diff --git a/services/std_svc/rmmd/aarch64/rmmd_helpers.S b/services/std_svc/rmmd/aarch64/rmmd_helpers.S
new file mode 100644
index 0000000..6229baf
--- /dev/null
+++ b/services/std_svc/rmmd/aarch64/rmmd_helpers.S
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "../rmmd_private.h"
+#include <asm_macros.S>
+
+	.global rmmd_rmm_enter
+	.global rmmd_rmm_exit
+
+	/* ---------------------------------------------------------------------
+	 * This function is called with SP_EL0 as stack. Here we stash our EL3
+	 * callee-saved registers on to the stack as a part of saving the C
+	 * runtime and enter the secure payload.
+	 * 'x0' contains a pointer to the memory where the address of the C
+	 *  runtime context is to be saved.
+	 * ---------------------------------------------------------------------
+	 */
+func rmmd_rmm_enter
+	/* Make space for the registers that we're going to save */
+	mov	x3, sp
+	str	x3, [x0, #0]
+	sub	sp, sp, #RMMD_C_RT_CTX_SIZE
+
+	/* Save callee-saved registers on to the stack */
+	stp	x19, x20, [sp, #RMMD_C_RT_CTX_X19]
+	stp	x21, x22, [sp, #RMMD_C_RT_CTX_X21]
+	stp	x23, x24, [sp, #RMMD_C_RT_CTX_X23]
+	stp	x25, x26, [sp, #RMMD_C_RT_CTX_X25]
+	stp	x27, x28, [sp, #RMMD_C_RT_CTX_X27]
+	stp	x29, x30, [sp, #RMMD_C_RT_CTX_X29]
+
+	/* ---------------------------------------------------------------------
+	 * Everything is setup now. el3_exit() will use the secure context to
+	 * restore to the general purpose and EL3 system registers to ERET
+	 * into the secure payload.
+	 * ---------------------------------------------------------------------
+	 */
+	b	el3_exit
+endfunc rmmd_rmm_enter
+
+	/* ---------------------------------------------------------------------
+	 * This function is called with 'x0' pointing to a C runtime context.
+	 * It restores the saved registers and jumps to that runtime with 'x0'
+	 * as the new SP register. This destroys the C runtime context that had
+	 * been built on the stack below the saved context by the caller. Later
+	 * the second parameter 'x1' is passed as a return value to the caller.
+	 * ---------------------------------------------------------------------
+	 */
+func rmmd_rmm_exit
+	/* Restore the previous stack */
+	mov	sp, x0
+
+	/* Restore callee-saved registers on to the stack */
+	ldp	x19, x20, [x0, #(RMMD_C_RT_CTX_X19 - RMMD_C_RT_CTX_SIZE)]
+	ldp	x21, x22, [x0, #(RMMD_C_RT_CTX_X21 - RMMD_C_RT_CTX_SIZE)]
+	ldp	x23, x24, [x0, #(RMMD_C_RT_CTX_X23 - RMMD_C_RT_CTX_SIZE)]
+	ldp	x25, x26, [x0, #(RMMD_C_RT_CTX_X25 - RMMD_C_RT_CTX_SIZE)]
+	ldp	x27, x28, [x0, #(RMMD_C_RT_CTX_X27 - RMMD_C_RT_CTX_SIZE)]
+	ldp	x29, x30, [x0, #(RMMD_C_RT_CTX_X29 - RMMD_C_RT_CTX_SIZE)]
+
+	/* ---------------------------------------------------------------------
+	 * This should take us back to the instruction after the call to the
+	 * last rmmd_rmm_enter().* Place the second parameter to x0
+	 * so that the caller will see it as a return value from the original
+	 * entry call.
+	 * ---------------------------------------------------------------------
+	 */
+	mov	x0, x1
+	ret
+endfunc rmmd_rmm_exit
diff --git a/services/std_svc/rmmd/rmmd.mk b/services/std_svc/rmmd/rmmd.mk
new file mode 100644
index 0000000..57031fe
--- /dev/null
+++ b/services/std_svc/rmmd/rmmd.mk
@@ -0,0 +1,13 @@
+#
+# Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+ifneq (${ARCH},aarch64)
+        $(error "Error: RMMD is only supported on aarch64.")
