QE tested this series's V5 again. Creating two vdpa_sim device, and boot
two VMs without shadow virtqueues. The migration was successful and
everything worked fine.
Tested-by: Lei Yang <leiyang@redhat.com>
Eugenio Pérez <eperezma@redhat.com> 于2023年3月4日周六 01:24写道：
> It's possible to migrate vdpa net devices if they are shadowed from the
> start. But to always shadow the dataplane is to effectively break its host
> passthrough, so its not efficient in vDPA scenarios.
>
> This series enables dynamically switching to shadow mode only at
> migration time. This allows full data virtqueues passthrough all the
> time qemu is not migrating.
>
> In this series only net devices with no CVQ are migratable. CVQ adds
> additional state that would make the series bigger and still had some
> controversy on previous RFC, so let's split it.
>
> Successfully tested with vdpa_sim_net with patch [1] applied and with the
> qemu
> emulated device with vp_vdpa with some restrictions:
> * No CVQ. No feature that didn't work with SVQ previously (packed, ...)
> * VIRTIO_RING_F_STATE patches implementing [2].
>
> Previous versions were tested by many vendors. Not carrying Tested-by
> because
> of code changes, so re-testing would be appreciated.
>
> A ready to clone tag named vdpa.d/stop-nocvq-v5 with this version of the
> series
> is available at https://gitlab.com/eperezmartin/qemu-kvm.git, with the
> commit
> 863d54ff00c558ffe54ed2c7ee148ab7f89d4864 ("vdpa: return VHOST_F_LOG_ALL in
> vhost-vdpa devices").
>
> Comments are welcome.
>
> v5:
> - Reverse SUSPEND polarity check, as qemu was never suspending devices with
> suspend capability.
> - Reorder suspend patch so it comes before the reset reorder after
> get_vring_base.
> - Remove patch to stop SVQ at vdpa stop, already present in staging
>
> v4:
> - Recover used_idx from guest's vring if device cannot suspend.
> - Fix starting device in the middle of a migration. Removed some
> duplication in setting / clearing enable_shadow_vqs and shadow_data
> members of vhost_vdpa.
> - Fix (again) "Check for SUSPEND in vhost_dev.backend_cap, as
> .backend_features is empty at the check moment.". It was reverted by
> mistake in v3.
> - Fix memory leak of iova tree.
> - Properly rewind SVQ as in flight descriptors were still being accounted
> in vq base.
> - Expand documentation.
>
> v3:
> - Start datapatch in SVQ in device started while migrating.
> - Properly register migration blockers if device present unsupported
> features.
> - Fix race condition because of not stopping the SVQ until device cleanup.
> - Explain purpose of iova tree in the first patch message.
> - s/dynamycally/dynamically/ in cover letter.
> - at
> lore.kernel.org/qemu-devel/20230215173850.298832-14-eperezma@redhat.com
>
> v2:
> - Check for SUSPEND in vhost_dev.backend_cap, as .backend_features is
> empty at
> the check moment.
> - at
> https://lore.kernel.org/all/20230208094253.702672-12-eperezma@redhat.com/T/
>
> v1:
> - Omit all code working with CVQ and block migration if the device supports
> CVQ.
> - Remove spurious kick.
> - Move all possible checks for migration to vhost-vdpa instead of the net
> backend. Move them to init code from start code.
> - Suspend on vhost_vdpa_dev_start(false) instead of in vhost-vdpa net
> backend.
> - Properly split suspend after geting base and adding of status_reset
> patches.
> - Add possible TODOs to points where this series can improve in the future.
> - Check the state of migration using migration_in_setup and
> migration_has_failed instead of checking all the possible migration
> status in
> a switch.
> - Add TODO with possible low hand fruit using RESUME ops.
> - Always offer _F_LOG from virtio/vhost-vdpa and let migration blockers do
> their thing instead of adding a variable.
> - RFC v2 at
> https://lists.gnu.org/archive/html/qemu-devel/2023-01/msg02574.html
>
> RFC v2:
> - Use a migration listener instead of a memory listener to know when
> the migration starts.
> - Add stuff not picked with ASID patches, like enable rings after
> driver_ok
> - Add rewinding on the migration src, not in dst
> - RFC v1 at
> https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01664.html
>
> [1]
> https://lore.kernel.org/lkml/20230203142501.300125-1-eperezma@redhat.com/T/
> [2]
> https://lists.oasis-open.org/archives/virtio-comment/202103/msg00036.html
>
> Eugenio Pérez (14):
> vdpa net: move iova tree creation from init to start
> vdpa: Remember last call fd set
> vdpa: Negotiate _F_SUSPEND feature
> vdpa: rewind at get_base, not set_base
> vdpa: add vhost_vdpa->suspended parameter
> vdpa: add vhost_vdpa_suspend
> vdpa: move vhost reset after get vring base
> vdpa: add vdpa net migration state notifier
> vdpa: disable RAM block discard only for the first device
> vdpa net: block migration if the device has CVQ
> vdpa: block migration if device has unsupported features
> vdpa: block migration if SVQ does not admit a feature
> vdpa net: allow VHOST_F_LOG_ALL
> vdpa: return VHOST_F_LOG_ALL in vhost-vdpa devices
>
> include/hw/virtio/vhost-backend.h | 4 +
> include/hw/virtio/vhost-vdpa.h | 3 +
> hw/virtio/vhost-shadow-virtqueue.c | 8 +-
> hw/virtio/vhost-vdpa.c | 126 ++++++++++++------
> hw/virtio/vhost.c | 3 +
> net/vhost-vdpa.c | 198 ++++++++++++++++++++++++-----
> hw/virtio/trace-events | 1 +
> 7 files changed, 272 insertions(+), 71 deletions(-)
>
> --
> 2.31.1
>
>
>