hEventToSignal));
982	int rc = SUPSemEventSignal(pVM->pSession, hEventToSignal);
983	AssertRC(rc);
984	}
985
986	/*
987	* Restore HM context if needed.
988	*/
989	if (!fLeaveCtx)
990	{ /* contention should be unlikely */ }
991	else
992	VMMR0EmtResumeAfterBlocking(pVCpu, &Ctx);
993
994	# ifdef DEBUG_bird
995	VMMTrashVolatileXMMRegs();
996	# endif
997	return VINF_SUCCESS;
998	}
999
1000	/*
1001	* Darn, someone raced in on us. Restore the state (this works only
1002	* because the semaphore is effectively controlling ownership).
1003	*/
1004	bool fRc;
1005	RTNATIVETHREAD hMessOwner = NIL_RTNATIVETHREAD;
1006	ASMAtomicCmpXchgExHandle(&pCritSect->s.Core.NativeThreadOwner, hNativeSelf, NIL_RTNATIVETHREAD, fRc, &hMessOwner);
1007	AssertLogRelMsgReturn(fRc, ("pCritSect=%p hMessOwner=%p\n", pCritSect, hMessOwner),
1008	pdmCritSectCorrupted(pCritSect, "owner race"));
1009	STAM_PROFILE_ADV_START(&pCritSect->s.StatLocked, l);
1010	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
1011	//pCritSect->s.Core.cNestings = 1;
1012	Assert(pCritSect->s.Core.cNestings == 1);
1013	# else
1014	//Assert(pCritSect->s.Core.cNestings == 0);
1015	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 1);
1016	# endif
1017	Assert(hEventToSignal == NIL_SUPSEMEVENT);
1018	}
1019
1020
1021	#else /* IN_RC */
1022	/*
1023	* Raw-mode: Try leave it.
1024	*/
1025	# error "This context is not use..."
1026	if (pCritSect->s.Core.cLockers == 0)
1027	{
1028	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
1029	//pCritSect->s.Core.cNestings = 0; /* not really needed */
1030	# else
1031	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 0);
1032	# endif
1033	ASMAtomicAndU32(&pCritSect->s.Core.fFlags, ~PDMCRITSECT_FLAGS_PENDING_UNLOCK);
1034	STAM_PROFILE_ADV_STOP(&pCritSect->s.StatLocked, l);
1035
1036	ASMAtomicWriteHandle(&pCritSect->s.Core.NativeThreadOwner, NIL_RTNATIVETHREAD);
1037	if (ASMAtomicCmpXchgS32(&pCritSect->s.Core.cLockers, -1, 0))
1038	return VINF_SUCCESS;
1039
1040	/*
1041	* Darn, someone raced in on us. Restore the state (this works only
1042	* because the semaphore is effectively controlling ownership).
1043	*/
1044	bool fRc;
1045	RTNATIVETHREAD hMessOwner = NIL_RTNATIVETHREAD;
1046	ASMAtomicCmpXchgExHandle(&pCritSect->s.Core.NativeThreadOwner, hNativeSelf, NIL_RTNATIVETHREAD, fRc, &hMessOwner);
1047	AssertLogRelMsgReturn(fRc, ("pCritSect=%p hMessOwner=%p\n", pCritSect, hMessOwner),
1048	pdmCritSectCorrupted(pCritSect, "owner race"));
1049	STAM_PROFILE_ADV_START(&pCritSect->s.StatLocked, l);
1050	# ifdef PDMCRITSECT_WITH_LESS_ATOMIC_STUFF
1051	//pCritSect->s.Core.cNestings = 1;
1052	Assert(pCritSect->s.Core.cNestings == 1);
1053	# else
1054	//Assert(pCritSect->s.Core.cNestings == 0);
1055	ASMAtomicWriteS32(&pCritSect->s.Core.cNestings, 1);
1056	# endif
1057	}
1058	#endif /* IN_RC */
1059
1060
1061	#ifndef IN_RING3
1062	/*
1063	* Ring-0/raw-mode: Unable to leave. Queue the leave for ring-3.
