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SubjectRe: [PATCH 4/4] remoteproc: qcom_q6v5_mss: Use a carveout to authenticate modem headers
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On 12/14/22 01:17, Krzysztof Kozlowski wrote:
> 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@linaro.org>
>> Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem ownership switch")
>> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.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?

memory-region property was used to specify mba/mpss region in a phandle
array only from SC7180 SoC. All the older dtbs in the wild/upstream
still had sub-nodes to achieve the same. Patch 3 allows for a sub-set
of the SoCs (MSM8996/MSM8998/SDM845) to use metadata as a sub-node so
as to not break bindings when newer kernel uses a older dtb.

- Sibi

>
>> + 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
>

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