On 01/16/20 04:15, Dong, Eric wrote: > Hi Laszlo, > >> -----Original Message----- >> From: Laszlo Ersek [mailto:ler...@redhat.com] >> Sent: Wednesday, January 15, 2020 6:05 PM >> To: Dong, Eric <eric.d...@intel.com>; devel@edk2.groups.io >> Cc: Ni, Ray <ray...@intel.com> >> Subject: Re: [PATCH] UefiCpuPkg/Library/MpInitLib: Remove BSP index == 0 >> Assumption. >> >> On 01/15/20 07:06, Eric Dong wrote: >>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2392 >>> >>> Current code implementation assumes BSP index is 0 at the begin. >>> This code change removes this assumption. It get BSP index from the >>> saved data structure if it existed. >>> >>> Cc: Ray Ni <ray...@intel.com> >>> Cc: Laszlo Ersek <ler...@redhat.com> >>> Signed-off-by: Eric Dong <eric.d...@intel.com> >>> --- >>> UefiCpuPkg/Library/MpInitLib/MpLib.c | 10 ++++++---- >>> 1 file changed, 6 insertions(+), 4 deletions(-) >>> >>> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c >>> b/UefiCpuPkg/Library/MpInitLib/MpLib.c >>> index 6ec9b172b8..922c87b766 100644 >>> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c >>> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c >>> @@ -636,7 +636,7 @@ ApWakeupFunction ( >>> // to initialize AP in InitConfig path. >>> // NOTE: IDTR.BASE stored in CpuMpData- >>> CpuData[0].VolatileRegisters points to a different IDT shared by all APs. >>> // >>> - RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, >> FALSE); >>> + RestoreVolatileRegisters >>> + (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, >>> + FALSE); >>> InitializeApData (CpuMpData, ProcessorNumber, BistData, >> ApTopOfStack); >>> ApStartupSignalBuffer = >>> CpuMpData->CpuData[ProcessorNumber].StartupApSignal; >>> >>> @@ -1615,6 +1615,7 @@ MpInitLibInitialize ( >>> UINTN ApResetVectorSize; >>> UINTN BackupBufferAddr; >>> UINTN ApIdtBase; >>> + UINT64 BspTopOfStack; >>> >>> OldCpuMpData = GetCpuMpDataFromGuidedHob (); >>> if (OldCpuMpData == NULL) { >>> @@ -1677,7 +1678,7 @@ MpInitLibInitialize ( >>> CpuMpData->BackupBufferSize = ApResetVectorSize; >>> CpuMpData->WakeupBuffer = (UINTN) -1; >>> CpuMpData->CpuCount = 1; >>> - CpuMpData->BspNumber = 0; >>> + CpuMpData->BspNumber = OldCpuMpData != NULL ? >> OldCpuMpData->BspNumber : 0; >>> CpuMpData->WaitEvent = NULL; >>> CpuMpData->SwitchBspFlag = FALSE; >>> CpuMpData->CpuData = (CPU_AP_DATA *) (CpuMpData + 1); >>> @@ -1704,11 +1705,12 @@ MpInitLibInitialize ( >>> // Don't pass BSP's TR to APs to avoid AP init failure. >>> // >>> VolatileRegisters.Tr = 0; >>> - CopyMem (&CpuMpData->CpuData[0].VolatileRegisters, >>> &VolatileRegisters, sizeof (VolatileRegisters)); >>> + CopyMem >>> + (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, >>> + &VolatileRegisters, sizeof (VolatileRegisters)); >>> // >>> // Set BSP basic information >>> // >>> - InitializeApData (CpuMpData, 0, 0, CpuMpData->Buffer + >>> ApStackSize); >>> + BspTopOfStack = CpuMpData->Buffer + (CpuMpData->BspNumber + 1) >> * >>> + CpuMpData->CpuApStackSize; InitializeApData (CpuMpData, >>> + CpuMpData->BspNumber, 0, BspTopOfStack); >>> // >>> // Save assembly code information >>> // >>> >> >> The patch seems reasonable to me (although I have not tried verifying that >> all necessary spots are updated). >> >> However, there is one thing I certainly don't understand, and the commit >> message doesn't explain it. In the "BspTopOfStack" calculation, why do we >> change the *second* factor, when we change the multiplication from: >> >> (0 + 1) * ApStackSize >> >> (where the (0 + 1) is implied in the old code), to: >> >> (CpuMpData->BspNumber + 1) * CpuMpData->CpuApStackSize >> >> ? >> >> I understand why the *first* factor is changed -- we basically replace "0" >> with >> "CpuMpData->BspNumber" --; what I don't understand is why we replace >> "ApStackSize" with "CpuMpData->CpuApStackSize", in the second factor. >> >> ... Higher up in the code, we have: >> >> CpuMpData->CpuApStackSize = ApStackSize; >> >> so this part of the patch might actually have no effect. But, even then, I >> think >> it makes the patch harder to understand. So in that case, I'd suggest >> sticking >> with "ApStackSize", just for keeping the patch simpler. >> > [[Eric]] driver has two places to call InitializeApData (). Here is one and > the other in ApWakeupFunction(). > InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack); > At that function, it calculates the ApTopOfStack like below: > ApTopOfStack = CpuMpData->Buffer + (ProcessorNumber + 1) * > CpuMpData->CpuApStackSize; > > I update new code to follow this coding style. I think after this change, the > exit two code pieces are follow > the same coding style. So I think we can keep my original change.
That's fine, but then please include this specific argument in the commit message. Thanks, Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#53303): https://edk2.groups.io/g/devel/message/53303 Mute This Topic: https://groups.io/mt/69712223/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
