SError Exception and HCR_EL2 Usage

[Vabhav Sharma <vabhav.sharma@nxp.com>]

Dear Experts,

I am facing SError exception during UEFI bring-up.
At boot , secure f/w starts in EL3 and loads UEFI image to DDR. After this secure f/w passes control to UEFI in EL2.

I debugged and manifest the problem by adding below lines in UEFI PrePi entry point(ModuleEntryPoint.S)

ASM_FUNC(_ModuleEntryPoint)

+msr  daifclr,#4

+isb

+mrs x0, hcr_el2

+ldr x1, =0x08000000

+orr x0, x0, x1

+msr hcr_el2, x0

+isb



Once exception occurs than ELR_EL2 point to 'isb' instruction and ESR_EL2 is SError Exception syndrome.

Could you please suggest if this is UEFI problem or Secure f/w issue?

Additionally, TGE bit is set in hcr_el2 three times during PrePei phase(ArmPlatformPkg/PrePi/AArch64/ArchPrePi.c),DxeMain(),ArmCpuDxe.
Please explain the purpose of setting it or require to be fixed?

Regards,
Vabhav