+endif
+
+RMMD_SOURCES	+=	$(addprefix services/std_svc/rmmd/,	\
+			${ARCH}/rmmd_helpers.S			\
+			rmmd_main.c)
diff --git a/services/std_svc/rmmd/rmmd_initial_context.h b/services/std_svc/rmmd/rmmd_initial_context.h
new file mode 100644
index 0000000..d7a743d
--- /dev/null
+++ b/services/std_svc/rmmd/rmmd_initial_context.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef RMMD_INITIAL_CONTEXT_H
+#define RMMD_INITIAL_CONTEXT_H
+
+#include <arch.h>
+
+/*
+ * SPSR_EL2
+ *   M=0x9 (0b1001 EL2h)
+ *   M[4]=0
+ *   DAIF=0xF Exceptions masked on entry.
+ *   BTYPE=0  BTI not yet supported.
+ *   SSBS=0   Not yet supported.
+ *   IL=0     Not an illegal exception return.
+ *   SS=0     Not single stepping.
+ *   PAN=1    RMM shouldn't access realm memory.
+ *   UAO=0
+ *   DIT=0
+ *   TCO=0
+ *   NZCV=0
+ */
+#define REALM_SPSR_EL2		(					\
+					SPSR_M_EL2H			| \
+					(0xF << SPSR_DAIF_SHIFT)	| \
+					SPSR_PAN_BIT			\
+				)
+
+#endif /* RMMD_INITIAL_CONTEXT_H */
diff --git a/services/std_svc/rmmd/rmmd_main.c b/services/std_svc/rmmd/rmmd_main.c
new file mode 100644
index 0000000..26a5b84
--- /dev/null
+++ b/services/std_svc/rmmd/rmmd_main.c
@@ -0,0 +1,341 @@
+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#include <arch_helpers.h>
+#include <arch_features.h>
+#include <bl31/bl31.h>
+#include <common/debug.h>
+#include <common/runtime_svc.h>
+#include <context.h>
+#include <lib/el3_runtime/context_mgmt.h>
+#include <lib/el3_runtime/pubsub.h>
+#include <lib/gpt/gpt_defs.h>
+
+#include <lib/spinlock.h>
+#include <lib/utils.h>
+#include <lib/xlat_tables/xlat_tables_v2.h>
+#include <plat/common/common_def.h>
+#include <plat/common/platform.h>
+#include <platform_def.h>
+#include <services/gtsi_svc.h>
+#include <services/rmi_svc.h>
+#include <services/rmmd_svc.h>
+#include <smccc_helpers.h>
+#include "rmmd_initial_context.h"
+#include "rmmd_private.h"
+
+/*******************************************************************************
+ * RMM context information.
+ ******************************************************************************/
+rmmd_rmm_context_t rmm_context[PLATFORM_CORE_COUNT];
+
+/*******************************************************************************
+ * RMM entry point information. Discovered on the primary core and reused
+ * on secondary cores.
+ ******************************************************************************/
+static entry_point_info_t *rmm_ep_info;
+
+/*******************************************************************************
+ * Static function declaration.
+ ******************************************************************************/
+static int32_t rmm_init(void);
+static uint64_t rmmd_smc_forward(uint32_t smc_fid, uint32_t src_sec_state,
+					uint32_t dst_sec_state, uint64_t x1,
+					uint64_t x2, uint64_t x3, uint64_t x4,
+					void *handle);
+
+/*******************************************************************************
+ * This function takes an RMM context pointer and performs a synchronous entry
+ * into it.
+ ******************************************************************************/
+uint64_t rmmd_rmm_sync_entry(rmmd_rmm_context_t *rmm_ctx)
+{
+	uint64_t rc;
+
+	assert(rmm_ctx != NULL);
+
+	cm_set_context(&(rmm_ctx->cpu_ctx), REALM);
+
+	/* Save the current el1/el2 context before loading realm context. */
+	cm_el1_sysregs_context_save(NON_SECURE);
+	cm_el2_sysregs_context_save(NON_SECURE);
+
+	/* Restore the realm context assigned above */
+	cm_el1_sysregs_context_restore(REALM);
+	cm_el2_sysregs_context_restore(REALM);
+	cm_set_next_eret_context(REALM);
+
+	/* Enter RMM */
+	rc = rmmd_rmm_enter(&rmm_ctx->c_rt_ctx);
+
+	/* Save realm context */
+	cm_el1_sysregs_context_save(REALM);
+	cm_el2_sysregs_context_save(REALM);
+
+	/* Restore the el1/el2 context again. */
+	cm_el1_sysregs_context_restore(NON_SECURE);
+	cm_el2_sysregs_context_restore(NON_SECURE);
+
+	return rc;
+}
+
+/*******************************************************************************
+ * This function returns to the place where rmmd_rmm_sync_entry() was
+ * called originally.
