Steven Price [off-list ref] writes:

At runtime if the realm guest accesses memory which hasn't yet been
mapped then KVM needs to either populate the region or fault the guest.

For memory in the lower (protected) region of IPA a fresh page is
provided to the RMM which will zero the contents. For memory in the
upper (shared) region of IPA, the memory from the memslot is mapped
into the realm VM non secure.

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v2:
 * Avoid leaking memory if failing to map it in the realm.
 * Correctly mask RTT based on LPA2 flag (see rtt_get_phys()).
 * Adapt to changes in previous patches.

....

-	gfn = ipa >> PAGE_SHIFT;
+	gfn = (ipa & ~gpa_stolen_mask) >> PAGE_SHIFT;
 	memslot = gfn_to_memslot(vcpu->kvm, gfn);
+
+	if (kvm_slot_can_be_private(memslot)) {
+		ret = private_memslot_fault(vcpu, fault_ipa, memslot);
+		if (ret != -EAGAIN)
+			goto out;
+	}

Shouldn't this be s/fault_ipa/ipa ?

	ret = private_memslot_fault(vcpu, ipa, memslot);

-aneesh