On Fri, 27 Jul 2018 at 16:40, Daniel Thompson <daniel.thomp...@linaro.org> wrote: > > On 26/07/18 09:42, Sumit Garg wrote: > > On Thu, 26 Jul 2018 at 13:20, Daniel Thompson > > <daniel.thomp...@linaro.org> wrote: > >> > >> On Thu, Jul 26, 2018 at 09:39:37AM +0200, Ard Biesheuvel wrote: > >>> On 26 July 2018 at 09:36, Daniel Thompson <daniel.thomp...@linaro.org> > >>> wrote: > >>>> On Wed, Jul 25, 2018 at 12:04:58PM +0200, Ard Biesheuvel wrote: > >>>>> On 23 July 2018 at 15:19, Sumit Garg <sumit.g...@linaro.org> wrote: > >>>>>> OP-TEE is optional on Developerbox controlled via SCP firmware. To > >>>>>> check > >>>>>> if we need to delete OP-TEE DT node, we use DRAM1 region info as SCP > >>>>>> firmware conditionally carves out Secure memory from DRAM1 region. > >>>>>> > >>>>>> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > >>>>>> Cc: Leif Lindholm <leif.lindh...@linaro.org> > >>>>>> Contributed-under: TianoCore Contribution Agreement 1.1 > >>>>>> Signed-off-by: Sumit Garg <sumit.g...@linaro.org> > >>>>>> --- > >>>>>> > >>>>> > >>>>> As discussed on IRC, i am not a fan of inferring the presence of > >>>>> OP-TEE from the base/size values of the first DRAM region. > >>>>> > >>>>> Please refer to the existing PCIe code how to read a GPIO in PEI and > >>>>> set a dynamic PCD accordingly, so you can use its value in > >>>>> PlatformDxe. > >>>> > >>>> For Trusted Firmware I asked Sumit to look for the OP-TEE memory carve > >>>> out rather than looking at the switches. This was based on concerns > >>>> about version skew (new C-A53 firmware, old SCP firmware[1]), in > >>>> particular > >>>> if TF-A jumps to an OP-TEE that isn't actually loaded the system will > >>>> fail in a not very transparent way (especially if the user hasn't found > >>>> the debug UART behind the back panel yet). > >>>> > >>>> What is the consequence of passing a DT with OP-TEE present if one is > >>>> not actually present? Do we at least get as far as bringing up the > >>>> framebuffer before things explode? > >>>> > > > > If we pass a DT with OP-TEE and OP-TEE not present, Linux TEE generic > > driver exits gracefully giving following message: > > > > [ 1.976021] optee: probing for conduit method from DT. > > [ 1.976033] optee: api uid mismatch > > That certainly means we can be pretty relaxed about version skew of > normal world components (since nothing bad happens if thinks get skewed). > > > >>> Is there any way we can let OP-TEE supply a DT overlay? > >> > >> I guess it could implement a secure monitor call to provide it. In > >> fact I find it a rather pleasing approach. However I think it still loops > >> us round to pretty much the same question as before. Does TF-A "protec > >> " a normal world that makes an SMC to an OP-TEE that isn't there by > >> failing the call in a nice way? > >> > > > > TF-A returns SMC call for OP-TEE as unknown (error code: -1 in "x0" > > register) if OP-TEE is not present. > > It is possible to experiment with getting EDK2 to detect OP-TEE using > SMC? This would be fully generic and presumably be the first step in > having an EFI OP-TEE driver. >
Agree. I will try to detect OP-TEE version via SMC call. If SMC unknown is returned, then we say OP-TEE is not present and remove corresponding DT node. So I think this EFI OP-TEE driver makes more sense in edk2 rather than edk2-platforms. -Sumit _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
