Re: [PATCH] UefiCpuPkg/Microcode: Fix incorrect checksum issue for extended table

["Zhang, Chao B" <chao.b.zhang@intel.com>]

Chen Chen:
   I think you can add uCode format info into comments. Also please highlight in comment
Which part is header checksum calculation, which part is for extended header

-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Chen A Chen
Sent: Monday, February 18, 2019 1:54 PM
To: edk2-devel@lists.01.org
Cc: Dong, Eric <eric.dong@intel.com>
Subject: [edk2] [PATCH] UefiCpuPkg/Microcode: Fix incorrect checksum issue for extended table

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1020

The following Microcode payload format is define in SDM spec.
Payload: |MicrocodeHeader|MicrocodeBinary|ExtendedHeader|ExtendedTable|.
When we verify the CheckSum32 with ExtendedTable, we should use the fields of ExtendedTable to replace corresponding fields in MicrocodeHeader, and then calculate the CheckSum32 with MicrocodeHeader+MicrocodeBinary.
This patch already verified on ICL platform.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Chen A Chen <chen.a.chen@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
---
 UefiCpuPkg/Library/MpInitLib/Microcode.c | 38 ++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c b/UefiCpuPkg/Library/MpInitLib/Microcode.c
index d84344c6f5..38880cdbec 100644
--- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
+++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
@@ -57,6 +57,7 @@ MicrocodeDetect (
   UINT32                                  LatestRevision;
   UINTN                                   TotalSize;
   UINT32                                  CheckSum32;
+  UINT32                                  InCompleteCheckSum32;
   BOOLEAN                                 CorrectMicrocode;
   VOID                                    *MicrocodeData;
   MSR_IA32_PLATFORM_ID_REGISTER           PlatformIdMsr;
@@ -121,6 +122,26 @@ MicrocodeDetect (
   MicrocodeData  = NULL;
   MicrocodeEnd = (UINTN) (CpuMpData->MicrocodePatchAddress + CpuMpData->MicrocodePatchRegionSize);
   MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (UINTN) CpuMpData->MicrocodePatchAddress;
+
+  //
+  // To avoid double calculate checksum32 value.
+  // Save the CheckSum32 of the common parts in advance.
+  //
+  if (MicrocodeEntryPoint->DataSize == 0) {
+    InCompleteCheckSum32 = CalculateSum32 (
+                             (UINT32 *) MicrocodeEntryPoint,
+                             sizeof (CPU_MICROCODE_HEADER) + 2000
+                             );
+  } else {
+    InCompleteCheckSum32 = CalculateSum32 (
+                             (UINT32 *) MicrocodeEntryPoint,
+                             sizeof (CPU_MICROCODE_HEADER) + MicrocodeEntryPoint->DataSize
+                             );
+  }
+  InCompleteCheckSum32 -= 
+ MicrocodeEntryPoint->ProcessorSignature.Uint32;
+  InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorFlags;
+  InCompleteCheckSum32 -= MicrocodeEntryPoint->Checksum;
+
   do {
     //
     // Check if the microcode is for the Cpu and the version is newer @@ -137,14 +158,10 @@ MicrocodeDetect (
           MicrocodeEntryPoint->UpdateRevision > LatestRevision &&
           (MicrocodeEntryPoint->ProcessorFlags & (1 << PlatformId))
           ) {
-        if (MicrocodeEntryPoint->DataSize == 0) {
-          CheckSum32 = CalculateSum32 ((UINT32 *) MicrocodeEntryPoint, 2048);
-        } else {
-          CheckSum32 = CalculateSum32 (
-                         (UINT32 *) MicrocodeEntryPoint,
-                         MicrocodeEntryPoint->DataSize + sizeof (CPU_MICROCODE_HEADER)
-                         );
-        }
+        CheckSum32 = InCompleteCheckSum32;
+        CheckSum32 += MicrocodeEntryPoint->ProcessorSignature.Uint32;
+        CheckSum32 += MicrocodeEntryPoint->ProcessorFlags;
+        CheckSum32 += MicrocodeEntryPoint->Checksum;
         if (CheckSum32 == 0) {
           CorrectMicrocode = TRUE;
           ProcessorFlags = MicrocodeEntryPoint->ProcessorFlags;
@@ -171,7 +188,10 @@ MicrocodeDetect (
               ExtendedTableCount = ExtendedTableHeader->ExtendedSignatureCount;
               ExtendedTable      = (CPU_MICROCODE_EXTENDED_TABLE *) (ExtendedTableHeader + 1);
               for (Index = 0; Index < ExtendedTableCount; Index ++) {
-                CheckSum32 = CalculateSum32 ((UINT32 *) ExtendedTable, sizeof(CPU_MICROCODE_EXTENDED_TABLE));
+                CheckSum32 = InCompleteCheckSum32;
+                CheckSum32 += ExtendedTable->ProcessorSignature.Uint32;
+                CheckSum32 += ExtendedTable->ProcessorFlag;
+                CheckSum32 += ExtendedTable->Checksum;
                 if (CheckSum32 == 0) {
                   //
                   // Verify Header
--
2.16.2.windows.1

_______________________________________________
edk2-devel mailing list
edk2-devel@lists.01.org
https://lists.01.org/mailman/listinfo/edk2-devel