+ ******************************************************************************/
+__dead2 void rmmd_rmm_sync_exit(uint64_t rc)
+{
+	rmmd_rmm_context_t *ctx = &rmm_context[plat_my_core_pos()];
+
+	/* Get context of the RMM in use by this CPU. */
+	assert(cm_get_context(REALM) == &(ctx->cpu_ctx));
+
+	/*
+	 * The RMMD must have initiated the original request through a
+	 * synchronous entry into RMM. Jump back to the original C runtime
+	 * context with the value of rc in x0;
+	 */
+	rmmd_rmm_exit(ctx->c_rt_ctx, rc);
+
+	panic();
+}
+
+static void rmm_el2_context_init(el2_sysregs_t *regs)
+{
+	regs->ctx_regs[CTX_SPSR_EL2 >> 3] = REALM_SPSR_EL2;
+	regs->ctx_regs[CTX_SCTLR_EL2 >> 3] = SCTLR_EL2_RES1;
+}
+
+/*******************************************************************************
+ * Jump to the RMM for the first time.
+ ******************************************************************************/
+static int32_t rmm_init(void)
+{
+
+	uint64_t rc;
+
+	rmmd_rmm_context_t *ctx = &rmm_context[plat_my_core_pos()];
+
+	INFO("RMM init start.\n");
+	ctx->state = RMM_STATE_RESET;
+
+	/* Initialize RMM EL2 context. */
+	rmm_el2_context_init(&ctx->cpu_ctx.el2_sysregs_ctx);
+
+	rc = rmmd_rmm_sync_entry(ctx);
+	if (rc != 0ULL) {
+		ERROR("RMM initialisation failed 0x%llx\n", rc);
+		panic();
+	}
+
+	ctx->state = RMM_STATE_IDLE;
+	INFO("RMM init end.\n");
+
+	return 1;
+}
+
+/*******************************************************************************
+ * Load and read RMM manifest, setup RMM.
+ ******************************************************************************/
+int rmmd_setup(void)
+{
+	uint32_t ep_attr;
+	unsigned int linear_id = plat_my_core_pos();
+	rmmd_rmm_context_t *rmm_ctx = &rmm_context[linear_id];
+
+	/* Make sure RME is supported. */
+	assert(get_armv9_2_feat_rme_support() != 0U);
+
+	rmm_ep_info = bl31_plat_get_next_image_ep_info(REALM);
+	if (rmm_ep_info == NULL) {
+		WARN("No RMM image provided by BL2 boot loader, Booting "
+		     "device without RMM initialization. SMCs destined for "
+		     "RMM will return SMC_UNK\n");
+		return -ENOENT;
+	}
+
+	/* Under no circumstances will this parameter be 0 */
+	assert(rmm_ep_info->pc == RMM_BASE);
+
+	/* Initialise an entrypoint to set up the CPU context */
+	ep_attr = EP_REALM;
+	if ((read_sctlr_el3() & SCTLR_EE_BIT) != 0U) {
+		ep_attr |= EP_EE_BIG;
+	}
+
+	SET_PARAM_HEAD(rmm_ep_info, PARAM_EP, VERSION_1, ep_attr);
+	rmm_ep_info->spsr = SPSR_64(MODE_EL2,
+					MODE_SP_ELX,
+					DISABLE_ALL_EXCEPTIONS);
+
+	/* Initialise RMM context with this entry point information */
+	cm_setup_context(&rmm_ctx->cpu_ctx, rmm_ep_info);
+
+	INFO("RMM setup done.\n");
+
+	/* Register init function for deferred init.  */
+	bl31_register_rmm_init(&rmm_init);
+
+	return 0;
+}
+
+/*******************************************************************************
+ * Forward SMC to the other security state
+ ******************************************************************************/
+static uint64_t	rmmd_smc_forward(uint32_t smc_fid, uint32_t src_sec_state,
+					uint32_t dst_sec_state, uint64_t x1,
+					uint64_t x2, uint64_t x3, uint64_t x4,
+					void *handle)
+{
+	/* Save incoming security state */
+	cm_el1_sysregs_context_save(src_sec_state);
+	cm_el2_sysregs_context_save(src_sec_state);
+
+	/* Restore outgoing security state */
+	cm_el1_sysregs_context_restore(dst_sec_state);
+	cm_el2_sysregs_context_restore(dst_sec_state);
+	cm_set_next_eret_context(dst_sec_state);
+
+	SMC_RET8(cm_get_context(dst_sec_state), smc_fid, x1, x2, x3, x4,
+			SMC_GET_GP(handle, CTX_GPREG_X5),
+			SMC_GET_GP(handle, CTX_GPREG_X6),
+			SMC_GET_GP(handle, CTX_GPREG_X7));
+}
+
+/*******************************************************************************
+ * This function handles all SMCs in the range reserved for RMI. Each call is
+ * either forwarded to the other security state or handled by the RMM dispatcher
+ ******************************************************************************/
+uint64_t rmmd_rmi_handler(uint32_t smc_fid, uint64_t x1, uint64_t x2,
+				uint64_t x3, uint64_t x4, void *cookie,
+				void *handle, uint64_t flags)
+{
+	rmmd_rmm_context_t *ctx = &rmm_context[plat_my_core_pos()];
+	uint32_t src_sec_state;
+
+	/* Determine which security state this SMC originated from */
+	src_sec_state = caller_sec_state(flags);
+
+	/* RMI must not be invoked by the Secure world */
+	if (src_sec_state == SMC_FROM_SECURE) {
+		WARN("RMM: RMI invoked by secure world.\n");
+		SMC_RET1(handle, SMC_UNK);
+	}
+
+	/*
+	 * Forward an RMI call from the Normal world to the Realm world as it
+	 * is.
