diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index d65b562..d6d1ff1 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -668,7 +668,7 @@ int efx_mcdi_get_board_cfg(struct efx_nic *efx, u8 *mac_address,
 			   u16 *fw_subtype_list, u32 *capabilities)
 {
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_BOARD_CFG_OUT_LENMAX);
-	size_t outlen, offset, i;
+	size_t outlen, i;
 	int port_num = efx_port_num(efx);
 	int rc;
 
@@ -684,22 +684,21 @@ int efx_mcdi_get_board_cfg(struct efx_nic *efx, u8 *mac_address,
 		goto fail;
 	}
 
-	offset = (port_num)
-		? MC_CMD_GET_BOARD_CFG_OUT_MAC_ADDR_BASE_PORT1_OFST
-		: MC_CMD_GET_BOARD_CFG_OUT_MAC_ADDR_BASE_PORT0_OFST;
 	if (mac_address)
-		memcpy(mac_address, outbuf + offset, ETH_ALEN);
+		memcpy(mac_address,
+		       port_num ?
+		       MCDI_PTR(outbuf, GET_BOARD_CFG_OUT_MAC_ADDR_BASE_PORT1) :
+		       MCDI_PTR(outbuf, GET_BOARD_CFG_OUT_MAC_ADDR_BASE_PORT0),
+		       ETH_ALEN);
 	if (fw_subtype_list) {
-		/* Byte-swap and truncate or zero-pad as necessary */
-		offset = MC_CMD_GET_BOARD_CFG_OUT_FW_SUBTYPE_LIST_OFST;
 		for (i = 0;
-		     i < MC_CMD_GET_BOARD_CFG_OUT_FW_SUBTYPE_LIST_MAXNUM;
-		     i++) {
-			fw_subtype_list[i] =
-				(offset + 2 <= outlen) ?
-				le16_to_cpup((__le16 *)(outbuf + offset)) : 0;
-			offset += 2;
-		}
+		     i < MCDI_VAR_ARRAY_LEN(outlen,
+					    GET_BOARD_CFG_OUT_FW_SUBTYPE_LIST);
+		     i++)
+			fw_subtype_list[i] = MCDI_ARRAY_WORD(
+				outbuf, GET_BOARD_CFG_OUT_FW_SUBTYPE_LIST, i);
+		for (; i < MC_CMD_GET_BOARD_CFG_OUT_FW_SUBTYPE_LIST_MAXNUM; i++)
+			fw_subtype_list[i] = 0;
 	}
 	if (capabilities) {
 		if (port_num)
@@ -980,7 +979,7 @@ static int efx_mcdi_read_assertion(struct efx_nic *efx)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_GET_ASSERTS_IN_LEN);
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_GET_ASSERTS_OUT_LEN);
-	unsigned int flags, index, ofst;
+	unsigned int flags, index;
 	const char *reason;
 	size_t outlen;
 	int retry;
@@ -1022,12 +1021,13 @@ static int efx_mcdi_read_assertion(struct efx_nic *efx)
 		  MCDI_DWORD(outbuf, GET_ASSERTS_OUT_THREAD_OFFS));
 
 	/* Print out the registers */
-	ofst = MC_CMD_GET_ASSERTS_OUT_GP_REGS_OFFS_OFST;
-	for (index = 1; index < 32; index++) {
-		netif_err(efx, hw, efx->net_dev, "R%.2d (?): 0x%.8x\n", index,
-			MCDI_DWORD2(outbuf, ofst));
-		ofst += sizeof(efx_dword_t);
-	}
+	for (index = 0;
+	     index < MC_CMD_GET_ASSERTS_OUT_GP_REGS_OFFS_NUM;
+	     index++)
+		netif_err(efx, hw, efx->net_dev, "R%.2d (?): 0x%.8x\n",
+			  1 + index,
+			  MCDI_ARRAY_DWORD(outbuf, GET_ASSERTS_OUT_GP_REGS_OFFS,
+					   index));
 
 	return 0;
 }
@@ -1201,34 +1201,31 @@ int efx_mcdi_flush_rxqs(struct efx_nic *efx)
 {
 	struct efx_channel *channel;
 	struct efx_rx_queue *rx_queue;
-	__le32 *qid;
+	MCDI_DECLARE_BUF(inbuf,
+			 MC_CMD_FLUSH_RX_QUEUES_IN_LEN(EFX_MAX_CHANNELS));
 	int rc, count;
 
