diff mbox series

[v4,21/24] nvme: support multiple namespaces

Message ID 20191219130921.309264-22-k.jensen@samsung.com (mailing list archive)
State New, archived
Headers show
Series nvme: support NVMe v1.3d, SGLs and multiple namespaces | expand

Commit Message

Klaus Jensen Dec. 19, 2019, 1:09 p.m. UTC
This adds support for multiple namespaces by introducing a new 'nvme-ns'
device model. The nvme device creates a bus named from the device name
('id'). The nvme-ns devices then connect to this and registers
themselves with the nvme device.

This changes how an nvme device is created. Example with two namespaces:

  -drive file=nvme0n1.img,if=none,id=disk1
  -drive file=nvme0n2.img,if=none,id=disk2
  -device nvme,serial=deadbeef,id=nvme0
  -device nvme-ns,drive=disk1,bus=nvme0,nsid=1
  -device nvme-ns,drive=disk2,bus=nvme0,nsid=2

The drive property is kept on the nvme device to keep the change
backward compatible, but the property is now optional. Specifying a
drive for the nvme device will always create the namespace with nsid 1.

Signed-off-by: Klaus Jensen <klaus.jensen@cnexlabs.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/block/Makefile.objs |   2 +-
 hw/block/nvme-ns.c     | 158 ++++++++++++++++++++++++++++
 hw/block/nvme-ns.h     |  60 +++++++++++
 hw/block/nvme.c        | 229 +++++++++++++++++++++++++----------------
 hw/block/nvme.h        |  47 ++++-----
 hw/block/trace-events  |   6 +-
 6 files changed, 386 insertions(+), 116 deletions(-)
 create mode 100644 hw/block/nvme-ns.c
 create mode 100644 hw/block/nvme-ns.h

Comments

Michal Privoznik Dec. 19, 2019, 3:11 p.m. UTC | #1
On 12/19/19 2:09 PM, Klaus Jensen wrote:
> This adds support for multiple namespaces by introducing a new 'nvme-ns'
> device model. The nvme device creates a bus named from the device name
> ('id'). The nvme-ns devices then connect to this and registers
> themselves with the nvme device.
> 
> This changes how an nvme device is created. Example with two namespaces:
> 
>   -drive file=nvme0n1.img,if=none,id=disk1
>   -drive file=nvme0n2.img,if=none,id=disk2
>   -device nvme,serial=deadbeef,id=nvme0
>   -device nvme-ns,drive=disk1,bus=nvme0,nsid=1
>   -device nvme-ns,drive=disk2,bus=nvme0,nsid=2
> 
> The drive property is kept on the nvme device to keep the change
> backward compatible, but the property is now optional. Specifying a
> drive for the nvme device will always create the namespace with nsid 1.
> 
> Signed-off-by: Klaus Jensen <klaus.jensen@cnexlabs.com>
> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>

Klaus, just to make sure I understand correctly, this implements
multiple namespaces for *emulated* NVMe, right? I'm asking because I
just merged libvirt patches to support:

-drive
file.driver=nvme,file.device=0000:01:00.0,file.namespace=1,format=raw,if=none,id=drive-virtio-disk0
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1

and seeing these patches made me doubt my design. But if your patches
touch emulated NVMe only, then libvirt's fine because it doesn't expose
that just yet.

Michal
Klaus Jensen Dec. 19, 2019, 5:26 p.m. UTC | #2
On Dec 19 16:11, Michal Prívozník wrote:
> On 12/19/19 2:09 PM, Klaus Jensen wrote:
> > This adds support for multiple namespaces by introducing a new 'nvme-ns'
> > device model. The nvme device creates a bus named from the device name
> > ('id'). The nvme-ns devices then connect to this and registers
> > themselves with the nvme device.
> > 
> > This changes how an nvme device is created. Example with two namespaces:
> > 
> >   -drive file=nvme0n1.img,if=none,id=disk1
> >   -drive file=nvme0n2.img,if=none,id=disk2
> >   -device nvme,serial=deadbeef,id=nvme0
> >   -device nvme-ns,drive=disk1,bus=nvme0,nsid=1
> >   -device nvme-ns,drive=disk2,bus=nvme0,nsid=2
> > 
> > The drive property is kept on the nvme device to keep the change
> > backward compatible, but the property is now optional. Specifying a
> > drive for the nvme device will always create the namespace with nsid 1.
> > 
> > Signed-off-by: Klaus Jensen <klaus.jensen@cnexlabs.com>
> > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> 
> Klaus, just to make sure I understand correctly, this implements
> multiple namespaces for *emulated* NVMe, right? I'm asking because I
> just merged libvirt patches to support:
> 
> -drive
> file.driver=nvme,file.device=0000:01:00.0,file.namespace=1,format=raw,if=none,id=drive-virtio-disk0
> -device
> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
> 
> and seeing these patches made me doubt my design. But if your patches
> touch emulated NVMe only, then libvirt's fine because it doesn't expose
> that just yet.
> 
> Michal
> 

