The default EfiSmbiosProtocol operates on an empty SMBIOS table.
The SMBIOS tables are provided by the bootloader on UefiPayloadPkg.
Scan for existing tables in SmbiosDxe and load them if they seem valid.

This fixes the settings menu not showing any hardware information, instead
only "0 MB RAM" was displayed.

Tests showed that the OS can still see the SMBIOS tables.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
---
 MdeModulePkg/Universal/SmbiosDxe/SmbiosDxe.c | 223 +++++++++++++++++++-
 1 file changed, 221 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/SmbiosDxe/SmbiosDxe.c b/MdeModulePkg/Universal/SmbiosDxe/SmbiosDxe.c
index 3cdb0b1ed7..958a249cf9 100644
--- a/MdeModulePkg/Universal/SmbiosDxe/SmbiosDxe.c
+++ b/MdeModulePkg/Universal/SmbiosDxe/SmbiosDxe.c
@@ -1408,6 +1408,177 @@ SmbiosTableConstruction (
   }
 }
 
+/**
+  Validates a SMBIOS 2.0 table entry point.
+
+  @param  EntryPointStructure   The SMBIOS_TABLE_ENTRY_POINT to validate.
+
+  @retval TRUE           SMBIOS table entry point is valid.
+  @retval FALSE          SMBIOS table entry point is malformed.
+
+**/
+STATIC
+BOOLEAN
+ValidateSmbios20Table(
+  IN SMBIOS_TABLE_ENTRY_POINT      *EntryPointStructure
+) {
+  UINT8 Checksum;
+
+  if (CompareMem (EntryPointStructure->AnchorString, "_SM_", 4) != 0) {
+    return FALSE;
+  }
+  if (EntryPointStructure->EntryPointLength < 0x1E) {
+    return FALSE;
+  }
+  if (EntryPointStructure->MajorVersion < 2) {
+    return FALSE;
+  }
+  if (EntryPointStructure->SmbiosBcdRevision > 0 &&
+    (EntryPointStructure->SmbiosBcdRevision >> 4) < 2) {
+    return FALSE;
+  }
+  if (EntryPointStructure->TableLength == 0) {
+    return FALSE;
+  }
+  if (EntryPointStructure->TableAddress == 0 ||
+    EntryPointStructure->TableAddress == ~0) {
+    return FALSE;
+  }
+
+  Checksum = CalculateSum8((UINT8 *) EntryPointStructure,
+    EntryPointStructure->EntryPointLength);
+  if (Checksum != 0) {
+    return FALSE;
+  }
+
+  Checksum = CalculateSum8((UINT8 *) EntryPointStructure + 0x10,
+    EntryPointStructure->EntryPointLength - 0x10);
+  if (Checksum != 0) {
+    return FALSE;
+  }
+  return TRUE;
+}
+
+/**
+  Validates a SMBIOS 3.0 table entry point.
+
+  @param  Smbios30EntryPointStructure   The SMBIOS_TABLE_3_0_ENTRY_POINT to validate.
+
+  @retval TRUE           SMBIOS table entry point is valid.
+  @retval FALSE          SMBIOS table entry point is malformed.
+
+**/
+STATIC
+BOOLEAN
+ValidateSmbios30Table(
+  IN SMBIOS_TABLE_3_0_ENTRY_POINT  *Smbios30EntryPointStructure
+) {
+  UINT8 Checksum;
+
+  if (CompareMem (Smbios30EntryPointStructure->AnchorString, "_SM3_", 5) != 0) {
+    return FALSE;
+  }
+  if (Smbios30EntryPointStructure->EntryPointLength < 0x18) {
+    return FALSE;
+  }
+  if (Smbios30EntryPointStructure->MajorVersion < 3) {
+    return FALSE;
+  }
+  if (Smbios30EntryPointStructure->TableMaximumSize == 0) {
+    return FALSE;
+  }
+  if (Smbios30EntryPointStructure->TableAddress == 0 ||
+    Smbios30EntryPointStructure->TableAddress == ~0) {
+    return FALSE;
+  }
+
+  Checksum = CalculateSum8((UINT8 *) Smbios30EntryPointStructure,
+    Smbios30EntryPointStructure->EntryPointLength);
+  if (Checksum != 0) {
+    return FALSE;
+  }
+  return TRUE;
+}
+
+/**
+  Parse an existing SMBIOS table and insert it using SmbiosAdd.
+
+  @param  ImageHandle           The EFI_HANDLE to this driver.
+  @param  Smbios                The SMBIOS table to parse.
+  @param  Length                The length of the SMBIOS table.
+
+  @retval EFI_SUCCESS           SMBIOS table was parsed and installed.
+  @retval EFI_OUT_OF_RESOURCES  Record was not added due to lack of system resources.
+
+**/
+STATIC
+EFI_STATUS
+ParseAndAddExistingSmbiosTable(
+  IN EFI_HANDLE                    ImageHandle,
+  IN SMBIOS_STRUCTURE_POINTER      Smbios,
+  IN UINTN                         Length
+) {
+  EFI_STATUS                    Status;
+  CHAR8                         *String;
+  EFI_SMBIOS_HANDLE             SmbiosHandle;
+  SMBIOS_STRUCTURE_POINTER      SmbiosEnd;
+
+  SmbiosEnd.Raw = Smbios.Raw + Length;
+
+  do {
+    // Check for end marker
+    if (Smbios.Hdr->Type == 127) {
+      break;
+    }
+
+    // Install the table
+    SmbiosHandle = SMBIOS_HANDLE_PI_RESERVED;
+    Status = SmbiosAdd (
+      &mPrivateData.Smbios,
+      ImageHandle,
+      &SmbiosHandle,
+      Smbios.Hdr
+      );
+
+    ASSERT_EFI_ERROR (Status);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+    //
+    // Go to the next SMBIOS structure. Each SMBIOS structure may include 2 parts:
+    // 1. Formatted section; 2. Unformatted string section. So, 2 steps are needed
+    // to skip one SMBIOS structure.
+    //
+
+    //
+    // Step 1: Skip over formatted section.
+    //
+    String = (CHAR8 *) (Smbios.Raw + Smbios.Hdr->Length);
+
+    //
+    // Step 2: Skip over unformatted string section.
+    //
+    do {
+      //
+      // Each string is terminated with a NULL(00h) BYTE and the sets of strings
+      // is terminated with an additional NULL(00h) BYTE.
+      //
+      for ( ; *String != 0; String++) {
+      }
+
+      if (*(UINT8*)++String == 0) {
+        //
+        // Pointer to the next SMBIOS structure.
+        //
+        Smbios.Raw = (UINT8 *)++String;
+        break;
+      }
+    } while (TRUE);
+  } while (Smbios.Raw < SmbiosEnd.Raw);
+
+  return EFI_SUCCESS;
+}
+
 /**
 