 	BUILD_BUG_ON(EFX_MAX_CHANNELS >
 		     MC_CMD_FLUSH_RX_QUEUES_IN_QID_OFST_MAXNUM);
 
-	qid = kmalloc(EFX_MAX_CHANNELS * sizeof(*qid), GFP_KERNEL);
-	if (qid == NULL)
-		return -ENOMEM;
-
 	count = 0;
 	efx_for_each_channel(channel, efx) {
 		efx_for_each_channel_rx_queue(rx_queue, channel) {
 			if (rx_queue->flush_pending) {
 				rx_queue->flush_pending = false;
 				atomic_dec(&efx->rxq_flush_pending);
-				qid[count++] = cpu_to_le32(
-					efx_rx_queue_index(rx_queue));
+				MCDI_SET_ARRAY_DWORD(
+					inbuf, FLUSH_RX_QUEUES_IN_QID_OFST,
+					count, efx_rx_queue_index(rx_queue));
+				count++;
 			}
 		}
 	}
 
-	rc = efx_mcdi_rpc(efx, MC_CMD_FLUSH_RX_QUEUES, (u8 *)qid,
-			  count * sizeof(*qid), NULL, 0, NULL);
+	rc = efx_mcdi_rpc(efx, MC_CMD_FLUSH_RX_QUEUES, inbuf,
+			  MC_CMD_FLUSH_RX_QUEUES_IN_LEN(count), NULL, 0, NULL);
 	WARN_ON(rc < 0);
 
-	kfree(qid);
-
 	return rc;
 }
 
diff --git a/drivers/net/ethernet/sfc/mcdi.h b/drivers/net/ethernet/sfc/mcdi.h
index 969ecc0..f8ab64f 100644
--- a/drivers/net/ethernet/sfc/mcdi.h
+++ b/drivers/net/ethernet/sfc/mcdi.h
@@ -94,9 +94,6 @@ extern void efx_mcdi_sensor_event(struct efx_nic *efx, efx_qword_t *ev);
 #define _MCDI_DWORD(_buf, _field)					\
 	((efx_dword_t *)MCDI_PTR(_buf, _field))
 
-#define MCDI_DWORD2(_buf, _ofst)                                       \
-	EFX_DWORD_FIELD(*(efx_dword_t *)((u8 *)(_buf) + (_ofst)), EFX_DWORD_0)
-
 #define MCDI_SET_DWORD(_buf, _field, _value)				\
 	EFX_POPULATE_DWORD_1(*_MCDI_DWORD(_buf, _field), EFX_DWORD_0, _value)
 #define MCDI_DWORD(_buf, _field)					\
diff --git a/drivers/net/ethernet/sfc/mcdi_mac.c b/drivers/net/ethernet/sfc/mcdi_mac.c
index fafdc8e..cf16bf1 100644
--- a/drivers/net/ethernet/sfc/mcdi_mac.c
+++ b/drivers/net/ethernet/sfc/mcdi_mac.c
@@ -17,7 +17,7 @@ int efx_mcdi_set_mac(struct efx_nic *efx)
 	u32 reject, fcntl;
 	MCDI_DECLARE_BUF(cmdbytes, MC_CMD_SET_MAC_IN_LEN);
 
-	memcpy(cmdbytes + MC_CMD_SET_MAC_IN_ADDR_OFST,
+	memcpy(MCDI_PTR(cmdbytes, SET_MAC_IN_ADDR),
 	       efx->net_dev->dev_addr, ETH_ALEN);
 
 	MCDI_SET_DWORD(cmdbytes, SET_MAC_IN_MTU,
diff --git a/drivers/net/ethernet/sfc/mcdi_phy.c b/drivers/net/ethernet/sfc/mcdi_phy.c
index 37b6ed9..86c0d21 100644
--- a/drivers/net/ethernet/sfc/mcdi_phy.c
+++ b/drivers/net/ethernet/sfc/mcdi_phy.c
@@ -615,17 +615,15 @@ static int efx_mcdi_bist(struct efx_nic *efx, unsigned int bist_mode,
 	unsigned int retry, i, count = 0;
 	size_t outlen;
 	u32 status;
-	u8 *buf, *ptr;
+	MCDI_DECLARE_BUF(inbuf, MC_CMD_START_BIST_IN_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_POLL_BIST_OUT_SFT9001_LEN);
+	u8 *ptr;
 	int rc;
 
-	buf = kzalloc(0x100, GFP_KERNEL);
-	if (buf == NULL)
-		return -ENOMEM;
-
 	BUILD_BUG_ON(MC_CMD_START_BIST_OUT_LEN != 0);
-	MCDI_SET_DWORD(buf, START_BIST_IN_TYPE, bist_mode);
-	rc = efx_mcdi_rpc(efx, MC_CMD_START_BIST, buf, MC_CMD_START_BIST_IN_LEN,
-			  NULL, 0, NULL);
+	MCDI_SET_DWORD(inbuf, START_BIST_IN_TYPE, bist_mode);
+	rc = efx_mcdi_rpc(efx, MC_CMD_START_BIST,
+			  inbuf, MC_CMD_START_BIST_IN_LEN, NULL, 0, NULL);
 	if (rc)
 		goto out;
 
@@ -633,11 +631,11 @@ static int efx_mcdi_bist(struct efx_nic *efx, unsigned int bist_mode,
 	for (retry = 0; retry < 100; ++retry) {
 		BUILD_BUG_ON(MC_CMD_POLL_BIST_IN_LEN != 0);
 		rc = efx_mcdi_rpc(efx, MC_CMD_POLL_BIST, NULL, 0,
-				  buf, 0x100, &outlen);
+				  outbuf, sizeof(outbuf), &outlen);
 		if (rc)
 			goto out;
 
-		status = MCDI_DWORD(buf, POLL_BIST_OUT_RESULT);
+		status = MCDI_DWORD(outbuf, POLL_BIST_OUT_RESULT);
 		if (status != MC_CMD_POLL_BIST_RUNNING)
 			goto finished;
 
@@ -654,7 +652,7 @@ finished:
 	if (efx->phy_type == PHY_TYPE_SFT9001B &&
 	    (bist_mode == MC_CMD_PHY_BIST_CABLE_SHORT ||
 	     bist_mode == MC_CMD_PHY_BIST_CABLE_LONG)) {
-		ptr = MCDI_PTR(buf, POLL_BIST_OUT_SFT9001_CABLE_LENGTH_A);
+		ptr = MCDI_PTR(outbuf, POLL_BIST_OUT_SFT9001_CABLE_LENGTH_A);
 		if (status == MC_CMD_POLL_BIST_PASSED &&
 		    outlen >= MC_CMD_POLL_BIST_OUT_SFT9001_LEN) {
 			for (i = 0; i < 8; i++) {
@@ -668,8 +666,6 @@ finished:
 	rc = count;
 
 out:
-	kfree(buf);
-
 	return rc;
 }
 
@@ -785,8 +781,7 @@ static int efx_mcdi_phy_get_module_eeprom(struct efx_nic *efx,
 			space_remaining : payload_len;
 
 		memcpy(user_data,
-		       outbuf + page_off +
-		       MC_CMD_GET_PHY_MEDIA_INFO_OUT_DATA_OFST,
+		       MCDI_PTR(outbuf, GET_PHY_MEDIA_INFO_OUT_DATA) + page_off,
 		       to_copy);
 
