TMAllCpu.cpp@ 32419

Last change on this file since 32419 was 32419, checked in by vboxsync, 14 years ago
TM,HWVMXR0: Use the preemption timer to make sure we stop executing guest code in time for the next TMCLOCK_VIRTUAL_SYNC timer deadline.
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1	/* $Id: TMAllCpu.cpp 32419 2010-09-10 15:41:00Z vboxsync $ */
2	/** @file
3	* TM - Timeout Manager, CPU Time, All Contexts.
4	*/
5
6	/*
7	* Copyright (C) 2006-2007 Oracle Corporation
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
18
19	/*******************************************************************************
20	* Header Files *
21	*******************************************************************************/
22	#define LOG_GROUP LOG_GROUP_TM
23	#include <VBox/tm.h>
24	#include <iprt/asm-amd64-x86.h> /* for SUPGetCpuHzFromGIP */
25	#include "../TMInternal.h"
26	#include <VBox/vm.h>
27	#include <VBox/sup.h>
28
29	#include <VBox/param.h>
30	#include <VBox/err.h>
31	#include <iprt/asm-math.h>
32	#include <iprt/assert.h>
33	#include <VBox/log.h>
34
35
36	/**
37	* Gets the raw cpu tick from current virtual time.
38	*/
39	DECLINLINE(uint64_t) tmCpuTickGetRawVirtual(PVM pVM, bool fCheckTimers)
40	{
41	uint64_t u64;
42	if (fCheckTimers)
43	u64 = TMVirtualSyncGet(pVM);
44	else
45	u64 = TMVirtualSyncGetNoCheck(pVM);
46	if (u64 != TMCLOCK_FREQ_VIRTUAL) /* what's the use of this test, document! */
47	u64 = ASMMultU64ByU32DivByU32(u64, pVM->tm.s.cTSCTicksPerSecond, TMCLOCK_FREQ_VIRTUAL);
48	return u64;
49	}
50
51
52	/**
53	* Resumes the CPU timestamp counter ticking.
54	*
55	* @returns VBox status code.
56	* @param pVM The VM to operate on.
57	* @param pVCpu The VMCPU to operate on.
58	* @internal
59	*/
60	int tmCpuTickResume(PVM pVM, PVMCPU pVCpu)
61	{
62	if (!pVCpu->tm.s.fTSCTicking)
63	{
64	pVCpu->tm.s.fTSCTicking = true;
65	if (pVM->tm.s.fTSCVirtualized)
66	{
67	/** @todo Test that pausing and resuming doesn't cause lag! (I.e. that we're
68	* unpaused before the virtual time and stopped after it. */
69	if (pVM->tm.s.fTSCUseRealTSC)
70	pVCpu->tm.s.offTSCRawSrc = ASMReadTSC() - pVCpu->tm.s.u64TSC;
71	else
72	pVCpu->tm.s.offTSCRawSrc = tmCpuTickGetRawVirtual(pVM, false /* don't check for pending timers */)
73	- pVCpu->tm.s.u64TSC;
74	}
75	return VINF_SUCCESS;
76	}
77	AssertFailed();
78	return VERR_INTERNAL_ERROR;
79	}
80
81
82	/**
83	* Pauses the CPU timestamp counter ticking.
84	*
85	* @returns VBox status code.
86	* @param pVM The VM to operate on.
87	* @param pVCpu The VMCPU to operate on.
88	* @internal
89	*/
90	int tmCpuTickPause(PVM pVM, PVMCPU pVCpu)
91	{
92	if (pVCpu->tm.s.fTSCTicking)
93	{
94	pVCpu->tm.s.u64TSC = TMCpuTickGetNoCheck(pVCpu);
95	pVCpu->tm.s.fTSCTicking = false;
96	return VINF_SUCCESS;
97	}
98	AssertFailed();
99	return VERR_INTERNAL_ERROR;
100	}
101
102	/**
103	* Record why we refused to use offsetted TSC.
104	*
105	* Used by TMCpuTickCanUseRealTSC and TMCpuTickGetDeadlineAndTscOffset.
106	*
107	* @param pVM The VM handle.
108	* @param pVCpu The current CPU.
