SecurityPkg: Introduce Dynamic TCG Log Scaling

MdePkg/Include/IndustryStandard/Tpm2Acpi.h

@@ -80,6 +80,36 @@ typedef struct {
   UINT8     Reserved[8];
 } EFI_TPM2_ACPI_START_METHOD_SPECIFIC_PARAMETERS_ARM_FFA;
 
+// MU_CHANGE - [BEGIN]
+
+typedef struct {
+  EFI_ACPI_DESCRIPTION_HEADER    Header;
+  // Flags field is replaced in version 4 and above
+  //    BIT0~15:  PlatformClass      This field is only valid for version 4 and above
+  //    BIT16~31: Reserved
+  UINT32                         Flags;
+  UINT64                         AddressOfControlArea;
+  UINT32                         StartMethod;
+  UINT8                          PlatformSpecificParameters[12]; // size up to 12
+  UINT32                         Laml;                           // Optional
+  UINT64                         Lasa;                           // Optional
+} EFI_TPM2_ACPI_TABLE_V4;
+
+typedef struct {
+  EFI_ACPI_DESCRIPTION_HEADER                               Header;
+  // Flags field is replaced in version 4 and above
+  //    BIT0~15:  PlatformClass      This field is only valid for version 4 and above
+  //    BIT16~31: Reserved
+  UINT32                                                    Flags;
+  UINT64                                                    AddressOfControlArea;
+  UINT32                                                    StartMethod;
+  EFI_TPM2_ACPI_START_METHOD_SPECIFIC_PARAMETERS_ARM_FFA    FfaParameters;
+  UINT32                                                    Laml; // Optional
+  UINT64                                                    Lasa; // Optional
+} EFI_TPM2_ACPI_TABLE_V5;
+
+// MU_CHANGE - [END]
+
 #define EFI_TPM2_ACPI_TABLE_ARM_FFA_PARAMETER_FLAG_NOTIFICATION_SUPPORT  BIT0
 
 #define EFI_TPM2_ACPI_TABLE_ARM_FFA_PARAMETER_ATTR_MEM_TYPE_MASK           0x3

MdePkg/Include/IndustryStandard/UefiTcgPlatform.h

@@ -101,6 +101,11 @@
 #define FIRMWARE_DEBUGGER_EVENT_STRING      "UEFI Debug Mode"
 #define FIRMWARE_DEBUGGER_EVENT_STRING_LEN  (sizeof(FIRMWARE_DEBUGGER_EVENT_STRING) - 1)
 
+// MU_CHANGE
+// String logged as a NO_ACTION event to mark the ACPI-visible TCG
+// log as truncated when dynamic scaling occurs post ReadyToBoot.
+#define TCG_LOG_TRUNCATION_EVENT_STRING  "TCG Event Log Truncated"
+
 //
 // Set structure alignment to 1-byte
 //

SecurityPkg/SecurityPkg.dec

@@ -301,6 +301,13 @@
   # Include/Protocol/MuTcg2Protocol.h
   gMuTcg2ProtocolExGuid              = {0x227e7984, 0x1a77, 0x4762, { 0x96, 0x69, 0x57, 0x4c, 0xda, 0xd1, 0xa0, 0x1e }}
   ## MU_CHANGE - END - Add a new protocol to support Log-only events.
+
+  ## MU_CHANGE - [BEGIN]
+  ## Protocol used to test dynamic TCG log scaling functionality.
+  # Tcg/TcgLogTest/TcgLogTest.h
+  gTcgLogTestProtocolGuid            = {0xa3c12f80, 0x7d9e, 0x4b5a, { 0x91, 0xe4, 0x6c, 0xf8, 0x2d, 0xa1, 0xb7, 0x03 }}
+  ## MU_CHANGE - [END]
+
 [Ppis]
   ## The PPI GUID for that TPM physical presence should be locked.
   # Include/Ppi/LockPhysicalPresence.h

SecurityPkg/SecurityPkg.dsc

@@ -249,6 +249,16 @@
 
   SecurityPkg/Applications/TpmShellApp/TpmShellApp.inf  ## MU_CHANGE
 
+  ## MU_CHANGE - [BEGIN]
+  SecurityPkg/Tcg/TcgLogTest/TcgLogTestDxe.inf
+  SecurityPkg/Tcg/TcgLogTest/TcgLogTestApp.inf {
+    <LibraryClasses>
+      UnitTestLib|UnitTestFrameworkPkg/Library/UnitTestLib/UnitTestLib.inf
+      UnitTestPersistenceLib|UnitTestFrameworkPkg/Library/UnitTestPersistenceLibNull/UnitTestPersistenceLibNull.inf
+      UnitTestResultReportLib|UnitTestFrameworkPkg/Library/UnitTestResultReportLib/UnitTestResultReportLibDebugLib.inf
+  }
+  ## MU_CHANGE - [END]
+
   #
   # TCG Storage.
   #

SecurityPkg/Tcg/Tcg2Acpi/Tcg2Acpi.c

@@ -74,7 +74,11 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 //
 #define MAX_PRS_INT_BUF_SIZE  (15*4)
 
-#pragma pack(1)
+// MU_CHANGE - [BEGIN]
+
+#if 0
+
+  #pragma pack(1)
 
 typedef struct {
   EFI_ACPI_DESCRIPTION_HEADER    Header;
@@ -89,7 +93,11 @@ typedef struct {
   UINT64                         Lasa;                           // Optional
 } EFI_TPM2_ACPI_TABLE_V4;
 
