Hi Marco, Am 27.06.25 um 10:46 schrieb Marco Felsch: > Hi, > > your e-mail configuration mixed my e-mail with your answer, which makes > it hard to read. Can you please check the quoting next time :) > > On 25-06-27, Pankaj Gupta wrote: >>>> Add driver for enabling MU based communication interface to >> secure-enclave. >>>> >>>> NXP hardware IP(s) for secure-enclaves like Edgelock Enclave(ELE), are >>>> embedded in the SoC to support the features like HSM, SHE & V2X, using >>>> message based communication interface. >>>> >>>> The secure enclave FW communicates with Linux over single or multiple >>>> dedicated messaging unit(MU) based interface(s). >>>> Exists on i.MX SoC(s) like i.MX8ULP, i.MX93, i.MX95 etc. >> >>> You write single or multiple MUs are possible. I'm aware that the i.MX93 >>> has two MUs one for the secure and one for the non-secure world. But I'm >>> really concerned about the fact that both MUs can't be used at the same time >>> from both world: >> >> Yes, you are correct. >> >> Fix is still work in progress. > > So after ~6 months no fix is available :( > >>> Also how is the secure and non-secure world talking to the ELE if there is >>> only one MU as you have written? >> >> Till the fix is WIP, either Linux or OPTEE can use the ELE, at one point in >> time. > > That has nothing to do with the fix. The fix is for platforms/SoCs which > do have 2-MUs, but you also have written that there are platforms with > only 1-MU. > > This MU can't be shared between secure and non-secure world. > >>> IMHO it makes much more sense to put the complete ELE communication into >>> (OP-)TEE and let the secure OS taking care of it. All non-secure world >>> requests are passed via (OP-)TEE to the ELE. This involves: >>> - eFuse access (done via OP-TEE i.MX specific PTA) >>> - ELE 23h59m ping (kernel SMC WDG driver, requires OP-TEE watchdog driver) >>> - HW-RNG (kernel OP-TEE HWRNG driver + OP-TEE HWRNG PTA) >> >> There is a dedicated MU "trusted-MU" for OPTEE-OS. The idea to converge to a > > Yes for systems with 2-MUs there is a "trusted-MU" and a > "non-trusted-MU". As of now, there is no fix available for using both > MUs at the same time. Furhtermore there are platforms/SoCs with only > 1-MU, as you have written in your commit message. This 1-MU system can > have the MU either trusted or non-trusted. > >> single path via OPTEE-OS, is good. But it will impact the performance of the >> features at Linux side. > > Performance? We are talking about a ping every 23h59m (I still don't > know if this is a feature or bug), eFuse write/read, and the HW-RNG > which can seed the Linux PRNG. > >> Since the fix is still WIP. Let's wait till then. > > The fix is for the 2-MUs SoCs but not the 1-MU case. > > I would like to have a system design which doesn't differ too much > between SoCs which are equipped with the ELE engine. Do we really want to depend on OP-TEE to be available for having things like OTP fuse access and HWRNG? Personally I'd like to be able to build systems with OTP access and HWRNG but without OP-TEE. Requiring OP-TEE only to make the ELE available to the kernel in cases where the secure world isn't used for anything else seems to be unnecessarily complex. Anyway, I see your point of having a single implementation for the ELE API in the "right" place. But as far as I know other platforms like STM32MP1 also implement both ways for the HWRNG, secure access via OPTEE and non-secure access via kernel directly. Thanks Frieder