1064	*/
1065	ASMAtomicOrU32(&pCritSect->s.Core.fFlags, PDMCRITSECT_FLAGS_PENDING_UNLOCK);
1066	# ifndef IN_RING0
1067	PVMCPUCC pVCpu = VMMGetCpu(pVM);
1068	# endif
1069	uint32_t i = pVCpu->pdm.s.cQueuedCritSectLeaves++;
1070	LogFlow(("PDMCritSectLeave: [%d]=%p => R3\n", i, pCritSect));
1071	VMM_ASSERT_RELEASE_MSG_RETURN(pVM, i < RT_ELEMENTS(pVCpu->pdm.s.apQueuedCritSectLeaves), ("%d\n", i), VERR_PDM_CRITSECT_IPE);
1072	pVCpu->pdm.s.apQueuedCritSectLeaves[i] = pCritSect->s.pSelfR3;
1073	VMM_ASSERT_RELEASE_MSG_RETURN(pVM,
1074	RT_VALID_PTR(pVCpu->pdm.s.apQueuedCritSectLeaves[i])
1075	&& ((uintptr_t)pVCpu->pdm.s.apQueuedCritSectLeaves[i] & HOST_PAGE_OFFSET_MASK)
1076	== ((uintptr_t)pCritSect & HOST_PAGE_OFFSET_MASK),
1077	("%p vs %p\n", pVCpu->pdm.s.apQueuedCritSectLeaves[i], pCritSect),
1078	pdmCritSectCorrupted(pCritSect, "Invalid pSelfR3 value"));
1079	VMCPU_FF_SET(pVCpu, VMCPU_FF_PDM_CRITSECT); /** @todo handle VMCPU_FF_PDM_CRITSECT in ring-0 outside the no-call-ring-3 part. */
1080	VMCPU_FF_SET(pVCpu, VMCPU_FF_TO_R3); /* unnecessary paranoia */
1081	STAM_REL_COUNTER_INC(&pVM->pdm.s.StatQueuedCritSectLeaves);
1082	STAM_REL_COUNTER_INC(&pCritSect->s.StatContentionRZUnlock);
1083
1084	return VINF_SUCCESS;
1085	#endif /* IN_RING3 */
1086	}
1087
1088
1089	#if defined(IN_RING0) \|\| defined(IN_RING3)
1090	/**
1091	* Schedule a event semaphore for signalling upon critsect exit.
1092	*
1093	* @returns VINF_SUCCESS on success.
1094	* @returns VERR_TOO_MANY_SEMAPHORES if an event was already scheduled.
1095	* @returns VERR_NOT_OWNER if we're not the critsect owner (ring-3 only).
1096	* @returns VERR_SEM_DESTROYED if RTCritSectDelete was called while waiting.
1097	*
1098	* @param pCritSect The critical section.
1099	* @param hEventToSignal The support driver event semaphore that should be
1100	* signalled.
1101	*/
1102	VMMDECL(int) PDMHCCritSectScheduleExitEvent(PPDMCRITSECT pCritSect, SUPSEMEVENT hEventToSignal)
1103	{
1104	AssertPtr(pCritSect);
1105	Assert(!(pCritSect->s.Core.fFlags & RTCRITSECT_FLAGS_NOP));
1106	Assert(hEventToSignal != NIL_SUPSEMEVENT);
1107	# ifdef IN_RING3
1108	if (RT_UNLIKELY(!RTCritSectIsOwner(&pCritSect->s.Core)))
1109	return VERR_NOT_OWNER;
1110	# endif
1111	if (RT_LIKELY( pCritSect->s.hEventToSignal == NIL_RTSEMEVENT
1112	\|\| pCritSect->s.hEventToSignal == hEventToSignal))
1113	{
1114	pCritSect->s.hEventToSignal = hEventToSignal;
1115	return VINF_SUCCESS;
1116	}
1117	return VERR_TOO_MANY_SEMAPHORES;
1118	}
1119	#endif /* IN_RING0 \|\| IN_RING3 */
1120
1121
1122	/**
1123	* Checks the caller is the owner of the critical section.
1124	*
1125	* @returns true if owner.
1126	* @returns false if not owner.
1127	* @param pVM The cross context VM structure.
1128	* @param pCritSect The critical section.
1129	*/
1130	VMMDECL(bool) PDMCritSectIsOwner(PVMCC pVM, PCPDMCRITSECT pCritSect)
1131	{
1132	#ifdef IN_RING3
1133	RT_NOREF(pVM);
1134	return RTCritSectIsOwner(&pCritSect->s.Core);
1135	#else
1136	PVMCPUCC pVCpu = VMMGetCpu(pVM);
1137	if ( !pVCpu
1138	\|\| pCritSect->s.Core.NativeThreadOwner != pVCpu->hNativeThread)
1139	return false;
1140	return (pCritSect->s.Core.fFlags & PDMCRITSECT_FLAGS_PENDING_UNLOCK) == 0
1141	\|\| pCritSect->s.Core.cNestings > 1;
1142	#endif
1143	}
1144
1145
1146	/**
1147	* Checks the specified VCPU is the owner of the critical section.
1148	*
1149	* @returns true if owner.
1150	* @returns false if not owner.
1151	* @param pVCpu The cross context virtual CPU structure.
1152	* @param pCritSect The critical section.
1153	*/
1154	VMMDECL(bool) PDMCritSectIsOwnerEx(PVMCPUCC pVCpu, PCPDMCRITSECT pCritSect)
1155	{
1156	#ifdef IN_RING3
1157	NOREF(pVCpu);
1158	return RTCritSectIsOwner(&pCritSect->s.Core);
1159	#else
1160	Assert(VMCC_GET_CPU(pVCpu->CTX_SUFF(pVM), pVCpu->idCpu) == pVCpu);
1161	if (pCritSect->s.Core.NativeThreadOwner != pVCpu->hNativeThread)
1162	return false;
1163	return (pCritSect->s.Core.fFlags & PDMCRITSECT_FLAGS_PENDING_UNLOCK) == 0
1164	\|\| pCritSect->s.Core.cNestings > 1;
1165	#endif
1166	}
1167
1168
1169	/**
1170	* Checks if anyone is waiting on the critical section we own.
1171	*
1172	* @returns true if someone is waiting.
1173	* @returns false if no one is waiting.
1174	* @param pVM The cross context VM structure.
1175	* @param pCritSect The critical section.
1176	*/
1177	VMMDECL(bool) PDMCritSectHasWaiters(PVMCC pVM, PCPDMCRITSECT pCritSect)
1178	{
1179	AssertReturn(pCritSect->s.Core.u32Magic == RTCRITSECT_MAGIC, false);
1180	Assert(pCritSect->s.Core.NativeThreadOwner == pdmCritSectGetNativeSelf(pVM, pCritSect)); RT_NOREF(pVM);
1181	return pCritSect->s.Core.cLockers >= pCritSect->s.Core.cNestings;
1182	}
1183
1184
1185	/**
1186	* Checks if a critical section is initialized or not.
1187	*
1188	* @returns true if initialized.
1189	* @returns false if not initialized.
1190	* @param pCritSect The critical section.
1191	*/
1192	VMMDECL(bool) PDMCritSectIsInitialized(PCPDMCRITSECT pCritSect)
1193	{
1194	return RTCritSectIsInitialized(&pCritSect->s.Core);
1195	}
1196
1197
1198	/**
1199	* Gets the recursion depth.
1200	*
1201	* @returns The recursion depth.
1202	* @param pCritSect The critical section.
1203	*/
1204	VMMDECL(uint32_t) PDMCritSectGetRecursion(PCPDMCRITSECT pCritSect)
1205	{
1206	return RTCritSectGetRecursion(&pCritSect->s.Core);
1207	}
1208

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source: vbox/trunk/src/VBox/VMM/VMMAll/PDMAllCritSect.cpp@ 98103

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