KVM: arm64: Enable Address Authentication at EL2 if available

While initializing EL2, enable Address Authentication if detected
from EL1. We still use the EL1-provided keys though.
Acked-by: Andrew Scull <ascull@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/kvm/hyp-init.S

@@ -104,6 +104,11 @@ alternative_else_nop_endif
 	 */
 	mov_q	x4, (SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
 CPU_BE(	orr	x4, x4, #SCTLR_ELx_EE)
+alternative_if ARM64_HAS_ADDRESS_AUTH
+	mov_q	x5, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
+		     SCTLR_ELx_ENDA | SCTLR_ELx_ENDB)
+	orr	x4, x4, x5
+alternative_else_nop_endif
 	msr	sctlr_el2, x4
 	isb