On Wed, 2020-06-03 at 17:34 +0800, Russell King - ARM Linux admin wrote: > On Wed, Jun 03, 2020 at 08:40:58AM +0100, Marc Zyngier wrote: > > On 2020-06-03 08:29, Neal Liu wrote: > > > On Tue, 2020-06-02 at 21:02 +0800, Marc Zyngier wrote: > > > > On 2020-06-02 13:14, Ard Biesheuvel wrote: > > > > > On Tue, 2 Jun 2020 at 10:15, Neal Liu <neal.liu@xxxxxxxxxxxx> wrote: > > > > >> > > > > >> These patch series introduce a security random number generator > > > > >> which provides a generic interface to get hardware rnd from Secure > > > > >> state. The Secure state can be Arm Trusted Firmware(ATF), Trusted > > > > >> Execution Environment(TEE), or even EL2 hypervisor. > > > > >> > > > > >> Patch #1..2 adds sec-rng kernel driver for Trustzone based SoCs. > > > > >> For security awareness SoCs on ARMv8 with TrustZone enabled, > > > > >> peripherals like entropy sources is not accessible from normal world > > > > >> (linux) and rather accessible from secure world (HYP/ATF/TEE) only. > > > > >> This driver aims to provide a generic interface to Arm Trusted > > > > >> Firmware or Hypervisor rng service. > > > > >> > > > > >> > > > > >> changes since v1: > > > > >> - rename mt67xx-rng to mtk-sec-rng since all MediaTek ARMv8 SoCs can > > > > >> reuse > > > > >> this driver. > > > > >> - refine coding style and unnecessary check. > > > > >> > > > > >> changes since v2: > > > > >> - remove unused comments. > > > > >> - remove redundant variable. > > > > >> > > > > >> changes since v3: > > > > >> - add dt-bindings for MediaTek rng with TrustZone enabled. > > > > >> - revise HWRNG SMC call fid. > > > > >> > > > > >> changes since v4: > > > > >> - move bindings to the arm/firmware directory. > > > > >> - revise driver init flow to check more property. > > > > >> > > > > >> changes since v5: > > > > >> - refactor to more generic security rng driver which > > > > >> is not platform specific. > > > > >> > > > > >> *** BLURB HERE *** > > > > >> > > > > >> Neal Liu (2): > > > > >> dt-bindings: rng: add bindings for sec-rng > > > > >> hwrng: add sec-rng driver > > > > >> > > > > > > > > > > There is no reason to model a SMC call as a driver, and represent it > > > > > via a DT node like this. > > > > > > > > +1. > > > > > > > > > It would be much better if this SMC interface is made truly generic, > > > > > and wired into the arch_get_random() interface, which can be used much > > > > > earlier. > > > > > > > > Wasn't there a plan to standardize a SMC call to rule them all? > > > > > > > > M. > > > > > > Could you give us a hint how to make this SMC interface more generic in > > > addition to my approach? > > > There is no (easy) way to get platform-independent SMC function ID, > > > which is why we encode it into device tree, and provide a generic > > > driver. In this way, different devices can be mapped and then get > > > different function ID internally. > > > > The idea is simply to have *one* single ID that caters for all > > implementations, just like we did for PSCI at the time. This > > requires ARM to edict a standard, which is what I was referring > > to above. > > This sounds all too familiar. > > This kind of thing is something that ARM have seems to shy away from > doing - it's a point I brought up many years ago when the whole > trustzone thing first appeared with its SMC call. Those around the > conference table were not interested - ARM seemed to prefer every > vendor to do off and do their own thing with the SMC interface. Does that mean it make sense to model a sec-rng driver, and get each vendor's SMC function id by DT node? > > Then OMAP came along with its SMC interfaces, and so did the pain of > not having a standardised way to configure the L2C when Linux was > running in the non-secure world, resulting in stuff like l2c_configure > etc, where each and every implementation has to supply a function to > call its platform specific SMC interfaces to configure a piece of > hardware common across many different platforms. > > ARM have seemed reluctant to standardise on stuff like this, so > unless someone pushes hard for it from inside ARM, I doubt it will > ever happen. >
