KVM: arm64: Expose FEAT_MTE_TAGGED_FAR feature to guest

expose FEAT_MTE_TAGGED_FAR feature to guest.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250618084513.1761345-4-yeoreum.yun@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: LeviYeoReum

arch/arm64/kvm/sys_regs.c

@@ -1617,8 +1617,8 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac);
 		break;
 	case SYS_ID_AA64PFR2_EL1:
-		/* We only expose FPMR */
-		val &= ID_AA64PFR2_EL1_FPMR;
+		val &= ID_AA64PFR2_EL1_FPMR |
+			(kvm_has_mte(vcpu->kvm) ? ID_AA64PFR2_EL1_MTEFAR : 0);
 		break;
 	case SYS_ID_AA64ISAR1_EL1:
 		if (!vcpu_has_ptrauth(vcpu))
@@ -2876,7 +2876,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 				       ID_AA64PFR1_EL1_MPAM_frac |
 				       ID_AA64PFR1_EL1_RAS_frac |
 				       ID_AA64PFR1_EL1_MTE)),
-	ID_WRITABLE(ID_AA64PFR2_EL1, ID_AA64PFR2_EL1_FPMR),
+	ID_WRITABLE(ID_AA64PFR2_EL1,
+		    ID_AA64PFR2_EL1_FPMR |
+		    ID_AA64PFR2_EL1_MTEFAR),
 	ID_UNALLOCATED(4,3),
 	ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0),
 	ID_HIDDEN(ID_AA64SMFR0_EL1),