Hi Michal,

Yes, this is only for the emulated nvme controller.
diff mbox series

Patch

diff --git a/hw/block/Makefile.objs b/hw/block/Makefile.objs
index 28c2495a00dc..45f463462f1e 100644
--- a/hw/block/Makefile.objs
+++ b/hw/block/Makefile.objs
@@ -7,7 +7,7 @@  common-obj-$(CONFIG_PFLASH_CFI02) += pflash_cfi02.o
 common-obj-$(CONFIG_XEN) += xen-block.o
 common-obj-$(CONFIG_ECC) += ecc.o
 common-obj-$(CONFIG_ONENAND) += onenand.o
-common-obj-$(CONFIG_NVME_PCI) += nvme.o
+common-obj-$(CONFIG_NVME_PCI) += nvme.o nvme-ns.o
 common-obj-$(CONFIG_SWIM) += swim.o
 
 obj-$(CONFIG_SH4) += tc58128.o
diff --git a/hw/block/nvme-ns.c b/hw/block/nvme-ns.c
new file mode 100644
index 000000000000..36deedee07a6
--- /dev/null
+++ b/hw/block/nvme-ns.c
@@ -0,0 +1,158 @@ 
+#include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "qemu/cutils.h"
+#include "qemu/log.h"
+#include "hw/block/block.h"
+#include "hw/pci/msix.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/block-backend.h"
+#include "qapi/error.h"
+
+#include "hw/qdev-properties.h"
+#include "hw/qdev-core.h"
+
+#include "nvme.h"
+#include "nvme-ns.h"
+
+static int nvme_ns_init(NvmeNamespace *ns)
+{
+    NvmeIdNs *id_ns = &ns->id_ns;
+
+    id_ns->lbaf[0].ds = BDRV_SECTOR_BITS;
+    id_ns->nuse = id_ns->ncap = id_ns->nsze =
+        cpu_to_le64(nvme_ns_nlbas(ns));
+
+    return 0;
+}
+
+static int nvme_ns_init_blk(NvmeCtrl *n, NvmeNamespace *ns, NvmeIdCtrl *id,
+    Error **errp)
+{
+    uint64_t perm, shared_perm;
+
+    Error *local_err = NULL;
+    int ret;
+
+    perm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE;
+    shared_perm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
+        BLK_PERM_GRAPH_MOD;
+
+    ret = blk_set_perm(ns->blk, perm, shared_perm, &local_err);
+    if (ret) {
+        error_propagate_prepend(errp, local_err, "blk_set_perm: ");
+        return ret;
+    }
+
+    ns->size = blk_getlength(ns->blk);
+    if (ns->size < 0) {
+        error_setg_errno(errp, -ns->size, "blk_getlength");
+        return 1;
+    }
+
+    switch (n->conf.wce) {
+    case ON_OFF_AUTO_ON:
+        n->features.volatile_wc = 1;
+        break;
+    case ON_OFF_AUTO_OFF:
+        n->features.volatile_wc = 0;
+    case ON_OFF_AUTO_AUTO:
+        n->features.volatile_wc = blk_enable_write_cache(ns->blk);
+        break;
+    default:
+        abort();
+    }
+
+    blk_set_enable_write_cache(ns->blk, n->features.volatile_wc);
+
+    return 0;
+}
+
+static int nvme_ns_check_constraints(NvmeNamespace *ns, Error **errp)
+{
+    if (!ns->blk) {
+        error_setg(errp, "block backend not configured");
+        return 1;
+    }
+
+    return 0;
+}
+
+int nvme_ns_setup(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
+{
+    Error *local_err = NULL;
+
+    if (nvme_ns_check_constraints(ns, &local_err)) {
+        error_propagate_prepend(errp, local_err,
+            "nvme_ns_check_constraints: ");
+        return 1;
+    }
+
+    if (nvme_ns_init_blk(n, ns, &n->id_ctrl, &local_err)) {
+        error_propagate_prepend(errp, local_err, "nvme_ns_init_blk: ");
+        return 1;
+    }
+
+    nvme_ns_init(ns);
+    if (nvme_register_namespace(n, ns, &local_err)) {
+        error_propagate_prepend(errp, local_err, "nvme_register_namespace: ");
+        return 1;
+    }
+
+    return 0;
+}
+
+static void nvme_ns_realize(DeviceState *dev, Error **errp)
+{
+    NvmeNamespace *ns = NVME_NS(dev);
+    BusState *s = qdev_get_parent_bus(dev);
+    NvmeCtrl *n = NVME(s->parent);
+    Error *local_err = NULL;
+
+    if (nvme_ns_setup(n, ns, &local_err)) {
+        error_propagate_prepend(errp, local_err, "nvme_ns_setup: ");
+        return;
+    }
+}
+
+static Property nvme_ns_props[] = {
+    DEFINE_NVME_NS_PROPERTIES(NvmeNamespace, params),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void nvme_ns_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+
+    dc->bus_type = TYPE_NVME_BUS;
+    dc->realize = nvme_ns_realize;
+    dc->props = nvme_ns_props;
+    dc->desc = "virtual nvme namespace";
+}
+
+static void nvme_ns_instance_init(Object *obj)
+{
+    NvmeNamespace *ns = NVME_NS(obj);
+    char *bootindex = g_strdup_printf("/namespace@%d,0", ns->params.nsid);
+
+    device_add_bootindex_property(obj, &ns->bootindex, "bootindex",
+        bootindex, DEVICE(obj), &error_abort);
+
+    g_free(bootindex);
+}
+
+static const TypeInfo nvme_ns_info = {
+    .name = TYPE_NVME_NS,
+    .parent = TYPE_DEVICE,
+    .class_init = nvme_ns_class_init,
+    .instance_size = sizeof(NvmeNamespace),
+    .instance_init = nvme_ns_instance_init,
+};
+
+static void nvme_ns_register_types(void)
+{
+    type_register_static(&nvme_ns_info);
+}
+
+type_init(nvme_ns_register_types)
diff --git a/hw/block/nvme-ns.h b/hw/block/nvme-ns.h
new file mode 100644
index 000000000000..b564bac25f6d
--- /dev/null
+++ b/hw/block/nvme-ns.h
@@ -0,0 +1,60 @@ 
+#ifndef NVME_NS_H
+#define NVME_NS_H
+
+#define TYPE_NVME_NS "nvme-ns"
+#define NVME_NS(obj) \
+    OBJECT_CHECK(NvmeNamespace, (obj), TYPE_NVME_NS)
+
+#define DEFINE_NVME_NS_PROPERTIES(_state, _props) \
+    DEFINE_PROP_DRIVE("drive", _state, blk), \
+    DEFINE_PROP_UINT32("nsid", _state, _props.nsid, 0)
+
+typedef struct NvmeNamespaceParams {
+    uint32_t nsid;
+} NvmeNamespaceParams;
+
+typedef struct NvmeNamespace {
+    DeviceState  parent_obj;
+    BlockBackend *blk;
+    int32_t      bootindex;
+    int64_t      size;
+
+    NvmeIdNs            id_ns;
+    NvmeNamespaceParams params;
+} NvmeNamespace;
+
+static inline uint32_t nvme_nsid(NvmeNamespace *ns)
+{
+    if (ns) {
+        return ns->params.nsid;
+    }
+
+    return -1;
+}
+
+static inline NvmeLBAF nvme_ns_lbaf(NvmeNamespace *ns)
+{
+    NvmeIdNs *id_ns = &ns->id_ns;
+    return id_ns->lbaf[NVME_ID_NS_FLBAS_INDEX(id_ns->flbas)];
+}
+
+static inline uint8_t nvme_ns_lbads(NvmeNamespace *ns)
+{
+    return nvme_ns_lbaf(ns).ds;
+}
+
+static inline size_t nvme_ns_lbads_bytes(NvmeNamespace *ns)
+{
+    return 1 << nvme_ns_lbads(ns);
+}
+
+static inline uint64_t nvme_ns_nlbas(NvmeNamespace *ns)
+{
+    return ns->size >> nvme_ns_lbads(ns);
+}
+
+typedef struct NvmeCtrl NvmeCtrl;
+
+int nvme_ns_setup(NvmeCtrl *n, NvmeNamespace *ns, Error **errp);
+
+#endif /* NVME_NS_H */
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index b3fca3c4ea58..e1bf9bf3798b 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -17,10 +17,11 @@ 
 /**
  * Usage: add options:
  *      -drive file=<file>,if=none,id=<drive_id>
- *      -device nvme,drive=<drive_id>,serial=<serial>,id=<id[optional]>, \
+ *      -device nvme,serial=<serial>,id=<id[optional]>, \
  *              cmb_size_mb=<cmb_size_mb[optional]>, \
  *              num_queues=<N[optional]>, \
  *              mdts=<mdts[optional]>
+ *      -device nvme-ns,drive=<drive_id>,bus=nvme0,nsid=1
  *
  * Note cmb_size_mb denotes size of CMB in MB. CMB is assumed to be at
  * offset 0 in BAR2 and supports only WDS, RDS and SQS for now.
@@ -28,6 +29,7 @@ 
 
