KVM: arm64: Use the in-context stage-1 in __kvm_find_s1_desc_level()

Running the external_aborts selftest at EL2 leads to an ugly splat due
to the stage-1 MMU being disabled for the walked context, owing to the
fact that __kvm_find_s1_desc_level() is hardcoded to the EL1&0 regime.

Select the appropriate translation regime for the stage-1 walk based on
the current vCPU context.

Fixes: b8e6251 ("KVM: arm64: Add S1 IPA to page table level walker")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: oupton

arch/arm64/kvm/at.c

@@ -1602,13 +1602,17 @@ int __kvm_find_s1_desc_level(struct kvm_vcpu *vcpu, u64 va, u64 ipa, int *level)
 			.fn	= match_s1_desc,
 			.priv	= &dm,
 		},
-		.regime	= TR_EL10,
 		.as_el0	= false,
 		.pan	= false,
 	};
 	struct s1_walk_result wr = {};
 	int ret;
 
+	if (is_hyp_ctxt(vcpu))
+		wi.regime = vcpu_el2_e2h_is_set(vcpu) ? TR_EL20 : TR_EL2;
+	else
+		wi.regime = TR_EL10;
+
 	ret = setup_s1_walk(vcpu, &wi, &wr, va);
 	if (ret)
 		return ret;