[PATCH v2 14/14] qemu: arm64: Add documentation for capsule update

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 12/21/20 6:12 PM, Sughosh Ganu wrote:
> On Mon, 21 Dec 2020 at 18:28, Heinrich Schuchardt <xypron.glpk@gmx.de>
> wrote:
>
>> On 12/21/20 12:43 PM, Sughosh Ganu wrote:
>>> Add documentation highlighting the steps for using the uefi capsule
>>> update feature for updating the u-boot firmware image.
>>>
>>> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
>>> ---
>>>
>>> Changes since V1:
>>> * Change the documentation to reflect the usage of overlays for
>>>     embedding the public key certs at runtime
>>> * Fix the build for 'make htmldocs'
>>>
>>>    doc/board/emulation/qemu-arm.rst | 188 +++++++++++++++++++++++++++++++
>>
>> Why do you put the information into doc/board/emulation/qemu-arm.rst?
>>
>> Isn't the same applicable to RISC-V QEMU?
>>
>
> Where do you want me to put it. Currently, I do not see any common document
> for qemu which can be shared between qemu-arm and qemu risc-v. Or do you
> think a new document should be created under doc/board/emulation/
> directory. Moreover, my series is adding support for capsule update feature
> on the qemu arm64 platform, and i have only tested this feature on the qemu
> arm64 platform. If someone wants to extend this on the qemu
> risc-v platform, that work i think needs to be done separately, with
> whatever changes that may be needed to get capsule updates working on qemu
> risc-v. If you so prefer, I can move the changes made for mtdparts and
> dfu(patches 4/14 and 5/14) under a common directory under board/emulation.


I have started putting the documentation for shell commands into
doc/usage. This is where a description of efidebug could be placed.

Equally I think we should put the documentation of tools like
mkeficapsule under doc/usage.

The description on the usage of the UEFI firmware protocol would fit
into doc/uefi/uefi.rst.

When it comes to things that are really QEMU specific
doc/board/emulation/ is the right folder.

See more comments below.

>
> -sughosh
>
>
>>
>> Best regards
>>
>> Heinrich
>>
>>>    1 file changed, 188 insertions(+)
>>>
>>> diff --git a/doc/board/emulation/qemu-arm.rst
>> b/doc/board/emulation/qemu-arm.rst
>>> index 8d7fda10f1..11d91811b3 100644
>>> --- a/doc/board/emulation/qemu-arm.rst
>>> +++ b/doc/board/emulation/qemu-arm.rst
>>> @@ -90,3 +90,191 @@ The debug UART on the ARM virt board uses these
>> settings::
>>>        CONFIG_DEBUG_UART_PL010=y
>>>        CONFIG_DEBUG_UART_BASE=0x9000000
>>>        CONFIG_DEBUG_UART_CLOCK=0
>>> +
>>> +Enabling Uefi Capsule Update feature
>>> +------------------------------------
>>> +
>>> +Support has been added for the uefi capsule update feature which
>>> +enables updating the u-boot image using the uefi firmware management

%s/uefi/UEFI/

>>> +protocol (fmp). The capsules are not passed to the firmware through
>>> +the UpdateCapsule runtime service. Instead, capsule-on-disk
>>> +functionality is used for fetching the capsule from the EFI System
>>> +Partition (ESP).

According to the UEFI spec the relevant directory is \EFI\UpdateCapsule.
I think you should mentions this path.

>>> +
>>> +Currently, support has been added for updating the u-boot binary as a

%s/u-boot/U-Boot/g

>>> +raw image when the platform is booted in non-secure mode, i.e with

%s/i.e/i.e./

>>> +CONFIG_TFABOOT disabled. For this configuration, the qemu platform

%s/qemu/QEMU/

>>> +needs to be booted with 'secure=off'. The u-boot binary placed on the

U-Boot

>>> +first bank of the Nor Flash at offset 0x0. The u-boot environment is

%s/Nor Flash/NOR flash/

U-Boot

>>> +placed on the second Nor Flash bank at offset 0x4000000.

