Re: [PATCH v1] UefiCpuPkg: Cpu feature data stored in memory may be migrated

["Ni, Ray" <ray.ni@intel.com>]

Eric,
it's related to how pool/page memory is allocated in PEI.

The PEI pool is allocated in HOB. HOB data is migrated by DXE core to a new location. The migration guarantees the HOB data is kept but doesn't fix up the ACPI_CPU_DATA pointer that points to the HOB data.

The PEI page is allocated between Phit->FreeMemoryTop and Phit->MemoryTop. The location is not changed in DXE.

Thanks,
Ray

> -----Original Message-----
> From: Dong, Eric <eric.dong@intel.com>
> Sent: Wednesday, September 29, 2021 10:36 PM
> To: Lou, Yun <yun.lou@intel.com>; devel@edk2.groups.io
> Cc: Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>; Kumar, Rahul1 <rahul1.kumar@intel.com>
> Subject: RE: [PATCH v1] UefiCpuPkg: Cpu feature data stored in memory may be migrated
> 
> Hi,
> 
> Can you help to explain more why PeiAllocatePages does not have the problem while PeiAllocatePool has?
> 
> Thanks,
> Eric
> 
> -----Original Message-----
> From: Lou, Yun <yun.lou@intel.com>
> Sent: Wednesday, September 29, 2021 7:53 PM
> To: devel@edk2.groups.io
> Cc: Lou, Yun <yun.lou@intel.com>; Ni, Ray <ray.ni@intel.com>; Dong, Eric <eric.dong@intel.com>; Laszlo Ersek
> <lersek@redhat.com>; Kumar, Rahul1 <rahul1.kumar@intel.com>
> Subject: [PATCH v1] UefiCpuPkg: Cpu feature data stored in memory may be migrated
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3634
> 
> The memory allocated through "PeiAllocatePool" is located in HOB, and
> in DXE phase, the HOB will be migrated to a different location.
> After the migration, the data stored in the HOB stays the same, but the
> address of pointer to the memory(such as the pointers in ACPI_CPU_DATA
> structure) changes, which may cause "PiSmmCpuDxeSmm" driver can't find
> the memory(the pointers in ACPI_CPU_DATA structure) that allocated in
> "PeiRegisterCpuFeaturesLib", so use "PeiAllocatePages" to allocate
> memory instead.
> 
> Signed-off-by: Jason Lou <yun.lou@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> ---
>  UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
> b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
> index 6e2ab79518..e9eba64914 100644
> --- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
> +++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/CpuFeaturesInitialize.c
> @@ -153,7 +153,7 @@ CpuInitDataInitialize (
>    CpuFeaturesData->AcpiCpuData= AcpiCpuData;
> 
> 
> 
>    CpuStatus = &AcpiCpuData->CpuFeatureInitData.CpuStatus;
> 
> -  Location = AllocateZeroPool (sizeof (EFI_CPU_PHYSICAL_LOCATION) * NumberOfCpus);
> 
> +  Location = AllocatePages (EFI_SIZE_TO_PAGES (sizeof (EFI_CPU_PHYSICAL_LOCATION) * NumberOfCpus));
> 
>    ASSERT (Location != NULL);
> 
>    AcpiCpuData->CpuFeatureInitData.ApLocation = (EFI_PHYSICAL_ADDRESS)(UINTN)Location;
> 
> 
> 
> @@ -205,11 +205,11 @@ CpuInitDataInitialize (
>    //
> 
>    // Collect valid core count in each package because not all cores are valid.
> 
>    //
> 
> -  ThreadCountPerPackage = AllocateZeroPool (sizeof (UINT32) * CpuStatus->PackageCount);
> 
> +  ThreadCountPerPackage = AllocatePages (EFI_SIZE_TO_PAGES (sizeof (UINT32) * CpuStatus->PackageCount));
> 
>    ASSERT (ThreadCountPerPackage != NULL);
> 
>    CpuStatus->ThreadCountPerPackage = (EFI_PHYSICAL_ADDRESS)(UINTN)ThreadCountPerPackage;
> 
> 
> 
> -  ThreadCountPerCore = AllocateZeroPool (sizeof (UINT8) * CpuStatus->PackageCount * CpuStatus->MaxCoreCount);
> 
> +  ThreadCountPerCore = AllocatePages (EFI_SIZE_TO_PAGES (sizeof (UINT8) * CpuStatus->PackageCount * CpuStatus-
> >MaxCoreCount));
> 
>    ASSERT (ThreadCountPerCore != NULL);
> 
>    CpuStatus->ThreadCountPerCore = (EFI_PHYSICAL_ADDRESS)(UINTN)ThreadCountPerCore;
> 
> 
> 
> --
> 2.28.0.windows.1