[PATCH v12 34/46] arm64: RMI: Prevent Device mappings for Realms

[Steven Price]

Physical device assignment is not supported by RMM v1.0, so it
doesn't make much sense to allow device mappings within the realm.
Prevent them when the guest is a realm.

Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
Changes from v6:
 * Fix the check in user_mem_abort() to prevent all pages that are not
   guest_memfd() from being mapped into the protected half of the IPA.
Changes from v5:
 * Also prevent accesses in user_mem_abort()
---
 arch/arm64/kvm/mmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index c30d7be27361..e71ef41fb6b1 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1221,6 +1221,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 	if (is_protected_kvm_enabled())
 		return -EPERM;
 
+	/* We don't support mapping special pages into a Realm */
+	if (kvm_is_realm(kvm))
+		return -EPERM;
+
 	size += offset_in_page(guest_ipa);
 	guest_ipa &= PAGE_MASK;
 
@@ -1955,6 +1959,15 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		return ret;
 	}
 
+	/*
+	 * For now we shouldn't be hitting protected addresses because they are
+	 * handled in private_memslot_fault(). In the future this check may be
+	 * relaxed to support e.g. protected devices.
+	 */
+	if (vcpu_is_rec(vcpu) &&
+	    kvm_gpa_from_fault(kvm, fault_ipa) == fault_ipa)
+		return -EINVAL;
+
 	if (nested)
 		adjust_nested_fault_perms(nested, &prot, &writable);
 
-- 
2.43.0