 #include "qemu/osdep.h"
 #include "qemu/units.h"
+#include "qemu/error-report.h"
 #include "hw/block/block.h"
 #include "hw/pci/msix.h"
 #include "hw/pci/pci.h"
@@ -43,6 +45,7 @@ 
 #include "qemu/cutils.h"
 #include "trace.h"
 #include "nvme.h"
+#include "nvme-ns.h"
 
 #define NVME_SPEC_VER 0x00010300
 #define NVME_MAX_QS PCI_MSIX_FLAGS_QSIZE
@@ -86,6 +89,17 @@  static int nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf, int size)
     return pci_dma_read(&n->parent_obj, addr, buf, size);
 }
 
+static uint16_t nvme_nsid_err(NvmeCtrl *n, uint32_t nsid)
+{
+    if (nsid && nsid < n->num_namespaces) {
+        trace_nvme_dev_err_inactive_ns(nsid, n->num_namespaces);
+        return NVME_INVALID_FIELD | NVME_DNR;
+    }
+
+    trace_nvme_dev_err_invalid_ns(nsid, n->num_namespaces);
+    return NVME_INVALID_NSID | NVME_DNR;
+}
+
 static int nvme_check_sqid(NvmeCtrl *n, uint16_t sqid)
 {
     return sqid < n->params.num_queues && n->sq[sqid] != NULL ? 0 : -1;
@@ -912,7 +926,7 @@  static inline uint16_t nvme_check_bounds(NvmeCtrl *n, uint64_t slba,
     uint64_t nsze = le64_to_cpu(ns->id_ns.nsze);
 
     if (unlikely((slba + nlb) > nsze)) {
-        block_acct_invalid(blk_get_stats(n->conf.blk),
+        block_acct_invalid(blk_get_stats(ns->blk),
             nvme_req_is_write(req) ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ);
         trace_nvme_dev_err_invalid_lba_range(slba, nlb, nsze);
         return NVME_LBA_RANGE | NVME_DNR;
@@ -947,11 +961,12 @@  static uint16_t nvme_check_rw(NvmeCtrl *n, NvmeRequest *req)
 
 static void nvme_rw_cb(NvmeRequest *req, void *opaque)
 {
+    NvmeNamespace *ns = req->ns;
     NvmeSQueue *sq = req->sq;
     NvmeCtrl *n = sq->ctrl;
     NvmeCQueue *cq = n->cq[sq->cqid];
 
