Flush the affinity data in psci_affinity_info

There is an edge case where the cache maintaince done in
psci_do_cpu_off may not seen by some cores. This case is handled in
psci_cpu_on_start but it hasn't handled in psci_affinity_info.

Change-Id: I4d64f3d1ca9528e364aea8d04e2d254f201e1702
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

lib/psci/psci_main.c

@@ -220,6 +220,23 @@ int psci_affinity_info(u_register_t target_affinity,
 	if (target_idx == -1)
 		return PSCI_E_INVALID_PARAMS;
 
+	/*
+	 * Generic management:
+	 * Perform cache maintanence ahead of reading the target CPU state to
+	 * ensure that the data is not stale.
+	 * There is a theoretical edge case where the cache may contain stale
+	 * data for the target CPU data - this can occur under the following
+	 * conditions:
+	 * - the target CPU is in another cluster from the current
+	 * - the target CPU was the last CPU to shutdown on its cluster
+	 * - the cluster was removed from coherency as part of the CPU shutdown
+	 *
+	 * In this case the cache maintenace that was performed as part of the
+	 * target CPUs shutdown was not seen by the current CPU's cluster. And
+	 * so the cache may contain stale data for the target CPU.
+	 */
+	flush_cpu_data_by_index(target_idx, psci_svc_cpu_data.aff_info_state);
+
 	return psci_get_aff_info_state_by_idx(target_idx);
 }