diff --git a/inc/hf/api.h b/inc/hf/api.h
index a808e5d..e041c96 100644
--- a/inc/hf/api.h
+++ b/inc/hf/api.h
@@ -55,8 +55,7 @@
 
 spci_return_t api_spci_msg_send(uint32_t attributes, struct vcpu *current,
 				struct vcpu **next);
-int32_t api_spci_msg_recv(uint32_t attributes, struct vcpu *current,
-			  struct vcpu **next);
+int32_t api_spci_msg_recv(bool block, struct vcpu *current, struct vcpu **next);
 int32_t api_spci_yield(struct vcpu *current, struct vcpu **next);
 int32_t api_spci_version(void);
 spci_return_t api_spci_share_memory(struct vm_locked to_locked,
diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index 67c8e35..9edc542 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -125,17 +125,16 @@
 }
 
 /**
- * Called by secondary VMs to receive a message. The call can optionally block
- * until a message is received.
+ * Called by secondary VMs to receive a message. This will block until a message
+ * is received.
  *
  * The mailbox must be cleared before a new message can be received.
  *
- * If no message is immediately available, `block` is true, and there are no
- * enabled and pending interrupts (irrespective of whether interrupts are
- * enabled globally), then this will block until a message is available or an
- * enabled interrupt becomes pending. This matches the behaviour of the WFI
- * instruction on aarch64, except that a message becoming available is also
- * treated like a wake-up event.
+ * If no message is immediately available and there are no enabled and pending
+ * interrupts (irrespective of whether interrupts are enabled globally), then
+ * this will block until a message is available or an enabled interrupt becomes
+ * pending. This matches the behaviour of the WFI instruction on aarch64, except
+ * that a message becoming available is also treated like a wake-up event.
  *
  * Returns:
  *  - SPCI_SUCCESS if a message is successfully received.
@@ -143,9 +142,26 @@
  *    during the call.
  *  - SPCI_RETRY if there was no pending message, and `block` was false.
  */
-static inline int32_t spci_msg_recv(int32_t attributes)
+static inline int32_t spci_msg_wait(void)
 {
-	return hf_call(SPCI_MSG_RECV_32, attributes, 0, 0);
+	return hf_call(SPCI_MSG_WAIT_32, 0, 0, 0);
+}
+
+/**
+ * Called by secondary VMs to receive a message. The call will return whether or
+ * not a message is available.
+ *
+ * The mailbox must be cleared before a new message can be received.
+ *
+ * Returns:
+ *  - SPCI_SUCCESS if a message is successfully received.
+ *  - SPCI_INTERRUPTED if the caller is the primary VM or an interrupt happened
+ *    during the call.
+ *  - SPCI_RETRY if there was no pending message, and `block` was false.
+ */
+static inline int32_t spci_msg_poll(void)
+{
+	return hf_call(SPCI_MSG_POLL_32, 0, 0, 0);
 }
 
 /**
diff --git a/inc/vmapi/hf/spci.h b/inc/vmapi/hf/spci.h
index 98d4155..39fcaf1 100644
--- a/inc/vmapi/hf/spci.h
+++ b/inc/vmapi/hf/spci.h
@@ -26,24 +26,31 @@
 #define SPCI_HIGH_32_ID 0x8400007F
 
 /* SPCI function identifiers. */
-#define SPCI_VERSION_32               0x84000060
-#define SPCI_MSG_BUF_LIST_EXCHANGE_32 0x84000061
-#define SPCI_MSG_RECV_32              0x84000062
-#define SPCI_MSG_PUT_32               0x84000063
-#define SPCI_MSG_SEND_32              0x84000064
-#define SPCI_MSG_SEND_REC_32          0x84000065
-#define SPCI_RUN_32                   0x84000066
-#define SPCI_YIELD_32                 0x84000067
+#define SPCI_ERROR_32                 0x84000060
+#define SPCI_SUCCESS_32               0x84000061
+#define SPCI_INTERRUPT_32             0x84000062
+#define SPCI_VERSION_32               0x84000063
+#define SPCI_RX_RELEASE_32            0x84000064
+#define SPCI_RXTX_MAP_32              0x84000065
+#define SPCI_RXTX_UNMAP_32            0x84000066
+#define SPCI_PARTITION_INFO_GET_32    0x84000067
+#define SPCI_ID_GET_32                0x84000068
+#define SPCI_MSG_WAIT_32              0x84000069
+#define SPCI_MSG_POLL_32              0x8400006A
+#define SPCI_YIELD_32                 0x8400006B
+#define SPCI_MSG_SEND_32              0x8400006C
+#define SPCI_RUN_32                   0x8400006D
+#define SPCI_MSG_SEND_DIRECT_REQ_32   0x8400006E
+#define SPCI_MSG_SEND_DIRECT_RESP_32  0x8400006F
 
