HVC Hypervisor call This instruction causes an exception to EL2. Software executing at EL1 can use this instruction to call the hypervisor to request a service. The HVC instruction is UNDEFINED: When EL3 is implemented and SCR_EL3.HCE is set to 0. When EL3 is not implemented and HCR_EL2.HCD is set to 1. When EL2 is not implemented. At EL1 if EL2 is not enabled in the current Security state. At EL0. On executing an HVC instruction, the PE records the exception as a Hypervisor Call exception in ESR_ELx, using the EC syndrome value 0x16, and the value of the immediate argument. 1 1 0 1 0 1 0 0 0 0 0 0 0 0 1 0 HVC #<imm> if !HaveEL(EL2) then EndOfDecode(Decode_UNDEF); end; let imm : bits(16) = imm16; <imm> Is a 16-bit unsigned immediate, in the range 0 to 65535, encoded in the "imm16" field. if PSTATE.EL == EL0 then Undefined(); end; if PSTATE.EL == EL1 && !EL2Enabled() then Undefined(); end; if !HaveEL(EL3) && HCR_EL2().HCD == '1' then Undefined(); end; if HaveEL(EL3) && SCR_EL3().HCE == '0' then Undefined(); end; AArch64_CallHypervisor(imm); 2026-03-12 12:23:09 2025-09_rel_asl1