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Does FVP Base RecV Support Permission Indirection Extension & Permission Overlay Extension?

RustyCohle

Hi there,

I want to verify whether FVP Base RecV (version 1125) supports the ARMv8.9-A Permission Indirection Extension (PIE) and Permission Overlay Extension (POE).

For the quick verification, I decided to run edk2 (UEFI) on FVP only.

The FVP options that I use:

 $ Base_RevC_AEMvA_pkg/models/Linux64_GCC-9.3/FVP_Base_RevC-2xAEMvA \
 -C pctl.startup=0.0.0.0 \
 -C bp.secure_memory=0 \
 -C cluster0.NUM_CORES=1 \
 -C cluster1.NUM_CORES=1 \
 -C cluster0.has_permission_indirection_s1=2 \
 -C cluster0.has_permission_indirection_s2=2 \
 -C cluster0.has_permission_overlay_s1=2 \
 -C cluster0.has_permission_overlay_s2=2 \
 -C cluster1.has_permission_indirection_s1=2 \
 -C cluster1.has_permission_indirection_s2=2 \
 -C cluster1.has_permission_overlay_s1=2 \
 -C cluster1.has_permission_overlay_s2=2 \
 -C cache_state_modelled=0 \
 -C bp.pl011_uart0.untimed_fifos=1 \
 -C bp.pl011_uart0.unbuffered_output=1 \
 -C bp.pl011_uart0.out_file=uart/uart0.log \
 -C bp.pl011_uart1.out_file=uart/uart1.log \
 -C bp.secureflashloader.fname=bl1.bin \
 -C bp.flashloader0.fname=fip.bin \
 -C bp.ve_sysregs.mmbSiteDefault=0 \
 -C bp.ve_sysregs.exit_on_shutdown=1

To this end, I added code to the edk2/ShellPkg/Application/Shell/Shell.c to read PIE-POE related system registers and print their value, as illustrated bellow:

 EFI_STATUS
 EFIAPI
 UefiMain (
   IN EFI_HANDLE        ImageHandle,
   IN EFI_SYSTEM_TABLE  *SystemTable
   )
 {
   EFI_STATUS                      Status;
   CHAR16                          *TempString;
   UINTN                           Size;
   EFI_HANDLE                      ConInHandle;
   EFI_SIMPLE_TEXT_INPUT_PROTOCOL  *OldConIn;
   SPLIT_LIST                      *Split;
  
   UINT64 REG_ID_AA64MMFR3_EL1 = 0;
  
   UINT64 REG_PIR_EL1 = 0;
   UINT64 REG_POR_EL1 = 0;
  
   if (PcdGet8 (PcdShellSupportLevel) > 3) {
     return (EFI_UNSUPPORTED);
   }
  
   __asm__ volatile ("mrs %0, ID_AA64MMFR3_EL1" : "=r" (REG_ID_AA64MMFR3_EL1));
   Print(L"ID_AA64MMFR3_EL1: 0x%016x\n", REG_ID_AA64MMFR3_EL1);
 â€‹
   __asm__ volatile ("mrs %0, PIR_EL1" : "=r" (REG_PIR_EL1));
   Print(L"PIR_EL1: 0x%016x\n", REG_PIR_EL1);
 â€‹
   __asm__ volatile ("mrs %0, POR_EL1" : "=r" (REG_POR_EL1));
   Print(L"POR_EL1: 0x%016x\n", REG_POR_EL1);
 }

Results:

 ID_AA64MMFR3_EL1: 0x0000000000111101

According to ID_AA64MMFR3_EL1, AArch64 Memory Model Feature Register 3, the value of ID_AA64MMFAR3_EL1 indicates that FVP_Base_RecV supports both PIE and POE.

However, the program gets stuck when it further reads PIR_EL1 and POR_EL1. If I remove related code of reading these two registers, the program executes normally.

My questions are:

  • Does FVP Base RecV (version 1125) really support PIE-POE?

  • If so, how can we read and write PIE-POE related system registers?

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