[edk2-devel] [PATCH 1/2] UefiCpuPkg/MpInitLib: Restore IDT context for APs.
Ni, Ray
ray.ni at intel.com
Wed Apr 22 07:54:04 UTC 2020
Please check my comments in below.
> -----Original Message-----
> From: Dong, Eric <eric.dong at intel.com>
> Sent: Wednesday, April 22, 2020 9:35 AM
> To: devel at edk2.groups.io
> Cc: Ni, Ray <ray.ni at intel.com>; Laszlo Ersek <lersek at redhat.com>; Kumar,
> Chandana C <chandana.c.kumar at intel.com>
> Subject: [PATCH 1/2] UefiCpuPkg/MpInitLib: Restore IDT context for APs.
>
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2683
>
>
>
> This patch used to fix a ASSERT because AP can't find the CpuMpData.
1. This patch fixes an assertion because AP can't find the CpuMpData.
>
>
> When AP been waked up through Init-Sipi-Sipi, the IDT should
> been restore to preallcated buffer to make it can get the
> CpuMpData through IDT base address.
> Not when CpuMpData->InitFlag is ApInitReconfig or ApInitConfig,
> AP will be wake up through Init-Sipi-Sipi. Current code already
> has logic to handle ApInitConfig, but miss the handler for
> ApInitReconfig. This patch fixes this gap.
2. When AP is waken up through Init-Sipi-Sipi, AP's IDT should
be restored to pre-allocated buffer so AP can get the CpuMpData
through the IDT base address.
Current code already has logic to handle this when CpuMpData->
InitFlag is ApInitConfig but misses the logic
when CpuMpData->InitFlag is ApInitReconfig.
This patch fixes this gap.
>
> Cc: Ray Ni <ray.ni at intel.com>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Chandana Kumar <chandana.c.kumar at intel.com>
> Signed-off-by: Eric Dong <eric.dong at intel.com>
> ---
> UefiCpuPkg/Library/MpInitLib/MpLib.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 64a4c3546e..ac7f92fd48 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -664,8 +664,9 @@ ApWakeupFunction (
> BistData = *(UINT32 *) ((UINTN) ApTopOfStack - sizeof (UINTN));
>
> //
>
> // CpuMpData->CpuData[0].VolatileRegisters is initialized based on BSP
> environment,
>
> - // to initialize AP in InitConfig path.
>
> - // NOTE: IDTR.BASE stored in CpuMpData->CpuData[0].VolatileRegisters
> points to a different IDT shared by all APs.
>
> + // to initialize AP in InitConfig/ApInitReconfig 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);
>
> InitializeApData (CpuMpData, ProcessorNumber, BistData,
> ApTopOfStack);
>
> @@ -673,6 +674,16 @@ ApWakeupFunction (
>
>
> InterlockedDecrement ((UINT32 *) &CpuMpData->MpCpuExchangeInfo-
> >NumApsExecuting);
>
> } else {
>
> + if ((CpuMpData->InitFlag == ApInitReconfig) && (CpuMpData-
> >ApLoopMode != ApInHltLoop)) {
>
> + //
>
> + // CpuMpData->CpuData[0].VolatileRegisters is initialized based on
> BSP environment,
>
> + // to initialize AP in InitConfig/ApInitReconfig path.
3.
Initialize AP volatile registers in ApInitReconfig path.
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.
>
> + // NOTE: IDTR.BASE stored in CpuMpData-
> >CpuData[0].VolatileRegisters points to a
>
> + // different IDT shared by all APs.
>
> + //
>
> + RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters,
> FALSE);
4. Is it possible to combine this function call with the restoration code below?
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[0].VolatileRegisters points to a
// different IDT shared by all APs.
//
RestoreVolatileRegisters (&CpuMpData->CpuData[0].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 ();
}
}
>
> + }
>
> +
>
> //
>
> // Execute AP function if AP is ready
>
> //
>
> --
> 2.23.0.windows.1
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