Message-ID: <20250819165447.4149674-1-mukesh.ojha@oss.qualcomm.com>
Date: Tue, 19 Aug 2025 22:24:35 +0530
From: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Vikash Garodia <quic_vgarodia@...cinc.com>,
        Dikshita Agarwal <quic_dikshita@...cinc.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Abhinav Kumar <abhinav.kumar@...ux.dev>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-media@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        Mukesh Ojha <mukesh.ojha@....qualcomm.com>
Subject: [PATCH v2 00/11] Peripheral Image Loader support for Qualcomm SoCs running Linux host at EL2 

This is a further continuation with a new approach to the topic
discussed in [1] regarding the enablement of Secure Peripheral Image
Loader support on Qualcomm SoCs when Linux runs at EL2.

A few months ago, we also discussed the challenges at Linaro Connect
2025 [2] related to enabling remoteproc when Linux is running at EL2.

[1]
https://lore.kernel.org/lkml/20241004212359.2263502-1-quic_mojha@quicinc.com/

[2]
https://resources.linaro.org/en/resource/sF8jXifdb9V1mUefdbfafa

Below, is the summary of the discussion.

Qualcomm is working to enable remote processors on the SA8775p SoC with
a Linux host running at EL2. In doing so, it has encountered several
challenges related to how the remoteproc framework is handled when Linux
runs at EL1.

One of the main challenges arises from differences in how IOMMU
translation is currently managed on SoCs running the Qualcomm EL2
hypervisor (QHEE), where IOMMU translation for any device is entirely
owned by the hypervisor. Additionally, the firmware for remote
processors does not contain a resource table, which would typically
include the necessary IOMMU configuration settings.

Qualcomm SoCs running with QHEE (EL2) have been utilizing the Peripheral
Authentication Service (PAS) from TrustZone (TZ) firmware to securely
authenticate and reset remote processors via a single SMC call,
_auth_and_reset_. This call is first trapped by QHEE, which then invokes
TZ for authentication. Once authentication is complete, the call returns
to QHEE, which sets up the IOMMU translation scheme for the remote
processors and subsequently brings them out of reset. The design of the
Qualcomm EL2 hypervisor dictates that the Linux host OS running at EL1
is not permitted to configure IOMMU translation for remote processors,
and only a single-stage translation is configured.

To make the remote processor bring-up (PAS) sequence
hypervisor-independent, the auth_and_reset SMC call is now handled
entirely by TZ. However, the issue of IOMMU configuration remains
unresolved, for example a scenario, when KVM host at EL2 has no
knowledge of the remote processors’ IOMMU settings.  This is being
addressed by overlaying the IOMMU properties when the SoC runs a Linux
host at EL2. SMC call is being provided from the TrustZone firmware to
retrieve the resource table for a given subsystem.

There are also remote processors—such as those for video, camera, and
graphics—that do not use the remoteproc framework to manage their
lifecycle. Instead, they rely on the Qualcomm PAS service to
authenticate their firmware. These processors also need to be brought
out of reset when Linux is running at EL2. The client drivers for these
processors use the MDT loader function to load and authenticate
firmware. Similar to the Qualcomm remoteproc PAS driver, they also need
to retrieve the resource table, create a shared memory bridge
(shmbridge), and map the resources before bringing the processors out of
reset.

This series has dependency on below patch for creating SHMbridge over
carveout memory.
https://lore.kernel.org/lkml/20250812-qcom-tee-using-tee-ss-without-mem-obj-v7-7-ce7a1a774803@oss.qualcomm.com/

Series is tested on SA8775p which is now called Lemans IOT platform and
the series does not addresses DMA problem discussed at [2] which is future
scope of the series.

Changes in v2: https://lore.kernel.org/lkml/20241004212359.2263502-1-quic_mojha@quicinc.com/
 - A lot has changed from the V1 and a fresh look would be preferred.
 - Removed approach where device tree contain devmem resources in
   remoteproc node.
 - SHMbridge need to created for both carveout and metadata memory
   shared to TZ in a new way.
 - Now, resource table would be given by SMC call which need to mapped
   along with carveout before triggering _auth_and_reset_.
 - IOMMU properties need to be added to firmware devices tree node when Linux
   control IOMMU.

Mukesh Ojha (11):
  firmware: qcom_scm: Introduce PAS context initialization helper
  soc: qcom: mdtloader: Add context aware qcom_mdt_pas_load() helper
  firmware: qcom_scm: Add a prep version of auth_and_reset function
  firmware: qcom_scm: Simplify qcom_scm_pas_init_image()
  firmware: qcom_scm: Add shmbridge support to pas_init/release function
  remoteproc: Move resource table data structure to its own header
  firmware: qcom_scm: Add qcom_scm_pas_get_rsc_table() to get resource
    table
  soc: qcom: mdt_loader: Add helper functions to map and unmap resources
  remoteproc: pas: Extend parse_fw callback to parse resource table
  remoteproc: qcom: pas: Enable Secure PAS support with IOMMU managed by
    Linux
  media: iris: Enable Secure PAS support with IOMMU managed by Linux

 drivers/firmware/qcom/qcom_scm.c              | 360 ++++++++++++++++--
 drivers/firmware/qcom/qcom_scm.h              |   1 +
 drivers/media/platform/qcom/iris/iris_core.c  |   9 +-
 drivers/media/platform/qcom/iris/iris_core.h  |   6 +
 .../media/platform/qcom/iris/iris_firmware.c  | 156 +++++++-
 .../media/platform/qcom/iris/iris_firmware.h  |   2 +
 drivers/remoteproc/qcom_q6v5_pas.c            | 147 +++++--
 drivers/soc/qcom/mdt_loader.c                 | 199 +++++++++-
 include/linux/firmware/qcom/qcom_scm.h        |  27 +-
 include/linux/remoteproc.h                    | 269 +------------
 include/linux/rsc_table.h                     | 306 +++++++++++++++
 include/linux/soc/qcom/mdt_loader.h           |  41 +-
 12 files changed, 1144 insertions(+), 379 deletions(-)
 create mode 100644 include/linux/rsc_table.h

-- 
2.50.1

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