-/* SPCI return codes. */
 #define SPCI_SUCCESS            INT32_C(0)
+/* SPCI error codes. */
 #define SPCI_NOT_SUPPORTED      INT32_C(-1)
 #define SPCI_INVALID_PARAMETERS INT32_C(-2)
 #define SPCI_NO_MEMORY          INT32_C(-3)
 #define SPCI_BUSY               INT32_C(-4)
 #define SPCI_INTERRUPTED        INT32_C(-5)
 #define SPCI_DENIED             INT32_C(-6)
-/* TODO: return code currently undefined in SPCI alpha2. */
 #define SPCI_RETRY              INT32_C(-7)
 
 /* Architected memory sharing message IDs. */
diff --git a/src/api.c b/src/api.c
index f4ec664..ff56751 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1040,13 +1040,10 @@
  *
  * No new messages can be received until the mailbox has been cleared.
  */
-int32_t api_spci_msg_recv(uint32_t attributes, struct vcpu *current,
-			  struct vcpu **next)
+int32_t api_spci_msg_recv(bool block, struct vcpu *current, struct vcpu **next)
 {
 	struct vm *vm = current->vm;
 	int32_t return_code;
-	bool block =
-		(attributes & SPCI_MSG_RECV_BLOCK_MASK) == SPCI_MSG_RECV_BLOCK;
 
 	/*
 	 * The primary VM will receive messages as a status code from running
diff --git a/src/arch/aarch64/hypervisor/handler.c b/src/arch/aarch64/hypervisor/handler.c
index d896c80..a695938 100644
--- a/src/arch/aarch64/hypervisor/handler.c
+++ b/src/arch/aarch64/hypervisor/handler.c
@@ -303,8 +303,11 @@
 	case SPCI_MSG_SEND_32:
 		*ret = api_spci_msg_send(arg1, current(), next);
 		return true;
-	case SPCI_MSG_RECV_32:
-		*ret = api_spci_msg_recv(arg1, current(), next);
+	case SPCI_MSG_WAIT_32:
+		*ret = api_spci_msg_recv(true, current(), next);
+		return true;
+	case SPCI_MSG_POLL_32:
+		*ret = api_spci_msg_recv(false, current(), next);
 		return true;
 	}
 
diff --git a/test/hftest/service.c b/test/hftest/service.c
index 72efa7d..3031772 100644
--- a/test/hftest/service.c
+++ b/test/hftest/service.c
@@ -102,7 +102,7 @@
 	hf_vm_configure(send_addr, recv_addr);
 
 	/* Receive the name of the service to run. */
-	spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+	spci_msg_wait();
 	memiter_init(&args, recv_msg->payload, recv_msg->length);
 	service = find_service(&args);
 	hf_mailbox_clear();
diff --git a/test/linux/hftest_socket.c b/test/linux/hftest_socket.c
index 0b69ea7..7a9d7f1 100644
--- a/test/linux/hftest_socket.c
+++ b/test/linux/hftest_socket.c
@@ -83,7 +83,7 @@
 		struct spci_message *recv_buf = (struct spci_message *)recv;
 
 		/* Receive the packet. */
-		spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		spci_msg_wait();
 		EXPECT_LE(recv_buf->length, SPCI_MSG_PAYLOAD_MAX);
 
 		/* Echo the message back to the sender. */
diff --git a/test/vmapi/gicv3/services/common.c b/test/vmapi/gicv3/services/common.c
index b6edc56..d5d3cd2 100644
--- a/test/vmapi/gicv3/services/common.c
+++ b/test/vmapi/gicv3/services/common.c
@@ -28,7 +28,7 @@
 	int32_t received;
 
 	do {
-		received = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		received = spci_msg_wait();
 	} while (received == SPCI_INTERRUPTED);
 
 	return received;
diff --git a/test/vmapi/gicv3/services/timer.c b/test/vmapi/gicv3/services/timer.c
index 0cc7341..d99aa78 100644
--- a/test/vmapi/gicv3/services/timer.c
+++ b/test/vmapi/gicv3/services/timer.c
@@ -113,7 +113,7 @@
 				event_wait();
 			}
 		} else if (receive) {
-			int32_t res = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+			int32_t res = spci_msg_wait();
 
 			EXPECT_EQ(res, SPCI_INTERRUPTED);
 		} else {
diff --git a/test/vmapi/primary_with_secondaries/no_services.c b/test/vmapi/primary_with_secondaries/no_services.c
index 975ea6d..2f2c0b5 100644
--- a/test/vmapi/primary_with_secondaries/no_services.c
+++ b/test/vmapi/primary_with_secondaries/no_services.c
@@ -146,7 +146,7 @@
  */
 TEST(hf_mailbox_receive, cannot_receive_from_primary_blocking)
 {
-	int32_t res = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+	int32_t res = spci_msg_wait();
 	EXPECT_NE(res, SPCI_SUCCESS);
 }
 
