Hi Eric, On 07/25/18 09:50, Eric Dong wrote: > Current CPU state definition include CpuStateIdle and CpuStateFinished. > After investigation, current code can use CpuStateIdle to replace the > CpuStateFinished. It will reduce the state number and easy for maintenance. > > Cc: Laszlo Ersek <ler...@redhat.com> > Cc: Ruiyu Ni <ruiyu...@intel.com> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Eric Dong <eric.d...@intel.com> > --- > UefiCpuPkg/Library/MpInitLib/MpLib.c | 18 ++++++++---------- > UefiCpuPkg/Library/MpInitLib/MpLib.h | 1 - > 2 files changed, 8 insertions(+), 11 deletions(-)
After looking over this patch, it seems that you are preserving the CpuStateReady enum constant, relative to: 20180628112920.5296-1-eric.dong@intel.com">http://mid.mail-archive.com/20180628112920.5296-1-eric.dong@intel.com However, based on your analysis in ED077930C258884BBCB450DB737E66224AC5A453@shsmsx102.ccr.corp.intel.com">http://mid.mail-archive.com/ED077930C258884BBCB450DB737E66224AC5A453@shsmsx102.ccr.corp.intel.com isn't it still possible to run into the exact same issue? (Namely, BSP thinks the AP has gone through Idle -> Busy -> Idle, but the AP has never actually left Idle?) Hm, wait, is it the case that the BSP first sets Ready, and so if the check for an AP returns Idle, it implies the AP must have gone through: Idle ----> Ready ----> Busy ----> Idle ? If this is correct, can you please include the following in the commit message: > Before this patch, the state transitions for an AP are: > > Idle ----> Ready ----> Busy ----> Finished ----> Idle > [BSP] [AP] [AP] [BSP] > > After the patch, the state transitions for an AP are: > > Idle ----> Ready ----> Busy ----> Idle > [BSP] [AP] [AP] Do you agree? I have another question: On 07/25/18 09:50, Eric Dong wrote: > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c > b/UefiCpuPkg/Library/MpInitLib/MpLib.c > index c82b985943..ff09a0e9e7 100644 > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c > @@ -696,7 +696,7 @@ ApWakeupFunction ( > } > } > } > - SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateFinished); > + SetApState (&CpuMpData->CpuData[ProcessorNumber], CpuStateIdle); > } > } > > @@ -1352,18 +1352,17 @@ CheckThisAP ( > CpuData = &CpuMpData->CpuData[ProcessorNumber]; > > // > - // Check the CPU state of AP. If it is CpuStateFinished, then the AP has > finished its task. > + // Check the CPU state of AP. If it is CpuStateIdle, then the AP has > finished its task. > // Only BSP and corresponding AP access this unit of CPU Data. This means > the AP will not modify the > - // value of state after setting the it to CpuStateFinished, so BSP can > safely make use of its value. > + // value of state after setting the it to CpuStateIdle, so BSP can safely > make use of its value. > // > // > // If the AP finishes for StartupThisAP(), return EFI_SUCCESS. > // > - if (GetApState(CpuData) == CpuStateFinished) { > + if (GetApState(CpuData) == CpuStateIdle) { > if (CpuData->Finished != NULL) { > *(CpuData->Finished) = TRUE; > } > - SetApState (CpuData, CpuStateIdle); > return EFI_SUCCESS; > } else { > // > @@ -1420,14 +1419,13 @@ CheckAllAPs ( > > CpuData = &CpuMpData->CpuData[ProcessorNumber]; > // > - // Check the CPU state of AP. If it is CpuStateFinished, then the AP has > finished its task. > + // Check the CPU state of AP. If it is CpuStateIdle, then the AP has > finished its task. > // Only BSP and corresponding AP access this unit of CPU Data. This > means the AP will not modify the > - // value of state after setting the it to CpuStateFinished, so BSP can > safely make use of its value. > + // value of state after setting the it to CpuStateIdle, so BSP can > safely make use of its value. > // > - if (GetApState(CpuData) == CpuStateFinished) { > + if (GetApState(CpuData) == CpuStateIdle) { > CpuMpData->RunningCount ++; > CpuMpData->CpuData[ProcessorNumber].Waiting = FALSE; > - SetApState(CpuData, CpuStateIdle); > > // > // If in Single Thread mode, then search for the next waiting AP for > execution. This part of the code, after the patch, does not seem idempotent; in other words, if the BSP calls CheckAllAPs() multiple times, then RunningCount will be increased every time. Before the patch, this wasn't the case, because after the Finished -> Idle transition, the increment wouldn't be reached again. Hmmm, wait, I'm wrong: we set the Waiting field to FALSE as well, so at the next call to CheckAllAPs(), we'll take the early "continue" branch. Looks OK after all. I'll follow up with test results. Thanks, Laszlo > @@ -1923,7 +1921,7 @@ SwitchBSPWorker ( > // > // Wait for old BSP finished AP task > // > - while (GetApState (&CpuMpData->CpuData[CallerNumber]) != CpuStateFinished) > { > + while (GetApState (&CpuMpData->CpuData[CallerNumber]) != CpuStateIdle) { > CpuPause (); > } > > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h > b/UefiCpuPkg/Library/MpInitLib/MpLib.h > index 9d0b866d09..962bce685d 100644 > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h > @@ -85,7 +85,6 @@ typedef enum { > CpuStateIdle, > CpuStateReady, > CpuStateBusy, > - CpuStateFinished, > CpuStateDisabled > } CPU_STATE; > > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
