linux-kernel - Re: [PATCH 4/4] remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem headers

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Date:   Tue, 13 Dec 2022 20:47:35 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sibi Sankar <quic_sibis@...cinc.com>, andersson@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, robh+dt@...nel.org,
        manivannan.sadhasivam@...aro.org
Cc:     agross@...nel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        konrad.dybcio@...ainline.org, amit.pundir@...aro.org,
        regressions@...mhuis.info, sumit.semwal@...aro.org,
        will@...nel.org, catalin.marinas@....com, robin.murphy@....com
Subject: Re: [PATCH 4/4] remoteproc: qcom_q6v5_mss: Use a carveout to
 authenticate modem headers

On 13/12/2022 15:07, Sibi Sankar wrote:
> The memory region allocated using dma_alloc_attr with no kernel mapping
> attribute set would still be a part of the linear kernel map. Any access
> to this region by the application processor after assigning it to the
> remote Q6 will result in a XPU violation. Fix this by replacing the
> dynamically allocated memory region with a no-map carveout and unmap the
> modem metadata memory region before passing control to the remote Q6.
> 
> Reported-by: Amit Pundir <amit.pundir@...aro.org>
> Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem ownership switch")
> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
> ---

Thank you for your patch. There is something to discuss/improve.
>  
>  	return ret < 0 ? ret : 0;
> @@ -1882,6 +1899,26 @@ static int q6v5_alloc_memory_region(struct q6v5 *qproc)
>  	qproc->mpss_phys = qproc->mpss_reloc = r.start;
>  	qproc->mpss_size = resource_size(&r);
>  
> +	if (!child) {
> +		node = of_parse_phandle(qproc->dev->of_node, "memory-region", 2);
> +	} else {
> +		child = of_get_child_by_name(qproc->dev->of_node, "metadata");

Bindings do not allow to have child "metadata", do they?

> +		node = of_parse_phandle(child, "memory-region", 0);
> +		of_node_put(child);
> +	}
> +
> +	if (!node)
> +		return 0;
> +
> +	ret = of_address_to_resource(node, 0, &r);
> +	of_node_put(node);
> +	if (ret) {
> +		dev_err(qproc->dev, "unable to resolve metadata region\n");
> +		return ret;
> +	}
> +
> +	qproc->mdata_phys = r.start;
> +
>  	return 0;
>  }
>  

Best regards,
Krzysztof