KVM: arm64: Handle data and instruction external aborts the same way

If the guest generates a synchronous external abort which is not handled
by the host, we inject it back into the guest as a virtual SError, but
only if the original fault was reported on the data side. Instruction
faults are reported as "Unsupported FSC", causing the vCPU run loop to
bail with -EFAULT.

Although synchronous external aborts from a guest are pretty unusual,
treat them the same regardless of whether they are taken as data or
instruction aborts by EL2.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20200729102821.23392-3-will@kernel.org

arch/arm64/kvm/mmu.c

@@ -2079,13 +2079,10 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		 * For RAS the host kernel may handle this abort.
 		 * There is no need to pass the error into the guest.
 		 */
-		if (!kvm_handle_guest_sea(fault_ipa, kvm_vcpu_get_esr(vcpu)))
-			return 1;
-
-		if (unlikely(!is_iabt)) {
+		if (kvm_handle_guest_sea(fault_ipa, kvm_vcpu_get_esr(vcpu)))
 			kvm_inject_vabt(vcpu);
-			return 1;
-		}
+
+		return 1;
 	}
 
 	trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),