 		space_remaining -= to_copy;
diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index f79f6fb..ec2cf4d 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -294,8 +294,7 @@ struct efx_ptp_data {
 	struct work_struct pps_work;
 	struct workqueue_struct *pps_workwq;
 	bool nic_ts_enabled;
-	u8 txbuf[ALIGN(MC_CMD_PTP_IN_TRANSMIT_LEN(
-			       MC_CMD_PTP_IN_TRANSMIT_PACKET_MAXNUM), 4)];
+	MCDI_DECLARE_BUF(txbuf, MC_CMD_PTP_IN_TRANSMIT_LENMAX);
 	struct efx_ptp_timeset
 	timeset[MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_MAXNUM];
 };
@@ -396,7 +395,8 @@ static void efx_ptp_send_times(struct efx_nic *efx,
 }
 
 /* Read a timeset from the MC's results and partial process. */
-static void efx_ptp_read_timeset(u8 *data, struct efx_ptp_timeset *timeset)
+static void efx_ptp_read_timeset(MCDI_DECLARE_STRUCT_PTR(data),
+				 struct efx_ptp_timeset *timeset)
 {
 	unsigned start_ns, end_ns;
 
@@ -425,12 +425,14 @@ static void efx_ptp_read_timeset(u8 *data, struct efx_ptp_timeset *timeset)
  * busy. A number of readings are taken so that, hopefully, at least one good
  * synchronisation will be seen in the results.
  */
-static int efx_ptp_process_times(struct efx_nic *efx, u8 *synch_buf,
-				 size_t response_length,
-				 const struct pps_event_time *last_time)
+static int
+efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
+		      size_t response_length,
+		      const struct pps_event_time *last_time)
 {
-	unsigned number_readings = (response_length /
-			       MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_LEN);
+	unsigned number_readings =
+		MCDI_VAR_ARRAY_LEN(response_length,
+				   PTP_OUT_SYNCHRONIZE_TIMESET);
 	unsigned i;
 	unsigned total;
 	unsigned ngood = 0;
@@ -447,8 +449,10 @@ static int efx_ptp_process_times(struct efx_nic *efx, u8 *synch_buf,
 	 * appera to be erroneous.
 	 */
 	for (i = 0; i < number_readings; i++) {
-		efx_ptp_read_timeset(synch_buf, &ptp->timeset[i]);
-		synch_buf += MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_LEN;
+		efx_ptp_read_timeset(
+			MCDI_ARRAY_STRUCT_PTR(synch_buf,
+					      PTP_OUT_SYNCHRONIZE_TIMESET, i),
+			&ptp->timeset[i]);
 	}
 
 	/* Find the last good host-MC synchronization result. The MC times
@@ -564,15 +568,15 @@ static int efx_ptp_synchronize(struct efx_nic *efx, unsigned int num_readings)
 /* Transmit a PTP packet, via the MCDI interface, to the wire. */
 static int efx_ptp_xmit_skb(struct efx_nic *efx, struct sk_buff *skb)
 {
-	u8 *txbuf = efx->ptp_data->txbuf;
+	struct efx_ptp_data *ptp_data = efx->ptp_data;
 	struct skb_shared_hwtstamps timestamps;
 	int rc = -EIO;
 	/* MCDI driver requires word aligned lengths */
 	size_t len = ALIGN(MC_CMD_PTP_IN_TRANSMIT_LEN(skb->len), 4);
 	MCDI_DECLARE_BUF(txtime, MC_CMD_PTP_OUT_TRANSMIT_LEN);
 