NOR flash

>>> +
>>> +The capsule update feature is enabled with the following configs::

%s/configs/configuration settings/

>>> +
>>> +    CONFIG_MTD=y
>>> +    CONFIG_FLASH_CFI_MTD=y
>>> +    CONFIG_CMD_MTDPARTS=y
>>> +    CONFIG_CMD_DFU=y
>>> +    CONFIG_DFU_MTD=y
>>> +    CONFIG_PCI_INIT_R=y
>>> +    CONFIG_EFI_CAPSULE_ON_DISK=y
>>> +    CONFIG_EFI_CAPSULE_FIRMWARE_MANAGEMENT=y
>>> +    CONFIG_EFI_CAPSULE_FIRMWARE=y
>>> +    CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
>>> +    CONFIG_EFI_CAPSULE_FMP_HEADER=y
>>> +
>>> +In addition, the following config needs to be disabled::
>>> +
>>> +    CONFIG_TFABOOT
>>> +
>>> +The capsule file can be generated by using the GenerateCapsule.py
>>> +script in edk2::

EDK II

>>> +
>>> +    $ ./BaseTools/BinWrappers/PosixLike/GenerateCapsule -e -o \
>>> +    <capsule_file_name> --fw-version <val> --lsv <val> --guid \
>>> +    e2bb9c06-70e9-4b14-97a3-5a7913176e3f --verbose --update-image-index
>> \
>>> +    <val> --verbose <u-boot.bin>
>>> +
>>> +As per the uefi specification, the capsule file needs to be placed on

UEFI

>>> +the EFI System Partition, under the EFI/UpdateCapsule/ directory. The

\EFI\UpdateCapsule\ (see UEFI specification)

>>> +EFI System Partition can be a virtio-blk-device.
>>> +
>>> +Before initiating the firmware update, the efi variables BootNext,

%s/efi/UEFI/

>>> +BootXXXX and OsIndications need to be set. The BootXXXX variable needs
>>> +to be pointing to the EFI System Partition which contains the capsule
>>> +file. The BootNext, BootXXXX and OsIndications variables can be set

Shouldn't OsIndications bit 2 be set by default when EFI capsule support
is enabled? How about bit 3 (EFI_OS_INDICATIONS_FMP_CAPSULE_SUPPORTED)?

>>> +using the following commands::
>>> +
>>> +    => efidebug boot add 0 Boot0000 virtio 0:1 <capsule_file_name>
>>> +    => efidebug boot next 0
>>> +    => setenv -e -nv -bs -rt -v OsIndications =0x04
>>> +    => saveenv
>>> +
>>> +Finally, the capsule update can be initiated with the following
>>> +command::
>>> +
>>> +    => efidebug capsule disk-update
>>> +
>>> +The updated u-boot image will be booted on subsequent boot.

U-Boot

>>> +
>>> +Enabling Capsule Authentication
>>> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> +
>>> +The uefi specification defines a way of authenticating the capsule to

UEFI

>>> +be updated by verifying the capsule signature. The capsule signature
>>> +is computed and prepended to the capsule payload at the time of
>>> +capsule generation. This signature is then verified by using the
>>> +public key stored as part of the X509 certificate. This certificate is
>>> +in the form of an efi signature list (esl) file, which is embedded as
>>> +part of the platform's device tree blob using the mkeficapsule
>>> +utility.
>>> +
>>> +On the qemu virt platforms, the device-tree is generated on the fly

QEMU

>>> +based on the devices configured. This device tree is then passed on to
>>> +the various software components booting on the platform, including
>>> +u-boot. Therefore, on the qemu virt platform, the signatute is

QEMU

>>> +embedded on an overlay. This overlay is then applied at runtime to the
>>> +base platform device-tree. Steps needed for embedding the esl file in
>>> +the overlay are highlighted below.
>>> +
>>> +The capsule authentication feature can be enabled through the
>>> +following config, in addition to the configs listed above for capsule
>>> +update::
>>> +
>>> +    CONFIG_EFI_CAPSULE_AUTHENTICATE=y
>>> +
>>> +The public and private keys used for the signing process are generated
>>> +and used by the steps highlighted below::
>>> +
>>> +    1. Install utility commands on your host
>>> +       * openssl

