Re: [PATCH 0/6] Peripheral Image Loader support for Qualcomm SoCs

[Dmitry Baryshkov]

On Sat, Oct 05, 2024 at 02:53:53AM GMT, Mukesh Ojha wrote:
> Qualcomm is looking to enable remote processors on the SA8775p SoC
> running KVM Linux host and is currently trying to figure out an
> upstream-compatible solution for the IOMMU translation scheme problem it
> is facing when SoCs running with KVM. This issue arises due to
> differences in how IOMMU translation is currently handled on SoCs
> running Qualcomm EL2 hypervisor(QHEE) where IOMMU translation for any
> device is completely owned by it and the other issue is that remote
> processors firmware does not contain resource table where these IOMMU
> configuration setting will be present.
> 
> Qualcomm SoCs running with the QHEE(EL2) have been utilizing the
> Peripheral Authentication Service (PAS) from its TrustZone (TZ) firmware
> to securely authenticate and reset via a single SMC call
> _auth_and_reset_.  This call first gets trapped to QHEE, which then
> makes a call to TZ for authentication. Once it is done, the call returns
> to QHEE, which sets up the IOMMU translation scheme for these remote
> processors and later brings them out of reset. The design of the
> Qualcomm EL2 hypervisor dictates that the Linux host OS running at EL1
> is not allowed to set up IOMMU translation for remote processors,
> and only a single stage is being configured for them.
> 
> To make the remote processors’ bring-up (PAS) sequence
> hypervisor-independent, the auth_and_reset SMC call is now entirely
> handled by TZ. However, the problem of IOMMU handling still remains with
> the KVM host, which has no knowledge of the remote processors’ IOMMU
> configuration.
> 
> We have looked up one approach where SoC remoteproc device tree could
> contain resources like iommus for remoteproc carveout and qcom,devmem
> specific binding for device memory needed for remoteproc and these
> properties are optional and will only be overlaid by the firmware if it
> is running with non-QHEE based hypervisor like KVM.

Can you follow the approach that has been implemented for existing
systems (ChromeOS) not using QHEE? See drivers/remoteproc/qcom_q6v5_adsp.c
If this approach can not be used, please describe why.

> 
> - Patch 1/6 adds the iommus and qcom,devmem binding for PAS common yaml.
> - Patch 2/6 and 3/6 add helper function to IOMMU map and unmap carveout
>   and device memory region.
> - Patch 4/6 adds a function to parse individual field of qcom,devmem property.
> - Patch 5/6 add helpers to create/destroy SHM bridge for remoteproc
>   carveout and to get memory from tzmem SHM bridge pool for remoteproc
>   firmware metadata.
> - Patch 6/6 enable all the required support to enable remoteproc for
>   non-QHEE hypervisor based systems like KVM host via parsing the iommus
>   properties and mapping/unmapping carveout and device memory based on
>   it.
> 
> Komal Bajaj (1):
>   remoteproc: qcom: Add iommu map_unmap helper function
> 
> Mukesh Ojha (2):
>   remoteproc: qcom: Add support of SHM bridge to enable memory
>     protection
>   remoteproc: qcom: Enable map/unmap and SHM bridge support
> 
> Shiraz Hashim (3):
>   dt-bindings: remoteproc: qcom,pas-common: Introduce iommus and
>     qcom,devmem property
>   remoteproc: qcom: Add helper function to support IOMMU devmem
>     translation
>   remoteproc: qcom: Add support to parse qcom,devmem property
> 
>  .../bindings/remoteproc/qcom,pas-common.yaml  |  42 +++++
>  .../bindings/remoteproc/qcom,sa8775p-pas.yaml |  20 +++
>  drivers/firmware/qcom/qcom_scm.c              |  29 +++-
>  drivers/firmware/qcom/qcom_tzmem.c            |  14 +-
>  drivers/remoteproc/qcom_common.c              | 148 ++++++++++++++++++
>  drivers/remoteproc/qcom_common.h              |  38 +++++
>  drivers/remoteproc/qcom_q6v5_pas.c            | 140 ++++++++++++++++-
>  include/linux/firmware/qcom/qcom_scm.h        |   1 +
>  include/linux/firmware/qcom/qcom_tzmem.h      |  10 ++
>  9 files changed, 423 insertions(+), 19 deletions(-)
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry