Re: [PATCH v6 0/5] efi/firmware/platform-x86: Add EFI embedded fw support

Hans de Goede
2018-06-06T18:17:26Z

Hi,

On 05-06-18 22:46, Luis R. Rodriguez wrote:
> On Fri, Jun 01, 2018 at 02:53:25PM +0200, Hans de Goede wrote:
>> Hi All,
>>
>> Here is v6 of my patch-set to add support for EFI embedded fw to the kernel.
>>
>> This patch-set applies on top of the "[PATCH v7 00/14] firmware_loader
>> changes for v4.18" series from mcgrof.
>>
>> It now also depends on the series from Andy Lutomirski which allow using the
>> sha256 code in a standalone manner. Andy what is the status of those?
>>
>> Changes since v5:
>> -Rework code to remove casts from if (prefix == mem) comparison
>> -Use SHA256 hashes instead of crc32 sums
>
> Nice! I see no updates on this progress, but it would seem this
> may then mean this cannot be merged until the release after?

Once the sha256 bits are in place the subsys tree which has them
merged can create an immutable branch for Greg to merge and
then these can be applied on top of that merge.

But yes this means that these probably won't go in for another
cycle or 2, that is fine.

>> -Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
>> -Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
>> to check if this is allowed before looking at EFI embedded fw
>
> There's a discussion over having security_kernel_read_file(NULL,
> READING_WHATEVER) become another LSM hook. So your series would conflict with
> that at the moment.
>
> So yet another piece of code which this series depends on.

Ah well, I'm in no big hurry to get this merged. OTOH if this is
ready and that discussion is not yet finished it might be better
to merge this as is and then have the security_kernel_read_file / LSM
hook series fix this up as necessary when it is merged.

Regards,

Hans

>
>> -Document why we are not using the PI Firmware Volume protocol
>>
>> For reference I've included the coverletter from v4 (which includes
>> previous covverletters) below.
>>
>> Regards,
>>
>> Hans
>>
>>
>> Previous coverletter:
>>
>> Here is v5 of my patch-set to add support for EFI embedded fw to the kernel.
>>
>> Changes since v4:
>> -Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS
>>
>> So I think this patch-set is getting close to ready for merging, which
>> brings us to the question of how to merge this, I think that patches 1
>> and 2 should probably both be merged through the same tree. Then an
>> unmutable branch should be created on that tree, merged into the
>> platform/x86 tree and then the last 3 patches can be merged through
>> that tree.
>>
>> Ard has already indicated he is fine with the EFI bits going upstream
>> through another tree, so perhaps patches 1-2 can be merged through the
>> firmware-loader-tree and then do an unmutable branch on the
>> firmware-loader-tree for the platform/x86 tree to merge?
>>
>> I don't think taking all 5 through 1 tree is a good idea because of
>> the file rename under platform/x86.
>>
>>
>> For the record here are the cover letters of the previous versions:
>>
>> Changes since v3:
>> -Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
>> UEFI proper, so the EFI maintainers don't want us referring people to it
>> -Use new EFI_BOOT_SERVICES flag
>> -Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
>> file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
>> -Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
>> EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
>> in firmware_loader/main.c
>> -Properly call security_kernel_post_read_file() on the firmware returned
>> by efi_get_embedded_fw() to make sure that we are allowed to use it
>>
>> The 3 most prominent changes in v2 are:
>>
>> 1) Add documentation describing the EFI embedded firmware mechanism to:
>> Documentation/driver-api/firmware/request_firmware.rst
>>
>> 2) Instead of having a single dmi_system_id array with its driver_data
>> members pointing to efi_embedded_fw_desc structs, have the drivers which
>> need EFI embedded-fw support export a dmi_system_id array and register
>> that with the EFI embedded-fw code
>>
>> This series also includes the first driver to use this, in the form of
>> the touchscreen_dmi code (formerly silead_dmi) from drivers/platfrom/x86
>>
>> 3) As discussed during the review of v1 we want to make the firmware_loader
>> code fallback to EFI embedded-fw optional. Rather the adding yet another
>> firmware_request_foo variant for this, with the risk of later also needing
>> firmware_request_foo_nowait, etc. variants I've decided to make the code
>> check if the device has a "efi-embedded-firmware" device-property bool set.
>>
>> This also seemed better because the same driver may want to use the
>> fallback on some systems, but not on others since e.g. not all (x86)
>> systems with a silead touchscreen have their touchscreen firmware embedded
>> in their EFI.
>>
>> Note that (as discussed) when the EFI fallback path is requested, the
>> usermodehelper fallback path is skipped.
>>
>> Here is the full changelog of patch 2/5 which is where most of the changes are:
>>
>> Changes in v2:
>> -Rebased on driver-core/driver-core-next
>> -Add documentation describing the EFI embedded firmware mechanism to:
>> Documentation/driver-api/firmware/request_firmware.rst
>> -Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
>> fw support if this is set. This is an invisible option which should be
>> selected by drivers which need this
>> -Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
>> from the efi-embedded-fw code, instead drivers using this are expected to
>> export a dmi_system_id array, with each entries' driver_data pointing to a
>> efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
>> -Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
>> this avoids us messing with the EFI memmap and avoids the need to make
>> changes to efi_mem_desc_lookup()
>> -Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
>> passed in device has the "efi-embedded-firmware" device-property bool set
>> -Skip usermodehelper fallback when "efi-embedded-firmware" device-property
>> is set
>>
>> Patches 3-5 are new and implement using the EFI embedded-fw mechanism for
>> Silead gslXXXX and Chipone icn8505 touchscreens on x86 devices.
>>
>>
>