diff --git a/include/spdk/nvme.h b/include/spdk/nvme.h
index 9153056d0..c816aa701 100644
--- a/include/spdk/nvme.h
+++ b/include/spdk/nvme.h
@@ -1911,22 +1911,27 @@ int spdk_nvme_ctrlr_update_firmware(struct spdk_nvme_ctrlr *ctrlr, void *payload
 volatile struct spdk_nvme_registers *spdk_nvme_ctrlr_get_registers(struct spdk_nvme_ctrlr *ctrlr);
 
 /**
- * Map the controller memory buffer for use in I/O operations.
+ * Reserve the controller memory buffer for data transfer use.
  *
- * This function maps registered memory which belongs to the Controller
- * Memory Buffer (CMB) of the specified NVMe controller so that it is visible
- * from the CPU. Note that the CMB has to support the WDS and RDS capabilities
- * for the mapping to be successful. Also, due to vtophys contraints the CMB must
- * be at least 4MiB in size.
+ * This function reserves the full size of the controller memory buffer
+ * for use in data transfers. If submission queues or completion queues are
+ * already placed in the controller memory buffer, this call will fail.
  *
- * This cannot be used in conjunction with placing submission queues in the
- * controller memory buffer.
+ * \param ctrlr Controller from which to allocate memory buffer
  *
- * \param ctrlr Controller from which to allocate memory buffer.
- * \param size Size of buffer that was mapped. Return value.
+ * \return The size of the controller memory buffer on success. Negated errno
+ * on failure.
+ */
+int spdk_nvme_ctrlr_reserve_cmb(struct spdk_nvme_ctrlr *ctrlr);
+
+/**
+ * Map a previously reserved controller memory buffer so that it's data is
+ * visible from the CPU. This operation is not always possible.
  *
- * \return Pointer to controller memory buffer, or NULL if mapping
- * was not possible.
+ * \param ctrlr Controller that contains the memory buffer
+ * \param size Size of buffer that was mapped.
+ *
+ * \return Pointer to controller memory buffer, or NULL on failure.
  */
 void *spdk_nvme_ctrlr_map_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size);
 
@@ -3080,6 +3085,8 @@ struct spdk_nvme_transport_ops {
 
 	uint16_t (*ctrlr_get_max_sges)(struct spdk_nvme_ctrlr *ctrlr);
 
+	int (*ctrlr_reserve_cmb)(struct spdk_nvme_ctrlr *ctrlr);
+
 	void *(*ctrlr_map_cmb)(struct spdk_nvme_ctrlr *ctrlr, size_t *size);
 
 	int (*ctrlr_unmap_cmb)(struct spdk_nvme_ctrlr *ctrlr);
diff --git a/lib/nvme/nvme_ctrlr.c b/lib/nvme/nvme_ctrlr.c
index 5d5abdd2c..a8060ae9d 100644
--- a/lib/nvme/nvme_ctrlr.c
+++ b/lib/nvme/nvme_ctrlr.c
@@ -3363,15 +3363,36 @@ spdk_nvme_ctrlr_update_firmware(struct spdk_nvme_ctrlr *ctrlr, void *payload, ui
 	return spdk_nvme_ctrlr_reset(ctrlr);
 }
 
+int
+spdk_nvme_ctrlr_reserve_cmb(struct spdk_nvme_ctrlr *ctrlr)
+{
+	int rc, size;
+	union spdk_nvme_cmbsz_register cmbsz;
+
+	cmbsz = spdk_nvme_ctrlr_get_regs_cmbsz(ctrlr);
+
+	if (cmbsz.bits.rds == 0 || cmbsz.bits.wds == 0) {
+		return -ENOTSUP;
+	}
+
+	size = cmbsz.bits.sz * (0x1000 << (cmbsz.bits.szu * 4));
+
+	nvme_robust_mutex_lock(&ctrlr->ctrlr_lock);
+	rc = nvme_transport_ctrlr_reserve_cmb(ctrlr);
+	nvme_robust_mutex_unlock(&ctrlr->ctrlr_lock);
+
+	if (rc < 0) {
+		return rc;
+	}
+
+	return size;
+}
+
 void *
 spdk_nvme_ctrlr_map_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size)
 {
 	void *buf;
 