-    trace_nvme_dev_rw_cb(nvme_cid(req), req->cmd.nsid);
+    trace_nvme_dev_rw_cb(nvme_cid(req), nvme_nsid(ns));
 
     nvme_enqueue_req_completion(cq, req);
 }
@@ -1034,7 +1049,8 @@  static void nvme_aio_cb(void *opaque, int ret)
 
 static uint16_t nvme_flush(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 {
-    NvmeAIO *aio = nvme_aio_new(n->conf.blk, 0x0, 0, NULL, NULL, req, NULL);
+    NvmeNamespace *ns = req->ns;
+    NvmeAIO *aio = nvme_aio_new(ns->blk, 0x0, 0, NULL, NULL, req, NULL);
 
     nvme_req_register_aio(req, aio, NVME_AIO_OPC_FLUSH);
     nvme_aio(aio);
@@ -1056,19 +1072,19 @@  static uint16_t nvme_write_zeros(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
     req->slba = le64_to_cpu(rw->slba);
     req->nlb  = le16_to_cpu(rw->nlb) + 1;
 
-    trace_nvme_dev_write_zeros(nvme_cid(req), le32_to_cpu(cmd->nsid),
-        req->slba, req->nlb);
+    trace_nvme_dev_write_zeros(nvme_cid(req), nvme_nsid(ns), req->slba,
+        req->nlb);
 
     status = nvme_check_bounds(n, req->slba, req->nlb, req);
     if (unlikely(status)) {
-        block_acct_invalid(blk_get_stats(n->conf.blk), BLOCK_ACCT_WRITE);
+        block_acct_invalid(blk_get_stats(ns->blk), BLOCK_ACCT_WRITE);
         return status;
     }
 
     offset = req->slba << nvme_ns_lbads(ns);
     count = req->nlb << nvme_ns_lbads(ns);
 
-    aio = nvme_aio_new(n->conf.blk, offset, count, NULL, NULL, req, NULL);
+    aio = nvme_aio_new(ns->blk, offset, count, NULL, NULL, req, NULL);
 
     nvme_req_register_aio(req, aio, NVME_AIO_OPC_WRITE_ZEROES);
     nvme_aio(aio);
@@ -1088,22 +1104,23 @@  static uint16_t nvme_rw(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
     req->nlb  = le16_to_cpu(rw->nlb) + 1;
     req->slba = le64_to_cpu(rw->slba);
 
-    trace_nvme_dev_rw(nvme_req_is_write(req) ? "write" : "read", req->nlb,
-        req->nlb << nvme_ns_lbads(req->ns), req->slba);
+    trace_nvme_dev_rw(nvme_cid(req), nvme_req_is_write(req) ? "write" : "read",
+        nvme_nsid(ns), req->nlb, req->nlb << nvme_ns_lbads(ns),
+        req->slba);
 
     status = nvme_check_rw(n, req);
     if (status) {
-        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
+        block_acct_invalid(blk_get_stats(ns->blk), acct);
         return status;
     }
 
     status = nvme_map(n, cmd, req);
     if (status) {
-        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
+        block_acct_invalid(blk_get_stats(ns->blk), acct);
         return status;
     }
 
-    nvme_rw_aio(n->conf.blk, req->slba << nvme_ns_lbads(ns), req);
+    nvme_rw_aio(ns->blk, req->slba << nvme_ns_lbads(ns), req);
     nvme_req_set_cb(req, nvme_rw_cb, NULL);
 
     return NVME_NO_COMPLETE;
@@ -1115,12 +1132,11 @@  static uint16_t nvme_io_cmd(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 
     trace_nvme_dev_io_cmd(nvme_cid(req), nsid, le16_to_cpu(req->sq->sqid), cmd->opcode);
 
-    if (unlikely(nsid == 0 || nsid > n->num_namespaces)) {
-        trace_nvme_dev_err_invalid_ns(nsid, n->num_namespaces);
-        return NVME_INVALID_NSID | NVME_DNR;
-    }
+    req->ns = nvme_ns(n, nsid);
 
-    req->ns = &n->namespaces[nsid - 1];
+    if (unlikely(!req->ns)) {
+        return nvme_nsid_err(n, nsid);
+    }
 
     switch (cmd->opcode) {
     case NVME_CMD_FLUSH:
@@ -1266,18 +1282,24 @@  static uint16_t nvme_smart_info(NvmeCtrl *n, NvmeCmd *cmd, uint8_t rae,
     uint64_t units_read = 0, units_written = 0, read_commands = 0,
         write_commands = 0;
     NvmeSmartLog smart;
-    BlockAcctStats *s;
 
     if (nsid && nsid != 0xffffffff) {
         return NVME_INVALID_FIELD | NVME_DNR;
     }
 
-    s = blk_get_stats(n->conf.blk);
+    for (int i = 1; i <= n->num_namespaces; i++) {
+        NvmeNamespace *ns = nvme_ns(n, i);
+        if (!ns) {
+            continue;
+        }
+
+        BlockAcctStats *s = blk_get_stats(ns->blk);
 
