On Mon, Mar 18, 2019 at 12:05:54PM +0100, Benjamin Gaignard wrote: > Le lun. 18 mars 2019 à 11:43, Sudeep Holla <[email protected]> a écrit : > > > > On Mon, Mar 18, 2019 at 11:05:58AM +0100, Benjamin Gaignard wrote: > > > Bus domains controllers allow to divided system on chip into multiple > > > domains > > > that can be used to select by who hardware blocks could be accessed. > > > A domain could be a cluster of CPUs (or coprocessors), a range of > > > addresses or > > > a group of hardware blocks. > > > > > > Framework architecture is inspirated by pinctrl framework: > > > - a default configuration could be applied before bind the driver > > > - configurations could be apllied dynamically by drivers > > > - device node provides the bus domains configurations > > > > > > An example of bus domains controller is STM32 ETZPC hardware block > > > which got 3 domains: > > > - secure: hardware blocks are only accessible by software running on trust > > > zone. > > > - non-secure: hardware blocks are accessible by non-secure software (i.e. > > > linux kernel). > > > - coprocessor: hardware blocks are only accessible by the corpocessor. > > > Up to 94 hardware blocks of the soc could be managed by ETZPC and > > > assigned to one of the three domains. > > > > > > > You fail to explain why do we need this in non-secure Linux ? > > You need to have solid reasons as why this can't be done in secure > > firmware. And yes I mean even on arm32. On platforms with such hardware > > capabilities you will need some secure firmware to be running and these > > things can be done there. I don't want this enabled for ARM64 at all, > > firmware *has to deal* with this. > > We use ETZPC to define if hardware blocks can be used by Cortex A7 or Cortex > M4 (both non-secure) on STM32MP1 SoC, this new framework allow to change > hardware block split at runtime. This could be done even on non-secure world > because their is nothing critical to change hardware blocks users.
OK, that's interesting, assuming Cortex M4 execution as non-secure. I would expect otherwise. Even if it's configurable, I would see that happen in secure entity via OPTEE or something similar from non-secure side. Do you have any documents that I can refer to get the overall security design for such platforms ? -- Regards, Sudeep
