linux-kernel - Re: [PATCH v8 00/14] Peripheral Image Loader support for Qualcomm SoCs running Linux host at EL2

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Message-ID: <238adfbb-3773-4318-93d3-b23697aa4b18@oss.qualcomm.com>
Date: Fri, 21 Nov 2025 16:08:36 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Mukesh Ojha <mukesh.ojha@....qualcomm.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 00/14] Peripheral Image Loader support for Qualcomm
 SoCs running Linux host at EL2

On 11/21/25 12:37 PM, Mukesh Ojha wrote:
> On Fri, Nov 21, 2025 at 11:27:57AM +0000, Bryan O'Donoghue wrote:
>> On 21/11/2025 11:01, Mukesh Ojha wrote:
>>> In May 2025, we discussed the challenges at Linaro Connect 2025 [1]
>>> related to Secure PAS remoteproc enablement when Linux is running at EL2
>>> for Qualcomm SoCs.
>>>
>>> [1] 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.
>>>
>>> It is based on next-20251120 and tested on SA8775p which is now called
>>> Lemans IOT platform and does not addresses DMA problem discussed at
>>> [1] which is future scope of the series.
>>>
>>> Changes in v8: https://lore.kernel.org/lkml/20251113-kvm-rproc-v7-v7-0-df4910b7c20a@oss.qualcomm.com/
>>>   - Addressed suggestion from Stephen which was regarding commit message(9/14),
>>>     debug log(12/14) suggestion, and return type change(4/14).
>>>   - Added R-b tag on 10/14 .
>> Sorry.
>>
>> Did we actually come up with a cogent reason to omit the video firmware
>> loading here ?
>>
>> AFAIU it is required for Lemans and Glymur - leaving it out is blocking
>> getting video stuff done and storing up trouble.
>>
>> What exactly is the blockage - is it something you want help with ?
> 
> I replied to you here[1] and given my reason..till something concluded on
> "multi-cell IOMMU[2]", I can not add video and block what is working
> already.
> 
> [1]
> https://lore.kernel.org/lkml/20251105081421.f6j7ks5bd4dfgr67@hu-mojha-hyd.qualcomm.com/
> 
> [2]
> https://lore.kernel.org/lkml/cover.1762235099.git.charan.kalla@oss.qualcomm.com/

I see that the following files call qcom_scm_pas_auth_.*():

drivers/firmware/qcom/qcom_scm.c
drivers/gpu/drm/msm/adreno/adreno_gpu.c
drivers/media/platform/qcom/iris/iris_firmware.c
drivers/media/platform/qcom/venus/firmware.c
drivers/net/ipa/ipa_main.c
drivers/net/wireless/ath/ath12k/ahb.c
drivers/remoteproc/qcom_q6v5_pas.c
drivers/remoteproc/qcom_wcnss.c

iris is difficult, rproc is done, adreno doesn't need it..

would ath12k_ahb or IPA be affected by this series as well?

Konrad