| Message ID | 20230224155438.112797-1-eperezma@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Dynamically switch to vhost shadow virtqueues at vdpa net migration | expand |
> > 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]. > * Expose _F_SUSPEND, but ignore it and suspend on ring state fetch like > DPDK. > > Previous versions were tested by many vendors. Not carrying Tested-by because > of code changes, so re-testing would be appreciated. > > Comments are welcome. > > 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 (15): > vdpa net: move iova tree creation from init to start > vdpa: Remember last call fd set > vdpa: stop svq at vhost_vdpa_dev_start(false) > vdpa: Negotiate _F_SUSPEND feature > vdpa: move vhost reset after get vring base > vdpa: add vhost_vdpa->suspended parameter > vdpa: add vhost_vdpa_suspend > vdpa: rewind at get_base, not set_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 | 128 +++++++++++++------ > hw/virtio/vhost.c | 3 + > net/vhost-vdpa.c | 198 ++++++++++++++++++++++++----- > hw/virtio/trace-events | 1 + > 7 files changed, 273 insertions(+), 72 deletions(-) > > -- The migration works with SolidNET DPU. Tested-by: Alvaro Karsz <alvaro.karsz@solid-run.com>