-	MCDI_SET_DWORD(txbuf, PTP_IN_OP, MC_CMD_PTP_OP_TRANSMIT);
-	MCDI_SET_DWORD(txbuf, PTP_IN_TRANSMIT_LENGTH, skb->len);
+	MCDI_SET_DWORD(ptp_data->txbuf, PTP_IN_OP, MC_CMD_PTP_OP_TRANSMIT);
+	MCDI_SET_DWORD(ptp_data->txbuf, PTP_IN_TRANSMIT_LENGTH, skb->len);
 	if (skb_shinfo(skb)->nr_frags != 0) {
 		rc = skb_linearize(skb);
 		if (rc != 0)
@@ -585,9 +589,10 @@ static int efx_ptp_xmit_skb(struct efx_nic *efx, struct sk_buff *skb)
 			goto fail;
 	}
 	skb_copy_from_linear_data(skb,
-				  &txbuf[MC_CMD_PTP_IN_TRANSMIT_PACKET_OFST],
+				  MCDI_PTR(ptp_data->txbuf,
+					   PTP_IN_TRANSMIT_PACKET),
 				  len);
-	rc = efx_mcdi_rpc(efx, MC_CMD_PTP, txbuf, len, txtime,
+	rc = efx_mcdi_rpc(efx, MC_CMD_PTP, ptp_data->txbuf, len, txtime,
 			  sizeof(txtime), &len);
 	if (rc != 0)
 		goto fail;
diff --git a/drivers/net/ethernet/sfc/siena_sriov.c b/drivers/net/ethernet/sfc/siena_sriov.c
index c376e90..198044f 100644
--- a/drivers/net/ethernet/sfc/siena_sriov.c
+++ b/drivers/net/ethernet/sfc/siena_sriov.c
@@ -240,25 +240,22 @@ static void efx_sriov_usrev(struct efx_nic *efx, bool enabled)
 static int efx_sriov_memcpy(struct efx_nic *efx, struct efx_memcpy_req *req,
 			    unsigned int count)
 {
-	u8 *inbuf, *record;
-	unsigned int used;
+	MCDI_DECLARE_BUF(inbuf, MCDI_CTL_SDU_LEN_MAX_V1);
+	MCDI_DECLARE_STRUCT_PTR(record);
+	unsigned int index, used;
 	u32 from_rid, from_hi, from_lo;
 	int rc;
 
 	mb();	/* Finish writing source/reading dest before DMA starts */
 
-	used = MC_CMD_MEMCPY_IN_LEN(count);
-	if (WARN_ON(used > MCDI_CTL_SDU_LEN_MAX_V1))
+	if (WARN_ON(count > MC_CMD_MEMCPY_IN_RECORD_MAXNUM))
 		return -ENOBUFS;
+	used = MC_CMD_MEMCPY_IN_LEN(count);
 
-	/* Allocate room for the largest request */
-	inbuf = kzalloc(MCDI_CTL_SDU_LEN_MAX_V1, GFP_KERNEL);
-	if (inbuf == NULL)
-		return -ENOMEM;
-
-	record = inbuf;
-	MCDI_SET_DWORD(record, MEMCPY_IN_RECORD, count);
-	while (count-- > 0) {
+	for (index = 0; index < count; index++) {
+		record = MCDI_ARRAY_STRUCT_PTR(inbuf, MEMCPY_IN_RECORD, index);
+		MCDI_SET_DWORD(record, MEMCPY_RECORD_TYPEDEF_NUM_RECORDS,
+			       count);
 		MCDI_SET_DWORD(record, MEMCPY_RECORD_TYPEDEF_TO_RID,
 			       req->to_rid);
 		MCDI_SET_DWORD(record, MEMCPY_RECORD_TYPEDEF_TO_ADDR_LO,
@@ -279,7 +276,8 @@ static int efx_sriov_memcpy(struct efx_nic *efx, struct efx_memcpy_req *req,
 			from_rid = MC_CMD_MEMCPY_RECORD_TYPEDEF_RID_INLINE;
 			from_lo = used;
 			from_hi = 0;
-			memcpy(inbuf + used, req->from_buf, req->length);
+			memcpy(_MCDI_PTR(inbuf, used), req->from_buf,
+			       req->length);
 			used += req->length;
 		}
 
