/* $Id: TMAllCpu.cpp 41965 2012-06-29 02:52:49Z vboxsync $ */ /** @file * TM - Timeout Manager, CPU Time, All Contexts. */ /* * Copyright (C) 2006-2007 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. */ /******************************************************************************* * Header Files * *******************************************************************************/ #define LOG_GROUP LOG_GROUP_TM #include #include /* for SUPGetCpuHzFromGIP */ #include "TMInternal.h" #include #include #include #include #include #include #include /** * Gets the raw cpu tick from current virtual time. */ DECLINLINE(uint64_t) tmCpuTickGetRawVirtual(PVM pVM, bool fCheckTimers) { uint64_t u64; if (fCheckTimers) u64 = TMVirtualSyncGet(pVM); else u64 = TMVirtualSyncGetNoCheck(pVM); if (u64 != TMCLOCK_FREQ_VIRTUAL) /* what's the use of this test, document! */ u64 = ASMMultU64ByU32DivByU32(u64, pVM->tm.s.cTSCTicksPerSecond, TMCLOCK_FREQ_VIRTUAL); return u64; } /** * Resumes the CPU timestamp counter ticking. * * @returns VBox status code. * @param pVM Pointer to the VM. * @param pVCpu Pointer to the VMCPU. * @internal */ int tmCpuTickResume(PVM pVM, PVMCPU pVCpu) { if (!pVCpu->tm.s.fTSCTicking) { pVCpu->tm.s.fTSCTicking = true; if (pVM->tm.s.fTSCVirtualized) { /** @todo Test that pausing and resuming doesn't cause lag! (I.e. that we're * unpaused before the virtual time and stopped after it. */ if (pVM->tm.s.fTSCUseRealTSC) pVCpu->tm.s.offTSCRawSrc = ASMReadTSC() - pVCpu->tm.s.u64TSC; else pVCpu->tm.s.offTSCRawSrc = tmCpuTickGetRawVirtual(pVM, false /* don't check for pending timers */) - pVCpu->tm.s.u64TSC; } return VINF_SUCCESS; } AssertFailed(); return VERR_TM_TSC_ALREADY_TICKING; } /** * Pauses the CPU timestamp counter ticking. * * @returns VBox status code. * @param pVCpu Pointer to the VMCPU. * @internal */ int tmCpuTickPause(PVMCPU pVCpu) { if (pVCpu->tm.s.fTSCTicking) { pVCpu->tm.s.u64TSC = TMCpuTickGetNoCheck(pVCpu); pVCpu->tm.s.fTSCTicking = false; return VINF_SUCCESS; } AssertFailed(); return VERR_TM_TSC_ALREADY_PAUSED; } /** * Record why we refused to use offsetted TSC. * * Used by TMCpuTickCanUseRealTSC and TMCpuTickGetDeadlineAndTscOffset. * * @param pVM Pointer to the VM. * @param pVCpu The current CPU. */ DECLINLINE(void) tmCpuTickRecordOffsettedTscRefusal(PVM pVM, PVMCPU pVCpu) { /* Sample the reason for refusing. */ if (!pVM->tm.s.fMaybeUseOffsettedHostTSC) STAM_COUNTER_INC(&pVM->tm.s.StatTSCNotFixed); else if (!pVCpu->tm.s.fTSCTicking) STAM_COUNTER_INC(&pVM->tm.s.StatTSCNotTicking); else if (!pVM->tm.s.fTSCUseRealTSC) { if (pVM->tm.s.fVirtualSyncCatchUp) { if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 10) STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE010); else if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 25) STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE025); else if (pVM->tm.s.u32VirtualSyncCatchUpPercentage <= 100) STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupLE100); else STAM_COUNTER_INC(&pVM->tm.s.StatTSCCatchupOther); } else if (!pVM->tm.s.fVirtualSyncTicking) STAM_COUNTER_INC(&pVM->tm.s.StatTSCSyncNotTicking); else if (pVM->tm.s.fVirtualWarpDrive) STAM_COUNTER_INC(&pVM->tm.s.StatTSCWarp); } } /** * Checks if AMD-V / VT-x can use an offsetted hardware TSC or not. * * @returns true/false accordingly. * @param pVCpu Pointer to the VMCPU. * @param poffRealTSC The offset against the TSC of the current CPU. * Can be NULL. * @thread EMT. */ VMM_INT_DECL(bool) TMCpuTickCanUseRealTSC(PVMCPU pVCpu, uint64_t *poffRealTSC) { PVM pVM = pVCpu->CTX_SUFF(pVM); /* * We require: * 1. A fixed TSC, this is checked at init time. * 2. That the TSC is ticking (we shouldn't be here if it isn't) * 3. Either that we're using the real TSC as time source or * a) we don't have any lag to catch up, and * b) the virtual sync clock hasn't been halted by an expired timer, and * c) we're not using warp drive (accelerated virtual guest time). */ if ( pVM->tm.s.fMaybeUseOffsettedHostTSC && RT_LIKELY(pVCpu->tm.s.fTSCTicking) && ( pVM->tm.s.fTSCUseRealTSC || ( !pVM->tm.s.fVirtualSyncCatchUp && RT_LIKELY(pVM->tm.s.fVirtualSyncTicking) && !pVM->tm.s.fVirtualWarpDrive)) ) { if (!pVM->tm.s.fTSCUseRealTSC) { /* The source is the timer synchronous virtual clock. */ Assert(pVM->tm.s.fTSCVirtualized); if (poffRealTSC) { uint64_t u64Now = tmCpuTickGetRawVirtual(pVM, false /* don't check for pending timers */) - pVCpu->tm.s.offTSCRawSrc; /** @todo When we start collecting statistics on how much time we spend executing * guest code before exiting, we should check this against the next virtual sync * timer timeout. If it's lower than the avg. length, we should trap rdtsc to increase * the chance that we'll get interrupted right after the timer expired. */ *poffRealTSC = u64Now - ASMReadTSC(); } } else if (poffRealTSC) { /* The source is the real TSC. */ if (pVM->tm.s.fTSCVirtualized) *poffRealTSC = pVCpu->tm.s.offTSCRawSrc; else *poffRealTSC = 0; } /** @todo count this? */ return true; } #ifdef VBOX_WITH_STATISTICS tmCpuTickRecordOffsettedTscRefusal(pVM, pVCpu); #endif return false; } /** * Calculates the number of host CPU ticks till the next virtual sync deadline. * * @note To save work, this function will not bother calculating the accurate * tick count for deadlines that are more than a second ahead. * * @returns The number of host cpu ticks to the next deadline. Max one second. * @param cNsToDeadline The number of nano seconds to the next virtual * sync deadline. */ DECLINLINE(uint64_t) tmCpuCalcTicksToDeadline(uint64_t cNsToDeadline) { AssertCompile(TMCLOCK_FREQ_VIRTUAL <= _4G); if (RT_UNLIKELY(cNsToDeadline >= TMCLOCK_FREQ_VIRTUAL)) return SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage); uint64_t cTicks = ASMMultU64ByU32DivByU32(SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage), cNsToDeadline, TMCLOCK_FREQ_VIRTUAL); if (cTicks > 4000) cTicks -= 4000; /* fudge to account for overhead */ else cTicks >>= 1; return cTicks; } /** * Gets the next deadline in host CPU clock ticks and the TSC offset if we can * use the raw TSC. * * @returns The number of host CPU clock ticks to the next timer deadline. * @param pVCpu The current CPU. * @param poffRealTSC The offset against the TSC of the current CPU. * @thread EMT(pVCpu). * @remarks Superset of TMCpuTickCanUseRealTSC. */ VMM_INT_DECL(uint64_t) TMCpuTickGetDeadlineAndTscOffset(PVMCPU pVCpu, bool *pfOffsettedTsc, uint64_t *poffRealTSC) { PVM pVM = pVCpu->CTX_SUFF(pVM); uint64_t cTicksToDeadline; /* * We require: * 1. A fixed TSC, this is checked at init time. * 2. That the TSC is ticking (we shouldn't be here if it isn't) * 3. Either that we're using the real TSC as time source or * a) we don't have any lag to catch up, and * b) the virtual sync clock hasn't been halted by an expired timer, and * c) we're not using warp drive (accelerated virtual guest time). */ if ( pVM->tm.s.fMaybeUseOffsettedHostTSC && RT_LIKELY(pVCpu->tm.s.fTSCTicking) && ( pVM->tm.s.fTSCUseRealTSC || ( !pVM->tm.s.fVirtualSyncCatchUp && RT_LIKELY(pVM->tm.s.fVirtualSyncTicking) && !pVM->tm.s.fVirtualWarpDrive)) ) { *pfOffsettedTsc = true; if (!pVM->tm.s.fTSCUseRealTSC) { /* The source is the timer synchronous virtual clock. */ Assert(pVM->tm.s.fTSCVirtualized); uint64_t cNsToDeadline; uint64_t u64NowVirtSync = TMVirtualSyncGetWithDeadlineNoCheck(pVM, &cNsToDeadline); uint64_t u64Now = u64NowVirtSync != TMCLOCK_FREQ_VIRTUAL /* what's the use of this? */ ? ASMMultU64ByU32DivByU32(u64NowVirtSync, pVM->tm.s.cTSCTicksPerSecond, TMCLOCK_FREQ_VIRTUAL) : u64NowVirtSync; u64Now -= pVCpu->tm.s.offTSCRawSrc; *poffRealTSC = u64Now - ASMReadTSC(); cTicksToDeadline = tmCpuCalcTicksToDeadline(cNsToDeadline); } else { /* The source is the real TSC. */ if (pVM->tm.s.fTSCVirtualized) *poffRealTSC = pVCpu->tm.s.offTSCRawSrc; else *poffRealTSC = 0; cTicksToDeadline = tmCpuCalcTicksToDeadline(TMVirtualSyncGetNsToDeadline(pVM)); } } else { #ifdef VBOX_WITH_STATISTICS tmCpuTickRecordOffsettedTscRefusal(pVM, pVCpu); #endif *pfOffsettedTsc = false; *poffRealTSC = 0; cTicksToDeadline = tmCpuCalcTicksToDeadline(TMVirtualSyncGetNsToDeadline(pVM)); } return cTicksToDeadline; } /** * Read the current CPU timestamp counter. * * @returns Gets the CPU tsc. * @param pVCpu Pointer to the VMCPU. */ DECLINLINE(uint64_t) tmCpuTickGetInternal(PVMCPU pVCpu, bool fCheckTimers) { uint64_t u64; if (RT_LIKELY(pVCpu->tm.s.fTSCTicking)) { PVM pVM = pVCpu->CTX_SUFF(pVM); if (pVM->tm.s.fTSCVirtualized) { if (pVM->tm.s.fTSCUseRealTSC) u64 = ASMReadTSC(); else u64 = tmCpuTickGetRawVirtual(pVM, fCheckTimers); u64 -= pVCpu->tm.s.offTSCRawSrc; } else u64 = ASMReadTSC(); /* Never return a value lower than what the guest has already seen. */ if (u64 < pVCpu->tm.s.u64TSCLastSeen) { STAM_COUNTER_INC(&pVM->tm.s.StatTSCUnderflow); pVCpu->tm.s.u64TSCLastSeen += 64; /* @todo choose a good increment here */ u64 = pVCpu->tm.s.u64TSCLastSeen; } } else u64 = pVCpu->tm.s.u64TSC; return u64; } /** * Read the current CPU timestamp counter. * * @returns Gets the CPU tsc. * @param pVCpu Pointer to the VMCPU. */ VMMDECL(uint64_t) TMCpuTickGet(PVMCPU pVCpu) { return tmCpuTickGetInternal(pVCpu, true /* fCheckTimers */); } /** * Read the current CPU timestamp counter, don't check for expired timers. * * @returns Gets the CPU tsc. * @param pVCpu Pointer to the VMCPU. */ VMM_INT_DECL(uint64_t) TMCpuTickGetNoCheck(PVMCPU pVCpu) { return tmCpuTickGetInternal(pVCpu, false /* fCheckTimers */); } /** * Sets the current CPU timestamp counter. * * @returns VBox status code. * @param pVM Pointer to the VM. * @param pVCpu Pointer to the VMCPU. * @param u64Tick The new timestamp value. * * @thread EMT which TSC is to be set. */ VMM_INT_DECL(int) TMCpuTickSet(PVM pVM, PVMCPU pVCpu, uint64_t u64Tick) { VMCPU_ASSERT_EMT(pVCpu); STAM_COUNTER_INC(&pVM->tm.s.StatTSCSet); /* * This is easier to do when the TSC is paused since resume will * do all the calculations for us. Actually, we don't need to * call tmCpuTickPause here since we overwrite u64TSC anyway. */ bool fTSCTicking = pVCpu->tm.s.fTSCTicking; pVCpu->tm.s.fTSCTicking = false; pVCpu->tm.s.u64TSC = u64Tick; pVCpu->tm.s.u64TSCLastSeen = u64Tick; if (fTSCTicking) tmCpuTickResume(pVM, pVCpu); /** @todo Try help synchronizing it better among the virtual CPUs? */ return VINF_SUCCESS; } /** * Sets the last seen CPU timestamp counter. * * @returns VBox status code. * @param pVCpu Pointer to the VMCPU. * @param u64LastSeenTick The last seen timestamp value. * * @thread EMT which TSC is to be set. */ VMM_INT_DECL(int) TMCpuTickSetLastSeen(PVMCPU pVCpu, uint64_t u64LastSeenTick) { VMCPU_ASSERT_EMT(pVCpu); LogFlow(("TMCpuTickSetLastSeen %RX64\n", u64LastSeenTick)); if (pVCpu->tm.s.u64TSCLastSeen < u64LastSeenTick) pVCpu->tm.s.u64TSCLastSeen = u64LastSeenTick; return VINF_SUCCESS; } /** * Gets the last seen CPU timestamp counter. * * @returns last seen TSC * @param pVCpu Pointer to the VMCPU. * * @thread EMT which TSC is to be set. */ VMM_INT_DECL(uint64_t) TMCpuTickGetLastSeen(PVMCPU pVCpu) { VMCPU_ASSERT_EMT(pVCpu); return pVCpu->tm.s.u64TSCLastSeen; } /** * Get the timestamp frequency. * * @returns Number of ticks per second. * @param pVM The VM. */ VMMDECL(uint64_t) TMCpuTicksPerSecond(PVM pVM) { if (pVM->tm.s.fTSCUseRealTSC) { uint64_t cTSCTicksPerSecond = SUPGetCpuHzFromGIP(g_pSUPGlobalInfoPage); if (RT_LIKELY(cTSCTicksPerSecond != ~(uint64_t)0)) return cTSCTicksPerSecond; } return pVM->tm.s.cTSCTicksPerSecond; }