109	*/
110	DECLINLINE(void) tmCpuTickRecordOffsettedTscRefusal(PVM pVM, PVMCPU pVCpu)
111	{
112
113	/* Sample the reason for refusing. */
114	if (!pVM->tm.s.fMaybeUseOffsettedHostTSC)
115	STAM_COUNTER_INC(&pVM->tm.s.StatTSCNotFixed);
116	else if (!pVCpu->tm.s.fTSCTicking)
117	STAM_COUNTER_INC(&pVM->tm.s.StatTSCNotTicking);
118	else if (!pVM->tm.s.fTSCUseRealTSC)
119	{
120	if (pVM->tm.s.fVirtualSyncCatchUp)
121	{
122	if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 10)
123	STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE010);
124	else if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 25)
125	STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE025);
126	else if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 100)
127	STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE100);
128	else
129	STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupOther);
130	}
131	else if (!pVM->tm.s.fVirtualSyncTicking)
132	STAM_COUNTER_INC(&pVM->tm.s.StatTSCSyncNotTicking);
133	else if (pVM->tm.s.fVirtualWarpDrive)
134	STAM_COUNTER_INC(&pVM->tm.s.StatTSCWarp);
135	}
136	}
137
138
139	/**
140	* Checks if AMD-V / VT-x can use an offsetted hardware TSC or not.
141	*
142	* @returns true/false accordingly.
143	* @param pVCpu The VMCPU to operate on.
144	* @param poffRealTSC The offset against the TSC of the current CPU.
145	* Can be NULL.
146	* @thread EMT.
147	*/
148	VMM_INT_DECL(bool) TMCpuTickCanUseRealTSC(PVMCPU pVCpu, uint64_t *poffRealTSC)
149	{
150	PVM pVM = pVCpu->CTX_SUFF(pVM);
151
152	/*
153	* We require:
154	* 1. A fixed TSC, this is checked at init time.
155	* 2. That the TSC is ticking (we shouldn't be here if it isn't)
156	* 3. Either that we're using the real TSC as time source or
157	* a) we don't have any lag to catch up, and
158	* b) the virtual sync clock hasn't been halted by an expired timer, and
159	* c) we're not using warp drive (accelerated virtual guest time).
160	*/
161	if ( pVM->tm.s.fMaybeUseOffsettedHostTSC
162	&& RT_LIKELY(pVCpu->tm.s.fTSCTicking)
163	&& ( pVM->tm.s.fTSCUseRealTSC
164	\|\| ( !pVM->tm.s.fVirtualSyncCatchUp
165	&& RT_LIKELY(pVM->tm.s.fVirtualSyncTicking)
166	&& !pVM->tm.s.fVirtualWarpDrive))
167	)
168	{
169	if (!pVM->tm.s.fTSCUseRealTSC)
170	{
171	/* The source is the timer synchronous virtual clock. */
172	Assert(pVM->tm.s.fTSCVirtualized);
173
174	if (poffRealTSC)
175	{
176	uint64_t u64Now = tmCpuTickGetRawVirtual(pVM, false /* don't check for pending timers */)
177	- pVCpu->tm.s.offTSCRawSrc;
178	/** @todo When we start collecting statistics on how much time we spend executing
179	* guest code before exiting, we should check this against the next virtual sync
180	* timer timeout. If it's lower than the avg. length, we should trap rdtsc to increase
181	* the chance that we'll get interrupted right after the timer expired. */
182	*poffRealTSC = u64Now - ASMReadTSC();
183	}
184	}
185	else if (poffRealTSC)
186	{
187	/* The source is the real TSC. */
188	if (pVM->tm.s.fTSCVirtualized)
189	*poffRealTSC = pVCpu->tm.s.offTSCRawSrc;
190	else
191	*poffRealTSC = 0;
192	}
193	/** @todo count this? */
194	return true;
195	}
196
197	#ifdef VBOX_WITH_STATISTICS
198	tmCpuTickRecordOffsettedTscRefusal(pVM, pVCpu);
199	#endif
200	return false;
201	}
202
203
204	/**
205	* Calculates the number of host CPU ticks till the next virtual sync deadline.
206	*
207	* @note To save work, this function will not bother calculating the accurate
208	* tick count for deadlines that are more than a second ahead.
209	*
210	* @returns The number of host cpu ticks to the next deadline. Max one second.
211	* @param cNsToDeadline The number of nano seconds to the next virtual
212	* sync deadline.
213	*/
214	DECLINLINE(uint64_t) tmCpuCalcTicksToDeadline(uint64_t cNsToDeadline)
215	{
216	AssertCompile(TMCLOCK_FREQ_VIRTUAL <= _4G);
217	if (RT_UNLIKELY(cNsToDeadline >= TMCLOCK_FREQ_VIRTUAL))
218	return SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage);
219	uint64_t cTicks = ASMMultU64ByU32DivByU32(SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage),
220	cNsToDeadline,
221	TMCLOCK_FREQ_VIRTUAL);
222	if (cTicks > 4000)
223	cTicks -= 4000; /* fudge to account for overhead */
224	else
225	cTicks >>= 1;
226	return cTicks;
227	}
228
229
230	/**
231	* Gets the next deadline in host CPU clock ticks and the TSC offset if we can
232	* use the raw TSC.