   Driver to produce Smbios protocol and pre-allocate 1 page for the final SMBIOS table.
@@ -1426,7 +1597,10 @@ SmbiosDriverEntryPoint (
   IN EFI_SYSTEM_TABLE     *SystemTable
   )
 {
-  EFI_STATUS            Status;
+  EFI_STATUS                    Status;
+  SMBIOS_TABLE_ENTRY_POINT      *SmbiosTable;
+  SMBIOS_TABLE_3_0_ENTRY_POINT  *Smbios30Table;
+  SMBIOS_STRUCTURE_POINTER      Smbios;
 
   mPrivateData.Signature                = SMBIOS_INSTANCE_SIGNATURE;
   mPrivateData.Smbios.Add               = SmbiosAdd;
@@ -1450,6 +1624,51 @@ SmbiosDriverEntryPoint (
                   EFI_NATIVE_INTERFACE,
                   &mPrivateData.Smbios
                   );
+  //
+  // Scan for existing SMBIOS tables installed by bootloader
+  //
+  Status = EfiGetSystemConfigurationTable (
+               &gEfiSmbios3TableGuid,
+               (VOID **) &Smbios30Table
+               );
+  if (!EFI_ERROR (Status) && ValidateSmbios30Table(Smbios30Table)) {
+    Smbios.Raw = AllocatePool(Smbios30Table->TableMaximumSize);
+    if (!Smbios.Raw) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+    //
+    // Backup old table in case it gets overwritten while parsing it
+    //
+    CopyMem (Smbios.Raw, (VOID *)Smbios30Table, Smbios30Table->TableMaximumSize);
+    Status = ParseAndAddExistingSmbiosTable(ImageHandle, Smbios, Smbios30Table->TableMaximumSize);
+    FreePool(Smbios.Raw);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "SmbiosDriverEntryPoint: Failed to parse preinstalled tables\n"));
+      Status = EFI_SUCCESS;
+    }
+  }
+
+  Status = EfiGetSystemConfigurationTable (
+               &gEfiSmbiosTableGuid,
+               (VOID **) &SmbiosTable
+               );
+  if (!EFI_ERROR (Status) && ValidateSmbios20Table(SmbiosTable)) {
+    Smbios.Raw = AllocatePool(SmbiosTable->TableLength);
+    if (!Smbios.Raw) {
+      return EFI_OUT_OF_RESOURCES;
+    }
+    //
+    // Backup old table in case it gets overwritten while parsing it
+    //
+    CopyMem (Smbios.Raw, (VOID *)(UINTN)SmbiosTable->TableAddress, SmbiosTable->TableLength);
 
-  return Status;
+    Status = ParseAndAddExistingSmbiosTable(ImageHandle, Smbios, SmbiosTable->TableLength);
+    FreePool(Smbios.Raw);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "SmbiosDriverEntryPoint: Failed to parse preinstalled tables\n"));
+      Status = EFI_SUCCESS;
+    }
+  }
+
+  return EFI_SUCCESS;
 }
-- 
2.26.2



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