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

[Sibi Sankar]

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@xxxxxxxxxx>
> > Fixes: 6c5a9dc2481b ("remoteproc: qcom: Make secure world call for mem ownership switch")
> > Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
> > ---
>
> 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