[PATCH v2 3/4] UefiCpuPkg/CpuS3DataDxe: do not allocate useless register tables

["Laszlo Ersek" <lersek@redhat.com>]

CpuS3DataDxe allocates the "RegisterTable" and "PreSmmInitRegisterTable"
arrays in ACPI_CPU_DATA just so every processor in the system can have its
own empty register table, matched by APIC ID. This has never been useful
in practice.

Given commit e992cc3f4859 ("UefiCpuPkg PiSmmCpuDxeSmm: Reduce SMRAM
consumption in CpuS3.c", 2021-01-11), simply leave both
"AcpiCpuData->RegisterTable" and "AcpiCpuData->PreSmmInitRegisterTable"
initialized to the zero address. This simplifies the driver, and saves
both normal RAM (boot services data type memory) and -- in PiSmmCpuDxeSmm
-- SMRAM.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3159
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
---

Notes:
    v2:
    
    - no changes, pick up feedback tags
    
    v1:
    
    - Tested by temporarily replacing OvmfPkgPkg/CpuS3DataDxe in the OVMF
      IA32 and IA32X64 platforms with this driver -- this driver works OK in
      OVMF as long as no CPUs are hot-plugged.

 UefiCpuPkg/CpuS3DataDxe/CpuS3Data.c | 32 --------------------
 1 file changed, 32 deletions(-)

diff --git a/UefiCpuPkg/CpuS3DataDxe/CpuS3Data.c b/UefiCpuPkg/CpuS3DataDxe/CpuS3Data.c
index 2be335d91903..078af36cfb41 100644
--- a/UefiCpuPkg/CpuS3DataDxe/CpuS3Data.c
+++ b/UefiCpuPkg/CpuS3DataDxe/CpuS3Data.c
@@ -165,10 +165,6 @@ CpuS3DataInitialize (
   UINTN                      NumberOfCpus;
   UINTN                      NumberOfEnabledProcessors;
   VOID                       *Stack;
-  UINTN                      TableSize;
-  CPU_REGISTER_TABLE         *RegisterTable;
-  UINTN                      Index;
-  EFI_PROCESSOR_INFORMATION  ProcessorInfoBuffer;
   UINTN                      GdtSize;
   UINTN                      IdtSize;
   VOID                       *Gdt;
@@ -255,34 +251,6 @@ CpuS3DataInitialize (
     AcpiCpuData->PreSmmInitRegisterTable = OldAcpiCpuData->PreSmmInitRegisterTable;
     AcpiCpuData->ApLocation              = OldAcpiCpuData->ApLocation;
     CopyMem (&AcpiCpuData->CpuStatus, &OldAcpiCpuData->CpuStatus, sizeof (CPU_STATUS_INFORMATION));
-  } else {
-    //
-    // Allocate buffer for empty RegisterTable and PreSmmInitRegisterTable for all CPUs
-    //
-    TableSize = 2 * NumberOfCpus * sizeof (CPU_REGISTER_TABLE);
-    RegisterTable = (CPU_REGISTER_TABLE *)AllocateZeroPages (TableSize);
-    ASSERT (RegisterTable != NULL);
-
-    for (Index = 0; Index < NumberOfCpus; Index++) {
-      Status = MpServices->GetProcessorInfo (
-                           MpServices,
-                           Index,
-                           &ProcessorInfoBuffer
-                           );
-      ASSERT_EFI_ERROR (Status);
-
-      RegisterTable[Index].InitialApicId      = (UINT32)ProcessorInfoBuffer.ProcessorId;
-      RegisterTable[Index].TableLength        = 0;
-      RegisterTable[Index].AllocatedSize      = 0;
-      RegisterTable[Index].RegisterTableEntry = 0;
-
-      RegisterTable[NumberOfCpus + Index].InitialApicId      = (UINT32)ProcessorInfoBuffer.ProcessorId;
-      RegisterTable[NumberOfCpus + Index].TableLength        = 0;
-      RegisterTable[NumberOfCpus + Index].AllocatedSize      = 0;
-      RegisterTable[NumberOfCpus + Index].RegisterTableEntry = 0;
-    }
-    AcpiCpuData->RegisterTable           = (EFI_PHYSICAL_ADDRESS)(UINTN)RegisterTable;
-    AcpiCpuData->PreSmmInitRegisterTable = (EFI_PHYSICAL_ADDRESS)(UINTN)(RegisterTable + NumberOfCpus);
   }
 
   //
-- 
2.19.1.3.g30247aa5d201