@@ -155,6 +155,6 @@
  */
 TEST(hf_mailbox_receive, cannot_receive_from_primary_non_blocking)
 {
-	int32_t res = spci_msg_recv(0);
+	int32_t res = spci_msg_poll();
 	EXPECT_NE(res, SPCI_SUCCESS);
 }
diff --git a/test/vmapi/primary_with_secondaries/services/echo.c b/test/vmapi/primary_with_secondaries/services/echo.c
index 04cb6a3..a9d5b02 100644
--- a/test/vmapi/primary_with_secondaries/services/echo.c
+++ b/test/vmapi/primary_with_secondaries/services/echo.c
@@ -25,7 +25,7 @@
 {
 	/* Loop, echo messages back to the sender. */
 	for (;;) {
-		spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		spci_msg_wait();
 		struct spci_message *send_buf = SERVICE_SEND_BUFFER();
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
 
diff --git a/test/vmapi/primary_with_secondaries/services/echo_with_notification.c b/test/vmapi/primary_with_secondaries/services/echo_with_notification.c
index 03dcfd4..b32a6f6 100644
--- a/test/vmapi/primary_with_secondaries/services/echo_with_notification.c
+++ b/test/vmapi/primary_with_secondaries/services/echo_with_notification.c
@@ -53,7 +53,7 @@
 
 	/* Loop, echo messages back to the sender. */
 	for (;;) {
-		spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		spci_msg_wait();
 
 		struct spci_message *send_buf = SERVICE_SEND_BUFFER();
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
diff --git a/test/vmapi/primary_with_secondaries/services/interruptible.c b/test/vmapi/primary_with_secondaries/services/interruptible.c
index 5a04515..adc9b16 100644
--- a/test/vmapi/primary_with_secondaries/services/interruptible.c
+++ b/test/vmapi/primary_with_secondaries/services/interruptible.c
@@ -56,7 +56,7 @@
 	int32_t received;
 
 	do {
-		received = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		received = spci_msg_wait();
 	} while (received == SPCI_INTERRUPTED);
 
 	return received;
diff --git a/test/vmapi/primary_with_secondaries/services/interruptible_echo.c b/test/vmapi/primary_with_secondaries/services/interruptible_echo.c
index 296065f..07a4cbc 100644
--- a/test/vmapi/primary_with_secondaries/services/interruptible_echo.c
+++ b/test/vmapi/primary_with_secondaries/services/interruptible_echo.c
@@ -38,14 +38,14 @@
 	arch_irq_enable();
 
 	for (;;) {
-		uint32_t res = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		uint32_t res = spci_msg_wait();
 		struct spci_message *message = SERVICE_SEND_BUFFER();
 		struct spci_message *recv_message = SERVICE_RECV_BUFFER();
 
 		/* Retry if interrupted but made visible with the yield. */
 		while (res == SPCI_INTERRUPTED) {
 			spci_yield();
-			res = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+			res = spci_msg_wait();
 		}
 
 		memcpy_s(message->payload, SPCI_MSG_PAYLOAD_MAX,
diff --git a/test/vmapi/primary_with_secondaries/services/memory.c b/test/vmapi/primary_with_secondaries/services/memory.c
index cfd05f6..fbd7cb1 100644
--- a/test/vmapi/primary_with_secondaries/services/memory.c
+++ b/test/vmapi/primary_with_secondaries/services/memory.c
@@ -28,7 +28,7 @@
 {
 	/* Loop, writing message to the shared memory. */
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+		EXPECT_EQ(spci_msg_wait(), 0);
 		uint8_t *ptr;
 		size_t i;
 
@@ -60,7 +60,7 @@
 {
 	/* Loop, giving memory back to the sender. */
 	for (;;) {
-		spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		spci_msg_wait();
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -98,7 +98,7 @@
 {
 	/* Loop, giving memory back to the sender. */
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+		EXPECT_EQ(spci_msg_wait(), 0);
 		uint8_t *ptr;
 
 		/* Check the memory was cleared. */
@@ -179,7 +179,7 @@
 {
 	/* Loop, giving memory back to the sender. */
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+		EXPECT_EQ(spci_msg_wait(), 0);
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -211,7 +211,7 @@
 
 TEST_SERVICE(spci_donate_check_upper_bound)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+	EXPECT_EQ(spci_msg_wait(), 0);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -227,7 +227,7 @@
 
