linux-kernel - Re: [PATCH v6 05/14] remoteproc: pas: Replace metadata context with PAS context structure

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Message-ID: <20251107112601.hiqtai4gvr76rqsh@hu-mojha-hyd.qualcomm.com>
Date: Fri, 7 Nov 2025 16:56:01 +0530
From: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
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 v6 05/14] remoteproc: pas: Replace metadata context with
 PAS context structure

On Fri, Nov 07, 2025 at 11:04:56AM +0100, Konrad Dybcio wrote:
> On 11/5/25 7:42 AM, Mukesh Ojha wrote:
> > On Tue, Nov 04, 2025 at 06:33:49PM +0100, Konrad Dybcio wrote:
> >> On 11/4/25 8:35 AM, Mukesh Ojha wrote:
> >>> As a superset of the existing metadata context, the PAS context
> >>> structure enables both remoteproc and non-remoteproc subsystems to
> >>> better support scenarios where the SoC runs with or without the Gunyah
> >>> hypervisor. To reflect this, relevant SCM and metadata functions are
> >>> updated to incorporate PAS context awareness.
> >>>
> >>> Signed-off-by: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
> >>> ---
> >>>  drivers/firmware/qcom/qcom_scm.c       | 25 +++++++++++++---------
> >>>  drivers/remoteproc/qcom_q6v5_pas.c     | 38 ++++++++++++++++++++++++----------
> >>>  drivers/soc/qcom/mdt_loader.c          |  4 ++--
> >>>  include/linux/firmware/qcom/qcom_scm.h |  4 ++--
> >>>  include/linux/soc/qcom/mdt_loader.h    |  6 +++---
> >>>  5 files changed, 49 insertions(+), 28 deletions(-)
> >>>
> >>> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> >>> index 5a525dbd0a2e..9cdd152da592 100644
> >>> --- a/drivers/firmware/qcom/qcom_scm.c
> >>> +++ b/drivers/firmware/qcom/qcom_scm.c
> >>> @@ -603,7 +603,7 @@ EXPORT_SYMBOL_GPL(devm_qcom_scm_pas_context_init);
> >>>   *		and optional blob of data used for authenticating the metadata
> >>>   *		and the rest of the firmware
> >>>   * @size:	size of the metadata
> >>> - * @ctx:	optional metadata context
> >>> + * @ctx:	optional pas context
> >>>   *
> >>>   * Return: 0 on success.
> >>>   *
> >>> @@ -612,8 +612,9 @@ EXPORT_SYMBOL_GPL(devm_qcom_scm_pas_context_init);
> >>>   * qcom_scm_pas_metadata_release() by the caller.
> >>>   */
> >>>  int qcom_scm_pas_init_image(u32 pas_id, const void *metadata, size_t size,
> >>> -			    struct qcom_scm_pas_metadata *ctx)
> >>> +			    struct qcom_scm_pas_context *ctx)
> >>>  {
> >>> +	struct qcom_scm_pas_metadata *mdt_ctx;
> >>
> >> This is never initialized
> >>
> >>>  	dma_addr_t mdata_phys;
> >>>  	void *mdata_buf;
> >>>  	int ret;
> >>> @@ -665,9 +666,10 @@ int qcom_scm_pas_init_image(u32 pas_id, const void *metadata, size_t size,
> >>>  	if (ret < 0 || !ctx) {
> >>>  		dma_free_coherent(__scm->dev, size, mdata_buf, mdata_phys);
> >>>  	} else if (ctx) {
> >>> -		ctx->ptr = mdata_buf;
> >>> -		ctx->phys = mdata_phys;
> >>> -		ctx->size = size;
> >>> +		mdt_ctx = ctx->metadata;
> >>> +		mdt_ctx->ptr = mdata_buf;
> >>> +		mdt_ctx->phys = mdata_phys;
> >>> +		mdt_ctx->size = size;
> >>
> >> So this will always cause stack corruption
> >>
> >>>  	}
> >>>  
> >>>  	return ret ? : res.result[0];
> >>> @@ -676,16 +678,19 @@ EXPORT_SYMBOL_GPL(qcom_scm_pas_init_image);
> >>>  
> >>>  /**
> >>>   * qcom_scm_pas_metadata_release() - release metadata context
> >>> - * @ctx:	metadata context
> >>> + * @ctx:	pas context
> >>>   */
> >>> -void qcom_scm_pas_metadata_release(struct qcom_scm_pas_metadata *ctx)
> >>> +void qcom_scm_pas_metadata_release(struct qcom_scm_pas_context *ctx)
> >>>  {
> >>> -	if (!ctx->ptr)
> >>> +	struct qcom_scm_pas_metadata *mdt_ctx;
> >>
> >> Is the existence of this struct any useful after you introduced
> >> pas_context?
> > 
> > Yes, it is still useful, mdt_ctx is only relevant for remoteproc based
> > subsystem like adsp, cdsp, modem while they are not required for video,
> > ipa, gpu etc. but the superset which is pas_context is needed by
> > whosoever need to support secure PAS method Linux at EL2.
> 
> $ b4 shazam 20251104-kvm_rproc_v6-v6-0-7017b0adc24e@....qualcomm.com
> $ rg 'struct qcom_scm_pas_metadata'
> 
> include/linux/firmware/qcom/qcom_scm.h
> 69:struct qcom_scm_pas_metadata {
> 80:     struct qcom_scm_pas_metadata *metadata;
> 
> drivers/firmware/qcom/qcom_scm.c
> 636:    struct qcom_scm_pas_metadata *mdt_ctx;
> 680:    struct qcom_scm_pas_metadata *mdt_ctx;
> 728:    struct qcom_scm_pas_metadata *mdt_ctx;
> 
> So really it seems like it always exists as part of the pas_context..
> should we just make the larger struct integrate the smaller one and drop
> the unnecessary layer?
> 
> TBF I don't really insist on this, but it surely looks a little odd

You are right, we could remove 'struct qcom_scm_pas_metadata' completely
and can add the fields of it to struct qcom_scm_pas_context.

Will do it next spin.

> 
> Konrad

-- 
-Mukesh Ojha