233	*
234	* @returns The number of host CPU clock ticks to the next timer deadline.
235	* @param pVCpu The current CPU.
236	* @param poffRealTSC The offset against the TSC of the current CPU.
237	* @thread EMT(pVCpu).
238	* @remarks Superset of TMCpuTickCanUseRealTSC.
239	*/
240	VMM_INT_DECL(uint64_t) TMCpuTickGetDeadlineAndTscOffset(PVMCPU pVCpu, bool pfOffsettedTsc, uint64_t poffRealTSC)
241	{
242	PVM pVM = pVCpu->CTX_SUFF(pVM);
243	uint64_t cTicksToDeadline;
244
245	/*
246	* We require:
247	* 1. A fixed TSC, this is checked at init time.
248	* 2. That the TSC is ticking (we shouldn't be here if it isn't)
249	* 3. Either that we're using the real TSC as time source or
250	* a) we don't have any lag to catch up, and
251	* b) the virtual sync clock hasn't been halted by an expired timer, and
252	* c) we're not using warp drive (accelerated virtual guest time).
253	*/
254	if ( pVM->tm.s.fMaybeUseOffsettedHostTSC
255	&& RT_LIKELY(pVCpu->tm.s.fTSCTicking)
256	&& ( pVM->tm.s.fTSCUseRealTSC
257	\|\| ( !pVM->tm.s.fVirtualSyncCatchUp
258	&& RT_LIKELY(pVM->tm.s.fVirtualSyncTicking)
259	&& !pVM->tm.s.fVirtualWarpDrive))
260	)
261	{
262	*pfOffsettedTsc = true;
263	if (!pVM->tm.s.fTSCUseRealTSC)
264	{
265	/* The source is the timer synchronous virtual clock. */
266	Assert(pVM->tm.s.fTSCVirtualized);
267
268	uint64_t cNsToDeadline;
269	uint64_t u64NowVirtSync = TMVirtualSyncGetWithDeadlineNoCheck(pVM, &cNsToDeadline);
270	uint64_t u64Now = u64NowVirtSync != TMCLOCK_FREQ_VIRTUAL /* what's the use of this? */
271	? ASMMultU64ByU32DivByU32(u64NowVirtSync, pVM->tm.s.cTSCTicksPerSecond, TMCLOCK_FREQ_VIRTUAL)
272	: u64NowVirtSync;
273	u64Now -= pVCpu->tm.s.offTSCRawSrc;
274	*poffRealTSC = u64Now - ASMReadTSC();
275	cTicksToDeadline = tmCpuCalcTicksToDeadline(cNsToDeadline);
276	}
277	else
278	{
279	/* The source is the real TSC. */
280	if (pVM->tm.s.fTSCVirtualized)
281	*poffRealTSC = pVCpu->tm.s.offTSCRawSrc;
282	else
283	*poffRealTSC = 0;
284	cTicksToDeadline = tmCpuCalcTicksToDeadline(TMVirtualSyncGetNsToDeadline(pVM));
285	}
286	}
287	else
288	{
289	#ifdef VBOX_WITH_STATISTICS
290	tmCpuTickRecordOffsettedTscRefusal(pVM, pVCpu);
291	#endif
292	*pfOffsettedTsc = false;
293	*poffRealTSC = 0;
294	cTicksToDeadline = tmCpuCalcTicksToDeadline(TMVirtualSyncGetNsToDeadline(pVM));
295	}
296	return cTicksToDeadline;
297	}
298
299
300	/**
301	* Read the current CPU timstamp counter.
302	*
303	* @returns Gets the CPU tsc.
304	* @param pVCpu The VMCPU to operate on.
305	*/
306	DECLINLINE(uint64_t) tmCpuTickGetInternal(PVMCPU pVCpu, bool fCheckTimers)
307	{
308	uint64_t u64;
309
310	if (RT_LIKELY(pVCpu->tm.s.fTSCTicking))
311	{
312	PVM pVM = pVCpu->CTX_SUFF(pVM);
313	if (pVM->tm.s.fTSCVirtualized)
314	{
315	if (pVM->tm.s.fTSCUseRealTSC)
316	u64 = ASMReadTSC();
317	else
318	u64 = tmCpuTickGetRawVirtual(pVM, fCheckTimers);
319	u64 -= pVCpu->tm.s.offTSCRawSrc;
320	}
321	else
322	u64 = ASMReadTSC();
323
324	/* Never return a value lower than what the guest has already seen. */
325	if (u64 < pVCpu->tm.s.u64TSCLastSeen)
326	{
327	STAM_COUNTER_INC(&pVM->tm.s.StatTSCUnderflow);
328	pVCpu->tm.s.u64TSCLastSeen += 64; /* @todo choose a good increment here */
329	u64 = pVCpu->tm.s.u64TSCLastSeen;
330	}
331	}
332	else
333	u64 = pVCpu->tm.s.u64TSC;
334	return u64;
335	}
336
337
338	/**
339	* Read the current CPU timstamp counter.