+	 */
+	if (src_sec_state == SMC_FROM_NON_SECURE) {
+		VERBOSE("RMM: RMI call from non-secure world.\n");
+		return rmmd_smc_forward(smc_fid, NON_SECURE, REALM,
+					x1, x2, x3, x4, handle);
+	}
+
+	assert(src_sec_state == SMC_FROM_REALM);
+
+	switch (smc_fid) {
+	case RMI_RMM_REQ_COMPLETE:
+		if (ctx->state == RMM_STATE_RESET) {
+			VERBOSE("RMM: running rmmd_rmm_sync_exit\n");
+			rmmd_rmm_sync_exit(x1);
+		}
+
+		return rmmd_smc_forward(x1, REALM, NON_SECURE,
+					x2, x3, x4, 0, handle);
+
+	default:
+		WARN("RMM: Unsupported RMM call 0x%08x\n", smc_fid);
+		SMC_RET1(handle, SMC_UNK);
+	}
+}
+
+/*******************************************************************************
+ * This cpu has been turned on. Enter RMM to initialise R-EL2.  Entry into RMM
+ * is done after initialising minimal architectural state that guarantees safe
+ * execution.
+ ******************************************************************************/
+static void *rmmd_cpu_on_finish_handler(const void *arg)
+{
+	int32_t rc;
+	uint32_t linear_id = plat_my_core_pos();
+	rmmd_rmm_context_t *ctx = &rmm_context[linear_id];
+
+	ctx->state = RMM_STATE_RESET;
+
+	/* Initialise RMM context with this entry point information */
+	cm_setup_context(&ctx->cpu_ctx, rmm_ep_info);
+
+	/* Initialize RMM EL2 context. */
+	rmm_el2_context_init(&ctx->cpu_ctx.el2_sysregs_ctx);
+
+	rc = rmmd_rmm_sync_entry(ctx);
+	if (rc != 0) {
+		ERROR("RMM initialisation failed (%d) on CPU%d\n", rc,
+		      linear_id);
+		panic();
+	}
+
+	ctx->state = RMM_STATE_IDLE;
+	return NULL;
+}
+
+/* Subscribe to PSCI CPU on to initialize RMM on secondary */
+SUBSCRIBE_TO_EVENT(psci_cpu_on_finish, rmmd_cpu_on_finish_handler);
+
+static int gtsi_transition_granule(uint64_t pa,
+					unsigned int src_sec_state,
+					unsigned int target_pas)
+{
+	int ret;
+
+	ret = gpt_transition_pas(pa, src_sec_state, target_pas);
+
+	/* Convert TF-A error codes into GTSI error codes */
+	if (ret == -EINVAL) {
+		ret = GRAN_TRANS_RET_BAD_ADDR;
+	} else if (ret == -EPERM) {
+		ret = GRAN_TRANS_RET_BAD_PAS;
+	}
+
+	return ret;
+}
+
+/*******************************************************************************
+ * This function handles all SMCs in the range reserved for GTF.