-    units_read = s->nr_bytes[BLOCK_ACCT_READ] >> BDRV_SECTOR_BITS;
-    units_written = s->nr_bytes[BLOCK_ACCT_WRITE] >> BDRV_SECTOR_BITS;
-    read_commands = s->nr_ops[BLOCK_ACCT_READ];
-    write_commands = s->nr_ops[BLOCK_ACCT_WRITE];
+        units_read += s->nr_bytes[BLOCK_ACCT_READ] >> BDRV_SECTOR_BITS;
+        units_written += s->nr_bytes[BLOCK_ACCT_WRITE] >> BDRV_SECTOR_BITS;
+        read_commands += s->nr_ops[BLOCK_ACCT_READ];
+        write_commands += s->nr_ops[BLOCK_ACCT_WRITE];
+    }
 
     if (off > sizeof(smart)) {
         return NVME_INVALID_FIELD | NVME_DNR;
@@ -1487,19 +1509,25 @@  static uint16_t nvme_identify_ctrl(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 
 static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 {
-    NvmeNamespace *ns;
+    NvmeIdNs *id_ns, inactive = { 0 };
     uint32_t nsid = le32_to_cpu(cmd->nsid);
+    NvmeNamespace *ns = nvme_ns(n, nsid);
 
     trace_nvme_dev_identify_ns(nsid);
 
-    if (unlikely(nsid == 0 || nsid > n->num_namespaces)) {
-        trace_nvme_dev_err_invalid_ns(nsid, n->num_namespaces);
-        return NVME_INVALID_NSID | NVME_DNR;
-    }
+    if (unlikely(!ns)) {
+        uint16_t status = nvme_nsid_err(n, nsid);
+
+        if (!nvme_status_is_error(status, NVME_INVALID_FIELD)) {
+            return status;
+        }
 
-    ns = &n->namespaces[nsid - 1];
+        id_ns = &inactive;
+    } else {
+        id_ns = &ns->id_ns;
+    }
 
-    return nvme_dma(n, (uint8_t *) &ns->id_ns, sizeof(ns->id_ns), cmd,
+    return nvme_dma(n, (uint8_t *) id_ns, sizeof(NvmeIdNs), cmd,
         DMA_DIRECTION_FROM_DEVICE, req);
 }
 
@@ -1515,11 +1543,11 @@  static uint16_t nvme_identify_ns_list(NvmeCtrl *n, NvmeCmd *cmd,
     trace_nvme_dev_identify_ns_list(min_nsid);
 
     list = g_malloc0(data_len);
-    for (i = 0; i < n->num_namespaces; i++) {
-        if (i < min_nsid) {
+    for (i = 1; i <= n->num_namespaces; i++) {
+        if (i <= min_nsid || !nvme_ns(n, i)) {
             continue;
         }
-        list[j++] = cpu_to_le32(i + 1);
+        list[j++] = cpu_to_le32(i);
         if (j == data_len / sizeof(uint32_t)) {
             break;
         }
@@ -1549,9 +1577,8 @@  static uint16_t nvme_identify_ns_descr_list(NvmeCtrl *n, NvmeCmd *cmd,
 
     trace_nvme_dev_identify_ns_descr_list(nsid);
 
-    if (unlikely(nsid == 0 || nsid > n->num_namespaces)) {
-        trace_nvme_dev_err_invalid_ns(nsid, n->num_namespaces);
-        return NVME_INVALID_NSID | NVME_DNR;
+    if (unlikely(!nvme_ns(n, nsid))) {
+        return nvme_nsid_err(n, nsid);
     }
 
     /*
@@ -1691,7 +1718,7 @@  static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
         result = cpu_to_le32(n->features.err_rec);
         break;
     case NVME_VOLATILE_WRITE_CACHE:
-        result = blk_enable_write_cache(n->conf.blk);
+        result = cpu_to_le32(n->features.volatile_wc);
         trace_nvme_dev_getfeat_vwcache(result ? "enabled" : "disabled");
         break;
     case NVME_NUMBER_OF_QUEUES:
@@ -1745,6 +1772,8 @@  static uint16_t nvme_set_feature_timestamp(NvmeCtrl *n, NvmeCmd *cmd,
 
 static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 {
+    NvmeNamespace *ns;
+
     uint32_t dw10 = le32_to_cpu(cmd->cdw10);
     uint32_t dw11 = le32_to_cpu(cmd->cdw11);
 
@@ -1776,8 +1805,19 @@  static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
 
         break;
     case NVME_VOLATILE_WRITE_CACHE:
-        blk_set_enable_write_cache(n->conf.blk, dw11 & 1);
+        n->features.volatile_wc = dw11;
+
+        for (int i = 1; i <= n->num_namespaces; i++) {
+            ns = nvme_ns(n, i);
+            if (!ns) {
+                continue;
+            }
+
+            blk_set_enable_write_cache(ns->blk, dw11 & 1);
+        }
+
         break;
+
     case NVME_NUMBER_OF_QUEUES:
         if (n->qs_created) {
             return NVME_CMD_SEQ_ERROR | NVME_DNR;
@@ -1902,9 +1942,17 @@  static void nvme_process_sq(void *opaque)
 
 static void nvme_clear_ctrl(NvmeCtrl *n)
 {
+    NvmeNamespace *ns;
     int i;
 
