security/intel/txt: Add helper function to disable TXT

Add a function to disable TXT as per TXT BIOS spec Section 6.2.5. AP
firmware can disable TXT if TXT fails or TPM is already enabled.

On platforms with TXT disabled, the memory can be unlocked using
MSR 0x2e6.

TEST=Able to perform disable_txt on SoC SKUs with TXT enabled.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I27f613428e82a1dd924172eab853d2ce9c32b473
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71574
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Reviewed-by: Sridhar Siricilla <sridhar.siricilla@intel.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>

0 files changed, 0 insertions, 0 deletions