I'm having problems running TF-A / Hafnium with S-EL2 support.

I can run Hafnium fine using the prebuilt TF-A binary in prebuilts/linux-aarch64/trusted-firmware-a-trusty/ but it doesn't work if I use TF-A master.

I'm building TF-A with:

make PLAT=fvp LOG_LEVEL=80 DEBUG=1 SPD=spmd CTX_INCLUDE_EL2_REGS=1 ARM_ARCH_MINOR=5 BRANCH_PROTECTION=1 CTX_INCLUDE_PAUTH_REGS=1 all fip BL32=../hafnium/out/reference/aem_v8a_fvp_clang/hafnium.bin BL33=../uefi/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/FV/FVP_AARCH64_EFI.fd SP_LAYOUT_FILE=sp_layout.json

And running it with:

../Base_RevC_AEMv8A_pkg/models/Linux64_GCC-6.4/FVP_Base_RevC-2xAEMv8A \ -C pctl.startup=0.0.0.0 \ -C cluster0.NUM_CORES=4 -C cluster1.NUM_CORES=4 -C bp.secure_memory=1 \ -C bp.secureflashloader.fname=../trusted-firmware-a/build/fvp/debug/bl1.bin \ -C bp.flashloader0.fname=../trusted-firmware-a/build/fvp/debug/fip.bin \ -C bp.pl011_uart0.out_file=fvp-uart0.log -C bp.pl011_uart1.out_file=fvp-uart1.log \ -C bp.pl011_uart2.out_file=fvp-uart2.log \ -C cluster0.has_arm_v8-5=1 -C cluster1.has_arm_v8-5=1 -C pci.pci_smmuv3.mmu.SMMU_AIDR=2 \ -C pci.pci_smmuv3.mmu.SMMU_IDR0=0x0046123B -C pci.pci_smmuv3.mmu.SMMU_IDR1=0x00600002 \ -C pci.pci_smmuv3.mmu.SMMU_IDR3=0x1714 -C pci.pci_smmuv3.mmu.SMMU_IDR5=0xFFFF0472 \ -C pci.pci_smmuv3.mmu.SMMU_S_IDR1=0xA0000002 -C pci.pci_smmuv3.mmu.SMMU_S_IDR2=0 \ -C pci.pci_smmuv3.mmu.SMMU_S_IDR3=0 \ -C cluster0.has_branch_target_exception=1 \ -C cluster1.has_branch_target_exception=1 \ -C cluster0.restriction_on_speculative_execution=2 \ -C cluster1.restriction_on_speculative_execution=2

TF-A prints this and then stops for a minute or two before resetting:

INFO:    Loading image id=5 at address 0x88000000 INFO:    Image id=5 loaded: 0x88000000 - 0x88280000 INFO:    BL2: Skip loading image id 27 INFO:    BL2: Loading image id 34 VERBOSE: Using Memmap VERBOSE: FIP header looks OK. VERBOSE: Trying alternative IO

I'm fairly new to working with Hafnium, TF-A _and_ Arm's FVP so there's probably something obvious I'm doing wrong?