nvme: Only memory map CMB if user requests it

We only need to register the memory for the CMB if the user
plans to map it for use with data. Delay the operation until then.

This also gives us a way to support unmapping the CMB.

Change-Id: I6121ae2cc3f6f44efae8b52b6582ff9f68432bc8
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/786
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

lib/nvme/nvme_pcie.c

@@ -92,8 +92,6 @@ struct nvme_pcie_ctrlr {
 
 		void *mem_register_addr;
 		size_t mem_register_size;
-
-		bool io_data_supported;
 	} cmb;
 
 	/** stride in uint32_t units between doorbell registers (1 = 4 bytes, 2 = 8 bytes, ...) */
@@ -480,7 +478,6 @@ nvme_pcie_ctrlr_map_cmb(struct nvme_pcie_ctrlr *pctrlr)
 	union spdk_nvme_cmbsz_register cmbsz;
 	union spdk_nvme_cmbloc_register cmbloc;
 	uint64_t size, unit_size, offset, bar_size, bar_phys_addr;
-	uint64_t mem_register_start, mem_register_end;
 
 	if (nvme_pcie_ctrlr_get_cmbsz(pctrlr, &cmbsz) ||
 	    nvme_pcie_ctrlr_get_cmbloc(pctrlr, &cmbloc)) {
@@ -529,33 +526,8 @@ nvme_pcie_ctrlr_map_cmb(struct nvme_pcie_ctrlr *pctrlr)
 		pctrlr->ctrlr.opts.use_cmb_sqs = false;
 	}
 
-	/* If only SQS is supported use legacy mapping */
-	if (cmbsz.bits.sqs && !(cmbsz.bits.wds || cmbsz.bits.rds)) {
-		return;
-	}
-
-	/* If CMB is less than 4MiB in size then abort CMB mapping */
-	if (pctrlr->cmb.size < (1ULL << 22)) {
-		goto exit;
-	}
-
-	mem_register_start = _2MB_PAGE((uintptr_t)pctrlr->cmb.bar_va + offset + VALUE_2MB - 1);
-	mem_register_end = _2MB_PAGE((uintptr_t)pctrlr->cmb.bar_va + offset + pctrlr->cmb.size);
-	pctrlr->cmb.mem_register_addr = (void *)mem_register_start;
-	pctrlr->cmb.mem_register_size = mem_register_end - mem_register_start;
-
-	rc = spdk_mem_register(pctrlr->cmb.mem_register_addr, pctrlr->cmb.mem_register_size);
-	if (rc) {
-		SPDK_ERRLOG("spdk_mem_register() failed\n");
-		goto exit;
-	}
-	pctrlr->cmb.current_offset = mem_register_start - ((uint64_t)pctrlr->cmb.bar_va);
-	pctrlr->cmb.end = mem_register_end - ((uint64_t)pctrlr->cmb.bar_va);
-	pctrlr->cmb.io_data_supported = true;
-
 	return;
 exit:
-	pctrlr->cmb.bar_va = NULL;
 	pctrlr->ctrlr.opts.use_cmb_sqs = false;
 	return;
 }
@@ -585,7 +557,15 @@ static void *
 nvme_pcie_ctrlr_map_io_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size)
 {
 	struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(ctrlr);
-	uint64_t offset;
+	union spdk_nvme_cmbsz_register cmbsz;
+	union spdk_nvme_cmbloc_register cmbloc;
+	uint64_t mem_register_start, mem_register_end;
+	int rc;
+
+	if (pctrlr->cmb.mem_register_addr != NULL) {
+		*size = pctrlr->cmb.mem_register_size;
+		return pctrlr->cmb.mem_register_addr;
+	}
 
 	*size = 0;
 
@@ -594,33 +574,65 @@ nvme_pcie_ctrlr_map_io_cmb(struct spdk_nvme_ctrlr *ctrlr, size_t *size)
 		return NULL;
 	}
 
-	if (!pctrlr->cmb.io_data_supported) {
-		SPDK_DEBUGLOG(SPDK_LOG_NVME, "CMB doesn't support I/O data\n");
-		return NULL;
-	}
-
 	if (ctrlr->opts.use_cmb_sqs) {
 		SPDK_ERRLOG("CMB is already in use for submission queues.\n");
 		return NULL;
 	}
 
-	offset = (pctrlr->cmb.current_offset + (3)) & ~(3);
+	if (nvme_pcie_ctrlr_get_cmbsz(pctrlr, &cmbsz) ||
-
+	    nvme_pcie_ctrlr_get_cmbloc(pctrlr, &cmbloc)) {
-	if (offset >= pctrlr->cmb.end) {
+		SPDK_ERRLOG("get registers failed\n");
 		return NULL;
 	}
 
-	*size = pctrlr->cmb.end - offset;
+	/* If only SQS is supported */
+	if (!(cmbsz.bits.wds || cmbsz.bits.rds)) {
+		return NULL;
+	}
 
-	pctrlr->cmb.current_offset = pctrlr->cmb.end;
+	/* If CMB is less than 4MiB in size then abort CMB mapping */
+	if (pctrlr->cmb.size < (1ULL << 22)) {
+		return NULL;
+	}
 
-	return pctrlr->cmb.bar_va + offset;
+	mem_register_start = _2MB_PAGE((uintptr_t)pctrlr->cmb.bar_va + pctrlr->cmb.current_offset +
+				       VALUE_2MB - 1);
+	mem_register_end = _2MB_PAGE((uintptr_t)pctrlr->cmb.bar_va + pctrlr->cmb.current_offset +
+				     pctrlr->cmb.size);
+	pctrlr->cmb.mem_register_addr = (void *)mem_register_start;
+	pctrlr->cmb.mem_register_size = mem_register_end - mem_register_start;
+
+	rc = spdk_mem_register((void *)mem_register_start, mem_register_end - mem_register_start);
+	if (rc) {
+		SPDK_ERRLOG("spdk_mem_register() failed\n");
+		return NULL;
+	}
+
+	pctrlr->cmb.mem_register_addr = (void *)mem_register_start;
+	pctrlr->cmb.mem_register_size = mem_register_end - mem_register_start;
+
+	*size = pctrlr->cmb.mem_register_size;
+	return pctrlr->cmb.mem_register_addr;
 }
 
 static int
 nvme_pcie_ctrlr_unmap_io_cmb(struct spdk_nvme_ctrlr *ctrlr)
 {
-	return 0;
+	struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(ctrlr);
+	int rc;
+
+	if (pctrlr->cmb.mem_register_addr == NULL) {
+		return 0;
+	}
+
+	rc = spdk_mem_unregister(pctrlr->cmb.mem_register_addr, pctrlr->cmb.mem_register_size);
+
+	if (rc == 0) {
+		pctrlr->cmb.mem_register_addr = NULL;
+		pctrlr->cmb.mem_register_size = 0;
+	}
+
+	return rc;
 }
 
 static int
@@ -971,6 +983,11 @@ nvme_pcie_ctrlr_alloc_cmb(struct spdk_nvme_ctrlr *ctrlr, uint64_t length, uint64
 	struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(ctrlr);
 	uint64_t round_offset;
 
+	if (pctrlr->cmb.mem_register_addr != NULL) {
+		/* BAR is mapped for data */
+		return -1;
+	}
+
 	round_offset = pctrlr->cmb.current_offset;
 	round_offset = (round_offset + (aligned - 1)) & ~(aligned - 1);