arm64/sme: Enable host kernel to access ZT0

The new register ZT0 introduced by SME2 comes with a new trap, disable it
for the host kernel so that we can implement support for it.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-7-f2fa0aef982f@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/hyp-stub.S

@@ -132,6 +132,12 @@ SYM_CODE_START_LOCAL(__finalise_el2)
 	orr	x0, x0, SMCR_ELx_FA64_MASK
 .Lskip_sme_fa64:
 
+	// ZT0 available?
+	__check_override id_aa64smfr0 ID_AA64SMFR0_EL1_SMEver_SHIFT 4 .Linit_sme_zt0 .Lskip_sme_zt0
+.Linit_sme_zt0:
+	orr	x0, x0, SMCR_ELx_EZT0_MASK
+.Lskip_sme_zt0:
+
 	orr	x0, x0, #SMCR_ELx_LEN_MASK	// Enable full SME vector
 	msr_s	SYS_SMCR_EL2, x0		// length for EL1.
 

arch/arm64/kernel/idreg-override.c

@@ -131,6 +131,7 @@ static const struct ftr_set_desc smfr0 __initconst = {
 	.name		= "id_aa64smfr0",
 	.override	= &id_aa64smfr0_override,
 	.fields		= {
+		FIELD("smever", ID_AA64SMFR0_EL1_SMEver_SHIFT, NULL),
 		/* FA64 is a one bit field... :-/ */
 		{ "fa64", ID_AA64SMFR0_EL1_FA64_SHIFT, 1, },
 		{}