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

[Sibi Sankar]

On 12/14/22 16:58, Krzysztof Kozlowski wrote:
> On 14/12/2022 11:33, Sibi Sankar wrote:
> > 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.
>
> This does not explain why you extend the driver without extending the
> bindings. You do not do it for legacy stuff but for SC7180. But even for
> legacy devices you cannot add new properties without having it in some
> legacy bindings.

https://patchwork.kernel.org/project/linux-arm-msm/patch/20221213140724.8612-4-quic_sibis@xxxxxxxxxxx/

The legacy bindings are a part of patch 3 ^^.

> Best regards,
> Krzysztof