diff --git a/services/std_svc/sdei/sdei_event.c b/services/std_svc/sdei/sdei_event.c
index e0c7971..cc8f557 100644
--- a/services/std_svc/sdei/sdei_event.c
+++ b/services/std_svc/sdei/sdei_event.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2022, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -19,14 +19,14 @@
  * Both shared and private maps are stored in single-dimensional array. Private
  * event entries are kept for each PE forming a 2D array.
  */
-sdei_entry_t *get_event_entry(sdei_ev_map_t *map)
+sdei_entry_t *get_event_entry(const sdei_ev_map_t *map)
 {
 	const sdei_mapping_t *mapping;
 	sdei_entry_t *cpu_priv_base;
 	unsigned int base_idx;
 	long int idx;
 
-	if (is_event_private(map)) {
+	if ((map->map_flags & BIT_32(SDEI_MAPF_PRIVATE_SHIFT_)) != 0U) {
 		/*
 		 * For a private map, find the index of the mapping in the
 		 * array.
@@ -52,6 +52,39 @@
 }
 
 /*
+ * Retrieve the SDEI entry for the given mapping and target PE.
+ *
+ * on success : Returns a pointer to the SDEI entry
+ *
+ * On error, returns NULL
+ *
+ * Both shared and private maps are stored in single-dimensional array. Private
+ * event entries are kept for each PE forming a 2D array.
+ */
+sdei_entry_t *get_event_entry_target_pe(long int mapsub, unsigned int nm, uint64_t target_pe)
+{
+	sdei_entry_t *cpu_priv_base;
+	unsigned int base_idx;
+	long int idx;
+
+	/*
+	 * For a private map, find the index of the mapping in the
+	 * array.
+	 */
+	idx = mapsub;
+
+	/* Base of private mappings for this CPU */
+	base_idx = (unsigned int) plat_core_pos_by_mpidr(target_pe);
+	base_idx *= nm;
+	cpu_priv_base = &sdei_private_event_table[base_idx];
+	/*
+	 * Return the address of the entry at the same index in the
+	 * per-CPU event entry.
+	 */
+	return &cpu_priv_base[idx];
+}
+
+/*
  * Find event mapping for a given interrupt number: On success, returns pointer
  * to the event mapping. On error, returns NULL.
  */
diff --git a/services/std_svc/sdei/sdei_intr_mgmt.c b/services/std_svc/sdei/sdei_intr_mgmt.c
index c58adba..4854b2e 100644
--- a/services/std_svc/sdei/sdei_intr_mgmt.c
+++ b/services/std_svc/sdei/sdei_intr_mgmt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,7 +29,8 @@
 #define MAX_EVENT_NESTING	2U
 
 /* Per-CPU SDEI state access macro */
-#define sdei_get_this_pe_state()	(&cpu_state[plat_my_core_pos()])
+#define sdei_get_this_pe_state()		(&cpu_state[plat_my_core_pos()])
+#define sdei_get_target_pe_state(_pe)	(&cpu_state[plat_core_pos_by_mpidr(_pe)])
 
 /* Structure to store information about an outstanding dispatch */
 typedef struct sdei_dispatch_context {
@@ -58,6 +59,13 @@
 /* SDEI states for all cores in the system */
 static sdei_cpu_state_t cpu_state[PLATFORM_CORE_COUNT];
 
+bool sdei_is_target_pe_masked(uint64_t target_pe)
+{
+	const sdei_cpu_state_t *state = sdei_get_target_pe_state(target_pe);
+
+	return state->pe_masked;
+}
+
 int64_t sdei_pe_mask(void)
 {
 	int64_t ret = 0;
diff --git a/services/std_svc/sdei/sdei_main.c b/services/std_svc/sdei/sdei_main.c
index 01cc131..bbc9f73 100644
--- a/services/std_svc/sdei/sdei_main.c
+++ b/services/std_svc/sdei/sdei_main.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2025, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -910,25 +910,54 @@
 /* Send a signal to another SDEI client PE */
 static int sdei_signal(int ev_num, uint64_t target_pe)
 {
+	unsigned int i;
 	sdei_ev_map_t *map;
+	sdei_ev_map_t *map_priv;
+	sdei_entry_t *se;
 
 	/* Only event 0 can be signalled */
-	if (ev_num != SDEI_EVENT_0)
+	if (ev_num != SDEI_EVENT_0) {
 		return SDEI_EINVAL;
+	}
 
 	/* Find mapping for event 0 */
 	map = find_event_map(SDEI_EVENT_0);
-	if (map == NULL)
+	if (map == NULL) {
 		return SDEI_EINVAL;
+	}
 
 	/* The event must be signalable */
-	if (!is_event_signalable(map))
+	if (!is_event_signalable(map)) {
 		return SDEI_EINVAL;
+	}
 
 	/* Validate target */
-	if (!is_valid_mpidr(target_pe))
+	if (!is_valid_mpidr(target_pe)) {
 		return SDEI_EINVAL;
+	}
 
+	/* The event must be unmasked */
+	if (sdei_is_target_pe_masked(target_pe)) {
+		return SDEI_EINVAL;
+	}
+
+	/* The event must be registered and enabled */
+	if (is_event_private(map)) {
+		map_priv = SDEI_PRIVATE_MAPPING()->map;
+		for (i = 0; i < SDEI_PRIVATE_MAPPING()->num_maps; i++) {
+			if (map_priv->ev_num == SDEI_EVENT_0) {
+				se = get_event_entry_target_pe((long int) i,
+				(unsigned int) SDEI_PRIVATE_MAPPING()->num_maps, target_pe);
+				if (!(GET_EV_STATE((se), REGISTERED))) {
+					return SDEI_EINVAL;
+				}
+				if (!(GET_EV_STATE((se), ENABLED))) {
+					return SDEI_EINVAL;
+				}
+			}
+			map_priv++;
+		}
+	}
 	/* Raise SGI. Platform will validate target_pe */
 	plat_ic_raise_el3_sgi((int) map->intr, (u_register_t) target_pe);
 
diff --git a/services/std_svc/sdei/sdei_private.h b/services/std_svc/sdei/sdei_private.h
index 44a7301..d48db46 100644
--- a/services/std_svc/sdei/sdei_private.h
+++ b/services/std_svc/sdei/sdei_private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2025, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -232,13 +232,15 @@
 
 sdei_ev_map_t *find_event_map_by_intr(unsigned int intr_num, bool shared);
 sdei_ev_map_t *find_event_map(int ev_num);
-sdei_entry_t *get_event_entry(sdei_ev_map_t *map);
+sdei_entry_t *get_event_entry(const sdei_ev_map_t *map);
+sdei_entry_t *get_event_entry_target_pe(long int mapsub, unsigned int nm, uint64_t target_pe);
 
 int64_t sdei_event_context(void *handle, unsigned int param);
 int sdei_event_complete(bool resume, uint64_t pc);
 
-void sdei_pe_unmask(void);
+bool sdei_is_target_pe_masked(uint64_t target_pe);
 int64_t sdei_pe_mask(void);
+void sdei_pe_unmask(void);
 
 int sdei_intr_handler(uint32_t intr_raw, uint32_t flags, void *handle,
 		void *cookie);