-#pragma pack()
+  #pragma pack()
+
+#endif
+
+// MU_CHANGE - [END]
 
 EFI_TPM2_ACPI_TABLE_V4  mTpm2AcpiTemplate = {
   {

SecurityPkg/Tcg/Tcg2AcpiFfa/Tcg2AcpiFfa.c

@@ -66,7 +66,11 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 //
 #define MAX_PRS_INT_BUF_SIZE  (15*4)
 
-#pragma pack(1)
+// MU_CHANGE - [BEGIN]
+
+#if 0
+
+  #pragma pack(1)
 
 typedef struct {
   EFI_ACPI_DESCRIPTION_HEADER                               Header;
@@ -81,7 +85,11 @@ typedef struct {
   UINT64                                                    Lasa; // Optional
 } EFI_TPM2_ACPI_TABLE_V5;
 
-#pragma pack()
+  #pragma pack()
+
+#endif
+
+// MU_CHANGE - [END]
 
 EFI_TPM2_ACPI_TABLE_V5  mTpm2AcpiTemplate = {
   {

SecurityPkg/Tcg/Tcg2Dxe/README.md

@@ -0,0 +1,83 @@
+# Tcg2Dxe
+
+Tcg2Dxe is a DXE-phase UEFI driver that publishes the TCG2 protocol defined
+by the [TCG EFI Protocol Specification](https://trustedcomputinggroup.org/resource/tcg-efi-protocol-specification/).
+It's main responsibilites are to expose a standard interface to a TPM device,
+measure components and events into PCRs, support measured boot, and enable
+secure boot attestation.
+
+## Dynamic Event Log Scaling
+
+The TCG event log is initially allocated with a fixed size defined by a
+PCD: PcdTcgLogAreaMinLen. As firmware components log measured boot
+events the log fills up. Traditionally, when the log is full, subsequent events
+are dropped and the log is marked as truncated.
+
+Tcg2Dxe extends this behavior with **dynamic scaling**: when the log is about
+to overflow, the driver doubles its allocation, copies the existing log into
+the new buffer, and frees the old one. This allows the log to grow as needed
+and avoids losing events.
+
+### How It Works
+
+1. **Scaling check** — Before logging a TCG 2.0 event,
+   `TcgLogDynamicScalingNeeded` calculates whether the new event (plus a
+   reserved truncation marker) would exceed the current allocation
+   (`EventLogAreaStruct->Laml`). Space is reserved for the truncation marker
+   as long as the ACPI log has not yet been marked truncated.
+
+2. **Reallocation** — When scaling is needed, `TcgScaleEventLog` allocates a
+   new `EfiBootServicesData` region at twice the current size, copies the
+   existing log, updates the `Lasa`/`Laml` fields in the event log area
+   struct, and frees the old region.
+
+3. **Logging** — After scaling, the new event is logged into the resized buffer
+   via `TcgDxeLogEvent` inside a TPL-raised critical section.
+
+### Normal Log vs. ACPI Log vs. Final Events Log
+
+Tcg2Dxe maintains three distinct event log regions:
+
+| Log | Memory Type | Lifetime | Can Scale |
+| --- | ----------- | -------- | --------- |
+| **Normal log** | `EfiBootServicesData` | Available until `ExitBootServices` | Yes |
+| **ACPI log** | `EfiACPIMemoryNVS` | Persistent | No |
+| **Final Events log** | `EfiACPIMemoryNVS` | Persistent | No |
+
+- The **Normal log** is the main log copy which is returned via `GetEventLog`.
+  It can grow dynamically via scaling. Note that previous calls to `GetEventLog`
+  could contain stale data if the log was scaled after. It is recommended to
+  call `GetEventLog` each time access is required.
+- The **ACPI log** is created at `ReadyToBoot` by `GenerateAcpiLog`. It
+  allocates an `EfiACPIMemoryNVS` region equal to the **Normal log** size at that
+  point, copies the log contents, and updates the TPM2 ACPI table's
+  `LAML`/`LASA` fields so the OS can find it. If the TPM2 table was already
+  installed via Tcg2Acpi/Tcg2AcpiFfa, `GenerateAcpiLog` will uninstall and
+  reinstall the ACPI table with the updated LAML and LASA pointing to the
+  newly allocated NVS region.
+- The **Final Events log** (`EFI_TCG2_FINAL_EVENTS_TABLE`) records events
+  logged after `GetEventLog` has been called. It is installed as a UEFI
+  configuration table so the OS can discover events that occurred between its
+  call to `GetEventLog` and `ExitBootServices`. Because the **Final Events log**
+  does not scale, it can become truncated.
+
+After `ReadyToBoot`, every new event is also appended to the ACPI log. Because
+the ACPI log's NVS allocation is fixed (the OS may already be referencing its
+address), it cannot be reallocated.
+
+### Post-ReadyToBoot Truncation
+
+When dynamic scaling is triggered after `ReadyToBoot`:
+
+1. A `NO_ACTION` event with the payload `"TCG Event Log Truncated"` is
+   appended to the **ACPI log** to notify the OS that the ACPI-visible log is
+   now incomplete.
+2. The ACPI log is marked truncated (`EventLogTruncated = TRUE`) so no further
+   events are written to it and no additional space is reserved for the
+   truncation marker.
+3. The **normal log** is scaled as usual — it continues to grow and accept new
+   events.
+
+This means the normal log accessed via `GetEventLog` always has the complete
+set of events, while the ACPI log visible to the OS may be truncated with a
+marker at the end.