+ ******************************************************************************/
+uint64_t rmmd_gtsi_handler(uint32_t smc_fid, uint64_t x1, uint64_t x2,
+				uint64_t x3, uint64_t x4, void *cookie,
+				void *handle, uint64_t flags)
+{
+	uint32_t src_sec_state;
+
+	/* Determine which security state this SMC originated from */
+	src_sec_state = caller_sec_state(flags);
+
+	if (src_sec_state != SMC_FROM_REALM) {
+		WARN("RMM: GTF call originated from secure or normal world\n");
+		SMC_RET1(handle, SMC_UNK);
+	}
+
+	switch (smc_fid) {
+	case SMC_ASC_MARK_REALM:
+		SMC_RET1(handle, gtsi_transition_granule(x1, SMC_FROM_REALM,
+								GPI_REALM));
+		break;
+	case SMC_ASC_MARK_NONSECURE:
+		SMC_RET1(handle, gtsi_transition_granule(x1, SMC_FROM_REALM,
+								GPI_NS));
+		break;
+	default:
+		WARN("RMM: Unsupported GTF call 0x%08x\n", smc_fid);
+		SMC_RET1(handle, SMC_UNK);
+	}
+}
diff --git a/services/std_svc/rmmd/rmmd_private.h b/services/std_svc/rmmd/rmmd_private.h
new file mode 100644
index 0000000..d170bcd
--- /dev/null
+++ b/services/std_svc/rmmd/rmmd_private.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef RMMD_PRIVATE_H
+#define RMMD_PRIVATE_H
+
+#include <context.h>
+
+/*******************************************************************************
+ * Constants that allow assembler code to preserve callee-saved registers of the
+ * C runtime context while performing a security state switch.
+ ******************************************************************************/
+#define RMMD_C_RT_CTX_X19		0x0
+#define RMMD_C_RT_CTX_X20		0x8
+#define RMMD_C_RT_CTX_X21		0x10
+#define RMMD_C_RT_CTX_X22		0x18
+#define RMMD_C_RT_CTX_X23		0x20
+#define RMMD_C_RT_CTX_X24		0x28
+#define RMMD_C_RT_CTX_X25		0x30
+#define RMMD_C_RT_CTX_X26		0x38
+#define RMMD_C_RT_CTX_X27		0x40
+#define RMMD_C_RT_CTX_X28		0x48
+#define RMMD_C_RT_CTX_X29		0x50
+#define RMMD_C_RT_CTX_X30		0x58
+
+#define RMMD_C_RT_CTX_SIZE		0x60
+#define RMMD_C_RT_CTX_ENTRIES		(RMMD_C_RT_CTX_SIZE >> DWORD_SHIFT)
+
+#ifndef __ASSEMBLER__
+#include <stdint.h>
+#include <services/rmi_svc.h>
+
+typedef enum rmm_state {
+	RMM_STATE_RESET = 0,
+	RMM_STATE_IDLE
+} rmm_state_t;
+
+/*
+ * Data structure used by the RMM dispatcher (RMMD) in EL3 to track context of
+ * the RMM at R-EL2.
+ */
+typedef struct rmmd_rmm_context {
+	uint64_t c_rt_ctx;
+	cpu_context_t cpu_ctx;
+	rmm_state_t state;
+} rmmd_rmm_context_t;
+
+/* Functions used to enter/exit the RMM synchronously */
+uint64_t rmmd_rmm_sync_entry(rmmd_rmm_context_t *ctx);
+__dead2 void rmmd_rmm_sync_exit(uint64_t rc);
+
+/* Assembly helpers */
+uint64_t rmmd_rmm_enter(uint64_t *c_rt_ctx);
+void __dead2 rmmd_rmm_exit(uint64_t c_rt_ctx, uint64_t ret);
+
+/* Reference to PM ops for the RMMD */
+extern const spd_pm_ops_t rmmd_pm;
+
+#endif /* __ASSEMBLER__ */
+
+#endif /* RMMD_PRIVATE_H */
diff --git a/services/std_svc/std_svc_setup.c b/services/std_svc/std_svc_setup.c
index 1917d0a..39db429 100644
--- a/services/std_svc/std_svc_setup.c
+++ b/services/std_svc/std_svc_setup.c
@@ -13,7 +13,9 @@
 #include <lib/pmf/pmf.h>
 #include <lib/psci/psci.h>
 #include <lib/runtime_instr.h>
+#include <services/gtsi_svc.h>
 #include <services/pci_svc.h>
+#include <services/rmmd_svc.h>
 #include <services/sdei.h>
 #include <services/spm_mm_svc.h>
 #include <services/spmd_svc.h>
@@ -158,6 +160,16 @@
 				flags);
 	}
 #endif
+#if ENABLE_RME
+	/*
+	 * Granule transition service interface functions (GTSI) are allocated
+	 * from the Std service range. Call the RMM dispatcher to handle calls.
+	 */
+	if (is_gtsi_fid(smc_fid)) {
+		return rmmd_gtsi_handler(smc_fid, x1, x2, x3, x4, cookie,
+						handle, flags);
+	}
+#endif
 
 #if SMC_PCI_SUPPORT
 	if (is_pci_fid(smc_fid)) {