Greetings! Another ping :)
On 8/17/26 10:29, Alexandr Moshkov wrote:
Greetings! Ping.
On 8/3/26 12:28, Alexandr Moshkov wrote:
v5 -> v6:
- block changing inflight-migration property while VM is not running
- remove checking runstate in vhost_user_blk_stop() since it's not
necessary
- updated cover letter: changed subject and description to focus on
runtime toggling of inflight-migration rather than cross-version
migration compatibility
v4 -> v5:
- introduce protocol feature
VHOST_USER_PROTOCOL_F_GET_VRING_BASE_SKIP_DRAIN
to guard the new message, instead of reusing the existing
VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INLIFGHT. Update docs.
- improved commit messages.
v3 -> v4:
- add new protocol message GET_VRING_BASE_SKIP_DRAIN instead of
parameter to GET_VRING_BASE message. This new message can be send
instead of GET_VRING_BASE, allowing back-end to suspend inflight I/O
immediately instead of waiting and completing them.
- rebase to newer master
v2 -> v3:
- fix complile problems
- add assert check in do_vhost_virtio_stop
- make inflight-migration property mutable
v1 -> v2:
- reorganize commits: make refactor commits first, then core semantic
change
- add additional pre_save check for inflight migration possibility
---
This is v6 of the series previously sent as:
"[PATCH v5 0/6] vhost-user-blk: add compatibility with older qemu
versions"
This series allows the inflight-migration property of vhost-user-blk to
be toggled at runtime via qom-set without restarting the VM or
reconnecting to the back-end.
Currently, the inflight migration behaviour is controlled by
VHOST_USER_PROTOCOL_F_GET_VRING_BASE_INFLIGHT, which is negotiated once
at connection time. Once negotiated, the back-end always uses suspend
semantics on GET_VRING_BASE -- there is no way for the front-end to
request normal drain behaviour on a per-call basis. This makes it
impossible to disable inflight-migration at runtime.
To solve this, the series introduces a new protocol message
VHOST_USER_GET_VRING_BASE_SKIP_DRAIN (id=45) guarded by a new protocol
feature VHOST_USER_PROTOCOL_F_GET_VRING_BASE_SKIP_DRAIN. The message
instructs the back-end to suspend in-flight I/O immediately rather than
draining it. This gives the front-end explicit per-call control:
GET_VRING_BASE for normal drain, GET_VRING_BASE_SKIP_DRAIN when
inflight-migration is enabled.
In vhost-user-blk, GET_VRING_BASE_SKIP_DRAIN is sent whenever
inflight-migration is on. The inflight-migration
property can only be changed while the VM is running, so its value at
stop time reliably reflects the user's intent.
Alexandr Moshkov (6):
vhost-user: add skip_drain param to do_vhost_virtqueue_stop
vhost-user: add GET_VRING_BASE_SKIP_DRAIN message
vhost-user: use skip_drain with GET_VRING_BASE_SKIP_DRAIN message
vhost-user-blk: make inflight-migration prop mutable on running vm
vhost-user-blk: move inflight_needed higher
vhost-user-blk: use GET_VRING_BASE_SKIP_DRAIN when inflight-migration
is on
backends/cryptodev-vhost.c | 2 +-
backends/vhost-user.c | 2 +-
docs/interop/vhost-user.rst | 88 +++++++++++++++++++------------
hw/block/vhost-user-blk.c | 60 ++++++++++++++++++---
hw/net/vhost_net.c | 9 ++--
hw/scsi/vhost-scsi-common.c | 2 +-
hw/virtio/vdpa-dev.c | 2 +-
hw/virtio/vhost-user-base.c | 2 +-
hw/virtio/vhost-user-fs.c | 2 +-
hw/virtio/vhost-user-scmi.c | 2 +-
hw/virtio/vhost-user.c | 47 ++++++++++++++---
hw/virtio/vhost-vsock-common.c | 2 +-
hw/virtio/vhost.c | 34 ++++++++----
include/hw/virtio/vhost-backend.h | 1 +
include/hw/virtio/vhost-user.h | 2 +-
include/hw/virtio/vhost.h | 7 ++-
16 files changed, 189 insertions(+), 75 deletions(-)
