OvmfPkg/IntelTdx: Enable separate-fv in IntelTdx/IntelTdxX64.fdf

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4152

In current DXE FV there are 100+ drivers. Some of the drivers are not
used in Td guest. (Such as USB support drivers, network related drivers,
etc).

From the security perspective if a driver is not used, we'd should prevent
it from being loaded / started. There are 2 benefits:
1. Reduce the attack surface
2. Improve the boot performance

So we separate DXEFV into 2 FVs: DXEFV and NCCFV. All the drivers which
are not needed by a Confidential Computing guest are moved from DXEFV
to NCCFV.

The following patch will find NCCFV for non-cc guest and build FVHob
so that NCCFV drivers can be loaded / started in DXE phase.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

OvmfPkg/IntelTdx/IntelTdxX64.dsc

@@ -31,6 +31,11 @@
   #
   DEFINE SECURE_BOOT_ENABLE      = FALSE
 
+  #
+  # Shell can be useful for debugging but should not be enabled for production
+  #
+  DEFINE BUILD_SHELL             = TRUE
+
   #
   # Device drivers
   #
@@ -204,7 +209,9 @@
   VariablePolicyHelperLib|MdeModulePkg/Library/VariablePolicyHelperLib/VariablePolicyHelperLib.inf
   VariableFlashInfoLib|MdeModulePkg/Library/BaseVariableFlashInfoLib/BaseVariableFlashInfoLib.inf
 
+!if $(BUILD_SHELL) == TRUE
   ShellLib|ShellPkg/Library/UefiShellLib/UefiShellLib.inf
+!endif
   ShellCEntryLib|ShellPkg/Library/UefiShellCEntryLib/UefiShellCEntryLib.inf
   S3BootScriptLib|MdeModulePkg/Library/PiDxeS3BootScriptLib/DxeS3BootScriptLib.inf
   SmbusLib|MdePkg/Library/BaseSmbusLibNull/BaseSmbusLibNull.inf
@@ -720,12 +727,13 @@
   MdeModulePkg/Bus/Usb/UsbKbDxe/UsbKbDxe.inf
   MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassStorageDxe.inf
 
-!if $(TOOL_CHAIN_TAG) != "XCODE5"
+!if $(TOOL_CHAIN_TAG) != "XCODE5" && $(BUILD_SHELL) == TRUE
   OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf {
     <PcdsFixedAtBuild>
       gEfiShellPkgTokenSpaceGuid.PcdShellLibAutoInitialize|FALSE
   }
 !endif
+!if $(BUILD_SHELL) == TRUE
   ShellPkg/Application/Shell/Shell.inf {
     <LibraryClasses>
       ShellCommandLib|ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.inf
@@ -744,6 +752,7 @@
       gEfiShellPkgTokenSpaceGuid.PcdShellLibAutoInitialize|FALSE
       gEfiMdePkgTokenSpaceGuid.PcdUefiLibMaxPrintBufferSize|8000
   }
+!endif
 
 !if $(SECURE_BOOT_ENABLE) == TRUE
   SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigDxe.inf