@@ -292,13 +290,10 @@ static int efx_sriov_memcpy(struct efx_nic *efx, struct efx_memcpy_req *req,
 			       req->length);
 
 		++req;
-		record += MC_CMD_MEMCPY_IN_RECORD_LEN;
 	}
 
 	rc = efx_mcdi_rpc(efx, MC_CMD_MEMCPY, inbuf, used, NULL, 0, NULL);
 out:
-	kfree(inbuf);
-
 	mb();	/* Don't write source/read dest before DMA is complete */
 
 	return rc;
@@ -685,16 +680,12 @@ static int efx_vfdi_fini_all_queues(struct efx_vf *vf)
 	unsigned vf_offset = EFX_VI_BASE + vf->index * efx_vf_size(efx);
 	unsigned timeout = HZ;
 	unsigned index, rxqs_count;
-	__le32 *rxqs;
+	MCDI_DECLARE_BUF(inbuf, MC_CMD_FLUSH_RX_QUEUES_IN_LENMAX);
 	int rc;
 
 	BUILD_BUG_ON(VF_MAX_RX_QUEUES >
 		     MC_CMD_FLUSH_RX_QUEUES_IN_QID_OFST_MAXNUM);
 
-	rxqs = kmalloc(count * sizeof(*rxqs), GFP_KERNEL);
-	if (rxqs == NULL)
-		return VFDI_RC_ENOMEM;
-
 	rtnl_lock();
 	siena_prepare_flush(efx);
 	rtnl_unlock();
@@ -709,14 +700,19 @@ static int efx_vfdi_fini_all_queues(struct efx_vf *vf)
 					     vf_offset + index);
 			efx_writeo(efx, &reg, FR_AZ_TX_FLUSH_DESCQ);
 		}
-		if (test_bit(index, vf->rxq_mask))
-			rxqs[rxqs_count++] = cpu_to_le32(vf_offset + index);
+		if (test_bit(index, vf->rxq_mask)) {
+			MCDI_SET_ARRAY_DWORD(
+				inbuf, FLUSH_RX_QUEUES_IN_QID_OFST,
+				rxqs_count, vf_offset + index);
+			rxqs_count++;
+		}
 	}
 
 	atomic_set(&vf->rxq_retry_count, 0);
 	while (timeout && (vf->rxq_count || vf->txq_count)) {
-		rc = efx_mcdi_rpc(efx, MC_CMD_FLUSH_RX_QUEUES, (u8 *)rxqs,
-				  rxqs_count * sizeof(*rxqs), NULL, 0, NULL);
+		rc = efx_mcdi_rpc(efx, MC_CMD_FLUSH_RX_QUEUES, inbuf,
+				  MC_CMD_FLUSH_RX_QUEUES_IN_LEN(rxqs_count),
+				  NULL, 0, NULL);
 		WARN_ON(rc < 0);
 
 		timeout = wait_event_timeout(vf->flush_waitq,
@@ -726,8 +722,10 @@ static int efx_vfdi_fini_all_queues(struct efx_vf *vf)
 		for (index = 0; index < count; ++index) {
 			if (test_and_clear_bit(index, vf->rxq_retry_mask)) {
 				atomic_dec(&vf->rxq_retry_count);
-				rxqs[rxqs_count++] =
-					cpu_to_le32(vf_offset + index);
+				MCDI_SET_ARRAY_DWORD(
+					inbuf, FLUSH_RX_QUEUES_IN_QID_OFST,
+					rxqs_count, vf_offset + index);
+				rxqs_count++;
 			}
 		}
 	}
@@ -750,7 +748,6 @@ static int efx_vfdi_fini_all_queues(struct efx_vf *vf)
 	}
 	efx_sriov_bufs(efx, vf->buftbl_base, NULL,
 		       EFX_VF_BUFTBL_PER_VI * efx_vf_size(efx));
-	kfree(rxqs);
 	efx_vfdi_flush_clear(vf);
 
 	vf->evq0_count = 0;
