Re: [PATCH v9 00/13] Introduce STM32 Firewall framework

[Alexandre TORGUE <alexandre.torgue@xxxxxxxxxxx>]

Hi Rob

On 4/9/24 19:13, Rob Herring wrote:
> On Mon, Apr 8, 2024 at 3:44 AM Alexandre TORGUE
> <alexandre.torgue@xxxxxxxxxxx> wrote:
> > Hi Gatien,
> >
> > On 1/5/24 14:03, Gatien Chevallier wrote:
> > > Introduce STM32 Firewall framework for STM32MP1x and STM32MP2x
> > > platforms. STM32MP1x(ETZPC) and STM32MP2x(RIFSC) Firewall controllers
> > > register to the framework to offer firewall services such as access
> > > granting.
> > >
> > > This series of patches is a new approach on the previous STM32 system
> > > bus, history is available here:
> > > https://lore.kernel.org/lkml/20230127164040.1047583/
> > >
> > > The need for such framework arises from the fact that there are now
> > > multiple hardware firewalls implemented across multiple products.
> > > Drivers are shared between different products, using the same code.
> > > When it comes to firewalls, the purpose mostly stays the same: Protect
> > > hardware resources. But the implementation differs, and there are
> > > multiple types of firewalls: peripheral, memory, ...
> > >
> > > Some hardware firewall controllers such as the RIFSC implemented on
> > > STM32MP2x platforms may require to take ownership of a resource before
> > > being able to use it, hence the requirement for firewall services to
> > > take/release the ownership of such resources.
> > >
> > > On the other hand, hardware firewall configurations are becoming
> > > more and more complex. These mecanisms prevent platform crashes
> > > or other firewall-related incoveniences by denying access to some
> > > resources.
> > >
> > > The stm32 firewall framework offers an API that is defined in
> > > firewall controllers drivers to best fit the specificity of each
> > > firewall.
> > >
> > > For every peripherals protected by either the ETZPC or the RIFSC, the
> > > firewall framework checks the firewall controlelr registers to see if
> > > the peripheral's access is granted to the Linux kernel. If not, the
> > > peripheral is configured as secure, the node is marked populated,
> > > so that the driver is not probed for that device.
> > >
> > > The firewall framework relies on the access-controller device tree
> > > binding. It is used by peripherals to reference a domain access
> > > controller. In this case a firewall controller. The bus uses the ID
> > > referenced by the access-controller property to know where to look
> > > in the firewall to get the security configuration for the peripheral.
> > > This allows a device tree description rather than a hardcoded peripheral
> > > table in the bus driver.
> > >
> > > The STM32 ETZPC device is responsible for filtering accesses based on
> > > security level, or co-processor isolation for any resource connected
> > > to it.
> > >
> > > The RIFSC is responsible for filtering accesses based on Compartment
> > > ID / security level / privilege level for any resource connected to
> > > it.
> > >
> > > STM32MP13/15/25 SoC device tree files are updated in this series to
> > > implement this mecanism.
> >
> > ...
> >
> > After minor cosmetic fixes, series applied on stm32-next.
> > Seen with Arnd: it will be part on my next PR and will come through
> > arm-soc tree.
>
> And there's some new warnings in next with it:
>
>        1  venc@480e0000: 'access-controllers' does not match any of the
> regexes: 'pinctrl-[0-9]+'
>        1  vdec@480d0000: 'access-controllers' does not match any of the
> regexes: 'pinctrl-[0-9]+'

Yes I noticed it to my colleague. YAML update has been sent for VEND/VDENC.

https://lore.kernel.org/lkml/171276671618.403884.13818480350194550959.robh@xxxxxxxxxx/T/

As soon as it is acked I could merge it in my tree.

Alex

> Rob