Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging

Pull request

This pull request contain's Sam Li's zoned storage support in the QEMU block
layer and virtio-blk emulation.

v2:
- Sam fixed the CI failures. CI passes for me now. [Richard]

# -----BEGIN PGP SIGNATURE-----
#
# iQEzBAABCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmRiWCgACgkQnKSrs4Gr
# c8h/7gf+MMm2cGEaf376t8HMwTc6wbXVfbmAlZrge2EXPZfFvEaxj7HClcEraOgV
# yJsGWeU6mOw4r68ICJ/4KhrY1cdv+VZym/LsMLMcFUTXFHnyX4pyU3am31FPOI4K
# +wrDYJOJhc4DkAESWGgEWiMKpuO/uUEgBmHdW+qPFCl77Yl/eP6H5uNP6nGFn55p
# QpS/l8iha7PDkc81EsrjA+e/YI0ubfNSP7+zZElhQ98354CQ0MCfmZ6h9bT+o2bu
# R7SBUj80e+2X0a1b9s/2Jz/x8l4TEsl8kr48/Q1usq3GVVkbjEgqsk6wTN13Q/4g
# CeIR7E61ZeYzmpb4tLFRIqK2Jw+NEQ==
# =Q8xW
# -----END PGP SIGNATURE-----
# gpg: Signature made Mon 15 May 2023 09:04:56 AM PDT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]

* tag 'block-pull-request' of https://gitlab.com/stefanha/qemu:
  docs/zoned-storage:add zoned emulation use case
  virtio-blk: add some trace events for zoned emulation
  block: add accounting for zone append operation
  virtio-blk: add zoned storage emulation for zoned devices
  block: add some trace events for zone append
  qemu-iotests: test zone append operation
  block: introduce zone append write for zoned devices
  file-posix: add tracking of the zone write pointers
  docs/zoned-storage: add zoned device documentation
  block: add some trace events for new block layer APIs
  iotests: test new zone operations
  block: add zoned BlockDriver check to block layer
  block/raw-format: add zone operations to pass through requests
  block/block-backend: add block layer APIs resembling Linux ZonedBlockDevice ioctls
  block/file-posix: introduce helper functions for sysfs attributes
  block/block-common: add zoned device structs

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 63 insertions, 0 deletions

diff --git a/docs/devel/index-api.rst b/docs/devel/index-api.rst
index 60c0d7459d..7108821746 100644
--- a/docs/devel/index-api.rst
+++ b/docs/devel/index-api.rst
@@ -12,3 +12,4 @@ generated from in-code annotations to function prototypes.
    memory
    modules
    ui
+   zoned-storage
diff --git a/docs/devel/zoned-storage.rst b/docs/devel/zoned-storage.rst
new file mode 100644
index 0000000000..30296d3c85
--- /dev/null
+++ b/docs/devel/zoned-storage.rst
@@ -0,0 +1,62 @@
+=============
+zoned-storage
+=============
+
+Zoned Block Devices (ZBDs) divide the LBA space into block regions called zones
+that are larger than the LBA size. They can only allow sequential writes, which
+can reduce write amplification in SSDs, and potentially lead to higher
+throughput and increased capacity. More details about ZBDs can be found at:
+
+https://zonedstorage.io/docs/introduction/zoned-storage
+
+1. Block layer APIs for zoned storage
+-------------------------------------
+QEMU block layer supports three zoned storage models:
+- BLK_Z_HM: The host-managed zoned model only allows sequential writes access
+to zones. It supports ZBD-specific I/O commands that can be used by a host to
+manage the zones of a device.
+- BLK_Z_HA: The host-aware zoned model allows random write operations in
+zones, making it backward compatible with regular block devices.
+- BLK_Z_NONE: The non-zoned model has no zones support. It includes both
+regular and drive-managed ZBD devices. ZBD-specific I/O commands are not
+supported.
+
+The block device information resides inside BlockDriverState. QEMU uses
+BlockLimits struct(BlockDriverState::bl) that is continuously accessed by the
+block layer while processing I/O requests. A BlockBackend has a root pointer to
+a BlockDriverState graph(for example, raw format on top of file-posix). The
+zoned storage information can be propagated from the leaf BlockDriverState all
+the way up to the BlockBackend. If the zoned storage model in file-posix is
+set to BLK_Z_HM, then block drivers will declare support for zoned host device.
+
+The block layer APIs support commands needed for zoned storage devices,
+including report zones, four zone operations, and zone append.
+
+2. Emulating zoned storage controllers
+--------------------------------------
+When the BlockBackend's BlockLimits model reports a zoned storage device, users
+like the virtio-blk emulation or the qemu-io-cmds.c utility can use block layer
+APIs for zoned storage emulation or testing.
+
+For example, to test zone_report on a null_blk device using qemu-io is::
+
+  $ path/to/qemu-io --image-opts -n driver=host_device,filename=/dev/nullb0 -c "zrp offset nr_zones"
+
+To expose the host's zoned block device through virtio-blk, the command line
+can be (includes the -device parameter)::
+
+  -blockdev node-name=drive0,driver=host_device,filename=/dev/nullb0,cache.direct=on \
+  -device virtio-blk-pci,drive=drive0
+
+Or only use the -drive parameter::
+
+  -driver driver=host_device,file=/dev/nullb0,if=virtio,cache.direct=on
+
+Additionally, QEMU has several ways of supporting zoned storage, including:
+(1) Using virtio-scsi: --device scsi-block allows for the passing through of
+SCSI ZBC devices, enabling the attachment of ZBC or ZAC HDDs to QEMU.
+(2) PCI device pass-through: While NVMe ZNS emulation is available for testing
+purposes, it cannot yet pass through a zoned device from the host. To pass on
+the NVMe ZNS device to the guest, use VFIO PCI pass the entire NVMe PCI adapter
+through to the guest. Likewise, an HDD HBA can be passed on to QEMU all HDDs
+attached to the HBA.