Comment 1 for bug 1956575

Details of the bisected commit :

https://kernel.ubuntu.com/git/ubuntu/ubuntu-focal.git/commit/?id=7ca05228f713c24eb55574b36e32d9b54c5a1b76

commit 7ca05228f713c24eb55574b36e32d9b54c5a1b76
Author: Lenny Szubowicz <email address hidden>
Date: Fri Sep 4 21:31:05 2020 -0400

    efi: Support for MOK variable config table

    BugLink: https://bugs.launchpad.net/bugs/1928679

    Because of system-specific EFI firmware limitations, EFI volatile
    variables may not be capable of holding the required contents of
    the Machine Owner Key (MOK) certificate store when the certificate
    list grows above some size. Therefore, an EFI boot loader may pass
    the MOK certs via a EFI configuration table created specifically for
    this purpose to avoid this firmware limitation.

    An EFI configuration table is a much more primitive mechanism
    compared to EFI variables and is well suited for one-way passage
    of static information from a pre-OS environment to the kernel.

    This patch adds initial kernel support to recognize, parse,
    and validate the EFI MOK configuration table, where named
    entries contain the same data that would otherwise be provided
    in similarly named EFI variables.

    Additionally, this patch creates a sysfs binary file for each
    EFI MOK configuration table entry found. These files are read-only
    to root and are provided for use by user space utilities such as
    mokutil.

    A subsequent patch will load MOK certs into the trusted platform
    key ring using this infrastructure.

    Signed-off-by: Lenny Szubowicz <email address hidden>
    Link: https://<email address hidden>
    Signed-off-by: Ard Biesheuvel <email address hidden>
    (cherry picked from commit 58c909022a5a56cd1d9e89c8c5461fd1f6a27bb5)
    Signed-off-by: Dimitri John Ledkov <email address hidden>
    Acked-by: Stefan Bader <email address hidden>
    Acked-by: Tim Gardner <email address hidden>
    Signed-off-by: Stefan Bader <email address hidden>

 arch/x86/kernel/setup.c | 1 +
 arch/x86/platform/efi/efi.c | 3 +
 drivers/firmware/efi/Makefile | 1 +
 drivers/firmware/efi/arm-init.c | 1 +
 drivers/firmware/efi/efi.c | 6 +
 drivers/firmware/efi/mokvar-table.c | 360 ++++++++++++++++++++++++++++++++++++
 include/linux/efi.h | 34 ++++
 7 files changed, 406 insertions(+)
 create mode 100644 drivers/firmware/efi/mokvar-table.c