KVM: arm64: Force trap of GMID_EL1 when the guest doesn't have MTE

If our host has MTE, but the guest doesn't, make sure we set HCR_EL2.TID5
to force GMID_EL1 being trapped. Such trap will be handled by the
FEAT_IDST handling.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Yuan Yao <yaoyuan@linux.alibaba.com>
Link: https://patch.msgid.link/20260108173233.2911955-7-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/kvm/sys_regs.c

@@ -5576,6 +5576,8 @@ static void vcpu_set_hcr(struct kvm_vcpu *vcpu)
 
 	if (kvm_has_mte(vcpu->kvm))
 		vcpu->arch.hcr_el2 |= HCR_ATA;
+	else
+		vcpu->arch.hcr_el2 |= HCR_TID5;
 
 	/*
 	 * In the absence of FGT, we cannot independently trap TLBI