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UefiCpuPkg: Let AP always save/restore volatile registers

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When enable stack guard, APs needs separate GDTs.
In current code, APs will lose their separate GDTs when AP get disabled
and later re-enabled. This is because when re-enabling AP, AP restores
volatile registers from BSP.
This patch updates the AP management to ensure that each AP saves and
restores its own set of volatile registers to solve this issue.

Key changes include:
- APs now maintain their own volatile register space, eliminating
dependency on the BSP's register state.
- Special handling is implemented for the first AP wake-up during the
PEI and DXE phases, where the volatile registers are synchronized from
the BSP.
- When switching BSP, remove manual handling the global variable
CpuMpData->CpuData[Index].VolatileRegisters. The manually handling
in previous code is because, old BSP may not save volatile registers
after the AP procedure and new BSP's VolatileRegisters buffer may be
used by other APs. Now, since AP always save/restore volatile registers
from their own buffer, no need to do the special handling.

Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>
This commit is contained in:
Zhiguang Liu 2024-05-30 14:16:25 +08:00 committed by mergify[bot]
parent 7fc08c68cd
commit 4a0c77be68
1 changed files with 25 additions and 46 deletions
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71
UefiCpuPkg/Library/MpInitLib/MpLib.c
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@ -119,10 +119,6 @@ FutureBSPProc (
SaveVolatileRegisters (&DataInHob->APInfo.VolatileRegisters);
AsmExchangeRole (&DataInHob->APInfo, &DataInHob->BSPInfo);
RestoreVolatileRegisters (&DataInHob->APInfo.VolatileRegisters, FALSE);
//
// Update VolatileRegisters saved in CpuMpData->CpuData
//
CopyMem (&DataInHob->CpuData[DataInHob->BspNumber].VolatileRegisters, &DataInHob->APInfo.VolatileRegisters, sizeof (CPU_VOLATILE_REGISTERS));
}
/**
@ -769,11 +765,11 @@ ApWakeupFunction (
BistData = (UINT32)ApStackData->Bist;
//
// CpuMpData->CpuData[BspNumber].VolatileRegisters is initialized based on BSP environment,
// CpuMpData->CpuData[ProcessorNumber].VolatileRegisters is initialized based on BSP environment,
// to initialize AP in InitConfig path.
// NOTE: IDTR.BASE stored in CpuMpData->CpuData[BspNumber].VolatileRegisters points to a different IDT shared by all APs.
// NOTE: IDTR.BASE stored in CpuMpData->CpuData[ProcessorNumber].VolatileRegisters points to a different IDT shared by all APs.
//
RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);
RestoreVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters, FALSE);
InitializeApData (CpuMpData, ProcessorNumber, BistData, ApTopOfStack);
ApStartupSignalBuffer = CpuMpData->CpuData[ProcessorNumber].StartupApSignal;
} else {
@ -800,31 +796,7 @@ ApWakeupFunction (
0
);
if (CpuMpData->InitFlag == ApInitReconfig) {
//
// ApInitReconfig happens when:
// 1. AP is re-enabled after it's disabled, in either PEI or DXE phase.
// 2. AP is initialized in DXE phase.
// In either case, use the volatile registers value derived from BSP.
// NOTE: IDTR.BASE stored in CpuMpData->CpuData[BspNumber].VolatileRegisters points to a
// different IDT shared by all APs.
//
RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);
} else {
if (CpuMpData->ApLoopMode == ApInHltLoop) {
//
// Restore AP's volatile registers saved before AP is halted
//
RestoreVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters, TRUE);
} else {
//
// The CPU driver might not flush TLB for APs on spot after updating
// page attributes. AP in mwait loop mode needs to take care of it when
// woken up.
//
CpuFlushTlb ();
}
}
RestoreVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters, TRUE);
if (GetApState (&CpuMpData->CpuData[ProcessorNumber]) == CpuStateReady) {
Procedure = (EFI_AP_PROCEDURE)CpuMpData->CpuData[ProcessorNumber].ApFunction;
@ -875,12 +847,7 @@ ApWakeupFunction (
}
}
if (CpuMpData->ApLoopMode == ApInHltLoop) {
//
// Save AP volatile registers
//
SaveVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters);
}
SaveVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters);
//
// AP finished executing C code
@ -935,7 +902,7 @@ DxeApEntryPoint (
AsmWriteMsr64 (MSR_IA32_EFER, EferMsr.Uint64);
}
RestoreVolatileRegisters (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, FALSE);
RestoreVolatileRegisters (&CpuMpData->CpuData[ProcessorNumber].VolatileRegisters, FALSE);
InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
PlaceAPInMwaitLoopOrRunLoop (
CpuMpData->ApLoopMode,
@ -2198,7 +2165,25 @@ MpInitLibInitialize (
// Don't pass BSP's TR to APs to avoid AP init failure.
//
VolatileRegisters.Tr = 0;
CopyMem (&CpuMpData->CpuData[CpuMpData->BspNumber].VolatileRegisters, &VolatileRegisters, sizeof (VolatileRegisters));
//
// Set DR as 0 since DR is set only for BSP.
//
VolatileRegisters.Dr0 = 0;
VolatileRegisters.Dr1 = 0;
VolatileRegisters.Dr2 = 0;
VolatileRegisters.Dr3 = 0;
VolatileRegisters.Dr6 = 0;
VolatileRegisters.Dr7 = 0;
//
// Copy volatile registers since either APs are the first time to bring up,
// or BSP is in DXE phase but APs are still running in PEI context.
// In both cases, APs need use volatile registers from BSP
//
for (Index = 0; Index < MaxLogicalProcessorNumber; Index++) {
CopyMem (&CpuMpData->CpuData[Index].VolatileRegisters, &VolatileRegisters, sizeof (VolatileRegisters));
}
//
// Set BSP basic information
//
@ -2633,12 +2618,6 @@ SwitchBSPWorker (
AsmExchangeRole (&CpuMpData->BSPInfo, &CpuMpData->APInfo);
RestoreVolatileRegisters (&CpuMpData->BSPInfo.VolatileRegisters, FALSE);
//
// Update VolatileRegisters saved in CpuMpData->CpuData
// Don't pass BSP's TR to APs to avoid AP init failure.
//
CopyMem (&CpuMpData->CpuData[CpuMpData->NewBspNumber].VolatileRegisters, &CpuMpData->BSPInfo.VolatileRegisters, sizeof (CPU_VOLATILE_REGISTERS));
CpuMpData->CpuData[CpuMpData->NewBspNumber].VolatileRegisters.Tr = 0;
//
// Set the BSP bit of MSR_IA32_APIC_BASE on new BSP
//
ApicBaseMsr.Uint64 = AsmReadMsr64 (MSR_IA32_APIC_BASE);