diff --git a/realm/aarch64/realm_entrypoint.S b/realm/aarch64/realm_entrypoint.S
index 1aff61e..7e535bb 100644
--- a/realm/aarch64/realm_entrypoint.S
+++ b/realm/aarch64/realm_entrypoint.S
@@ -19,8 +19,21 @@
 	/* Save x0 - context_id */
 	mov	x20, x0
 	mrs	x0, mpidr_el1
-	mov_imm	x1, MPID_MASK
-	and	x0, x0, x1
+
+	/*
+	 * Convert MPIDR_EL1 register type value
+	 * Aff3[39:32].Aff2[23:16].Aff1[15:8].RES0[7:4].Aff0[3:0]
+	 * to REC linear index
+	 * Aff3[27:20].Aff2[19:12].Aff1[11:4].Aff0[3:0].
+	 */
+	and	x1, x0, #(MPIDR_AFFLVL_MASK << MPIDR_AFF3_SHIFT)	/* 0xff00000000 */
+	and	x0, x0, #((MPIDR_AFFLVL_MASK << MPIDR_AFF0_SHIFT) | \
+			  (MPIDR_AFFLVL_MASK << MPIDR_AFF1_SHIFT) | \
+			  (MPIDR_AFFLVL_MASK << MPIDR_AFF2_SHIFT))	/* 0xffffff */
+	orr	x1, x0, x1, lsr #(MPIDR_AFF3_SHIFT - MPIDR_AFF2_SHIFT - \
+				  MPIDR_AFF1_SHIFT - MPIDR_AFF0_SHIFT)	/* 8 */
+	and	x0, x0, #MPIDR_AFFLVL_MASK				/* 0xff */
+	orr	x0, x0, x1, lsr #(MPIDR_AFF1_SHIFT - RMI_MPIDR_AFF0_WIDTH)	/* 4 */
 
 	/* Setup the stack pointer */
 	bl	realm_setup_my_stack
diff --git a/realm/realm_rsi.c b/realm/realm_rsi.c
index 04f57fc..cd4342f 100644
--- a/realm/realm_rsi.c
+++ b/realm/realm_rsi.c
@@ -1,6 +1,6 @@
 
 /*
- * Copyright (c) 2022, Arm Limited. All rights reserved.
+ * Copyright (c) 2022-2024, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -47,7 +47,7 @@
 	struct rsi_host_call host_cal __aligned(sizeof(struct rsi_host_call));
 
 	host_cal.imm = exit_code;
-	host_cal.gprs[0] = read_mpidr_el1() & MPID_MASK;
+	host_cal.gprs[0] = read_mpidr_el1();
 	tftf_smc(&(smc_args) {RSI_HOST_CALL, (u_register_t)&host_cal,
 		0UL, 0UL, 0UL, 0UL, 0UL, 0UL});
 }
diff --git a/realm/realm_shared_data.c b/realm/realm_shared_data.c
index 2d09f78..2825796 100644
--- a/realm/realm_shared_data.c
+++ b/realm/realm_shared_data.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Arm Limited. All rights reserved.
+ * Copyright (c) 2022-2024, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -8,6 +8,7 @@
 #include <arch_helpers.h>
 #include <assert.h>
 #include <host_shared_data.h>
+#include <realm_def.h>
 
 /**
  *   @brief    - Returns the base address of the shared region
@@ -30,7 +31,7 @@
  */
 host_shared_data_t *realm_get_my_shared_structure(void)
 {
-	return &guest_shared_data[read_mpidr_el1() & MPID_MASK];
+	return &guest_shared_data[REC_IDX(read_mpidr_el1())];
 }
 
 /*
@@ -39,7 +40,7 @@
 u_register_t realm_shared_data_get_my_host_val(uint8_t index)
 {
 	assert(index < MAX_DATA_SIZE);
-	return guest_shared_data[read_mpidr_el1() & MPID_MASK].host_param_val[index];
+	return guest_shared_data[REC_IDX(read_mpidr_el1())].host_param_val[index];
 }
 
 /*
@@ -47,7 +48,7 @@
  */
 uint8_t realm_shared_data_get_my_realm_cmd(void)
 {
-	return guest_shared_data[read_mpidr_el1() & MPID_MASK].realm_cmd;
+	return guest_shared_data[REC_IDX(read_mpidr_el1())].realm_cmd;
 }
 
 /*
@@ -56,6 +57,6 @@
 void realm_shared_data_set_my_realm_val(uint8_t index, u_register_t val)
 {
 	assert(index < MAX_DATA_SIZE);
-	guest_shared_data[read_mpidr_el1() & MPID_MASK].realm_out_val[index] = val;
+	guest_shared_data[REC_IDX(read_mpidr_el1())].realm_out_val[index] = val;
 }