340	*
341	* @returns Gets the CPU tsc.
342	* @param pVCpu The VMCPU to operate on.
343	*/
344	VMMDECL(uint64_t) TMCpuTickGet(PVMCPU pVCpu)
345	{
346	return tmCpuTickGetInternal(pVCpu, true /* fCheckTimers */);
347	}
348
349
350	/**
351	* Read the current CPU timstamp counter, don't check for expired timers.
352	*
353	* @returns Gets the CPU tsc.
354	* @param pVCpu The VMCPU to operate on.
355	*/
356	VMM_INT_DECL(uint64_t) TMCpuTickGetNoCheck(PVMCPU pVCpu)
357	{
358	return tmCpuTickGetInternal(pVCpu, false /* fCheckTimers */);
359	}
360
361
362	/**
363	* Sets the current CPU timestamp counter.
364	*
365	* @returns VBox status code.
366	* @param pVM The VM handle.
367	* @param pVCpu The virtual CPU to operate on.
368	* @param u64Tick The new timestamp value.
369	*
370	* @thread EMT which TSC is to be set.
371	*/
372	VMM_INT_DECL(int) TMCpuTickSet(PVM pVM, PVMCPU pVCpu, uint64_t u64Tick)
373	{
374	VMCPU_ASSERT_EMT(pVCpu);
375	STAM_COUNTER_INC(&pVM->tm.s.StatTSCSet);
376
377	/*
378	* This is easier to do when the TSC is paused since resume will
379	* do all the calcuations for us. Actually, we don't need to
380	* call tmCpuTickPause here since we overwrite u64TSC anyway.
381	*/
382	bool fTSCTicking = pVCpu->tm.s.fTSCTicking;
383	pVCpu->tm.s.fTSCTicking = false;
384	pVCpu->tm.s.u64TSC = u64Tick;
385	pVCpu->tm.s.u64TSCLastSeen = u64Tick;
386	if (fTSCTicking)
387	tmCpuTickResume(pVM, pVCpu);
388	/** @todo Try help synchronizing it better among the virtual CPUs? */
389
390	return VINF_SUCCESS;
391	}
392
393	/**
394	* Sets the last seen CPU timestamp counter.
395	*
396	* @returns VBox status code.
397	* @param pVCpu The virtual CPU to operate on.
398	* @param u64LastSeenTick The last seen timestamp value.
399	*
400	* @thread EMT which TSC is to be set.
401	*/
402	VMM_INT_DECL(int) TMCpuTickSetLastSeen(PVMCPU pVCpu, uint64_t u64LastSeenTick)
403	{
404	VMCPU_ASSERT_EMT(pVCpu);
405
406	LogFlow(("TMCpuTickSetLastSeen %RX64\n", u64LastSeenTick));
407	if (pVCpu->tm.s.u64TSCLastSeen < u64LastSeenTick)
408	pVCpu->tm.s.u64TSCLastSeen = u64LastSeenTick;
409	return VINF_SUCCESS;
410	}
411
412	/**
413	* Gets the last seen CPU timestamp counter.
414	*
415	* @returns last seen TSC
416	* @param pVCpu The virtual CPU to operate on.
417	*
418	* @thread EMT which TSC is to be set.
419	*/
420	VMM_INT_DECL(uint64_t) TMCpuTickGetLastSeen(PVMCPU pVCpu)
421	{
422	VMCPU_ASSERT_EMT(pVCpu);
423
424	return pVCpu->tm.s.u64TSCLastSeen;
425	}
426
427
428	/**
429	* Get the timestamp frequency.
430	*
431	* @returns Number of ticks per second.
432	* @param pVM The VM.
433	*/
434	VMMDECL(uint64_t) TMCpuTicksPerSecond(PVM pVM)
435	{
436	if (pVM->tm.s.fTSCUseRealTSC)
437	{
438	uint64_t cTSCTicksPerSecond = SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage);
439	if (RT_LIKELY(cTSCTicksPerSecond != ~(uint64_t)0))
440	return cTSCTicksPerSecond;
441	}
442	return pVM->tm.s.cTSCTicksPerSecond;
443	}
444

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source: vbox/trunk/src/VBox/VMM/VMMAll/TMAllCpu.cpp@ 32419

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