Re: [PATCH v7 0/8] hw/nvme: add basic live migration support

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, May 11, 2026 at 05:11:23PM +0200, Alexander Mikhalitsyn wrote:
> From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> 
> Dear friends,
> 
> This patchset adds basic live migration support for
> QEMU emulated NVMe device.
> 
> Implementation has some limitations:
> - only one NVMe namespace is supported
> - SMART counters are not preserved
> - CMB is not supported
> - PMR is not supported
> - SPDM is not supported
> - SR-IOV is not supported
> 
> I believe this is something I can support in next patchset versions or
> separately on-demand (when usecase appears).
> 
> Testing.
> 
> This patch series was manually tested on:
> - Debian 13.3 VM (kernel 6.12.69+deb13-amd64) using fio on *non-root* NVMe disk
>   (root disk was virtio-scsi):
> 
> time fio --name=nvme-verify \
>     --filename=/dev/nvme0n1 \
>     --size=5G \
>     --rw=randwrite \
>     --bs=4k \
>     --iodepth=16 \
>     --numjobs=1 \
>     --direct=0 \
>     --ioengine=io_uring \
>     --verify=crc32c \
>     --verify_fatal=1
> 
> - Windows Server 2022 VM (NVMe drive was a *root* disk) with opened browser
>   playing video.
> 
> No defects were found.
> 
> Git tree:
> https://github.com/mihalicyn/qemu/commits/nvme-live-migration
> 
> Changelog for version 7:
> - rebased on top of recent main
> - addressed review comments from Stefan Hajnoczi:
>   - better incoming migration stream validation (SQ/CQids correctness)
>   - endianness bugs are fixed in qtest (validated on s390x)
> - added RWB tags from Klaus
> 
> Changelog for version 6:
> - rebased on top of:
>   https://gitlab.com/peterx/qemu/-/tree/vmstate-array-null
>   (see also https://lore.kernel.org/all/20260401202844.673494-1-peterx@redhat.com)
> - addressed review comments from Stefan Hajnoczi:
>   - supported "full CQ" case by serializing NvmeRequest state
>   - added qtest for NVMe device migration with full CQ
> 
> Changelog for version 5:
> - rebased on top of https://lore.kernel.org/all/20260304212303.667141-1-vsementsov@yandex-team.ru/
>   (as Peter has requested)
> 
> Changelog for version 4:
> - vmstate dynamic array support reworked as suggested by Peter Xu
>   VMS_ARRAY_OF_POINTER_ALLOW_NULL flag was introduced
>   qtests were added
> - NVMe migration blockers were reworked as Klaus has requested earlier
>   Now, instead of having "deny list" approach, we have more strict pattern
>   of NVMe features filtering and it should be harded to break migration when
>   adding new NVMe features.
> 
> Changelog for version 3:
> - rebased
> - simple functional test was added (in accordance with Klaus Jensen's review comment)
>   $ meson test 'func-x86_64-nvme_migration' --setup thorough -C build
> 
> Changelog for version 2:
> - full support for AERs (in-flight requests and queued events too)
> 
> Kind regards,
> Alex
> 
> Alexander Mikhalitsyn (8):
>   tests/functional/migration: add VM launch/configure hooks
>   hw/nvme: add migration blockers for non-supported cases
>   hw/nvme: split nvme_init_sq/nvme_init_cq into helpers
>   hw/nvme: set CQE.sq_id earlier in nvme_process_sq
>   hw/nvme: unmap req->sg earlier in nvme_enqueue_req_completion
>   hw/nvme: add basic live migration support
>   tests/functional/x86_64: add migration test for NVMe device
>   tests/qtest/nvme-test: add migration test with full CQ
> 
>  hw/nvme/ctrl.c                                | 1007 ++++++++++++++++-
>  hw/nvme/ns.c                                  |  160 +++
>  hw/nvme/nvme.h                                |   12 +
>  hw/nvme/trace-events                          |   10 +
>  include/block/nvme.h                          |   12 +
>  tests/functional/migration.py                 |   22 +-
>  tests/functional/x86_64/meson.build           |    1 +
>  .../functional/x86_64/test_nvme_migration.py  |  159 +++
>  tests/qtest/nvme-test.c                       |  395 +++++++
>  9 files changed, 1742 insertions(+), 36 deletions(-)
>  create mode 100755 tests/functional/x86_64/test_nvme_migration.py
> 
> -- 
> 2.47.3
> 

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

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