Enable SVE instructions

Question

I am in EL1. The EL3 Code is supposed to have activated sve using CPTR_EL3 for all levels. I am trying to do a simple FMOV to sve registers. It crashes.

• What else should I check/set for SVE instruction to be available?

This is compiled using clang/llvm-as

.arch armv8-a+sve

// load feature register
MRS     x1, CPACR_EL1 

// Bit 32 is sve actually implemented
MRS     x4, ID_AA64PFR0_EL1
TBZ     x4, #32, no_sve

// Set bit 16-17 and 20-21 to '1'
MOV     x2, #3
ORR     x1, x1, x2, LSL #16
ORR     x1, x1, x2, LSL #20
MSR     CPACR_EL1, x1

// Set Length to Max
MOV     x1, #15
// crash: MSR     ZCR_EL1, x1

// Clobber Register
// crash: fmov    z0.d, #3.0

// If sve is available return #0x7
mov     w0, #0x7
ret

no_sve:
// If sve is NOT available return #0x9
mov     w0, #0x9
ret