[edk2-devel] [PATCH] UefiCpuPkg/MpInitLib: Decrease NumApsExecuting only for ApInitConfig
Ni, Ray
ray.ni at intel.com
Fri May 31 09:42:54 UTC 2019
The patch fixes the bug that the memory under 1MB is modified by
firmware in S3 boot.
Root cause is a racing condition in MpInitLib:
1. BSP: WakeUpByInitSipiSipi is set by NotifyOnS3SmmInitDonePpi()
2. BSP: WakeUpAP() wakes all APs to run certain procedure.
2.1. AllocateResetVector() uses <1MB memory for wake up vector.
2.1. FillExchangeInfoData() resets NumApsExecuting to 0.
2.2. WaitApWakeup() waits AP to clear WAKEUP_AP_SIGNAL.
3. AP: ApWakeupFunction() clears WAKEUP_AP_SIGNAL to inform BSP.
5. BSP: FreeResetVector() restores the <1MB memory
4. AP: ApWakeupFunction() calls the certain procedure.
4.1. NumApsExecuting is decreased.
#4.1 happens after the 1MB memory is restored so the result is
memory below 1MB is changed by #4.1
It happens only when the AP executes procedure a bit longer.
AP returns back to ApWakeupFunction() from procedure after
BSP restores the <1MB memory.
Since NumApsExecuting is only used when InitFlag == ApInitConfig
for counting the processor count.
The patch moves the NumApsExecuting decrease to the path when
InitFlag == ApInitConfig.
Signed-off-by: Ray Ni <ray.ni at intel.com>
Cc: Eric Dong <eric.dong at intel.com>
Cc: Nandagopal Sathyanarayanan <nandagopal.sathyanarayanan at intel.com>
---
UefiCpuPkg/Library/MpInitLib/MpLib.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 3337488892..84f1cb92e3 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1,7 +1,7 @@
/** @file
CPU MP Initialize Library common functions.
- Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2016 - 2019, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
@@ -619,6 +619,8 @@ ApWakeupFunction (
RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack);
ApStartupSignalBuffer = CpuMpData->CpuData[ProcessorNumber].StartupApSignal;
+
+ InterlockedDecrement ((UINT32 *) &CpuMpData->MpCpuExchangeInfo->NumApsExecuting);
} else {
//
// Execute AP function if AP is ready
@@ -698,7 +700,6 @@ ApWakeupFunction (
// AP finished executing C code
//
InterlockedIncrement ((UINT32 *) &CpuMpData->FinishedCount);
- InterlockedDecrement ((UINT32 *) &CpuMpData->MpCpuExchangeInfo->NumApsExecuting);
//
// Place AP is specified loop mode
@@ -805,6 +806,7 @@ FillExchangeInfoData (
ExchangeInfo->CFunction = (UINTN) ApWakeupFunction;
ExchangeInfo->ApIndex = 0;
ExchangeInfo->NumApsExecuting = 0;
+ DEBUG ((DEBUG_ERROR, "NumApsExecuting = %p\n", &ExchangeInfo->NumApsExecuting));
ExchangeInfo->InitFlag = (UINTN) CpuMpData->InitFlag;
ExchangeInfo->CpuInfo = (CPU_INFO_IN_HOB *) (UINTN) CpuMpData->CpuInfoInHob;
ExchangeInfo->CpuMpData = CpuMpData;
@@ -1598,6 +1600,7 @@ MpInitLibInitialize (
CpuMpData->Buffer = Buffer;
CpuMpData->CpuApStackSize = ApStackSize;
CpuMpData->BackupBuffer = BackupBufferAddr;
+ DEBUG ((DEBUG_ERROR, "BackupBuffer = %p\n", BackupBufferAddr));
CpuMpData->BackupBufferSize = ApResetVectorSize;
CpuMpData->WakeupBuffer = (UINTN) -1;
CpuMpData->CpuCount = 1;
--
2.21.0.windows.1
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