Re: [RFC v2 0/7] Add persistence to NVMe ZNS emulation

[Klaus Jensen]

On Nov 27 16:56, Sam Li wrote:
> ZNS emulation follows NVMe ZNS spec but the state of namespace
> zones does not persist accross restarts of QEMU. This patch makes the
> metadata of ZNS emulation persistent by using new block layer APIs and
> the qcow2 img as backing file. It is the second part after the patches
> - adding full zoned storage emulation to qcow2 driver.
> https://patchwork.kernel.org/project/qemu-devel/cover/20231127043703.49489-1-faithilikerun@gmail.com/
> 
> The metadata of ZNS emulation divides into two parts, zone metadata and
> zone descriptor extension data. The zone metadata is composed of zone
> states, zone type, wp and zone attributes. The zone information can be
> stored at an uint64_t wp to save space and easy access. The structure of
> wp of each zone is as follows:
> |0000(4)| zone type (1)| zone attr (8)| wp (51) ||
> 
> The zone descriptor extension data is relatively small comparing to the
> overall size therefore we adopt the option that store zded of all zones
> in an array regardless of the valid bit set.
> 
> Creating a zns format qcow2 image file adds one more option zd_extension_size
> to zoned device configurations.
> 
> To attach this file as emulated zns drive in the command line of QEMU, use:
>   -drive file=${znsimg},id=nvmezns0,format=qcow2,if=none \
>   -device nvme-ns,drive=nvmezns0,bus=nvme0,nsid=1,uuid=xxx \
> 
> Sorry, send this one more time due to network problems.
> 
> v1->v2:
> - split [v1 2/5] patch to three (doc, config, block layer API)
> - adapt qcow2 v6
> 
> Sam Li (7):
>   docs/qcow2: add zd_extension_size option to the zoned format feature
>   qcow2: add zd_extension configurations to zoned metadata
>   hw/nvme: use blk_get_*() to access zone info in the block layer
>   hw/nvme: add blk_get_zone_extension to access zd_extensions
>   hw/nvme: make the metadata of ZNS emulation persistent
>   hw/nvme: refactor zone append write using block layer APIs
>   hw/nvme: make ZDED persistent
> 
>  block/block-backend.c             |   88 ++
>  block/qcow2.c                     |  119 ++-
>  block/qcow2.h                     |    2 +
>  docs/interop/qcow2.txt            |    3 +
>  hw/nvme/ctrl.c                    | 1247 ++++++++---------------------
>  hw/nvme/ns.c                      |  162 +---
>  hw/nvme/nvme.h                    |   95 +--
>  include/block/block-common.h      |    9 +
>  include/block/block_int-common.h  |    8 +
>  include/sysemu/block-backend-io.h |   11 +
>  include/sysemu/dma.h              |    3 +
>  qapi/block-core.json              |    4 +
>  system/dma-helpers.c              |   17 +
>  13 files changed, 647 insertions(+), 1121 deletions(-)
> 
> -- 
> 2.40.1
> 

Hi Sam,

This is awesome. For the hw/nvme parts,

Acked-by: Klaus Jensen <k.jensen@samsung.com>

I'll give it a proper R-b when you drop the RFC status.

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