diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index bcb1bbcf50df..ad8bd6bd728a 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -71,9 +71,9 @@ int copy_data(struct rxe_pd *pd, int access, struct rxe_dma_info *dma,
 	      void *addr, int length, enum rxe_mr_copy_dir dir);
 int rxe_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sg,
 		  int sg_nents, unsigned int *sg_offset);
-void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length);
 int rxe_mr_do_atomic_op(struct rxe_mr *mr, u64 iova, int opcode,
 			u64 compare, u64 swap_add, u64 *orig_val);
+int rxe_mr_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value);
 struct rxe_mr *lookup_mr(struct rxe_pd *pd, int access, u32 key,
 			 enum rxe_mr_lookup_type type);
 int mr_check_range(struct rxe_mr *mr, u64 iova, size_t length);
diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index df9741474f1f..5c4ce43914fa 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -297,7 +297,7 @@ static void lookup_iova(struct rxe_mr *mr, u64 iova, int *m_out, int *n_out,
 	}
 }
 
-void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length)
+static void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length)
 {
 	size_t offset;
 	int m, n;
@@ -565,6 +565,42 @@ int rxe_mr_do_atomic_op(struct rxe_mr *mr, u64 iova, int opcode,
 	return 0;
 }
 
+/* only implemented for 64 bit architectures */
+#if defined CONFIG_64BIT
+int rxe_mr_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
+{
+	u64 *va;
+
+	/* See IBA oA19-28 */
+	if (unlikely(mr->state != RXE_MR_STATE_VALID)) {
+		rxe_dbg_mr(mr, "mr not in valid state");
+		return RESPST_ERR_RKEY_VIOLATION;
+	}
+
+	va = iova_to_vaddr(mr, iova, sizeof(value));
+	if (unlikely(!va)) {
+		rxe_dbg_mr(mr, "iova out of range");
+		return RESPST_ERR_RKEY_VIOLATION;
+	}
+
+	/* See IBA A19.4.2 */
+	if (unlikely((uintptr_t)va & 0x7 || iova & 0x7)) {
+		rxe_dbg_mr(mr, "misaligned address");
+		return RESPST_ERR_MISALIGNED_ATOMIC;
+	}
+
+	/* Do atomic write after all prior operations have completed */
+	smp_store_release(va, value);
+
+	return 0;
+}
+#else
+int rxe_mr_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
+{
+	return RESPST_ERR_UNSUPPORTED_OPCODE;
+}
+#endif
+
 int advance_dma_data(struct rxe_dma_info *dma, unsigned int length)
 {
 	struct rxe_sge		*sge	= &dma->sge[dma->cur_sge];
diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index 9d4b4e9b42fc..cd2d88de287c 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -723,30 +723,32 @@ static enum resp_states atomic_reply(struct rxe_qp *qp,
 	return RESPST_ACKNOWLEDGE;
 }
 
-#ifdef CONFIG_64BIT
-static enum resp_states do_atomic_write(struct rxe_qp *qp,
-					struct rxe_pkt_info *pkt)
+static enum resp_states atomic_write_reply(struct rxe_qp *qp,
+					   struct rxe_pkt_info *pkt)
 {
-	struct rxe_mr *mr = qp->resp.mr;
-	int payload = payload_size(pkt);
-	u64 src, *dst;
-
-	if (mr->state != RXE_MR_STATE_VALID)
-		return RESPST_ERR_RKEY_VIOLATION;
+	struct resp_res *res = qp->resp.res;
+	struct rxe_mr *mr;
+	u64 value;
+	u64 iova;
+	int err;
 
-	memcpy(&src, payload_addr(pkt), payload);
+	if (!res) {
+		res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_WRITE_MASK);
+		qp->resp.res = res;
+	}
 
-	dst = iova_to_vaddr(mr, qp->resp.va + qp->resp.offset, payload);
-	/* check vaddr is 8 bytes aligned. */
-	if (!dst || (uintptr_t)dst & 7)
-		return RESPST_ERR_MISALIGNED_ATOMIC;
+	if (res->replay)
+		return RESPST_ACKNOWLEDGE;
 
-	/* Do atomic write after all prior operations have completed */
-	smp_store_release(dst, src);
+	mr = qp->resp.mr;
+	value = *(u64 *)payload_addr(pkt);
+	iova = qp->resp.va + qp->resp.offset;
 
-	/* decrease resp.resid to zero */
-	qp->resp.resid -= sizeof(payload);
+	err = rxe_mr_do_atomic_write(mr, iova, value);
+	if (err)
+		return err;
 
+	qp->resp.resid = 0;
 	qp->resp.msn++;
 
 	/* next expected psn, read handles this separately */
@@ -755,29 +757,8 @@ static enum resp_states do_atomic_write(struct rxe_qp *qp,
 
 	qp->resp.opcode = pkt->opcode;
 	qp->resp.status = IB_WC_SUCCESS;
-	return RESPST_ACKNOWLEDGE;
-}
-#else
-static enum resp_states do_atomic_write(struct rxe_qp *qp,
-					struct rxe_pkt_info *pkt)
-{
-	return RESPST_ERR_UNSUPPORTED_OPCODE;
-}
-#endif /* CONFIG_64BIT */
-
-static enum resp_states atomic_write_reply(struct rxe_qp *qp,
-					   struct rxe_pkt_info *pkt)
-{
-	struct resp_res *res = qp->resp.res;
 
-	if (!res) {
-		res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_WRITE_MASK);
-		qp->resp.res = res;
-	}
-
-	if (res->replay)
-		return RESPST_ACKNOWLEDGE;
-	return do_atomic_write(qp, pkt);
+	return RESPST_ACKNOWLEDGE;
 }
 
 static struct sk_buff *prepare_ack_packet(struct rxe_qp *qp,
