linux-kernel - Re: [PATCH v9 11/14] firmware: qcom_scm: Add qcom_scm_pas_get_rsc

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Message-ID: <646c0f6a-9d84-490b-a55c-7ff92e2b26f5@oss.qualcomm.com>
Date: Thu, 18 Dec 2025 14:34:27 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Mukesh Ojha <mukesh.ojha@....qualcomm.com>,
        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>
Cc: linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 11/14] firmware: qcom_scm: Add
 qcom_scm_pas_get_rsc_table() to get resource table

On 12/17/25 5:34 PM, Mukesh Ojha wrote:
> Qualcomm remote processor may rely on Static and Dynamic resources for
> it to be functional. Static resources are fixed like for example,
> memory-mapped addresses required by the subsystem and dynamic
> resources, such as shared memory in DDR etc., are determined at
> runtime during the boot process.
> 
> For most of the Qualcomm SoCs, when run with Gunyah or older QHEE
> hypervisor, all the resources whether it is static or dynamic, is
> managed by the hypervisor. Dynamic resources if it is present for a
> remote processor will always be coming from secure world via SMC call
> while static resources may be present in remote processor firmware
> binary or it may be coming qcom_scm_pas_get_rsc_table() SMC call along
> with dynamic resources.
> 
> Some of the remote processor drivers, such as video, GPU, IPA, etc., do
> not check whether resources are present in their remote processor
> firmware binary. In such cases, the caller of this function should set
> input_rt and input_rt_size as NULL and zero respectively. Remoteproc
> framework has method to check whether firmware binary contain resources
> or not and they should be pass resource table pointer to input_rt and
> resource table size to input_rt_size and this will be forwarded to
> TrustZone for authentication. TrustZone will then append the dynamic
> resources and return the complete resource table in output_rt
> 
> More about documentation on resource table format can be found in
> include/linux/remoteproc.h
> 
> Signed-off-by: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
> ---

[...]

> +	memcpy(input_rt_tzm, input_rt, input_rt_size);
> +
> +	do {
> +		output_rt_tzm = qcom_tzmem_alloc(__scm->mempool, size, GFP_KERNEL);
> +		if (!output_rt_tzm) {
> +			ret = -ENOMEM;
> +			goto free_input_rt;
> +		}
> +
> +		ret = __qcom_scm_pas_get_rsc_table(ctx->pas_id, input_rt_tzm,
> +						   input_rt_size, output_rt_tzm,
> +						   &size);
> +		if (ret)
> +			qcom_tzmem_free(output_rt_tzm);
> +
> +	} while (ret == -EOVERFLOW);

This still looks shaky (do-while is convenient for calling this twice, but perhaps
the allocation could be moved to __qcom_scm_pas_get_rsc_table() since it's static
anyway, and then we can just do:

ret = __qcom_scm_pas_get_rsc_table(...)
if (ret == -EOVERFLOW) {
	/* Try again with the size requested by the TZ */
	ret = __qcom_scm_pas_get_rsc_table(...)
}

Other than that, it looks good (although there's still a lot of boilerplate
that we can't really get rid of with C)

Konrad