-	if (size == 0) {
-		return NULL;
-	}
-
 	nvme_robust_mutex_lock(&ctrlr->ctrlr_lock);
 	buf = nvme_transport_ctrlr_map_cmb(ctrlr, size);
 	nvme_robust_mutex_unlock(&ctrlr->ctrlr_lock);
diff --git a/lib/nvme/nvme_internal.h b/lib/nvme/nvme_internal.h
index 19199b461..1d53c6f85 100644
--- a/lib/nvme/nvme_internal.h
+++ b/lib/nvme/nvme_internal.h
@@ -1162,6 +1162,7 @@ uint32_t nvme_transport_ctrlr_get_max_xfer_size(struct spdk_nvme_ctrlr *ctrlr);
 uint16_t nvme_transport_ctrlr_get_max_sges(struct spdk_nvme_ctrlr *ctrlr);
 struct spdk_nvme_qpair *nvme_transport_ctrlr_create_io_qpair(struct spdk_nvme_ctrlr *ctrlr,
 		uint16_t qid, const struct spdk_nvme_io_qpair_opts *opts);
+int nvme_transport_ctrlr_reserve_cmb(struct spdk_nvme_ctrlr *ctrlr);
 void *nvme_transport_ctrlr_map_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size);
 int nvme_transport_ctrlr_unmap_cmb(struct spdk_nvme_ctrlr *ctrlr);
 int nvme_transport_ctrlr_delete_io_qpair(struct spdk_nvme_ctrlr *ctrlr,
diff --git a/lib/nvme/nvme_pcie.c b/lib/nvme/nvme_pcie.c
index f02a2ad7c..e35b83a3b 100644
--- a/lib/nvme/nvme_pcie.c
+++ b/lib/nvme/nvme_pcie.c
@@ -553,6 +553,24 @@ nvme_pcie_ctrlr_unmap_cmb(struct nvme_pcie_ctrlr *pctrlr)
 	return rc;
 }
 
+static int
+nvme_pcie_ctrlr_reserve_cmb(struct spdk_nvme_ctrlr *ctrlr)
+{
+	struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(ctrlr);
+
+	if (pctrlr->cmb.bar_va == NULL) {
+		SPDK_DEBUGLOG(SPDK_LOG_NVME, "CMB not available\n");
+		return -ENOTSUP;
+	}
+
+	if (ctrlr->opts.use_cmb_sqs) {
+		SPDK_ERRLOG("CMB is already in use for submission queues.\n");
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
 static void *
 nvme_pcie_ctrlr_map_io_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size)
 {
@@ -2433,6 +2451,7 @@ const struct spdk_nvme_transport_ops pcie_ops = {
 	.ctrlr_get_max_xfer_size = nvme_pcie_ctrlr_get_max_xfer_size,
 	.ctrlr_get_max_sges = nvme_pcie_ctrlr_get_max_sges,
 
+	.ctrlr_reserve_cmb = nvme_pcie_ctrlr_reserve_cmb,
 	.ctrlr_map_cmb = nvme_pcie_ctrlr_map_io_cmb,
 	.ctrlr_unmap_cmb = nvme_pcie_ctrlr_unmap_io_cmb,
 
diff --git a/lib/nvme/nvme_transport.c b/lib/nvme/nvme_transport.c
index 0e090869c..9b1a0821b 100644
--- a/lib/nvme/nvme_transport.c
+++ b/lib/nvme/nvme_transport.c
@@ -215,6 +215,19 @@ nvme_transport_ctrlr_get_max_sges(struct spdk_nvme_ctrlr *ctrlr)
 	return transport->ops.ctrlr_get_max_sges(ctrlr);
 }
 
+int
+nvme_transport_ctrlr_reserve_cmb(struct spdk_nvme_ctrlr *ctrlr)
+{
+	const struct spdk_nvme_transport *transport = nvme_get_transport(ctrlr->trid.trstring);
+
+	assert(transport != NULL);
+	if (transport->ops.ctrlr_reserve_cmb != NULL) {
+		return transport->ops.ctrlr_reserve_cmb(ctrlr);
+	}
+
+	return -ENOTSUP;
+}
+
 void *
 nvme_transport_ctrlr_map_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size)
 {