-    blk_drain(n->conf.blk);
+    for (i = 1; i <= n->num_namespaces; i++) {
+        ns = nvme_ns(n, i);
+        if (!ns) {
+            continue;
+        }
+
+        blk_drain(ns->blk);
+    }
 
     for (i = 0; i < n->params.num_queues; i++) {
         if (n->sq[i] != NULL) {
@@ -1927,7 +1975,15 @@  static void nvme_clear_ctrl(NvmeCtrl *n)
     n->outstanding_aers = 0;
     n->qs_created = false;
 
-    blk_flush(n->conf.blk);
+    for (i = 1; i <= n->num_namespaces; i++) {
+        ns = nvme_ns(n, i);
+        if (!ns) {
+            continue;
+        }
+
+        blk_flush(ns->blk);
+    }
+
     n->bar.cc = 0;
 }
 
@@ -2347,8 +2403,8 @@  static int nvme_check_constraints(NvmeCtrl *n, Error **errp)
 {
     NvmeParams *params = &n->params;
 
-    if (!n->conf.blk) {
-        error_setg(errp, "nvme: block backend not configured");
+    if (!n->namespace.blk && !n->parent_obj.qdev.id) {
+        error_setg(errp, "nvme: invalid 'id' parameter");
         return 1;
     }
 
@@ -2365,22 +2421,10 @@  static int nvme_check_constraints(NvmeCtrl *n, Error **errp)
     return 0;
 }
 
-static int nvme_init_blk(NvmeCtrl *n, Error **errp)
-{
-    blkconf_blocksizes(&n->conf);
-    if (!blkconf_apply_backend_options(&n->conf, blk_is_read_only(n->conf.blk),
-        false, errp)) {
-        return 1;
-    }
-
-    return 0;
-}
-
 static void nvme_init_state(NvmeCtrl *n)
 {
-    n->num_namespaces = 1;
+    n->num_namespaces = 0;
     n->reg_size = pow2ceil(0x1004 + 2 * (n->params.num_queues + 1) * 4);
-    n->namespaces = g_new0(NvmeNamespace, n->num_namespaces);
     n->sq = g_new0(NvmeSQueue *, n->params.num_queues);
     n->cq = g_new0(NvmeCQueue *, n->params.num_queues);
 
@@ -2495,12 +2539,7 @@  static void nvme_init_ctrl(NvmeCtrl *n)
     id->cqes = (0x4 << 4) | 0x4;
     id->nn = cpu_to_le32(n->num_namespaces);
     id->oncs = cpu_to_le16(NVME_ONCS_WRITE_ZEROS | NVME_ONCS_TIMESTAMP);
-
-
-    if (blk_enable_write_cache(n->conf.blk)) {
-        id->vwc = 1;
-    }
-
+    id->vwc = 1;
     id->sgls = cpu_to_le32(0x1);
 
     strcpy((char *) id->subnqn, "nqn.2019-08.org.qemu:");
@@ -2521,22 +2560,25 @@  static void nvme_init_ctrl(NvmeCtrl *n)
     n->bar.intmc = n->bar.intms = 0;
 }
 
-static int nvme_init_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
+int nvme_register_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
 {
-    int64_t bs_size;
-    NvmeIdNs *id_ns = &ns->id_ns;
+    uint32_t nsid = nvme_nsid(ns);
+
+    if (nsid == 0 || nsid > NVME_MAX_NAMESPACES) {
+        error_setg(errp, "invalid nsid");
+        return 1;
+    }
 
-    bs_size = blk_getlength(n->conf.blk);
-    if (bs_size < 0) {
-        error_setg_errno(errp, -bs_size, "blk_getlength");
+    if (n->namespaces[nsid - 1]) {
+        error_setg(errp, "nsid must be unique");
         return 1;
     }
 
-    id_ns->lbaf[0].ds = BDRV_SECTOR_BITS;
-    n->ns_size = bs_size;
+    trace_nvme_dev_register_namespace(nsid);
 
-    id_ns->ncap = id_ns->nuse = id_ns->nsze =
-        cpu_to_le64(nvme_ns_nlbas(n, ns));
+    n->namespaces[nsid - 1] = ns;
+    n->num_namespaces = MAX(n->num_namespaces, nsid);
+    n->id_ctrl.nn = cpu_to_le32(n->num_namespaces);
 
     return 0;
 }
@@ -2544,30 +2586,31 @@  static int nvme_init_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
 static void nvme_realize(PCIDevice *pci_dev, Error **errp)
 {
     NvmeCtrl *n = NVME(pci_dev);
+    NvmeNamespace *ns;
     Error *local_err = NULL;
-    int i;
 
     if (nvme_check_constraints(n, &local_err)) {
         error_propagate_prepend(errp, local_err, "nvme_check_constraints: ");
         return;
     }
 
+    qbus_create_inplace(&n->bus, sizeof(NvmeBus), TYPE_NVME_BUS,
+        &pci_dev->qdev, n->parent_obj.qdev.id);
+
     nvme_init_state(n);
+    nvme_init_pci(n, pci_dev);
+    nvme_init_ctrl(n);
 
-    if (nvme_init_blk(n, &local_err)) {
-        error_propagate_prepend(errp, local_err, "nvme_init_blk: ");
-        return;
-    }
+    /* setup a namespace if the controller drive property was given */
+    if (n->namespace.blk) {
+        ns = &n->namespace;
+        ns->params.nsid = 1;
 
