drivers/security/cbnt: Fix bootblock size

Change-Id: Ic5ad9d29f247b6f828501bfacc27a8af08761d55
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50082
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jonathan Zhang <jonzhang@fb.com>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/mainboard/ocp/deltalake/Kconfig

@@ -57,4 +57,11 @@ config CONSOLE_POST
 	bool
 	default y
 
+config C_ENV_BOOTBLOCK_SIZE
+	hex
+	default 0xc000 if FIXED_BOOTBLOCK_SIZE
+	help
+	  This matches the IBB size used for CBnT. Adjust this to the
+	  used CBnT settings.
+
 endif # BOARD_OCP_DELTALAKE

src/security/intel/cbnt/Kconfig

@@ -6,6 +6,8 @@ config INTEL_CBNT_SUPPORT
 	depends on CPU_INTEL_FIRMWARE_INTERFACE_TABLE
 	#depends on PLATFORM_HAS_DRAM_CLEAR
 	select INTEL_TXT
+	# With CBnT the bootblock is set up as a CBnT IBB and needs a fixed size
+	select FIXED_BOOTBLOCK_SIZE
 	help
 	  Enables Intel Converged Bootguard and Trusted Execution Technology
 	  Support. This will enable one to add a Key Manifest (KM) and a Boot