[PATCH v3 00/12] tpm: Add wolfTPM library support for TPM 2.0

[Peter Robinson]

Hi Aidan,

> This is v3 of the wolfTPM TPM 2.0 stack integration for U-Boot.
>
> wolfTPM (https://github.com/wolfSSL/wolfTPM) is a portable, GPLv2 TPM 2.0

I go to the github link and it says  GPL-3.0 license so which is it?

IANAL but I'm not sure if the GPLv3 is compatible with GPLv2 in the
context of U-Boot because it would make the whole output a GPLv3
application

> library that provides a full TPM 2.0 command set, an SPI/MMIO HAL, and
> firmware-update support for Infineon SLB9672/SLB9673 hardware.  This
> series wires it into U-Boot as an optional backend behind the existing
> 'tpm2' command, alongside support for QEMU+swtpm, sandbox emulation, and
> real Raspberry Pi 4 + Infineon SLB9672 hardware.

So that provides the technical detail, but what value does it provide
to U-Boot? We already have a relatively complete TPM stack, do people
do firmware updates in the early boot process, why else would someone
choose to use this over the existing implementation?

One part of what I want to know in a cover letter is what value this
provides to the project, what are the pros/cons etc, like what
maintenance looks like.

Peter

> Branch (full 14-commit history including the subtree squash + merge):
>   https://github.com/aidangarske/u-boot wolftpm-v2-patches
>
> Note on the subtree commits omitted from this email thread:
>   The branch above contains 14 commits; the email series is 12 patches.
>   Two commits are deliberately not sent to the list:
>
>     * "Squashed 'lib/wolftpm/' content from commit 664db130d57"
>         - the parentless squash commit produced by `git subtree add`.
>           Its diff is ~3.4MB / ~90k lines and would be rejected by the
>           mailing list on size.
>     * "Merge commit 'd42fd7b146...' as 'lib/wolftpm'"
>         - the corresponding subtree merge commit. Merges have no patch
>           form and are routinely omitted by `git format-patch`.
>
>   Please pull from the branch above (or wolfssl/wolfTPM @ 664db130d57)
>   to inspect the imported wolfTPM source. Subsequent updates will go
>   via tools/update-subtree.sh, matching how mbedTLS, lwIP, and
>   dts/upstream are maintained in tree.
>
> Changes since v2:
>   - Replaced the lib/wolftpm git submodule with a git subtree import
>     (squash + merge), matching the convention used for mbedTLS, lwIP,
>     and dts/upstream.  tools/update-subtree.sh is updated to know
>     about the wolftpm subtree (path lib/wolftpm, upstream
>     https://github.com/wolfssl/wolfTPM.git).
>     [feedback: Ilias Apalodimas]
>   - Reverted the changes to include/linux/byteorder/generic.h.  The
>     redefinition workaround for cpu_to_beXX / beXX_to_cpu now lives
>     on the wolfTPM side: include/configs/user_settings.h pulls in
>     <asm/byteorder.h> up front so U-Boot's macros are defined before
>     wolfTPM's #ifndef-guarded fallbacks in tpm2_packet.h.
>     [feedback: Ilias Apalodimas]
>
> Testing:
>   - QEMU arm64 + swtpm Python test framework
>     (./test/py/test.py --bd qemu_arm64 -k "test_wolftpm and not ut_cmd"):
>     19 passed, 2 skipped (matching doc/usage/cmd/wolftpm.rst).
>   - Manual QEMU arm64 + swtpm walkthrough per
>     doc/usage/cmd/wolftpm.rst section "Building and Running wolfTPM
>     with U-Boot using QEMU": tpm2 help/info/autostart/startup/
>     get_capability/pcr_read/pcr_print/caps all return expected output.
>   - Raspberry Pi 4 + Infineon SLB9672 (real hardware): all wolfTPM
>     cmd tests pass, including firmware update path.
>
> v2 thread:
>   https://lore.kernel.org/u-boot/?q=PATCH+v2+tpm+wolfTPM
>
> Aidan Garske (12):
>   tpm: export tpm_show_device, tpm_set_device, and get_tpm
>   include/hash: add SHA384 hash wrapper declaration for wolfTPM
>   spi: add BCM2835/BCM2711 hardware SPI controller driver
>   dts: add TPM device tree nodes for RPi4, QEMU, and sandbox
>   tpm: add wolfTPM build rules and Kconfig
>   tpm: add wolfTPM headers and SHA384 glue code
>   tpm: add wolfTPM driver helpers and Kconfig options
>   cmd: refactor tpm2 command into frontend/backend architecture
>   tpm: add sandbox TPM SPI emulator
>   test: add wolfTPM C unit tests and Python integration tests
>   doc: add wolfTPM documentation
>   configs: enable wolfTPM in rpi_4_defconfig
>
> --
> 2.47.3
>