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UefiCpuPkg/Microcode: Fix incorrect checksum issue for extended table
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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 <[email protected]>
Cc: Ray Ni <[email protected]>
Cc: Eric Dong <[email protected]>
Cc: Zhang Chao B <[email protected]>
Reviewed-by: Ray Ni <[email protected]>
Reviewed-by: Eric Dong <[email protected]>
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@chenc2 @ydong10
chenc2 authored and ydong10 committed Feb 21, 2019
1 parent b49758c commit b6f67b4
Showing 1 changed file with 73 additions and 9 deletions.
82 changes: 73 additions & 9 deletions UefiCpuPkg/Library/MpInitLib/Microcode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,42 @@ GetCurrentMicrocodeSignature (
/**
Detect whether specified processor can find matching microcode patch and load it.
Microcode Payload as the following format:
+----------------------------------------+------------------+
| CPU_MICROCODE_HEADER | |
+----------------------------------------+ CheckSum Part1 |
| Microcode Binary | |
+----------------------------------------+------------------+
| CPU_MICROCODE_EXTENDED_TABLE_HEADER | |
+----------------------------------------+ CheckSum Part2 |
| CPU_MICROCODE_EXTENDED_TABLE | |
| ... | |
+----------------------------------------+------------------+
There may by multiple CPU_MICROCODE_EXTENDED_TABLE in this format.
The count of CPU_MICROCODE_EXTENDED_TABLE is indicated by ExtendedSignatureCount
of CPU_MICROCODE_EXTENDED_TABLE_HEADER structure.
When we are trying to verify the CheckSum32 with extended table.
We should use the fields of exnteded table to replace the corresponding
fields in CPU_MICROCODE_HEADER structure, and recalculate the
CheckSum32 with CPU_MICROCODE_HEADER + Microcode Binary. We named
it as CheckSum Part3.
The CheckSum Part2 is used to verify the CPU_MICROCODE_EXTENDED_TABLE_HEADER
and CPU_MICROCODE_EXTENDED_TABLE parts. We should make sure CheckSum Part2
is correct before we are going to verify each CPU_MICROCODE_EXTENDED_TABLE.
Only ProcessorSignature, ProcessorFlag and CheckSum are different between
CheckSum Part1 and CheckSum Part3. To avoid multiple computing CheckSum Part3.
Save an in-complete CheckSum32 from CheckSum Part1 for common parts.
When we are going to calculate CheckSum32, just should use the corresponding part
of the ProcessorSignature, ProcessorFlag and CheckSum with in-complete CheckSum32.
Notes: CheckSum32 is not a strong verification.
It does not guarantee that the data has not been modified.
CPU has its own mechanism to verify Microcode Binary part.
@param[in] CpuMpData The pointer to CPU MP Data structure.
@param[in] IsBspCallIn Indicate whether the caller is BSP or not.
**/
Expand All @@ -57,6 +93,7 @@ MicrocodeDetect (
UINT32 LatestRevision;
UINTN TotalSize;
UINT32 CheckSum32;
UINT32 InCompleteCheckSum32;
BOOLEAN CorrectMicrocode;
VOID *MicrocodeData;
MSR_IA32_PLATFORM_ID_REGISTER PlatformIdMsr;
Expand Down Expand Up @@ -121,6 +158,25 @@ MicrocodeDetect (
MicrocodeData = NULL;
MicrocodeEnd = (UINTN) (CpuMpData->MicrocodePatchAddress + CpuMpData->MicrocodePatchRegionSize);
MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (UINTN) CpuMpData->MicrocodePatchAddress;

//
// Save an in-complete CheckSum32 from CheckSum Part1 for common parts.
//
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
Expand All @@ -137,14 +193,13 @@ 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)
);
}
//
// Calculate CheckSum Part1.
//
CheckSum32 = InCompleteCheckSum32;
CheckSum32 += MicrocodeEntryPoint->ProcessorSignature.Uint32;
CheckSum32 += MicrocodeEntryPoint->ProcessorFlags;
CheckSum32 += MicrocodeEntryPoint->Checksum;
if (CheckSum32 == 0) {
CorrectMicrocode = TRUE;
ProcessorFlags = MicrocodeEntryPoint->ProcessorFlags;
Expand All @@ -163,6 +218,9 @@ MicrocodeDetect (
// Calculate Extended Checksum
//
if ((ExtendedTableLength % 4) == 0) {
//
// Calculate CheckSum Part2.
//
CheckSum32 = CalculateSum32 ((UINT32 *) ExtendedTableHeader, ExtendedTableLength);
if (CheckSum32 == 0) {
//
Expand All @@ -171,7 +229,13 @@ 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));
//
// Calculate CheckSum Part3.
//
CheckSum32 = InCompleteCheckSum32;
CheckSum32 += ExtendedTable->ProcessorSignature.Uint32;
CheckSum32 += ExtendedTable->ProcessorFlag;
CheckSum32 += ExtendedTable->Checksum;
if (CheckSum32 == 0) {
//
// Verify Header
Expand Down

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