Hi Star, That line is only active when (CpuMpData->SevEsIsEnabled) is TRUE.
The race condition addressed by this BZ is for systems with SecEsIsEnabled FALSE. From comments in this file the SecEsIsEnabled cases have already been handled. Mike > -----Original Message----- > From: Zeng, Star <star.z...@intel.com> > Sent: Sunday, January 24, 2021 7:15 PM > To: devel@edk2.groups.io; Kinney, Michael D <michael.d.kin...@intel.com> > Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Laszlo > Ersek <ler...@redhat.com>; Kumar, Rahul1 > <rahul1.ku...@intel.com>; Zeng, Star <star.z...@intel.com> > Subject: RE: [edk2-devel] [Patch 1/1] UefiCpuPkg/Library/MpInitLib: Fix AP > VolatileRegisters race condition > > Does > https://github.com/tianocore/edk2/blob/master/UefiCpuPkg/Library/MpInitLib/MpLib.c#L909 > (also decrements > NumApsExecuting) also need be handled? > > Thanks, > Star > > > -----Original Message----- > > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Michael > > D Kinney > > Sent: Saturday, January 23, 2021 1:10 AM > > To: devel@edk2.groups.io > > Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Laszlo > > Ersek <ler...@redhat.com>; Kumar, Rahul1 <rahul1.ku...@intel.com> > > Subject: [edk2-devel] [Patch 1/1] UefiCpuPkg/Library/MpInitLib: Fix AP > > VolatileRegisters race condition > > > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3182 > > > > Fix the order of operations in ApWakeupFunction() when > > PcdCpuApLoopMode > > is set to HLT mode that uses INIT-SIPI-SIPI to wake APs. In this mode, > > volatile state is restored and saved each time a INIT-SIPI-SIPI is sent > > to an AP to request a function to be executed on the AP. When the > > function is completed the volatile state of the AP is saved. However, > > the counters NumApsExecuting and FinishedCount are updated before > > the volatile state is saved. This allows for a race condition window > > for the BSP that is waiting on these counters to request a new > > INIT-SIPI-SIPI before all the APs have completely saved their volatile > > state. The fix is to save the AP volatile state before updating the > > NumApsExecuting and FinishedCount counters. > > > > Cc: Eric Dong <eric.d...@intel.com> > > Cc: Ray Ni <ray...@intel.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Cc: Rahul Kumar <rahul1.ku...@intel.com> > > Signed-off-by: Michael D Kinney <michael.d.kin...@intel.com> > > --- > > UefiCpuPkg/Library/MpInitLib/MpLib.c | 31 ++++++++++++++++------------ > > 1 file changed, 18 insertions(+), 13 deletions(-) > > > > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > index 681fa79b4cff..8b1f7f84bad6 100644 > > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > @@ -769,15 +769,6 @@ ApWakeupFunction ( > > RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, > > FALSE); > > InitializeApData (CpuMpData, ProcessorNumber, BistData, > > ApTopOfStack); > > ApStartupSignalBuffer = CpuMpData- > > >CpuData[ProcessorNumber].StartupApSignal; > > - > > - // > > - // Delay decrementing the APs executing count when SEV-ES is enabled > > - // to allow the APs to issue an AP_RESET_HOLD before the BSP possibly > > - // performs another INIT-SIPI-SIPI sequence. > > - // > > - if (!CpuMpData->SevEsIsEnabled) { > > - InterlockedDecrement ((UINT32 *) &CpuMpData- > > >MpCpuExchangeInfo->NumApsExecuting); > > - } > > } else { > > // > > // Execute AP function if AP is ready > > @@ -866,19 +857,33 @@ ApWakeupFunction ( > > } > > } > > > > + if (CpuMpData->ApLoopMode == ApInHltLoop) { > > + // > > + // Save AP volatile registers > > + // > > + SaveVolatileRegisters (&CpuMpData- > > >CpuData[ProcessorNumber].VolatileRegisters); > > + } > > + > > // > > // AP finished executing C code > > // > > InterlockedIncrement ((UINT32 *) &CpuMpData->FinishedCount); > > > > + if (CpuMpData->InitFlag == ApInitConfig) { > > + // > > + // Delay decrementing the APs executing count when SEV-ES is enabled > > + // to allow the APs to issue an AP_RESET_HOLD before the BSP possibly > > + // performs another INIT-SIPI-SIPI sequence. > > + // > > + if (!CpuMpData->SevEsIsEnabled) { > > + InterlockedDecrement ((UINT32 *) &CpuMpData- > > >MpCpuExchangeInfo->NumApsExecuting); > > + } > > + } > > + > > // > > // Place AP is specified loop mode > > // > > if (CpuMpData->ApLoopMode == ApInHltLoop) { > > - // > > - // Save AP volatile registers > > - // > > - SaveVolatileRegisters (&CpuMpData- > > >CpuData[ProcessorNumber].VolatileRegisters); > > // > > // Place AP in HLT-loop > > // > > -- > > 2.29.2.windows.2 > > > > > > > > > > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#70714): https://edk2.groups.io/g/devel/message/70714 Mute This Topic: https://groups.io/mt/80035510/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
