On Thu, Jul 26, 2018 at 09:39:37AM +0200, Ard Biesheuvel wrote: > On 26 July 2018 at 09:36, Daniel Thompson <[email protected]> wrote: > > On Wed, Jul 25, 2018 at 12:04:58PM +0200, Ard Biesheuvel wrote: > >> On 23 July 2018 at 15:19, Sumit Garg <[email protected]> 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 <[email protected]> > >> > Cc: Leif Lindholm <[email protected]> > >> > Contributed-under: TianoCore Contribution Agreement 1.1 > >> > Signed-off-by: Sumit Garg <[email protected]> > >> > --- > >> > > >> > >> 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? > > > > 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? Daniel. _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