-    for (i = 0; i < n->num_namespaces; i++) {
-        if (nvme_init_namespace(n, &n->namespaces[i], &local_err)) {
-            error_propagate_prepend(errp, local_err, "nvme_init_namespace: ");
+        if (nvme_ns_setup(n, ns, &local_err)) {
+            error_propagate_prepend(errp, local_err, "nvme_ns_setup: ");
             return;
         }
     }
-
-    nvme_init_pci(n, pci_dev);
-    nvme_init_ctrl(n);
 }
 
 static void nvme_exit(PCIDevice *pci_dev)
@@ -2588,7 +2631,8 @@  static void nvme_exit(PCIDevice *pci_dev)
 }
 
 static Property nvme_props[] = {
-    DEFINE_BLOCK_PROPERTIES(NvmeCtrl, conf),
+    DEFINE_BLOCK_PROPERTIES_BASE(NvmeCtrl, conf), \
+    DEFINE_PROP_DRIVE("drive", NvmeCtrl, namespace.blk), \
     DEFINE_NVME_PROPERTIES(NvmeCtrl, params),
     DEFINE_PROP_END_OF_LIST(),
 };
@@ -2620,26 +2664,35 @@  static void nvme_instance_init(Object *obj)
 {
     NvmeCtrl *s = NVME(obj);
 
-    device_add_bootindex_property(obj, &s->conf.bootindex,
-                                  "bootindex", "/namespace@1,0",
-                                  DEVICE(obj), &error_abort);
+    if (s->namespace.blk) {
+        device_add_bootindex_property(obj, &s->conf.bootindex,
+                                      "bootindex", "/namespace@1,0",
+                                      DEVICE(obj), &error_abort);
+    }
 }
 
 static const TypeInfo nvme_info = {
     .name          = TYPE_NVME,
     .parent        = TYPE_PCI_DEVICE,
     .instance_size = sizeof(NvmeCtrl),
-    .class_init    = nvme_class_init,
     .instance_init = nvme_instance_init,
+    .class_init    = nvme_class_init,
     .interfaces = (InterfaceInfo[]) {
         { INTERFACE_PCIE_DEVICE },
         { }
     },
 };
 
+static const TypeInfo nvme_bus_info = {
+    .name = TYPE_NVME_BUS,
+    .parent = TYPE_BUS,
+    .instance_size = sizeof(NvmeBus),
+};
+
 static void nvme_register_types(void)
 {
     type_register_static(&nvme_info);
+    type_register_static(&nvme_bus_info);
 }
 
 type_init(nvme_register_types)
diff --git a/hw/block/nvme.h b/hw/block/nvme.h
index 2fe3e7b415c2..8a6eec72d81d 100644
--- a/hw/block/nvme.h
+++ b/hw/block/nvme.h
@@ -2,6 +2,9 @@ 
 #define HW_NVME_H
 
 #include "block/nvme.h"
+#include "nvme-ns.h"
+
+#define NVME_MAX_NAMESPACES 256
 
 #define DEFINE_NVME_PROPERTIES(_state, _props) \
     DEFINE_PROP_STRING("serial", _state, _props.serial), \
@@ -100,26 +103,6 @@  typedef struct NvmeCQueue {
     QTAILQ_HEAD(, NvmeRequest) req_list;
 } NvmeCQueue;
 
-typedef struct NvmeNamespace {
-    NvmeIdNs        id_ns;
-} NvmeNamespace;
-
-static inline NvmeLBAF nvme_ns_lbaf(NvmeNamespace *ns)
-{
-    NvmeIdNs *id_ns = &ns->id_ns;
-    return id_ns->lbaf[NVME_ID_NS_FLBAS_INDEX(id_ns->flbas)];
-}
-
-static inline uint8_t nvme_ns_lbads(NvmeNamespace *ns)
-{
-    return nvme_ns_lbaf(ns).ds;
-}
-
-static inline size_t nvme_ns_lbads_bytes(NvmeNamespace *ns)
-{
-    return 1 << nvme_ns_lbads(ns);
-}
-
 typedef enum NvmeAIOOp {
     NVME_AIO_OPC_NONE         = 0x0,
     NVME_AIO_OPC_FLUSH        = 0x1,
@@ -174,6 +157,13 @@  static inline bool nvme_req_is_write(NvmeRequest *req)
     }
 }
 
+#define TYPE_NVME_BUS "nvme-bus"
+#define NVME_BUS(obj) OBJECT_CHECK(NvmeBus, (obj), TYPE_NVME_BUS)
+
+typedef struct NvmeBus {
+    BusState parent_bus;
+} NvmeBus;
+
 #define TYPE_NVME "nvme"
 #define NVME(obj) \
         OBJECT_CHECK(NvmeCtrl, (obj), TYPE_NVME)
@@ -183,8 +173,9 @@  typedef struct NvmeCtrl {
     MemoryRegion iomem;
     MemoryRegion ctrl_mem;
     NvmeBar      bar;
-    BlockConf    conf;
     NvmeParams   params;
+    NvmeBus      bus;
+    BlockConf    conf;
 
     bool        qs_created;
     uint32_t    page_size;
@@ -195,7 +186,6 @@  typedef struct NvmeCtrl {
     uint32_t    reg_size;
     uint32_t    num_namespaces;
     uint32_t    max_q_ents;
-    uint64_t    ns_size;
     uint8_t     outstanding_aers;
     uint32_t    cmbsz;
     uint32_t    cmbloc;
@@ -211,7 +201,8 @@  typedef struct NvmeCtrl {
     QTAILQ_HEAD(, NvmeAsyncEvent) aer_queue;
     int         aer_queued;
 