OpenSSL

>>> +       * efitools
>>> +
>>> +    2. Create signing keys and certificate files on your host
>>> +
>>> +        $ openssl req -x509 -sha256 -newkey rsa:2048 -subj /CN=CRT/ \
>>> +            -keyout CRT.key -out CRT.crt -nodes -days 365
>>> +        $ cert-to-efi-sig-list CRT.crt CRT.esl
>>> +
>>> +        $ openssl x509 -in CRT.crt -out CRT.cer -outform DER
>>> +        $ openssl x509 -inform DER -in CRT.cer -outform PEM -out
>> CRT.pub.pem
>>> +
>>> +        $ openssl pkcs12 -export -out CRT.pfx -inkey CRT.key -in CRT.crt
>>> +        $ openssl pkcs12 -in CRT.pfx -nodes -out CRT.pem
>>> +
>>> +The capsule file can be generated by using the GenerateCapsule.py
>>> +script in edk2::

EDK II

>>> +
>>> +    $ ./BaseTools/BinWrappers/PosixLike/GenerateCapsule -e -o \

Above you wrote GenerateCapsule.py. I understand that the binary wrapper
shall be used. But somehow this should be explained.

>>> +      <capsule_file_name> --monotonic-count <val> --fw-version \
>>> +      <val> --lsv <val> --guid \
>>> +      e2bb9c06-70e9-4b14-97a3-5a7913176e3f --verbose \
>>> +      --update-image-index <val> --signer-private-cert \
>>> +      /path/to/CRT.pem --trusted-public-cert \
>>> +      /path/to/CRT.pub.pem --other-public-cert /path/to/CRT.pub.pem \
>>> +      <u-boot.bin>
>>> +
>>> +Place the capsule generated in the above step on the EFI System
>>> +Partition under the EFI/UpdateCapsule directory
>>> +
>>> +For embedding the public key certificate, the following steps need to
>>> +be followed::
>>> +
>>> +    1. Generate a skeleton overlay dts file, with a single fragment
>>> +       node and an empty __overlay__ node

A typical user will be lost here. Please, provide the content of the
file here.

>>> +
>>> +    2. Convert the dts to a corresponding dtb with the following
>>> +       command
>>> +        ./scripts/dtc/dtc -@ -I dts -O dtb -o <ov_dtb_file_name> \
>>> +        <dts_file>
>>> +
>>> +    3. Run the dtb file generated above through the mkeficapsule tool
>>> +       in u-boot
>>> +        ./tools/mkeficapsule -O <pub_key.esl> -D <ov_dtb>
>>> +
>>> +Running the above command results in the creation of a 'signature'
>>> +node in the dtb, under which the public key is stored as a
>>> +'capsule-key' property. The '-O' option is to be used since the
>>> +public key certificate(esl) file is being embedded in an overlay.
>>> +
>>> +The dtb file embedded with the certificate is now to be placed on an
>>> +EFI System Partition. This would then be loaded and "merged" with the
>>> +base platform fdt at runtime.

%s/fdt/flattened device-tree (dtb)/

>>> +
>>> +Build u-boot with the following steps::

U-Boot

>>> +
>>> +    $ make qemu_arm64_defconfig
>>> +    $ make menuconfig
>>> +        Disable CONFIG_TFABOOT
>>> +        Enable CONFIG_EFI_CAPSULE_AUTHENTICATE
>>> +        Enable all configs needed for capsule update(listed above)
>>> +    $ make all
>>> +
>>> +Boot the platform and perform the following steps on the u-boot
>>> +command line::
>>> +
>>> +    1. Enable capsule authentication by setting the following env
>>> +       variable
>>> +
>>> +        => setenv capsule_authentication_enabled 1
>>> +        => saveenv
>>> +
>>> +    2. Load the overlay dtb to memory and merge it with the base fdt
>>> +
>>> +        => fatload virtio 0:1 <$fdtovaddr> EFI/<ov_dtb_file>
>>> +        => fdt addr $fdtcontroladdr
>>> +        => fdt resize <size_of_ov_dtb_file>
>>> +        => fdt apply <$fdtovaddr>
>>> +
>>> +    3. Set the following env and efi Boot variables

environment and UEFI boot variables

>>> +
>>> +        => setenv -e -nv -bs -rt -v OsIndications =0x04
>>> +        => efidebug boot add 0 Boot0000 virtio 0:1 <capsule_file_name>
>>> +        => efidebug boot next 0
>>> +        => saveenv
>>> +
>>> +    4. Finally, the capsule update can be initiated with the following
>>> +       command
>>> +
>>> +        => efidebug capsule disk-update
>>> +
>>> +On subsequent reboot, the platform should boot the updated u-boot

U-Boot

Best regards

Heinrich

>> binary.
>>>
>>
>>
>