[PATCH RFC v2 00/16] hw/nvme: experimental user-creatable objects

[Klaus Jensen]

From: Klaus Jensen <k.jensen@samsung.com>

v2
  * Use 'zns' instead of 'zoned' for various zns based function name
    prefixes (Keith)

  * Fix the intialization order and get rid of the machine done
    notifier (Kevin). This requires removing the 'attached-ctrls'
    parameter and instead controller just attaching to all namespaces in
    the subsystem. The example below in the cover letter has been
    updated to reflect this.

    Kevin just posted a series that would allow an 'attached-ns'
    list-style parameter on the device, so this functionality may be
    added in the future, but let's see if there is actually any request
    for this.

  * Added patch from Hannes to attach namespaces on hotplug (this is
    also out in non-RFC, but this depends on it, so including it here).

  * Added preliminary documentation on the new experimental setup.

Hi,

This is an attempt at adressing a bunch of issues that have presented
themselves since we added subsystem support. It's been brewing for a
while now.

Fundamentally, I've come to the conclusion that modeling namespaces and
subsystems as "devices" is wrong. They should have been user-creatable
objects. We've run into multiple issues with wrt. hotplugging due to how
namespaces hook up to the controller with a bus. The bus-based design
made a lot of sense when we didn't have subsystem support and it follows
the design of hw/scsi. But, the problem here is that the bus-based
design dictates a one parent relationship, and with shared namespaces,
that is just not true. If the namespaces are considered to have a single
parent, that parent is the subsystem, not any specific controller.

This series adds a set of experimental user-creatable objects:

  -object x-nvme-subsystem
  -object x-nvme-ns-nvm
  -object x-nvme-ns-zoned

It also adds a new controller device (-device x-nvme-ctrl) that supports
these new objects (and gets rid of a bunch of deprecated and confusing
parameters). Invoking with an nvme controller now becomes along these
lines:

  -object x-nvme-subsystem,id=nvme-subsys-0,subnqn=foo
  -drive  id=blk-nvm-1,file=nvm-1.img,if=none
  -object x-nvme-ns-nvm,id=nvme-ns-nvm-1,blockdev=blk-nvm-1,subsys=nvme-subsys-0
  -device x-nvme-ctrl,id=nvme-ctrl-0,serial=foo,subsys=nvme-subsys-0

This new approach has a bunch of benefits (other than just
fixing the hotplugging issues properly) - we also get support for some
nice introspection through some new dynamic properties.

  (qemu) qom-get /objects/nvme-subsys-0 controllers
  [
      "/machine/peripheral/nvme-ctrl-1",
      "/machine/peripheral/nvme-ctrl-0"
  ]

  (qemu) qom-get /objects/nvme-subsys-0 namespaces
  [
      "/objects/nvme-ns-nvm-1",
      "/objects/nvme-ns-zns-1"
  ]

  (qemu) qom-list /objects/nvme-ns-zns-1
  type (string)
  subsys (link<x-nvme-subsystem>)
  nsid (string)
  uuid (string)
  eui64 (string)
  blockdev (string)
  pi-first (bool)
  pi-type (NvmeProtInfoType)
  extended-lba (bool)
  metadata-size (uint16)
  lba-size (size)
  zone-descriptor-extension-size (size)
  zone-cross-read (bool)
  zone-max-open (uint32)
  zone-capacity (size)
  zone-size (size)
  zone-max-active (uint32)

  (qemu) qom-get /objects/nvme-ns-zns-1 pi-type
  "none"

  (qemu) qom-get /objects/nvme-ns-zns-1 eui64
  "52:54:00:17:67:a0:40:15"

  (qemu) qom-get /objects/nvme-ns-zns-1 zone-capacity
  12582912

The first patches in this series reorganize a bunch of structs to make
it easier to separate them in later patches. Then, it proceeds to hoist
the device states into separate structures such that we can reuse the
core logic in both the new objects and the existing devices. Thus, full
backwards compatibility is kept and the existing device all work as the
do prior to this series being applied. I have chosen to separate the nvm
and zoned namespace types in to individual objects. The core namespace
functionality is contained in an abstract (non user-creatable) x-nvme-ns
object and the x-nvme-ns-nvm object extends this and serves at the
parent of the x-nvme-ns-zoned object itself.

There are definitely an alternative to this approach - one that I've
previously discussed with Hannes (and other QEMU devs, thanks!), and
that would be to add the subsystem as a system bus device.

Cheers, Klaus

Hannes Reinecke (1):
  hw/nvme: reattach subsystem namespaces on hotplug

Klaus Jensen (15):
  hw/nvme: change nvme-ns 'shared' default
  hw/nvme: move dif/pi prototypes into dif.h
  hw/nvme: move zns helpers and types into zns.h
  hw/nvme: move zoned namespace members to separate struct
  hw/nvme: move nvm namespace members to separate struct
  hw/nvme: move BlockBackend to NvmeNamespaceNvm
  hw/nvme: hoist qdev state from namespace
  hw/nvme: hoist qdev state from subsystem
  hw/nvme: hoist qdev state from controller
  hw/nvme: add experimental object x-nvme-subsystem
  nvme: add structured type for nguid
  hw/nvme: add experimental abstract object x-nvme-ns
  hw/nvme: add experimental objects x-nvme-ns-{nvm,zoned}
  hw/nvme: add experimental device x-nvme-ctrl
  docs: add documentation for experimental nvme emulation

 docs/system/device-emulation.rst          |    1 +
 docs/system/devices/nvme-experimental.rst |  107 ++
 docs/system/devices/nvme.rst              |   24 +-
 hw/core/machine.c                         |    4 +-
 hw/nvme/ctrl.c                            | 1157 ++++++++++++---------
 hw/nvme/dif.c                             |  120 ++-
 hw/nvme/dif.h                             |   55 +
 hw/nvme/meson.build                       |    2 +-
 hw/nvme/ns-nvm.c                          |  354 +++++++
 hw/nvme/ns-zoned.c                        |  443 ++++++++
 hw/nvme/ns.c                              |  752 ++++++-------
 hw/nvme/nvm.h                             |   65 ++
 hw/nvme/nvme.h                            |  324 ++----
 hw/nvme/subsys.c                          |  240 ++++-
 hw/nvme/zns.h                             |  147 +++
 include/block/nvme.h                      |   11 +-
 qapi/qom.json                             |   82 ++
 softmmu/vl.c                              |    8 +
 18 files changed, 2711 insertions(+), 1185 deletions(-)
 create mode 100644 docs/system/devices/nvme-experimental.rst
 create mode 100644 hw/nvme/dif.h
 create mode 100644 hw/nvme/ns-nvm.c
 create mode 100644 hw/nvme/ns-zoned.c
 create mode 100644 hw/nvme/nvm.h
 create mode 100644 hw/nvme/zns.h

-- 
2.33.0