SDEI: Unconditionally resume Secure if it was interrupted

Secure world execution nearly always expect a controlled exit to
Non-secure world. SDEI interrupts, although targets EL3, occur on behalf
of Non-secure world, and may have higher priority than Secure world
interrupts. Therefore they might preempt Secure execution, and yield
execution to Non-secure SDEI handler. Upon completion of SDEI event
handling (regardless of whether it's COPLETE or COMPLETE_AND_RESUME), we
must resume Secure execution if it was preempted.

Change-Id: I6edd991032588588427ba2fe6c3d7668f7080e3d
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

services/std_svc/sdei/sdei_intr_mgmt.c

@@ -485,15 +485,14 @@ int sdei_intr_handler(uint32_t intr_raw, uint32_t flags, void *handle,
 	/*
 	 * We reach here when client completes the event.
 	 *
-	 * If the cause of dispatch originally interrupted the Secure world, and
-	 * if Non-secure world wasn't allowed to preempt Secure execution,
+	 * If the cause of dispatch originally interrupted the Secure world,
 	 * resume Secure.
 	 *
 	 * No need to save the Non-secure context ahead of a world switch: the
 	 * Non-secure context was fully saved before dispatch, and has been
 	 * returned to its pre-dispatch state.
 	 */
-	if ((sec_state == SECURE) && (ehf_is_ns_preemption_allowed() == 0U))
+	if (sec_state == SECURE)
 		restore_and_resume_secure_context();
 
 	/*