 TEST_SERVICE(spci_donate_check_lower_bound)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+	EXPECT_EQ(spci_msg_wait(), 0);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -246,7 +246,7 @@
  */
 TEST_SERVICE(spci_donate_secondary_and_fault)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+	EXPECT_EQ(spci_msg_wait(), 0);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -274,7 +274,7 @@
  */
 TEST_SERVICE(spci_donate_twice)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+	EXPECT_EQ(spci_msg_wait(), 0);
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
 	struct spci_message *send_buf = SERVICE_SEND_BUFFER();
@@ -307,7 +307,7 @@
 TEST_SERVICE(spci_memory_receive)
 {
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+		EXPECT_EQ(spci_msg_wait(), 0);
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -330,7 +330,7 @@
  */
 TEST_SERVICE(spci_donate_invalid_source)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), 0);
+	EXPECT_EQ(spci_msg_wait(), 0);
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
 	struct spci_message *send_buf = SERVICE_SEND_BUFFER();
@@ -356,7 +356,7 @@
 {
 	/* Loop, giving memory back to the sender. */
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+		EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -396,7 +396,7 @@
 TEST_SERVICE(spci_memory_donate_relinquish)
 {
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+		EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -429,7 +429,7 @@
  */
 TEST_SERVICE(spci_lend_invalid_source)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+	EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
 	struct spci_message *send_buf = SERVICE_SEND_BUFFER();
@@ -465,7 +465,7 @@
 TEST_SERVICE(spci_memory_lend_relinquish_X)
 {
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+		EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 		uint64_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -499,7 +499,7 @@
 TEST_SERVICE(spci_memory_lend_relinquish_RW)
 {
 	for (;;) {
-		EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+		EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 		uint8_t *ptr;
 
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -537,7 +537,7 @@
  */
 TEST_SERVICE(spci_lend_check_lower_bound)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+	EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -557,7 +557,7 @@
  */
 TEST_SERVICE(spci_lend_check_upper_bound)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+	EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
@@ -574,7 +574,7 @@
 
 TEST_SERVICE(spci_memory_lend_twice)
 {
-	EXPECT_EQ(spci_msg_recv(SPCI_MSG_RECV_BLOCK), SPCI_SUCCESS);
+	EXPECT_EQ(spci_msg_wait(), SPCI_SUCCESS);
 	uint8_t *ptr;
 
 	struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
diff --git a/test/vmapi/primary_with_secondaries/services/receive_block.c b/test/vmapi/primary_with_secondaries/services/receive_block.c
index 0b8a1b5..1b03506 100644
--- a/test/vmapi/primary_with_secondaries/services/receive_block.c
+++ b/test/vmapi/primary_with_secondaries/services/receive_block.c
@@ -46,7 +46,7 @@
 	hf_interrupt_enable(EXTERNAL_INTERRUPT_ID_A, true);
 
 	for (i = 0; i < 10; ++i) {
-		int32_t res = spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		int32_t res = spci_msg_wait();
 		EXPECT_EQ(res, SPCI_INTERRUPTED);
 	}
 
diff --git a/test/vmapi/primary_with_secondaries/services/relay.c b/test/vmapi/primary_with_secondaries/services/relay.c
index 5ccda5f..86eed79 100644
--- a/test/vmapi/primary_with_secondaries/services/relay.c
+++ b/test/vmapi/primary_with_secondaries/services/relay.c
@@ -36,7 +36,7 @@
 		uint32_t next_message_size;
 
 		/* Receive the message to relay. */
-		spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+		spci_msg_wait();
 
 		/* Prepare to relay the message. */
 		struct spci_message *recv_buf = SERVICE_RECV_BUFFER();
diff --git a/test/vmapi/primary_with_secondaries/services/spci_check.c b/test/vmapi/primary_with_secondaries/services/spci_check.c
index d44da6a..1d626ba 100644
--- a/test/vmapi/primary_with_secondaries/services/spci_check.c
+++ b/test/vmapi/primary_with_secondaries/services/spci_check.c
@@ -41,7 +41,7 @@
 	};
 
 	/* Wait for single message to be sent by the primary VM. */
-	spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+	spci_msg_wait();
 
 	/* Ensure message header has all fields correctly set. */
 	EXPECT_EQ(recv_buf->flags, expected_message.flags);
@@ -70,7 +70,7 @@
 	const char message[] = "this should be truncated";
 
 	/* Wait for single message to be sent by the primary VM. */
-	spci_msg_recv(SPCI_MSG_RECV_BLOCK);
+	spci_msg_wait();
 
 	/* Verify the length is as expected. */
 	EXPECT_EQ(16, recv_buf->length);
@@ -85,7 +85,7 @@
 TEST_SERVICE(spci_recv_non_blocking)
 {
 	/* Wait for single message to be sent by the primary VM. */
-	EXPECT_EQ(spci_msg_recv(0), SPCI_RETRY);
+	EXPECT_EQ(spci_msg_poll(), SPCI_RETRY);
 
 	spci_yield();
 }