[Virtio-fs] [PATCH v3 0/5] vhost-user: Back-end state migration
Hanna Czenczek
hreitz at redhat.com
Fri Sep 15 10:25:25 UTC 2023
RFC:
https://lists.nongnu.org/archive/html/qemu-devel/2023-03/msg04263.html
v1:
https://lists.nongnu.org/archive/html/qemu-devel/2023-04/msg01575.html
v2:
https://lists.nongnu.org/archive/html/qemu-devel/2023-07/msg02604.html
Hi,
I’ve decided not to work on vhost-user SUSPEND/RESUME for now – it is
not technically required for virtio-fs migration, which is the actual
priority for me now. While we do want to have SUSPEND/RESUME at some
point, the only practically existing reason for it is to be able to
implement vhost-level resetting in virtiofsd, but that is not related to
migration.
So one of the changes in v3 is that it no longer depends on the
vhost-user SUSPEND/RESUME series, and describes the migration protocol
without the device being suspended at any point, but merely that the
vrings are stopped.
Other changes include:
- Patch 1:
- Rephrased a lot
- Added a description for the VHOST_USER_SET_DEVICE_STATE_FD
parameters
- Renamed VHOST_USER_PROTOCOL_F_MIGRATORY_STATE to
VHOST_USER_PROTOCOL_F_DEVICE_STATE
- enum variants changed in value due to dropping the SUSPEND/RESUME
dependency
- Patch 2:
- Pulled in, was a stand-alone patch before
- Dropped a sentence about ring state before feature negotiations, as
the rings are not to be used during that period anyway
- Bit of rephrasing
- Patch 3:
- Renamed “migratory state” to “device state”
- enum variants changed in value due to dropping the SUSPEND/RESUME
dependency
- Patch 4:
- Changed `f` to @f (referencing parameter “f”) in comments
- Use g_autofree for the transfer buffer
- Note SUSPEND state as a future feature, not currently existing
- Wrap read() and write() in RETRY_ON_EINTR()
- Patch 5:
- Renamed “migratory state” to “device state”
- (kept R-b still)
Hanna Czenczek (5):
vhost-user.rst: Migrating back-end-internal state
vhost-user.rst: Clarify enabling/disabling vrings
vhost-user: Interface for migration state transfer
vhost: Add high-level state save/load functions
vhost-user-fs: Implement internal migration
docs/interop/vhost-user.rst | 188 ++++++++++++++++++++++-
include/hw/virtio/vhost-backend.h | 24 +++
include/hw/virtio/vhost.h | 114 ++++++++++++++
hw/virtio/vhost-user-fs.c | 101 ++++++++++++-
hw/virtio/vhost-user.c | 148 ++++++++++++++++++
hw/virtio/vhost.c | 241 ++++++++++++++++++++++++++++++
6 files changed, 810 insertions(+), 6 deletions(-)
--
2.41.0
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