Hi all,

I make StandaloneMM with secure varstore work on SBSA-QEMU.

One item I would like to discuss is the location of non-secure shared memory between UEFI and Secure-EL0(StandaloneMM).

For StandaloneMM, non-secure shared memory must be defined in compile time, because there is no method to know the shared memory address between uefi and tf-a in runtime.

I allocated this non-secure shared memory at the bottom of the DRAM, because DRAM size varies depending on the QEMU parameter.

DRAM layout is as follows(when the DRAM size is 1GB) 0x10000000000 - 0x10000FFFFFF(16MB) non-secure shared memory for StandaloneMM 0x10001000000 - 0x1003FFFFFFF(1GB - 16MB)

Does anyone have comments on this? My concern is allocating something at the bottom of the DRAM is not the usual implementation? # Other packages like SGI allocate it at the top of DRAM. https://github.com/tianocore/edk2-platforms/blob/master/Platform/ARM/SgiPkg/...

--- patch --- diff --git a/Platform/Qemu/SbsaQemu/SbsaQemu.dsc b/Platform/Qemu/SbsaQemu/SbsaQemu.dsc index 7d9a9cc50bf3..7ec5669615f0 100644 --- a/Platform/Qemu/SbsaQemu/SbsaQemu.dsc +++ b/Platform/Qemu/SbsaQemu/SbsaQemu.dsc @@ -387,7 +387,8 @@ [PcdsFixedAtBuild.common] gArmTokenSpaceGuid.PcdVFPEnabled|1

# System Memory Base -- fixed - gArmTokenSpaceGuid.PcdSystemMemoryBase|0x10000000000 + gArmTokenSpaceGuid.PcdSystemMemoryBase|0x10001000000

diff --git a/Silicon/Qemu/SbsaQemu/Library/SbsaQemuLib/SbsaQemuMem.c b/Silicon/Qemu/SbsaQemu/Library/SbsaQemuLib/SbsaQemuMem.c index 8c2eb0b6a028..7af9f5a4a1dc 100644 --- a/Silicon/Qemu/SbsaQemu/Library/SbsaQemuLib/SbsaQemuMem.c +++ b/Silicon/Qemu/SbsaQemu/Library/SbsaQemuLib/SbsaQemuMem.c @@ -73,8 +73,13 @@ SbsaQemuLibConstructor ( } }

+ // For StandaloneMM Non-Secure Shared buffer, reserve 16MB + // at the bottom of DRAM. + NewSize -= 0x1000000; + // Make sure the start of DRAM matches our expectation - ASSERT (FixedPcdGet64 (PcdSystemMemoryBase) == NewBase); + // remove base address check +// ASSERT (FixedPcdGet64 (PcdSystemMemoryBase) == NewBase); PcdStatus = PcdSet64S (PcdSystemMemorySize, NewSize); ------

Regards, Masahisa