-    NvmeNamespace   *namespaces;
+    NvmeNamespace   namespace;
+    NvmeNamespace   *namespaces[NVME_MAX_NAMESPACES];
     NvmeSQueue      **sq;
     NvmeCQueue      **cq;
     NvmeSQueue      admin_sq;
@@ -220,9 +211,13 @@  typedef struct NvmeCtrl {
     NvmeFeatureVal  features;
 } NvmeCtrl;
 
-static inline uint64_t nvme_ns_nlbas(NvmeCtrl *n, NvmeNamespace *ns)
+static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid)
 {
-    return n->ns_size >> nvme_ns_lbads(ns);
+    if (!nsid || nsid > n->num_namespaces) {
+        return NULL;
+    }
+
+    return n->namespaces[nsid - 1];
 }
 
 static inline uint16_t nvme_cid(NvmeRequest *req)
@@ -245,4 +240,6 @@  static inline NvmeCtrl *nvme_ctrl(NvmeRequest *req)
     return req->sq->ctrl;
 }
 
+int nvme_register_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp);
+
 #endif /* HW_NVME_H */
diff --git a/hw/block/trace-events b/hw/block/trace-events
index 8901cf087ee2..02f301aa05a8 100644
--- a/hw/block/trace-events
+++ b/hw/block/trace-events
@@ -29,6 +29,7 @@  hd_geometry_guess(void *blk, uint32_t cyls, uint32_t heads, uint32_t secs, int t
 
 # nvme.c
 # nvme traces for successful events
+nvme_dev_register_namespace(uint32_t nsid) "nsid %"PRIu32""
 nvme_dev_irq_msix(uint32_t vector) "raising MSI-X IRQ vector %u"
 nvme_dev_irq_pin(void) "pulsing IRQ pin"
 nvme_dev_irq_masked(void) "IRQ is masked"
@@ -38,7 +39,7 @@  nvme_dev_map_sgl(uint16_t cid, uint8_t typ, uint32_t nlb, uint64_t len) "cid %"P
 nvme_dev_req_register_aio(uint16_t cid, void *aio, const char *blkname, uint64_t offset, uint64_t count, const char *opc, void *req) "cid %"PRIu16" aio %p blk \"%s\" offset %"PRIu64" count %"PRIu64" opc \"%s\" req %p"
 nvme_dev_aio_cb(uint16_t cid, void *aio, const char *blkname, uint64_t offset, const char *opc, void *req) "cid %"PRIu16" aio %p blk \"%s\" offset %"PRIu64" opc \"%s\" req %p"
 nvme_dev_io_cmd(uint16_t cid, uint32_t nsid, uint16_t sqid, uint8_t opcode) "cid %"PRIu16" nsid %"PRIu32" sqid %"PRIu16" opc 0x%"PRIx8""
-nvme_dev_rw(const char *verb, uint32_t blk_count, uint64_t byte_count, uint64_t lba) "%s %"PRIu32" blocks (%"PRIu64" bytes) from LBA %"PRIu64""
+nvme_dev_rw(uint16_t cid, const char *verb, uint32_t nsid, uint32_t nlb, uint64_t count, uint64_t lba) "cid %"PRIu16" %s nsid %"PRIu32" nlb %"PRIu32" count %"PRIu64" lba 0x%"PRIx64""
 nvme_dev_rw_cb(uint16_t cid, uint32_t nsid) "cid %"PRIu16" nsid %"PRIu32""
 nvme_dev_write_zeros(uint16_t cid, uint32_t nsid, uint64_t slba, uint32_t nlb) "cid %"PRIu16" nsid %"PRIu32" slba %"PRIu64" nlb %"PRIu32""
 nvme_dev_create_sq(uint64_t addr, uint16_t sqid, uint16_t cqid, uint16_t qsize, uint16_t qflags) "create submission queue, addr=0x%"PRIx64", sqid=%"PRIu16", cqid=%"PRIu16", qsize=%"PRIu16", qflags=%"PRIu16""
@@ -93,7 +94,8 @@  nvme_dev_err_invalid_prplist_ent(uint64_t prplist) "PRP list entry is null or no
 nvme_dev_err_invalid_prp2_align(uint64_t prp2) "PRP2 is not page aligned: 0x%"PRIx64""
 nvme_dev_err_invalid_prp2_missing(void) "PRP2 is null and more data to be transferred"
 nvme_dev_err_invalid_prp(void) "invalid PRP"
-nvme_dev_err_invalid_ns(uint32_t ns, uint32_t limit) "invalid namespace %u not within 1-%u"
+nvme_dev_err_invalid_ns(uint32_t nsid, uint32_t nn) "nsid %"PRIu32" nn %"PRIu32""
+nvme_dev_err_inactive_ns(uint32_t nsid, uint32_t nn) "nsid %"PRIu32" nn %"PRIu32""
 nvme_dev_err_invalid_opc(uint8_t opc) "invalid opcode 0x%"PRIx8""
 nvme_dev_err_invalid_admin_opc(uint8_t opc) "invalid admin opcode 0x%"PRIx8""
 nvme_dev_err_invalid_lba_range(uint64_t start, uint64_t len, uint64_t limit) "Invalid LBA start=%"PRIu64" len=%"PRIu64" limit=%"PRIu64""