[PATCH 0/4] firmware: Add support for Qualcomm UEFI Secure Application

Maximilian Luz
2022-07-23T22:50:20Z

On modern Qualcomm platforms, access to EFI variables is restricted to
the secure world / TrustZone, i.e. the Trusted Execution Environment
(TrEE or TEE) as Qualcomm seems to call it. To access EFI variables, we
therefore need to talk to the UEFI Secure Application (uefisecapp),
residing in the TrEE.

This series adds support for accessing EFI variables on those platforms.

To do this, we first need to add some SCM call functions used to manage
and talk to Secure Applications. A very small subset of this interface
is added in the second patch (whereas the first one exports the required
functions for that). Interface specifications are extracted from [1].
While this does not (yet) support re-entrant SCM calls (including
callbacks and listeners), this is enough to talk to the aforementioned
uefisecapp on a couple of platforms (I've tested this on a Surface Pro X
and heard reports from Lenovo Flex 5G, Lenovo Thinkpad x13s, and Lenovo
Yoga C630 devices).

The third patch adds a client driver for uefisecapp, installing the
respective efivar operations. The application interface has been reverse
engineered from the Windows QcTrEE8180.sys driver.

Apart from uefisecapp, there are more Secure Applications running that
we might want to support in the future. For example, on the Surface Pro
X (sc8180x-based), the TPM is also managed via one.

I'm not sure whether this should go to drivers/firmware or to
drivers/soc/qcom. I've put this into firmware as all of this is
essentially an interface to the secure firmware running in the TrustZone
(and SCM stuff is handled here already), but please let me know if I
should move this.

Regards,
Max

[1]: https://git.codelinaro.org/clo/la/kernel/msm-4.14/-/blob/auto-kernel.lnx.4.14.c34/drivers/misc/qseecom.c

Maximilian Luz (4):
firmware: qcom_scm: Export SCM call functions
firmware: Add support for Qualcomm Trusted Execution Environment SCM
calls
firmware: Add support for Qualcomm UEFI Secure Application
dt-bindings: firmware: Add Qualcomm UEFI Secure Application client

.../firmware/qcom,tee-uefisecapp.yaml | 38 +
MAINTAINERS | 14 +
drivers/firmware/Kconfig | 20 +
drivers/firmware/Makefile | 2 +
drivers/firmware/qcom_scm.c | 118 ++-
drivers/firmware/qcom_scm.h | 47 --
drivers/firmware/qcom_tee.c | 213 +++++
drivers/firmware/qcom_tee_uefisecapp.c | 761 ++++++++++++++++++
include/linux/qcom_scm.h | 49 ++
include/linux/qcom_tee.h | 179 ++++
10 files changed, 1355 insertions(+), 86 deletions(-)
create mode 100644 Documentation/devicetree/bindings/firmware/qcom,tee-uefisecapp.yaml
create mode 100644 drivers/firmware/qcom_tee.c
create mode 100644 drivers/firmware/qcom_tee_uefisecapp.c
create mode 100644 include/linux/qcom_tee.h

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