[edk2-devel] [PATCH] UefiCpuPkg: Remove ASSERT checking if FinishedCount equal to CpuCount-1

[Yuanhao Xie]

The purpose is to fix an assertion with applying the following patch
series:

UefiCpuPkg: Refactor the logic for placing APs in HltLoop.
UefiCpuPkg: Refactor the logic for placing APs in Mwait/Runloop.
UefiCpuPkg: Create MpHandOff.
UefiCpuPkg: ApWakeupFunction directly use CpuMpData.
UefiCpuPkg: Eliminate the second INIT-SIPI-SIPI sequence.
UefiCpuPkg: Decouple the SEV-ES functionality.

The assertion arises from a timing discrepancy between BSP completing
its startup signal check and the APs incrementing the FinishedCount.

Instead of assertion, use while loop to waits until all the APs have
incremented the FinishedCount.

Cc: Ray Ni <ray.ni at intel.com>
Cc: Eric Dong <eric.dong at intel.com>
Cc: Rahul Kumar <rahul1.kumar at intel.com>
Cc: Tom Lendacky <thomas.lendacky at amd.com>
Signed-off-by: Yuanhao Xie <yuanhao.xie at intel.com>
---
 UefiCpuPkg/Library/MpInitLib/MpLib.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 6f1456cfe1..9a6ec5db5c 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -913,8 +913,8 @@ DxeApEntryPoint (
   UINTN  ProcessorNumber;
 
   GetProcessorNumber (CpuMpData, &ProcessorNumber);
-  InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
   RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
+  InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
   PlaceAPInMwaitLoopOrRunLoop (
     CpuMpData->ApLoopMode,
     CpuMpData->CpuData[ProcessorNumber].StartupApSignal,
@@ -2201,7 +2201,12 @@ MpInitLibInitialize (
       // looping process there.
       //
       SwitchApContext (MpHandOff);
-      ASSERT (CpuMpData->FinishedCount == (CpuMpData->CpuCount - 1));
+      //
+      // Wait for all APs finished initialization
+      //
+      while (CpuMpData->FinishedCount < (CpuMpData->CpuCount - 1)) {
+        CpuPause ();
+      }
 
       //
       // Set Apstate as Idle, otherwise Aps cannot be waken-up again.
-- 
2.36.1.windows.1



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